Bipolar disorder

Bipolar disorder (BD), historically referred to as manic depression, is a psychiatric condition marked by alternating episodes of depression and unusually elevated mood, which can persist for days, weeks, or occasionally months. When this elevated mood is severe or accompanied by psychotic features, it is termed mania; conversely, if it does not substantially impair daily functioning, it is identified as hypomania. Individuals experiencing a manic episode typically exhibit abnormal levels of energy, euphoria, or irritability, frequently making impulsive choices without adequately considering the repercussions. Sleep disturbances are commonly observed during manic phases. Conversely, during depressive episodes, affected individuals may manifest crying spells, a pessimistic perspective, and reduced eye contact. It is estimated that 15–20% of individuals diagnosed with BD ultimately die by suicide. Furthermore, approximately 30–60% of these individuals attempt suicide at some point in their lives. Self-harming behaviors have been reported in 40–50% of all BD patients and in 78% of adolescents with the disorder.

Bipolar disorder (BD), previously known as manic depression, is a mental disorder characterized by periods of depression and abnormally elevated mood, lasting days to weeks, and in some cases months. If the elevated mood is severe or associated with psychosis, it is called mania; if it does not significantly affect functioning, it is called hypomania. During mania, an individual behaves or feels abnormally energetic, happy, or irritable, and often makes impulsive decisions with little regard for the consequences. There is usually sleep disturbance during manic phases. During periods of depression, the individual may experience crying, have a negative outlook, and demonstrate poor eye contact. An estimated 15–20% of those with BD die by suicide. Approximately 30–60% attempt suicide during their lifetime. Among those with BD, 40–50% overall and 78% of adolescents engaged in self-harm.

The underlying mechanisms of bipolar disorder remain incompletely elucidated, although current research indicates promising avenues for future clinical investigation. Neuroimaging studies, specifically structural and functional MRI, have identified distinct differences in brain regions among individuals with BD, particularly in areas associated with risk-reward perception and emotional regulation. A systematic review and meta-analysis conducted by Murri et al. revealed a correlation between elevated cortisol levels and the manic phase of BD. Similarly, numerous other investigations underscore the significant involvement of the hypothalamic-pituitary-adrenal (HPA) axis in the disorder. Escelsior et al. observed increased mu-opioid receptor gene expression in individuals currently experiencing mania, relative to both depressed patients and healthy control subjects. Further research suggests the involvement of neurotransmitters like dopamine and serotonin, along with intracellular signaling pathways and mitochondrial dysfunctions.

The etiology of bipolar disorder is considered multifactorial, involving genetic predispositions, environmental influences, and co-occurring medical conditions. Regarding heritability, genetic factors are estimated to contribute to 70–90% of the risk for developing BD. The concordance rate for BD in monozygotic (identical) twins is approximately 40%, significantly higher than the ~5% observed in dizygotic (fraternal) twins. Environmental risk factors encompass a history of childhood abuse and chronic stress. Both a meta-analysis and an independent critical literature review have linked childhood maltreatment and "early emotional trauma" to a poorer prognosis and an earlier onset of BD. Furthermore, comorbid conditions like ADHD and specific personality disorders are known to influence the risk of bipolar disorder, although their precise mechanisms remain to be fully elucidated.

Bipolar disorder is categorized as bipolar I disorder when at least one manic episode has occurred, irrespective of co-occurring depressive episodes. It is classified as bipolar II disorder if there has been at least one hypomanic episode (without any full manic episodes) alongside at least one major depressive episode. Cyclothymia is diagnosed when individuals experience hypomanic episodes interspersed with depressive periods that do not fulfill the diagnostic criteria for major depressive episodes. Importantly, if these symptoms are attributable to substance use or other medical conditions, a diagnosis of BD is not warranted.

Therapeutic interventions for bipolar disorder include mood stabilizers, notably lithium, and anticonvulsants like lamotrigine and valproate, in addition to atypical antipsychotics. Atypical antipsychotics are prescribed for acute manic episodes or when mood stabilizers prove ineffective or are poorly tolerated; long-acting injectable formulations are available for patients with adherence challenges. Evidence suggests that psychotherapy can enhance the trajectory of BD. The administration of antidepressants during depressive episodes remains a contentious issue: while potentially effective, specific classes of antidepressants may elevate the risk of inducing mania. Consequently, managing depressive episodes in BD often presents significant clinical challenges. Electroconvulsive therapy (ECT) demonstrates efficacy in treating acute manic and depressive episodes, particularly when accompanied by psychosis or catatonia. Historically, guidelines have advocated for psychiatric hospitalization when an individual poses a risk to themselves or others, and for involuntary treatment in cases of treatment refusal. Nevertheless, the United Nations Committee on the Rights of Persons with Disabilities (CRPD) has called for the elimination of institutionalization and coercive treatments, including "sedatives, mood stabilizers, [and] electro-convulsive therapy."

Bipolar I and bipolar II disorders affect approximately 2% of the population, while bipolar spectrum disorder is estimated to impact up to 6%. Symptom onset typically occurs between 20 and 25 years of age, with an earlier onset correlating with a less favorable prognosis. Approximately 30% of individuals diagnosed with BD experience financial, social, or occupational difficulties attributable to the disorder. Globally, bipolar disorder ranks as the sixth leading cause of disability, incurring significant societal economic burdens. Individuals with BD face a twofold increased risk of mortality from natural causes, such as coronary artery disease, a consequence of both lifestyle factors and medication side effects.

Signs and Symptoms

The manifestation of bipolar symptoms typically commences during adolescence or early adulthood. The disorder is defined by recurrent episodes of mania, which frequently (though not universally) alternate with periods of depression, interspersed with symptom-free intervals. During these symptomatic phases, individuals with bipolar disorder demonstrate disturbances across several domains, including mood, psychomotor activity (defined as the degree of physical movement influenced by emotional state, exemplified by persistent fidgeting during mania or decelerated movements during depression), circadian rhythm, and cognitive function. Manic presentations encompass a spectrum of mood disturbances, extending from euphoria, characteristic of "classic mania," to states of dysphoria and heightened irritability.

Psychotic manifestations, including delusions or hallucinations, can emerge during both manic and depressive episodes, with their thematic content and qualitative nature aligning with the individual's prevailing mood state. An estimated 60–75% of individuals diagnosed with bipolar I disorder report a history of psychotic experiences. While psychotic symptoms are more prevalent in bipolar type I, individuals with bipolar type II can also manifest psychotic features.

For certain individuals with bipolar disorder, depressive symptomatology is predominant, and manic episodes consistently manifest as the less severe hypomanic type. The DSM-5 criteria differentiate mania from hypomania primarily by duration: hypomania is diagnosed when elevated mood symptoms persist for a minimum of four consecutive days, whereas mania requires these symptoms to endure for over one week. In contrast to mania, hypomania does not invariably result in significant functional impairment. The underlying biological mechanisms governing the transition between manic or hypomanic episodes and depressive episodes, and vice versa, are not yet fully elucidated.

Recent research has indicated that hypersexuality constitutes an overlooked and insufficiently investigated symptom of bipolar disorder (BD). A survey conducted among individuals with BD revealed that almost 90% of respondents reported experiencing hypersexuality. Another investigation involving 1170 participants with BD and hypersexual behaviors identified that 34.3% of respondents had experienced sexual assault, 22.3% had been victims of rape, and 14.8% had attempted suicide. These findings have led researchers to suggest that current diagnostic terminology requires updating and that psychoeducational interventions should incorporate discussions on hypersexuality. Furthermore, an additional study posited that existing therapeutic approaches might be inadequate for addressing the intricate behavioral and emotional challenges linked to hypersexuality in BD, potentially impeding recovery and perpetuating unresolved trauma.

Manic Episodes

A manic episode, also referred to as mania, is characterized by a sustained period of at least one week featuring an elevated or irritable mood, spanning from euphoria to delirium. The cardinal symptom of mania is an escalation in psychomotor activity and energy. Additional manifestations of mania may include heightened self-esteem or grandiosity, accelerated thought processes, rapid and difficult-to-interrupt speech, a reduced requirement for sleep, disinhibited social conduct, an increase in goal-directed activities, and compromised judgment, which can precipitate impulsive or high-risk behaviors like hypersexuality or excessive expenditure. For a diagnosis of a manic episode, these behavioral patterns must significantly impair the individual's social or occupational functioning. Without therapeutic intervention, a manic episode typically persists for a duration of three to six months.

During severe manic episodes, individuals may manifest psychotic symptoms, impacting both thought content and mood. These symptoms can include feelings of invincibility, paranoia, a perceived divine connection, a sense of having a significant mission, or other grandiose or delusional ideations. Such manifestations can precipitate violent behavior and, in some instances, necessitate inpatient psychiatric hospitalization. While the Young Mania Rating Scale is utilized to assess the severity of manic symptoms, concerns persist regarding the reliability of such scales. Severe mania constitutes a medical emergency.

Sleep disturbances frequently precede the onset of both manic and depressive episodes. Individuals experiencing mania commonly present with a history of substance use disorder, often developed over several years and perceived as a form of self-medication.

Hypomanic Episodes

Hypomania represents a less severe manifestation of mania, characterized by at least four consecutive days meeting similar diagnostic criteria to mania, yet without significantly impairing an individual's social or occupational functioning. It is distinguished by the absence of psychotic features and does not necessitate psychiatric hospitalization. During hypomanic episodes, overall functioning may improve, and some theories propose it acts as a protective mechanism against depression. Progression from hypomanic to full manic episodes is uncommon. While some individuals experiencing hypomania report heightened creativity, others exhibit irritability or impaired judgment.

While some individuals find hypomania to be a positive experience, the majority report the associated stress as profoundly distressing. Those with bipolar disorder experiencing hypomania often overlook the repercussions of their behavior on others. Even when family and friends identify mood fluctuations, affected individuals frequently deny any issues. Unless accompanied by depressive episodes, hypomanic episodes are generally not considered problematic unless the mood shifts become uncontrollable or volatile. In bipolar II disorder, depressive symptoms commonly co-occur with hypomanic symptoms. Affected individuals may not recognize these specific manifestations as hypomania, instead perceiving them as typical depression with minor mood variations. Symptom duration typically ranges from several weeks to a few months.

Depressive Episodes

The depressive phase of bipolar disorder is characterized by symptoms such as persistent sadness, irritability or anger, anhedonia (loss of interest in previously pleasurable activities), excessive or unwarranted guilt, hopelessness, sleep disturbances (insomnia or hypersomnia), alterations in appetite or weight, fatigue, concentration difficulties, self-loathing or feelings of worthlessness, and suicidal ideation or thoughts of death. Although the DSM-5 diagnostic criteria for unipolar and bipolar depressive episodes are identical, certain clinical presentations are more prevalent in bipolar depression, including hypersomnia, abrupt symptom onset and resolution, substantial weight fluctuations, and severe postpartum episodes.

An earlier age of onset correlates with a higher probability of initial episodes being depressive. In the majority of individuals with bipolar I and II disorders, depressive episodes are considerably longer than manic or hypomanic episodes. Given that a bipolar disorder diagnosis mandates the occurrence of a manic or hypomanic episode, numerous affected individuals are initially misdiagnosed with major depression and subsequently treated with antidepressants.

Mixed Affective Episodes

Within bipolar disorder, a mixed state denotes an episode characterized by the simultaneous presentation of both manic and depressive symptoms. Individuals in a mixed state might exhibit grandiose thoughts, typical of mania, concurrently with depressive symptoms like profound guilt or suicidal ideation. This co-occurrence is associated with an elevated risk of suicidal behavior, as feelings of hopelessness often combine with mood lability or impaired impulse control. Anxiety disorders are more frequently comorbid with mixed bipolar episodes compared to non-mixed bipolar depression or mania. Similarly, substance use, including alcohol, shows a higher prevalence in mixed episodes, which can sometimes lead to the misinterpretation of bipolar symptoms as solely a consequence of substance use.

Psychosis

A significant proportion of individuals with bipolar disorder, specifically one-half to two-thirds, experience psychosis at some point in their lives. Psychotic manifestations encompass delusions, hallucinations, or a combination of both. Within the context of bipolar disorder, delusions are observed with greater frequency than hallucinations. These psychotic symptoms typically manifest more frequently during manic or mixed episodes. The presence of psychotic episodes is indicative of a more severe disease presentation. Individuals experiencing psychosis often exhibit diminished insight, alongside heightened agitation, anxiety, and hostility. Psychosis is observed more frequently in bipolar I disorder compared to bipolar II disorder.

Cycling

While possible, predictable patterns in mood episode transitions are uncommon in bipolar disorder. A systematic review conducted by Geoffroy et al. (2014) identified a seasonal pattern of mania in 15% of affected individuals. Furthermore, a cross-sectional study by Teobaldi et al. (2021), involving 806 patients hospitalized in a psychiatric unit, revealed that 50.2% exhibited irregular cycling without a discernible sequence, 31.5% followed a Mania-Depression-Interval sequence, and 16% adhered to a Depression-Mania-Interval sequence.

Causes

The etiology of bipolar disorder is likely heterogeneous across individuals, and the precise underlying mechanisms remain incompletely understood. Genetic factors are estimated to contribute to 73–93% of the risk for developing the disorder, underscoring a significant hereditary predisposition. The overall heritability for the bipolar spectrum has been calculated at 0.71. While constrained by relatively small sample sizes, twin studies have consistently pointed to a substantial genetic contribution alongside environmental influences. Specifically for bipolar I disorder, the concordance rate for identical twins (monozygotic) is approximately 40%, whereas for fraternal twins (dizygotic), it is around 5%. When considering a broader spectrum encompassing bipolar I, II, and cyclothymia, concordance rates were similarly observed at 42% for identical twins and 11% for fraternal twins. Conversely, concordance rates for bipolar II combinations excluding bipolar I are lower: 23% for identical and 17% for fraternal twins for bipolar II alone, and 33% for identical and 14% for fraternal twins when bipolar II is combined with cyclothymia. These lower rates may suggest a relatively higher degree of genetic heterogeneity.

The etiological factors contributing to bipolar disorders exhibit overlap with those implicated in major depressive disorder. If concordance is defined as co-twins presenting with either bipolar disorder or major depression, the rate increases to 67% for identical twins and 19% for fraternal twins. The comparatively low concordance observed among fraternal twins raised in the same environment implies that shared familial environmental effects are limited, although the capacity to definitively identify such effects has been constrained by insufficient sample sizes.

Genetic

Behavioral genetic research indicates that numerous chromosomal regions and candidate genes are associated with susceptibility to bipolar disorder, with each gene contributing a mild to moderate effect. The risk of developing bipolar disorder is almost ten times greater in first-degree relatives of affected individuals compared to the general population. Concurrently, the risk of major depressive disorder is three times higher in relatives of those with bipolar disorder than in the general population.

Despite the initial genetic linkage finding for mania in 1969, subsequent linkage studies have yielded inconsistent results. These findings strongly suggest genetic heterogeneity, indicating that distinct genes may be implicated across different families. Robust and replicable genome-wide significant associations have identified several common single-nucleotide polymorphisms (SNPs) linked to bipolar disorder, including variants within the genes CACNA1C, ODZ4, and NCAN. The most extensive and recent genome-wide association study did not identify any single locus exerting a substantial effect, thereby reinforcing the concept that bipolar disorder is not typically caused by a solitary gene. Polymorphisms in BDNF, DRD4, DAO, and TPH1 have been frequently linked to bipolar disorder and initially showed association in a meta-analysis; however, this association was no longer significant after correction for multiple testing. Conversely, two specific polymorphisms within TPH2 have been identified as associated with bipolar disorder.

Given the inconsistent outcomes from genome-wide association studies, numerous investigations have adopted an approach focused on analyzing single nucleotide polymorphisms (SNPs) within biological pathways. These studies have corroborated the involvement of several signaling pathways traditionally linked to bipolar disorder, such as corticotropin-releasing hormone, cardiac β-adrenergic, phospholipase C, glutamate receptor, cardiac hypertrophy, Wnt, Notch, and endothelin 1 signaling pathways. Among the sixteen genes identified within these pathways, three—specifically CACNA1C, GNG2, and ITPR2—exhibited dysregulation in the dorsolateral prefrontal cortex during post-mortem examinations.

Bipolar disorder is characterized by a diminished expression of particular DNA repair enzymes and elevated levels of oxidative DNA damage. In 2022, the AKAP11 gene was identified as the inaugural gene definitively associated with bipolar disorder. This discovery stemmed from an analysis of approximately 14,000 exomes from individuals diagnosed with bipolar disorder, which were then compared to control subjects. These results were subsequently integrated with data from the Schizophrenia Exome Sequencing Meta-Analysis (SCHEMA), which involved genomic sequencing of an additional 24,000 individuals, complementing the initial 14,000 bipolar disorder cases. The comprehensive investigation pinpointed genetic variants, notably the AKAP11 gene, that correlate with an elevated susceptibility to bipolar disorder. Furthermore, the observed interaction between the AKAP11 gene and the GSK3B protein, a known molecular target of lithium, suggests a potential mechanism underlying the therapeutic efficacy of this medication.

Environmental

Psychosocial elements exert a substantial influence on the etiology and progression of bipolar disorder, with individual psychosocial variables potentially interacting with genetic predispositions. Contemporary life events and interpersonal dynamics are posited to contribute to both the initiation and recurrence of bipolar mood episodes, mirroring their impact on unipolar depression. Survey data indicate that 30–50% of adults with a bipolar disorder diagnosis report experiencing traumatic or abusive events during childhood. Such experiences are correlated with an earlier age of onset, an elevated incidence of suicide attempts, and a greater prevalence of comorbid conditions, including post-traumatic stress disorder. Specific forms of abuse, including sexual and emotional abuse, are also implicated in the manifestation of violent behaviors among individuals with bipolar disorder. Individuals diagnosed with an adult bipolar spectrum disorder report a higher frequency of stressful childhood events compared to those without the diagnosis, particularly when these events originate from an adverse environment rather than from the child's own actions. In an acute context, sleep deprivation can precipitate manic episodes in approximately 30% of individuals with bipolar disorder.

Neurological

Infrequently, bipolar disorder or a bipolar-like syndrome can manifest as a consequence of, or in conjunction with, various neurological conditions or injuries. These include, but are not limited to, stroke, traumatic brain injury, HIV infection, multiple sclerosis, porphyria, and, in rare instances, temporal lobe epilepsy.

Proposed mechanisms

The exact pathophysiological mechanisms underlying bipolar disorder remain incompletely elucidated. However, bipolar disorder is hypothesized to involve structural and functional aberrations within specific cerebral regions critical for cognitive processing and emotional regulation. One prominent neurological model posits a bifurcation of the brain's emotional circuitry into two primary components. The ventral system, which governs emotional perception, encompasses structures such as the amygdala, insula, ventral striatum, ventral anterior cingulate cortex, and portions of the prefrontal cortex. Conversely, the dorsal system, tasked with emotional regulation, comprises the hippocampus, dorsal anterior cingulate cortex, and other segments of the prefrontal cortex. This model postulates that bipolar disorder may arise from an overactivation of the ventral system coupled with an underactivation of the dorsal system. Alternative theoretical frameworks propose that emotional regulation capabilities are impaired in individuals with bipolar disorder, with ventricular prefrontal cortex dysfunction being a pivotal factor in this disruption.

Structural magnetic resonance imaging (MRI) meta-analyses have revealed distinct volumetric differences in the brains of individuals with bipolar disorder. Specifically, certain regions, including the left rostral anterior cingulate cortex, fronto-insular cortex, ventral prefrontal cortex, and claustrum, exhibit reduced size. Conversely, other areas, such as the lateral ventricles, globus pallidus, subgenual anterior cingulate, and the amygdala, appear enlarged. Furthermore, these analyses consistently indicate a higher prevalence of deep white matter hyperintensities in individuals diagnosed with bipolar disorder.

Functional MRI studies indicate that the ventricular prefrontal cortex (vPFC) plays a crucial role in regulating the limbic system, particularly the amygdala. In individuals with bipolar disorder, diminished vPFC activity is associated with dysregulated amygdala function, which is hypothesized to contribute to mood lability and impaired emotional regulation. Supporting this, pharmacological interventions for mania have been shown to restore vPFC activity to levels observed in euthymic individuals, suggesting that vPFC activity may serve as a biomarker for mood state. Nevertheless, despite pharmacological treatment reducing amygdala hyperactivity during mania, its activity often remains elevated compared to individuals without bipolar disorder, implying that amygdala activity might be a trait marker of the disorder rather than solely reflecting the current mood state. Manic and depressive episodes are typically characterized by distinct patterns of vPFC dysfunction. Manic episodes are linked to reduced activation in the right vPFC, while depressive episodes correlate with decreased activation in the left vPFC. These functional disruptions frequently emerge during developmental stages, potentially associated with synaptic pruning irregularities.

Individuals with bipolar disorder in a euthymic state exhibit reduced activity in the lingual gyrus when compared to healthy controls. Conversely, during manic episodes, these individuals display diminished activity in the inferior frontal cortex relative to those without the disorder. Despite these specific findings, broader comparative studies investigating brain activity differences between individuals with and without bipolar disorder have not consistently identified a single brain region exhibiting uniform hypo- or hyperactivity across all comparisons. Patients with bipolar disorder demonstrate heightened activation in left hemisphere ventral limbic areas, which are instrumental in mediating emotional experiences and generating emotional responses. Simultaneously, they show decreased activation in right hemisphere cortical structures associated with cognition and emotional regulation. Nonetheless, further research is imperative to integrate and standardize neuroimaging findings, given their current heterogeneity and inconsistent reporting methodologies.

Neuroscientists have advanced several additional models to elucidate the etiology of bipolar disorder. One prominent hypothesis posits that mania arises from hypersensitivity within frontostriatal reward circuits, while depression results from a diminished sensitivity in these same circuits. The "kindling" hypothesis suggests that in genetically predisposed individuals, repeated exposure to stressful events progressively lowers the stress threshold required to trigger mood episodes, eventually leading to spontaneous onset and recurrence. Furthermore, evidence supports a link between early-life stress, such as childhood trauma, and hypothalamic-pituitary-adrenal (HPA) axis dysfunction, characterized by its overactivation, which may contribute to the pathogenesis of bipolar disorder. Other brain components implicated in bipolar disorder include mitochondria and the sodium ATPase pump. Alterations in circadian rhythms and melatonin regulation have also been observed.

Dopamine, a neurotransmitter implicated in mood regulation, exhibits elevated transmission during the manic phase of bipolar disorder. The dopamine hypothesis proposes that this increase in dopamine leads to a subsequent homeostatic downregulation of critical system components and receptors, including reduced sensitivity of dopaminergic receptors. This downregulation, in turn, results in the decreased dopamine transmission characteristic of the depressive phase. The depressive phase is then hypothesized to conclude with homeostatic upregulation, potentially initiating a new cycle. Additionally, glutamate levels are significantly elevated within the left dorsolateral prefrontal cortex during the manic phase of bipolar disorder, normalizing once the phase subsides.

Pharmacological interventions for bipolar disorder are thought to exert their effects through the modulation of intracellular signaling, including the depletion of myo-inositol levels, the inhibition of cAMP signaling, and alterations to subunits of the dopamine-associated G-protein. Supporting this hypothesis, elevated concentrations of G_αi, G_αs, and G_αq/11 have been documented in both cerebral and peripheral samples, concurrently with heightened protein kinase A (PKA) expression and sensitivity. PKA typically becomes active within the intracellular signaling cascade following the dissociation of the G_αs subunit from the G protein complex.

Reduced concentrations of 5-hydroxyindoleacetic acid, a serotonin metabolite, have been observed in the cerebrospinal fluid of individuals with bipolar disorder during both depressive and manic episodes. Elevated dopaminergic activity is postulated in manic states, supported by the capacity of dopamine agonists to induce mania in individuals with bipolar disorder. Diminished sensitivity of regulatory α₂ adrenergic receptors, alongside elevated cell counts in the locus coeruleus, suggests heightened noradrenergic activity in individuals experiencing mania. Subdued plasma GABA levels have been identified across both poles of the mood spectrum. A systematic review indicated no significant variation in overall monoamine levels, yet revealed atypical norepinephrine turnover in individuals with bipolar disorder. Tyrosine depletion has been shown to mitigate the effects of methamphetamine and reduce manic symptoms in individuals with bipolar disorder, thereby implicating dopamine in the pathophysiology of mania. One investigation reported increased VMAT2 binding in individuals experiencing bipolar mania.

Diagnosis

Bipolar disorder is frequently diagnosed during adolescence or early adulthood, although its onset can manifest at any point across the lifespan. The diagnostic process relies on the individual's self-reported experiences, observations of atypical behavior by family members, friends, or colleagues, clinically observable signs of the illness, and, ideally, a comprehensive medical evaluation to exclude alternative etiologies. Caregiver-completed rating scales, particularly those provided by mothers, have demonstrated greater accuracy than reports from teachers or self-assessments by youths in identifying adolescents with bipolar disorder. Assessment typically occurs in an outpatient setting; however, inpatient admission is warranted when there is a significant risk of harm to the individual or others.

The predominant diagnostic criteria for bipolar disorder are derived from the American Psychiatric Association's (APA) Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), and the World Health Organization's (WHO) International Statistical Classification of Diseases and Related Health Problems, 10th Edition (ICD-10). While ICD-10 criteria are more frequently applied in clinical practice outside the United States, DSM criteria are utilized domestically and represent the dominant framework for international research. Published in 2013, the DSM-5 incorporates more refined and precise specifiers compared to its antecedent, the DSM-IV-TR. This development has subsequently informed the eleventh revision of the ICD (ICD-11), which now encompasses the diverse diagnoses within the DSM-5's bipolar spectrum.

Numerous rating scales are available for the screening and assessment of bipolar disorder, such as the Bipolar Spectrum Diagnostic Scale, the Mood Disorder Questionnaire, the General Behavior Inventory, and the Hypomania Checklist. While these evaluation scales do not replace a comprehensive clinical interview, they facilitate the systematic collection of symptomatic information. Conversely, screening instruments for bipolar disorder generally exhibit reduced sensitivity.

Differential diagnosis

Several psychiatric conditions can present with symptoms that overlap with bipolar disorder, including schizophrenia, major depressive disorder, attention deficit hyperactivity disorder (ADHD), and specific personality disorders, notably borderline personality disorder. A critical distinction between bipolar disorder and borderline personality disorder lies in the characteristic patterns of mood fluctuation; unlike the prolonged mood shifts spanning days to weeks or more observed in bipolar disorder, the emotional dysregulation typical of borderline personality disorder manifests as abrupt, often transient changes, frequently triggered by social stressors.

While no specific biological tests definitively diagnose bipolar disorder, blood tests and imaging studies are conducted to rule out medical conditions presenting with similar clinical features before a conclusive diagnosis is established. Neurological disorders such as multiple sclerosis, complex partial seizures, strokes, brain tumors, Wilson's disease, traumatic brain injury, Huntington's disease, and complex migraines can manifest symptoms resembling bipolar disorder. An electroencephalogram (EEG) may be employed to exclude neurological conditions like epilepsy, and a CT scan or MRI of the head can identify or rule out brain lesions. Furthermore, endocrine system dysfunctions, including hypothyroidism, hyperthyroidism, and Cushing's disease, are considered in the differential diagnosis, as is the connective tissue disorder systemic lupus erythematosus. Infectious agents that can induce mania, mimicking bipolar mania, include herpes encephalitis, HIV, influenza, and neurosyphilis. Certain nutritional deficiencies, such as pellagra (niacin deficiency), vitamin B₁₂ deficiency, folate deficiency, and Wernicke–Korsakoff syndrome (thiamine deficiency), can also precipitate manic states. Common pharmacological agents capable of inducing manic symptoms encompass antidepressants, prednisone, Parkinson's disease medications, thyroid hormone, stimulants (e.g., cocaine and methamphetamine), and specific antibiotics.

Bipolar Spectrum

Bipolar spectrum disorders encompass bipolar I disorder, bipolar II disorder, cyclothymic disorder, and instances where subthreshold symptoms lead to clinically significant impairment or distress. These conditions are characterized by major depressive episodes that alternate with either manic or hypomanic episodes, or with mixed episodes exhibiting features of both mood states. The conceptualization of the bipolar spectrum aligns with Emil Kraepelin's original framework of manic-depressive illness. Bipolar II disorder was formally recognized as a diagnosis in 1994 within the DSM-IV, although ongoing debate persists regarding its status as a distinct entity, a component of a broader spectrum, or its very existence.

Diagnostic Criteria and Subtypes

Both the DSM and the ICD characterize bipolar disorder as a spectrum of conditions existing along a continuum. The DSM-5 and ICD-11 delineate three specific subtypes:

• Bipolar I disorder: A diagnosis necessitates the occurrence of at least one manic episode. While depressive episodes are prevalent in the majority of Bipolar I cases, they are not a prerequisite for diagnosis. Applicable specifiers, such as "mild, moderate, moderate-severe, severe" and "with psychotic features," should be appended to describe the disorder's presentation and trajectory.
• Bipolar II disorder: This diagnosis requires the absence of manic episodes, coupled with one or more hypomanic episodes and one or more major depressive episodes. Hypomanic episodes do not reach the full intensity of mania (i.e., they typically do not cause severe social or occupational impairment and are not accompanied by psychosis). This distinction can complicate the diagnosis of Bipolar II, as hypomanic episodes may be perceived merely as periods of heightened productivity and are reported less frequently than the more distressing and debilitating depressive episodes.
• Cyclothymia: Defined by a history of hypomanic episodes interspersed with periods of depression that do not fulfill the criteria for major depressive episodes. In cyclothymia, hypomanic and depressive episodes alternate for a minimum of two years in adults and at least one year in children and adolescents.

When appropriate, specifiers such as peripartum onset and with rapid cycling should be applied to any subtype. Individuals experiencing subthreshold symptoms that cause clinically significant distress or impairment, but do not fully meet the criteria for one of the three primary subtypes, may receive a diagnosis of other specified or unspecified bipolar disorder. Other specified bipolar disorder is utilized when a clinician provides a rationale for why the full diagnostic criteria were not met (e.g., hypomania without a preceding major depressive episode). If a non-psychiatric medical condition is believed to be the etiology, the diagnosis of bipolar and related disorder due to another medical condition is assigned, whereas substance/medication-induced bipolar and related disorder is used when a medication is considered the trigger for the condition.

Although hyperthymic temperament is not classified as a pathological disorder, it exhibits a genetic link with bipolar I and can increase an individual's susceptibility to manic-depressive episodes. This temperament is also characterized as a subsyndromal manifestation within the extensive bipolar spectrum.

Rapid Cycling

Individuals meeting the diagnostic criteria for bipolar disorder typically experience multiple episodes, averaging 0.4 to 0.7 annually, each persisting for three to six months. In contrast, rapid cycling serves as a course specifier applicable across all bipolar subtypes, characterized by the occurrence of four or more mood disturbance episodes within a single year. While generally transient, rapid cycling is prevalent among individuals with bipolar disorder, affecting 25.8–45.3% of them at some point in their lives. These episodes are delineated by either a partial or full remission lasting a minimum of two months, or a shift in mood polarity (e.g., transitioning from a depressive to a manic episode, or vice versa). The most widely referenced definition of rapid cycling in academic literature, including the DSM-5 and ICD-11, originates from Dunner and Fieve, specifying at least four major depressive, manic, hypomanic, or mixed episodes within a 12-month timeframe.

Research on the pharmacological treatment of rapid cycling remains limited, and a definitive consensus regarding its optimal management strategies is currently lacking. Terms such as "ultra rapid" and "ultradian" have been introduced to categorize more accelerated forms of bipolar disorder cycling. Individuals presenting with rapid cycling or faster-cycling bipolar subtypes generally exhibit greater treatment resistance and reduced responsiveness to pharmacotherapy compared to those with other bipolar presentations. Furthermore, evidence suggests that rapid cycling may be iatrogenic, potentially induced by antidepressant usage. Conversely, atypical antipsychotics and mood stabilizers have not been observed to exacerbate rapid cycling.

Comorbid Psychiatric Conditions

Diagnosing bipolar disorder can be intricate due to the presence of coexisting (comorbid) psychiatric conditions, such as obsessive–compulsive disorder, substance-use disorder, eating disorders, attention deficit hyperactivity disorder, social phobia, premenstrual syndrome (including premenstrual dysphoric disorder), and panic disorder. When these comorbidities are present, a comprehensive longitudinal assessment of symptoms and episodes, ideally supplemented by insights from friends and family, is essential for developing an effective treatment plan. Moreover, children of parents diagnosed with bipolar disorder exhibit a higher incidence of other mental health issues.

Prevention

Preventive efforts for bipolar disorder have largely concentrated on mitigating stress, including factors like childhood adversity or highly conflictual family environments. While stress is not a diagnostically specific causal factor for bipolar disorder, it significantly elevates the risk for a more severe illness trajectory in genetically and biologically predisposed individuals. Longitudinal research indicates that fully developed manic episodes are frequently heralded by various prodromal clinical manifestations, suggesting the existence of an at-risk state where timely intervention could potentially avert further progression or enhance outcomes. Furthermore, disruptions to circadian rhythms, such as those caused by extensive trans-meridian travel (jet lag), can destabilize bipolar disorder, potentially precipitating manic or psychotic episodes.

Management

The primary objective of bipolar disorder management involves the safe pharmacological treatment of acute episodes, coupled with long-term patient collaboration to prevent recurrence and optimize functional capacity through integrated pharmacological and psychotherapeutic approaches. Hospitalization may become necessary, particularly during manic episodes characteristic of bipolar I, and can be either voluntary or, where permitted by local legislation, involuntary. While long-term inpatient admissions have become less frequent due to deinstitutionalization, they remain a possibility. Post-hospitalization, or as an alternative, available support services encompass drop-in centers, visits from community mental health teams or Assertive Community Treatment teams, supported employment initiatives, patient-led support groups, and intensive outpatient programs, sometimes termed partial-inpatient programs. Individuals with bipolar disorder exhibit a lower propensity for regular physical exercise compared to the general population. Although exercise may confer both physical and mental health advantages for those with bipolar disorder, further research in this area is needed.

Psychosocial Interventions

Psychotherapeutic interventions are designed to facilitate an individual's acceptance and comprehension of their bipolar disorder diagnosis, enhance stress management strategies, improve interpersonal functioning, and enable the recognition of prodromal indicators prior to a full-scale recurrence. Cognitive behavioral therapy (CBT), family-focused therapy, and psychoeducation demonstrate the strongest empirical support for preventing relapse, while interpersonal and social rhythm therapy and cognitive-behavioral therapy appear most effective in addressing residual depressive symptomatology. However, the majority of research has focused exclusively on bipolar I disorder, and managing treatment during the acute phase presents a distinct challenge. Certain clinicians advocate for direct communication with individuals experiencing manic episodes to foster a therapeutic alliance that supports recovery.

Medication

Pharmacological agents are frequently prescribed to ameliorate the symptoms of bipolar disorder. Approved pharmacological treatments for bipolar disorder encompass mood stabilizers and atypical antipsychotics. Combination pharmacotherapy may also be recommended in certain cases. Pharmacological selection can vary based on the specific bipolar disorder episode type or whether the individual is experiencing unipolar or bipolar depression. Additional considerations for determining an appropriate treatment strategy include the presence of comorbidities, prior treatment responses, potential adverse effects, and the patient's preference for treatment.

Mood stabilizers

Lithium and the anticonvulsants carbamazepine, lamotrigine, and valproic acid are categorized as mood stabilizers owing to their regulatory effects on mood states in bipolar disorder.

• Lithium possesses the most robust overall evidence and is recognized as an efficacious treatment for acute manic episodes, relapse prevention, and bipolar depression. It mitigates the risk of suicide, self-harm, and mortality among individuals with bipolar disorder. Lithium is the preferred agent for long-term mood stabilization. However, lithium therapy is also associated with adverse effects, having demonstrated a propensity to impair renal and thyroid function over prolonged durations.
• Valproate has emerged as a frequently prescribed therapeutic agent and effectively manages manic episodes.
• Carbamazepine demonstrates lower efficacy in relapse prevention compared to lithium or valproate. It is effective in treating manic episodes, with some evidence suggesting enhanced benefits in cases of rapid-cycling bipolar disorder, or for individuals presenting with more pronounced psychotic symptoms or symptomatology resembling schizoaffective disorder.
• Lamotrigine exhibits some efficacy in managing depressive episodes, with its benefits being most pronounced in severe depression. It may offer comparable effectiveness to lithium in the treatment of bipolar disorder; however, evidence indicates that lamotrigine is less effective in preventing recurrent manic episodes. Lamotrigine therapy has demonstrated a more favorable safety profile compared to lithium treatment, characterized by fewer adverse effects.

Valproate and carbamazepine are teratogenic and thus contraindicated for women of childbearing potential; however, discontinuing these medications during pregnancy carries a substantial risk of relapse. Lithium also exhibits teratogenic properties during the first trimester, although its use may be deemed acceptable during this period following a meticulous assessment of potential benefits and risks.

The efficacy of topiramate remains undetermined. While mood stabilizers are employed for long-term maintenance, they have not demonstrated rapid efficacy in treating acute bipolar depression. Conversely, several atypical antipsychotics have received FDA approval for the treatment of bipolar depression.

Antipsychotics

Antipsychotic medications demonstrate efficacy for the short-term management of bipolar manic episodes and appear to surpass lithium and anticonvulsants in this application. Several atypical antipsychotics have received FDA approval for treating bipolar depression, including lurasidone, quetiapine, the olanzapine-fluoxetine combination, cariprazine, and lumateperone. Furthermore, atypical antipsychotics like lurasidone and clozapine are indicated for bipolar depression that is refractory to mood stabilizer treatment. Olanzapine demonstrates efficacy in preventing relapses, though the supporting evidence is less robust compared to that for lithium. A review published in 2006 indicated that haloperidol was an effective treatment for acute mania; however, limited data suggested no significant difference in overall efficacy among haloperidol, olanzapine, or risperidone, and it potentially exhibited lower effectiveness than aripiprazole.

Antidepressant Medications

Monotherapy with antidepressants is not advised for bipolar disorder treatment, as it offers no discernible advantage over mood stabilizers. Atypical antipsychotic agents are favored over antidepressants for enhancing the effects of mood stabilizers, primarily because antidepressants demonstrate limited efficacy in managing bipolar disorder. The U.S. Food and Drug Administration (FDA) has sanctioned five distinct atypical antipsychotic medications specifically for the treatment of bipolar depression. The administration of antidepressants for bipolar disorder may precipitate affective switches, characterized by a transition from depressive states to manic, hypomanic, or mixed episodes.

Furthermore, antidepressant use in bipolar disorder may accelerate the cycling between phases, a phenomenon termed rapid cycling. The propensity for affective switches is elevated in individuals with bipolar I depression; consequently, antidepressants are typically eschewed in bipolar I disorder or employed only in conjunction with mood stabilizers when clinically indispensable. The assertion that contemporary antidepressants induce mania or rapid cycling in bipolar disorder remains a subject of considerable debate, as does the question of whether antidepressants offer any advantage beyond mood stabilizers alone. While selective serotonin reuptake inhibitors (SSRIs) and bupropion still pose a risk of rapid cycling and manic switching, this risk is comparatively lower than that associated with other antidepressant classes. Conversely, serotonin-norepinephrine reuptake inhibitors (SNRIs), including venlafaxine and duloxetine, as well as tetracyclic antidepressants like mirtazapine and tricyclic antidepressants, are associated with higher incidences of manic switching and rapid cycling.

Combination Treatment Strategies

The concurrent administration of atypical antipsychotics and mood stabilizers demonstrates superior efficacy and rapidity in treating mania compared to the use of either drug class independently. Guidelines from the International Society for Bipolar Disorders (ISBD) and the Canadian Network for Mood and Anxiety Treatments (CANMAT) recommend a first-line combination therapy for bipolar depression comprising the atypical antipsychotic lurasidone alongside either lithium or valproate as mood stabilizers.

Alternative Pharmacological Interventions

Benzodiazepines are prescribed for short durations as an adjunct to other medications, primarily to induce a calming effect until mood-stabilizing agents achieve therapeutic efficacy. Electroconvulsive therapy (ECT) constitutes an effective treatment modality for acute mood disturbances in individuals with bipolar disorder, particularly when psychotic or catatonic features are present. Furthermore, ECT is advised for pregnant women diagnosed with bipolar disorder. A solitary intravenous administration of ketamine has been observed to elicit a rapid, albeit transient, antidepressant effect in bipolar depression; however, the certainty of this evidence ranges from low to very low, and data regarding other glutamate receptor modulators, sustained remission, and long-term safety remain inconclusive. Gabapentin and pregabalin have not demonstrated proven efficacy in the treatment of bipolar disorder.

Pediatric Population

The management of bipolar disorder in children typically encompasses both pharmacotherapy and psychotherapy. Existing literature and research concerning the impact of psychosocial therapy on bipolar spectrum disorders are limited, thereby impeding a definitive assessment of the efficacy of diverse therapeutic approaches. Mood stabilizers and atypical antipsychotics are frequently prescribed agents. Notably, among mood stabilizers, lithium is the sole compound approved by the FDA for pediatric use. Psychological interventions typically integrate psychoeducation regarding the disorder, group therapy, and cognitive behavioral therapy. Sustained pharmacotherapy is frequently requisite.

Treatment Resistance

The suboptimal therapeutic response observed in a subset of bipolar patients has substantiated the concept of treatment-resistant bipolar disorder. Definitional guidelines for treatment-resistant bipolar disorder and evidence-based management strategies were comprehensively reviewed in 2020.

Obesity Management

A substantial proportion (approximately 68%) of individuals seeking treatment for bipolar disorder are classified as obese or overweight; consequently, effective obesity management is crucial for mitigating the risk of associated comorbidities. Management strategies encompass non-pharmacological, pharmacological, and surgical interventions. Non-pharmacological examples include dietary modifications, physical exercise, behavioral therapies, or integrated approaches. Pharmacological strategies involve the use of weight-loss medications or adjustments to existing prescribed pharmacotherapy. Certain individuals with bipolar disorder and obesity may also qualify for bariatric surgery. The overall efficacy of these diverse approaches in ameliorating or managing obesity among individuals with bipolar disorder remains to be definitively established.

Prognosis

Bipolar disorder, a chronic condition characterized by recurrent episodes of relapse interspersed with periods of partial or full remission, represents a significant global health concern due to elevated rates of disability and premature mortality. This disorder is frequently linked to comorbid psychiatric and medical conditions, an increased incidence of mortality from natural causes (such as cardiovascular disease), and a high prevalence of initial underdiagnosis or misdiagnosis. Such diagnostic delays impede timely and appropriate treatment, thereby contributing to less favorable prognoses. Individuals with bipolar disorder exhibit a higher incidence of other severe medical comorbidities, including diabetes mellitus, respiratory illnesses, HIV, and hepatitis C virus infection, when contrasted with the general population. Even after diagnosis, achieving complete symptomatic remission with current psychiatric pharmacotherapies remains challenging, and symptoms frequently exhibit progressive exacerbation over time.

Adherence to prescribed pharmacotherapy constitutes a critical determinant in mitigating the frequency and intensity of relapses, thereby positively influencing the overall prognosis. Nevertheless, the medications typically employed in bipolar disorder treatment often induce adverse effects, leading over 75% of affected individuals to exhibit inconsistent medication adherence for diverse reasons. Among the various presentations of the disorder, rapid cycling (defined as four or more mood episodes within a single year) correlates with the most unfavorable prognosis, primarily due to elevated risks of self-harm and suicide. Patients with a bipolar disorder diagnosis and a familial history of the condition face an increased susceptibility to more frequent manic or hypomanic episodes. Furthermore, early disease onset, the presence of psychotic features, and subtypes unresponsive to lithium therapy are also linked to poorer clinical outcomes.

Prompt identification and therapeutic intervention similarly enhance prognosis, given that symptoms in the initial stages tend to be less severe and more amenable to treatment. An onset of bipolar disorder occurring post-adolescence is associated with improved prognoses for both sexes, with male gender serving as a protective factor against more severe depressive symptomatology. In women, superior social functioning prior to the onset of bipolar disorder and parenthood are identified as protective factors against suicide attempts.

Functional Impairment

Mood disorders are characterized by alterations in cognitive processes and abilities, with these impairments being more pronounced in bipolar disorder compared to major depressive disorder. Specifically, these deficits encompass diminished attentional and executive functions, alongside impaired memory. Individuals with bipolar disorder frequently exhibit a decline in cognitive functioning either during or potentially preceding their initial episode. Subsequently, a persistent level of cognitive dysfunction typically ensues, manifesting as more severe impairment during acute phases and moderate impairment during periods of remission. Consequently, two-thirds of individuals with bipolar disorder continue to experience impaired psychosocial functioning even during inter-episode periods when their mood symptoms are in full remission. This pattern is observed in both Bipolar I and Bipolar II disorders, although individuals with Bipolar II disorder typically exhibit a less severe degree of impairment. Furthermore, individuals with bipolar disorder face an elevated risk of developing dementia, a risk that lithium therapy has been shown to reduce by 50%.

The manifestation of bipolar disorder in childhood profoundly and detrimentally impacts psychosocial development. Pediatric and adolescent populations diagnosed with bipolar disorder exhibit increased rates of substantial challenges, including substance use disorders, psychosis, academic underachievement, behavioral disturbances, social difficulties, and legal issues. Cognitive deficits generally intensify throughout the progression of the illness. More pronounced levels of impairment are correlated with a greater number of prior manic episodes and hospitalizations, as well as with the presence of psychotic symptoms. While early intervention can mitigate the progression of cognitive impairment, therapeutic approaches implemented in later stages primarily aim to alleviate distress and adverse outcomes associated with cognitive dysfunction.

Manic episodes often involve excessively ambitious goals; however, the associated symptoms typically impede goal attainment and frequently impair an individual's social and occupational capabilities. A significant proportion, specifically one-third, of individuals diagnosed with bipolar disorder (BD) experience unemployment for a year subsequent to hospitalization for a manic episode. Depressive symptomatology, prevalent both during and between episodes—and occurring more frequently than hypomanic or manic symptoms throughout the illness trajectory for most individuals—is linked to diminished functional recovery during inter-episode periods, manifesting as unemployment or underemployment in both BD-I and BD-II diagnoses. Nevertheless, the most robust predictors of employment outcomes in individuals with bipolar disorder are the illness course (encompassing duration, age of onset, hospitalization frequency, and the presence of rapid cycling) and cognitive performance, with depressive symptoms and educational attainment also serving as significant, albeit secondary, indicators.

Recovery and Relapse Patterns

A 2003 naturalistic investigation conducted by Tohen and colleagues, focusing on individuals following their initial hospitalization for a manic or mixed episode (thereby representing the most severe presentations), revealed that 50% attained syndromal recovery (defined as no longer fulfilling diagnostic criteria) within six weeks, with this figure rising to 98% within two years. Over the same two-year period, 72% of participants achieved complete symptomatic remission, while 43% demonstrated functional recovery, characterized by the restoration of previous occupational and residential statuses. Nevertheless, 40% subsequently experienced a new manic or depressive episode within two years of achieving syndromal recovery, and 19% transitioned between phases without achieving any form of recovery.

Individuals with bipolar disorder are often capable of reliably identifying prodromal symptoms, particularly those indicative of an impending manic relapse. Interventions aimed at educating patients on coping strategies for managing these emergent symptoms have yielded promising outcomes.

Suicidal Ideation and Risk

Bipolar disorder is frequently associated with the development of suicidal ideation, which can culminate in suicide attempts. A poorer prognosis and an elevated risk of suicide are observed in individuals whose bipolar disorder onset is characterized by a depressive or mixed affective episode. Approximately half of all individuals with bipolar disorder will attempt suicide at least once during their lifetime, with a substantial number of these attempts resulting in death. The annual average suicide rate ranges from 0.4% to 1.4%, representing a 30- to 60-fold increase compared to the general population. Mortality from suicide among individuals with bipolar disorder is 18 to 25 times greater than anticipated in age-matched cohorts without the condition. The lifetime risk of suicide is considerably elevated in individuals with bipolar disorder, with estimates indicating that 34% attempt suicide and 15–20% die by suicide.

Several factors are associated with an increased risk of suicide attempts and death by suicide in individuals with bipolar disorder. These include advanced age, a history of previous suicide attempts, an initial (index) episode characterized by depression or mixed features, a manic index episode accompanied by psychotic symptoms, the presence of hopelessness or psychomotor agitation during episodes, comorbid anxiety disorders, a first-degree relative with a mood disorder or a history of suicide, interpersonal conflicts, occupational difficulties, bereavement, and social isolation.

Lithium therapy has demonstrated efficacy in mitigating the risk of suicide in individuals with bipolar disorder or major depression, bringing it to a level comparable to that observed in the general population. Over four decades of research, including numerous randomized controlled trials, have consistently established lithium's substantial effectiveness in reducing suicide rates among individuals with bipolar disorder. Furthermore, beyond its antisuicidal effects, lithium has been shown to reduce all-cause mortality in individuals diagnosed with bipolar disorder.

Epidemiology

Bipolar disorder ranks as the sixth most significant cause of disability globally, with a lifetime prevalence estimated between 1% and 3% within the general population. Nevertheless, a subsequent analysis of data from the National Epidemiological Catchment Area survey in the United States indicated that 0.8% of the populace experiences at least one manic episode, which constitutes the diagnostic criterion for bipolar I, while an additional 0.5% exhibits a hypomanic episode, meeting the diagnostic threshold for bipolar II or cyclothymia. When sub-threshold diagnostic criteria, such as the presence of one or two symptoms over a brief duration, are included, an additional 5.1% of the population, totaling 6.4%, were categorized as having a bipolar spectrum disorder. A more contemporary analysis of data from a subsequent U.S. National Comorbidity Survey revealed that 1% fulfilled the lifetime prevalence criteria for bipolar I, 1.1% for bipolar II, and 2.4% for subthreshold symptomatology. Estimates regarding the prevalence of bipolar disorder among children and young adults exhibit considerable variability. These figures span from 0.6% to 15%, contingent upon diverse clinical settings, methodologies, and referral contexts, thereby prompting concerns about potential overdiagnosis. A global meta-analysis focusing on bipolar disorder in young individuals estimated that approximately 1.8% of those aged between seven and 21 years are affected by the condition. Consistent with adult populations, bipolar disorder in pediatric and adolescent cohorts is believed to manifest with comparable frequency across both sexes.

The research findings are subject to conceptual and methodological constraints, leading to variations. Prevalence investigations concerning bipolar disorder are commonly conducted by non-specialist interviewers adhering to rigidly structured interview protocols; consequently, responses to individual items within these interviews may possess limited validity. Furthermore, diagnoses—and, by extension, prevalence estimates—fluctuate based on the adoption of either a categorical or a spectrum approach. This factor has generated apprehension regarding the potential for both underdiagnosis and overdiagnosis of the condition.

The incidence of bipolar disorder demonstrates comparable rates between men and women, and also across diverse cultural and ethnic populations. A study conducted by the World Health Organization in 2000 indicated a high degree of similarity in the global prevalence and incidence of bipolar disorder. Age-standardized prevalence rates per 100,000 individuals ranged from 421.0 in South Asia to 481.7 in Africa and Europe for males, and from 450.3 in Africa and Europe to 491.6 in Oceania for females. Nevertheless, the severity of the disorder can exhibit substantial global variation. For instance, disability-adjusted life year rates tend to be elevated in developing nations, where healthcare access may be limited and pharmaceutical availability reduced. Within the United States, Asian Americans exhibit notably lower rates compared to their African American and European American counterparts. In 2017, the Global Burden of Disease Study estimated 4.5 million new cases and a cumulative total of 45.5 million cases worldwide.

Comorbid Conditions

Individuals diagnosed with bipolar disorder frequently present with co-occurring psychiatric conditions, including anxiety (observed in approximately 71% of affected individuals), substance abuse (56%), personality disorders (36%), and attention deficit hyperactivity disorder (10–20%), all of which can exacerbate the disease burden and negatively impact prognosis. Furthermore, specific medical conditions are more prevalent among individuals with bipolar disorder when contrasted with the general population. These include metabolic syndrome (present in 37% of individuals with bipolar disorder), migraine headaches (35%), obesity (21%), and type 2 diabetes (14%). This constellation of factors contributes to a twofold increased mortality risk for individuals with bipolar disorder compared to the general populace. Hypothyroidism is also frequently observed, irrespective of pharmacological treatment selection.

Substance use disorder represents a frequent comorbidity in bipolar disorder, a topic that has been extensively examined in the literature.

Homelessness and Housing Instability

Prevalence

Research indicates a substantially higher prevalence of bipolar disorder among individuals experiencing homelessness compared to the general populace. A 2024 meta-analysis and systematic review estimated a global prevalence of approximately 8% for bipolar disorder within homeless populations, a figure several times greater than general population averages. Prior reviews similarly identified elevated rates, ranging from 6% to 9%; however, these estimates exhibit variability based on diagnostic criteria and study design. Investigators suggest that methodological disparities, including inconsistent definitions of homelessness and limited sample sizes, may account for the broad spectrum of reported prevalence rates.

Risk Factors

Bipolar disorder is linked to several risk factors for homelessness, such as incarceration, substance use, and socioeconomic instability. In the United States, a study reported that 55% of veterans with bipolar disorder had experienced homelessness at some point, with 12% having been homeless within the preceding four weeks. Homelessness also demonstrated a strong association with previous incarceration and co-occurring substance use, underscoring the cyclical relationship between social instability and mental illness.

Furthermore, individuals with bipolar disorder experiencing homelessness frequently exhibit an early onset of the condition, more recurrent manic or depressive episodes, and suboptimal medication adherence. These factors can elevate the likelihood of relapse and housing loss. Veterans and individuals with histories of correctional or psychiatric institutionalization are particularly vulnerable. This underscores how insufficient post-discharge support contributes to persistent cycles of instability.

Social determinants, such as poverty, unemployment, and stigma, also heighten vulnerability to both bipolar disorder and homelessness. For individuals experiencing homelessness, factors like chronic stress, sleep deprivation, and exposure to unsafe environments are highly prevalent and can exacerbate mood symptomatology, thereby impeding sustained recovery and reintegration.

Access to Care

Individuals experiencing homelessness encounter substantial barriers to consistent and high-quality mental health treatment. A study involving over 10,000 patients with serious mental illness within the public health system revealed that homeless patients, compared to housed individuals, were less likely to possess insurance or maintain continuous care, and more prone to relying on emergency services. Disruptions in care contribute to suboptimal adherence to treatment plans, elevated rates of psychiatric hospitalization, and poorer long-term outcomes. Individuals with bipolar disorder necessitate consistent medication management and therapeutic monitoring; however, unstable living conditions render meeting these needs exceptionally challenging, often preventing medication refills, appointment attendance, or engagement in therapy.

Limitations

Research concerning the prevalence of bipolar disorder within the homeless population is constrained by varying definitions of homelessness, challenges in tracking mobile individuals, and inconsistencies in diagnostic methods across studies. Consequently, current prevalence estimates for bipolar disorder in this population may be subject to underestimation. The expansion of integrated care models, which combine psychiatric treatment with housing and social services, has been proposed as a strategy to enhance long-term stability and decrease reliance on emergency services.

History

In the early 1800s, French psychiatrist Jean-Étienne Dominique Esquirol introduced lypemania, categorized among his affective monomanias, as a foundational concept for what would later evolve into modern depression. The contemporary understanding of bipolar disorder originates from developments in the 1850s. In 1850, Jean-Pierre Falret described "circular insanity" (la folie circulaire, French pronunciation: [lafɔlisiʁ.ky.lɛʁ]), with a summary of his lecture appearing in the Gazette des hôpitaux ("Hospital Gazette") in 1851. Subsequently, in 1854, Jules-Gabriel-François Baillarger (1809–1890) presented to the French Imperial Académie Nationale de Médecine a biphasic mental illness characterized by recurrent oscillations between mania and melancholia, which he termed la folie à double forme (French pronunciation: [lafɔliadublfɔʀm], or "madness in double form"). His seminal paper, "De la folie à double forme," was published in the medical journal Annales médico-psychologiques (Medico-psychological annals) that same year.

These foundational concepts were further refined by the German psychiatrist Emil Kraepelin (1856–1926), who, incorporating Kahlbaum's notion of cyclothymia, systematically categorized and investigated the natural progression of bipolar disorder in untreated individuals. Kraepelin introduced the term manic depressive psychosis, observing that acute episodes of either mania or depression were typically interspersed with periods of relative remission during which patients maintained normal functioning.

The designation "manic–depressive reaction" was introduced in the inaugural edition of the DSM in 1952, reflecting the influence of Adolf Meyer's work. The differentiation between "unipolar" depressive disorders and bipolar disorders stems from Karl Kleist's conceptualization, dating back to 1911, of unipolar and bipolar affective disorders. This distinction was subsequently employed by Karl Leonhard in 1957 to delineate unipolar and bipolar forms within the spectrum of depression. Since the publication of the DSM-III, these subtypes have been recognized as distinct clinical entities. Bipolar II and rapid cycling subtypes were incorporated into the DSM-IV, building upon research conducted in the 1970s by David Dunner, Elliot Gershon, Frederick Goodwin, Ronald Fieve, and Joseph Fleiss.

Society and culture

Cost

In 2015, the United States incurred an estimated expenditure of $202.1 billion for individuals diagnosed with bipolar I disorder, a figure that excludes other bipolar subtypes and undiagnosed populations. A separate analysis indicated that the United Kingdom's expenditure on the disorder reached approximately £5.2 billion in 2007. Beyond its substantial economic burden, bipolar disorder represents a primary global contributor to disability and diminished productivity. Individuals afflicted with bipolar disorder typically exhibit greater disability, reduced functional capacity, extended illness duration, and elevated rates of work absenteeism and productivity loss when contrasted with those experiencing other mental health conditions. Furthermore, the decline in productivity observed among caregivers of individuals with bipolar disorder substantially augments these overall costs.

Advocacy

Individuals diagnosed with bipolar disorder frequently encounter pervasive issues related to social stigma, stereotypes, and prejudice. In 2000, actress Carrie Fisher publicly disclosed her diagnosis of bipolar disorder. Fisher subsequently emerged as a prominent public advocate for individuals with bipolar disorder, passionately campaigning to dismantle the stigma associated with mental illnesses, including bipolar disorder. Stephen Fried, a prolific writer on the subject, highlighted Fisher's role in emphasizing the disorder's chronic and relapsing characteristics, underscoring that relapses do not signify a lack of discipline or moral failing. Following his diagnosis at age 37, actor Stephen Fry has actively promoted awareness of the condition, notably through his 2006 documentary, Stephen Fry: The Secret Life of the Manic Depressive. To mitigate the social stigma linked to bipolar disorder, orchestra conductor Ronald Braunstein cofounded the ME/2 Orchestra with his wife, Caroline Whiddon, in 2011. Braunstein, diagnosed with bipolar disorder in 1985, conceptualized the ME/2 Orchestra's concerts to foster an inclusive performance setting for his fellow musicians and simultaneously elevate public understanding of mental illness.

Advocacy organizations

Numerous advocacy organizations are dedicated to supporting individuals with bipolar disorder, their caregivers, and researchers investigating the condition.

• The International Society for Bipolar Disorders (ISBD) functions as a research and educational entity specifically addressing bipolar disorder. This organization provides valuable resources for mental health professionals, patients, and their families, and is responsible for publishing the journal *Bipolar Disorders*.
• The International Bipolar Foundation (IBPF) delivers educational materials and support resources to individuals affected by bipolar disorder.
• CREST.BD represents a Canadian network dedicated to the study and support of bipolar disorder. This network comprises researchers, mental health professionals, and individuals living with the condition.
• The Canadian Network for Mood and Anxiety Treatments (CANMAT), in collaboration with the International Society for Bipolar Disorders (ISBD), issues treatment guidelines pertinent to bipolar disorder.

World Bipolar Day

World Bipolar Day is observed annually on March 30, coinciding with Vincent Van Gogh's birthday. The primary objective of this observance is to eradicate the stigma associated with bipolar disorder. Sponsorship for the day is provided by the International Society for Bipolar Disorders, the International Bipolar Foundation, and the Asian Network of Bipolar Disorder (ANBD).

Support Groups

The Depression and Bipolar Support Alliance (DBSA), previously known as the National Depressive and Manic Depressive Association, operates as a patient-led support and advocacy organization. It maintains approximately 200 chapters and 700 support groups, predominantly located within the United States. Participation in DBSA support groups has been correlated with enhanced functioning and improved well-being among attendees.

Bipolar UK, formerly designated as the Manic Depression Fellowship, functions as a patient-led mental health support and advocacy organization within the United Kingdom. This organization facilitates 85 support groups across the UK for individuals affected by bipolar disorder.

Notable Cases

A multitude of authors have explored bipolar disorder in their writings, and numerous accomplished individuals have openly shared their personal experiences with the condition. Kay Redfield Jamison, a distinguished clinical psychologist and professor of psychiatry at the Johns Hopkins University School of Medicine, documented her own journey with bipolar disorder in her 1995 memoir, An Unquiet Mind. Historical analysis suggests that Grigory Potemkin, a prominent Russian statesman and alleged spouse of Catherine the Great, may have experienced a form of bipolar disorder. Furthermore, several public figures have disclosed their bipolar disorder diagnoses, including Carrie Fisher, Stephen Fry, Catherine Zeta-Jones, Mariah Carey, Kanye West, Jane Pauley, Demi Lovato, Selena Gomez, and Russell Brand.

Media Portrayals

Various dramatic productions have depicted characters exhibiting characteristics indicative of a bipolar diagnosis, prompting extensive discussion among both psychiatrists and film scholars.

In the 1993 film Mr. Jones, the titular character, portrayed by Richard Gere, experiences cyclical shifts between manic and depressive phases, necessitating hospitalization and demonstrating numerous features of the syndrome. Similarly, Allie Fox, played by Harrison Ford in the 1986 production The Mosquito Coast, exhibits traits such as recklessness, grandiosity, heightened goal-directed activity, mood lability, and elements of paranoia. Psychiatrists have also posited that Willy Loman, the central figure in Arthur Miller's seminal play Death of a Salesman, presents with characteristics consistent with bipolar disorder.

The 2009 drama 90210 depicted a character, Silver, diagnosed with bipolar disorder. Similarly, Stacey Slater, a character in the BBC soap opera EastEnders, received a diagnosis of the disorder, with this narrative arc developed through the BBC's Headroom campaign. Earlier, the Channel 4 soap opera Brookside explored bipolar disorder through the character Jimmy Corkhill's diagnosis. In 2011, Showtime's political thriller drama Homeland introduced Carrie Mathison, a protagonist who had secretly managed bipolar disorder since her school years. The 2014 ABC medical drama Black Box also featured a globally recognized neuroscientist with the condition. The television series Dave portrays its titular main character, an aspiring rapper played by Lil Dicky as a fictionalized version of himself. Lil Dicky's real-life hype man, GaTa, also appears as himself in the series. In a particular episode, following a period without medication and experiencing an episode, GaTa emotionally reveals his bipolar disorder diagnosis. GaTa genuinely lives with bipolar disorder but, mirroring his on-screen persona, effectively manages it with medication.

Since 2024, Nicola Coughlan has co-starred with Lydia West in the British Channel 4 dark television comedy-drama Big Mood. Coughlan's character, Maggie, holds a leading role and is diagnosed with bipolar disorder. The series centers on two close friends navigating their relationship amidst a mental health crisis.

Creativity

Historical accounts from figures such as Socrates, Seneca the Younger, and Cesare Lombroso have posited a connection between mental illness and professional achievement or creativity. However, despite its prevalence in popular discourse, the relationship between creativity and bipolar disorder lacks rigorous scientific investigation. This field of inquiry is also potentially influenced by confirmation bias. Preliminary evidence indicates an overlap between certain heritable components of bipolar disorder and those associated with creativity. Individuals with a family history of bipolar disorder tend to exhibit greater professional success and display temperamental characteristics akin to those seen in bipolar disorder. Moreover, while research on the incidence of bipolar disorder within creative populations has yielded inconsistent results, the occurrence of full-spectrum bipolar disorder in such samples remains uncommon.

Special populations

Children

During the 1920s, Kraepelin observed the infrequent occurrence of manic episodes prior to puberty. Generally, bipolar disorder in pediatric populations remained largely unrecognized throughout the first half of the twentieth century. This diagnostic challenge lessened as adherence to DSM criteria became more widespread in the latter part of the century. Consequently, the diagnosis of childhood bipolar disorder, once contentious, has achieved broader acceptance among child and adolescent psychiatrists. In the United States, diagnoses of bipolar disorder among children and adolescents in community hospitals quadrupled, reaching up to 40% over a decade around the turn of the 21st century, while diagnoses in outpatient clinics doubled to 6%. Research employing DSM criteria indicates that up to 1% of young individuals may experience bipolar disorder. The DSM-5 introduced the diagnosis of disruptive mood dysregulation disorder to address children exhibiting chronic, persistent irritability, which had occasionally been misdiagnosed as bipolar disorder, distinguishing it from the irritability specific to discrete mood episodes in bipolar disorder.

Adults

On average, the onset of bipolar disorder occurs during adulthood. Specifically, Bipolar I typically manifests around 18 years of age, while Bipolar II generally begins around 22 years of age. Nevertheless, most individuals experience an average delay of eight years in seeking treatment following symptom onset. Bipolar disorder is frequently misdiagnosed as other psychiatric conditions. No definitive correlation has been established between bipolar disorder and race, ethnicity, or socioeconomic status (SES). Adults living with bipolar disorder often report a diminished quality of life, even during periods outside of manic or depressive episodes. The condition can significantly strain marital and other interpersonal relationships, impact employment, and impair daily functioning. Bipolar disorder is linked to elevated rates of unemployment. Many individuals struggle with job retention, which can impede access to healthcare and subsequently lead to a further deterioration in mental health due to insufficient treatment, including medication and therapy.

Elderly

Bipolar disorder exhibits a low prevalence among older adults, with a documented lifetime prevalence of 1% in individuals over 60 and a 12-month prevalence ranging from 0.1% to 0.5% in those over 65. Nevertheless, it is disproportionately represented in psychiatric admissions, accounting for 4% to 8% of inpatient admissions to aged care psychiatry units, aligning with a general increase in mood disorder incidence within the aging demographic. Depressive episodes in older patients frequently manifest as sleep disturbances, fatigue, future-oriented hopelessness, cognitive slowing, and impaired concentration and memory; the latter three symptoms are characteristic of pseudodementia. Furthermore, clinical presentations vary between individuals with late-onset bipolar disorder and those with early-onset forms. The late-onset group typically experiences milder manic episodes, more pronounced cognitive alterations, and a history of poorer psychosocial functioning. Conversely, the early-onset group more often presents with mixed affective episodes and demonstrates a stronger familial predisposition to the illness. Older individuals diagnosed with bipolar disorder commonly experience cognitive deficits, particularly affecting executive functions such as abstract reasoning, cognitive set-shifting, sustained attention, and decision-making.

Individuals Diagnosed with Bipolar Disorder

• List of people with bipolar disorder
• Overview of Bipolar Disorder
• Depression and Bipolar Support Alliance

Notes

References

Cited Texts