Bipolar disorder is a chronic, recurrent mood disorder characterized by alternating episodes of pathologically elevated mood (mania or hypomania) and major depression, with euthymic intervals between episodes. Lifetime prevalence is approximately 1-2% globally with no significant sex difference. Heritability is among the highest in psychiatry (60-85%), with first-degree relatives having 5-10x increased risk. Pathophysiology involves disturbances in monoaminergic neurotransmission, neuroplasticity, mitochondrial function, circadian rhythms, and neuroinflammation. Suicide risk is significantly elevated (lifetime 6-15% versus general population 1%), and bipolar disorder is associated with substantial morbidity, functional impairment, and reduced life expectancy (10-15 years from cardiovascular disease, suicide).
DSM-5-TR distinguishes: Bipolar I disorder (>=1 manic episode lasting >=7 days or requiring hospitalization, with elevated/expansive/irritable mood plus >=3 of 7 symptoms: inflated self-esteem/grandiosity, decreased sleep need, more talkative/pressured speech, flight of ideas, distractibility, increased goal-directed activity or psychomotor agitation, excessive risky behavior; depressive episodes typically present but not required for diagnosis); Bipolar II disorder (>=1 hypomanic episode lasting >=4 days plus >=1 major depressive episode; never had a manic episode; less functional impairment than mania); Cyclothymic disorder (>=2 years of fluctuating subthreshold hypomanic and depressive symptoms); other specified bipolar disorder. Specifiers include rapid cycling (>=4 mood episodes/year), psychotic features (mood-congruent or incongruent), mixed features (manic and depressive symptoms simultaneously), peripartum onset, seasonal pattern, and anxious distress.
Treatment is phase-specific and individualized: acute mania treated with mood stabilizers (lithium 600-1800 mg/day with target serum level 0.6-1.2 mEq/L, valproate 750-2000 mg/day with serum level 50-125 mcg/mL) and/or atypical antipsychotics (olanzapine, risperidone, quetiapine, aripiprazole, asenapine, ziprasidone), often in combination for severe mania; acute bipolar depression managed with quetiapine, lurasidone, olanzapine-fluoxetine combination, lamotrigine (better for prevention than acute), or cariprazine; antidepressant monotherapy is contraindicated due to manic switching risk. Maintenance therapy with lithium (gold standard, anti-suicide effects), valproate, lamotrigine (better for depressive recurrence), or atypical antipsychotics is essential to prevent recurrence. Adjunctive psychosocial interventions include psychoeducation (Barcelona protocol), CBT, family-focused therapy, interpersonal and social rhythm therapy (IPSRT), and group therapy. Electroconvulsive therapy (ECT) effective for severe/treatment-resistant mania, mixed states, depression with psychosis, catatonia, and pregnancy. Long-term complications include cognitive deficits, cardiometabolic comorbidity (lithium nephrotoxicity, valproate teratogenicity, atypical antipsychotic weight gain/diabetes), substance use disorders (40-60%), and elevated suicide risk requiring lifelong management.