Bipolar Disorder

Genetic and neurodevelopmental (non-modifiable)

• Family history: the single strongest predictor; heritability is high (~80% as noted above), and a first-degree relative with bipolar I raises risk many-fold over baseline. Risk genes converge on ion-channel and synaptic scaffolding function (CACNA1C, ANK3), consistent with the neuronal excitability model.
• Age and sex: onset clusters in late adolescence/early adulthood; earlier onset predicts more episodes and more comorbid substance use. Sex prevalence is equal, but women are more likely to present first with depression and to have rapid cycling.
• Peripartum state: the postpartum period is the highest-risk window in a woman's life for a first or recurrent manic/psychotic episode — driven by abrupt hormonal withdrawal plus sleep fragmentation.

Environmental and modifiable

• Sleep deprivation and circadian disruption: shift work, jet lag, or a single sleepless night can precipitate mania; this is the mechanistic rationale for interpersonal and social rhythm therapy.
• Substance use: stimulants (cocaine, amphetamines), alcohol, and cannabis both precipitate episodes and worsen course; comorbid substance use disorder is the rule, not the exception.
• Antidepressant monotherapy: unopposed serotonergic/noradrenergic drive can trigger a manic "switch" or rapid cycling — the classic stem is depression treated with an SSRI that flips into mania.
• Psychosocial stress and childhood adversity: stressful life events and early trauma interact with genetic loading (gene–environment interaction) to advance onset.
• Non-adherence: the most common proximate cause of relapse, often because hypomania feels good.

Secondary (organic) mania to exclude

• Drugs: corticosteroids, levodopa/dopamine agonists, sympathomimetics, interferon.
• Endocrine: hyperthyroidism, Cushing syndrome.
• Neurologic: stroke or tumor involving right frontal/subcortical circuits, traumatic brain injury, multiple sclerosis, temporal lobe epilepsy, neurosyphilis, HIV.
• Clinical pearl: new-onset mania after roughly age 40, or mania accompanied by focal neurologic findings, cognitive decline, or an abnormal level of consciousness, should prompt a search for a secondary cause before labeling the illness primary bipolar disorder. DSM-5-TR (APA) itself requires only that a manic episode not be attributable to a substance or another medical condition; the age and neurologic red flags are teaching heuristics, not DSM criteria.

• Monoamine hypothesis: Dysregulation of serotonin, norepinephrine, and dopamine systems; mania involves hyperactivity in dopaminergic and noradrenergic pathways, while depression involves hypoactivity; mood stabilizers modulate these systems
• Second messenger system dysfunction: Abnormalities in intracellular signaling (particularly phosphoinositide cascade and protein kinase C), contributing to altered neuronal excitability and plasticity
• HPA axis dysregulation: Hyperactivity of the hypothalamic-pituitary-adrenal axis similar to unipolar depression; cortisol hypersecretion and dexamethasone suppression test abnormalities
• Circadian rhythm disruption: Alterations in circadian pacemaker function affecting sleep-wake cycles; sleep deprivation can trigger manic episodes
• Neuroinflammation and oxidative stress: Elevated inflammatory cytokines (IL-6, TNF-α), increased oxidative stress markers, and mitochondrial dysfunction
• Structural brain abnormalities: Reduced gray matter volume in prefrontal cortex and anterior cingulate; enlarged amygdala; abnormal white matter connectivity between limbic and prefrontal regions
• Genetic factors: Multiple susceptibility genes identified (BDNF, CACNA1C, ANK3); environmental stressors interact with genetic predisposition (gene-environment interactions)

• Elevated, expansive, or irritable mood (often irritable rather than euphoric, especially in adolescents and males)
• Grandiosity and inflated self-esteem: Unrealistic belief in abilities, increased goal-directed activity
• Decreased need for sleep (feels rested after 3 hours) — classic finding, often precedes full manic episode
• Racing thoughts and flight of ideas: Speech rapid, pressured, hard to interrupt; tangential or incoherent
• Distractibility and increased goal-directed activity: Excessive involvement in risky behaviors (spending sprees, sexual indiscretions, reckless driving)
• Psychotic features (in severe mania): Mood-congruent delusions of grandeur, paranoia

• Similar to mania but less severe, shorter duration, and no psychosis
• Mild impairment in functioning (unlike mania which causes marked impairment or hospitalization)
• Often feels subjectively pleasant to patient; may lead to treatment non-adherence

• Depressed mood, anhedonia, anergia: Indistinguishable from major depressive disorder
• Worthlessness, guilt, concentration problems, psychomotor changes, suicidal ideation
• Mixed features possible: Simultaneous depressive and manic symptoms (agitated depression with racing thoughts)

Between Episodes

• Euthymia: Return to baseline functioning; some patients have residual subsyndromal symptoms
• Rapid cycling: ≥4 mood episodes per year; associated with worse prognosis, bipolar II > bipolar I

Important Presentation Variants

• Bipolar I disorder: At least one manic episode (depressive episodes optional); more severe, higher hospitalization rates
• Bipolar II disorder: Hypomanic episodes and major depressive episodes, but no full manic episodes; more common than bipolar I; often misdiagnosed as unipolar depression
• Cyclothymia: Chronic fluctuation between hypomanic and depressive symptoms (not meeting full criteria) for ≥2 years; milder but unremitting course

• Clinical diagnosis based on DSM-5 criteria: No laboratory test confirms bipolar disorder; diagnosis requires careful history of mood episodes with specific duration, frequency, and symptom criteria from patient and collateral sources (family members often provide critical information)
• Structured mood assessment tools: MDQ (Mood Disorder Questionnaire) is sensitive screener; YMRS (Young Mania Rating Scale) and HDRS (Hamilton Depression Rating Scale) quantify symptom severity for tracking
• Medical workup to exclude secondary causes:
• Thyroid function (TSH, free T4): Hyperthyroidism can mimic mania; hypothyroidism depression
• Substance screening (urine drug screen, alcohol history): Stimulants (cocaine, amphetamines) cause manic-like states; alcohol/benzodiazepine withdrawal
• Brain imaging (MRI/CT): Rule out structural lesions, space-occupying lesions, multiple sclerosis if atypical presentation
• EEG: If seizure disorder suspected (temporal lobe seizures can mimic mood episodes)
• Careful differentiation from unipolar depression: Patient with unipolar depression misdiagnosed and treated with antidepressants alone may experience treatment-emergent mania ("switch"); detailed history of past mood states is essential
• Assess for psychotic features: Determine if psychosis is mood-congruent (bipolar) or mood-incongruent (suggests schizophrenia spectrum)

• First-line mood stabilizers:
• Lithium carbonate: Gold standard; therapeutic range 0.6-1.2 mEq/L (monitor levels 5 days after initiation, then regularly); requires baseline renal function, thyroid function, EKG; side effects include tremor, polyuria/polydipsia, cognitive dulling, teratogenicity (Ebstein anomaly in first trimester—use only if clear benefit >risk); narrow therapeutic window
• Valproate (divalproex): 1500-3000 mg/day; rapid onset; monitor LFTs, CBC; teratogenic (especially neural tube defects); more weight gain and metabolic effects than lithium
• Lamotrigine: Most effective for bipolar depression; less for acute mania; slower onset; requires slow titration to avoid Stevens-Johnson syndrome
• Atypical antipsychotics (FDA-approved): Quetiapine, olanzapine, aripiprazole, risperidone—often used first-line due to faster onset and easier dosing; combine with mood stabilizer for optimal response

• Acute sedation/behavioral control:
• Benzodiazepines (lorazepam, clonazepam) for agitation and insomnia; short-term only
• Intramuscular antipsychotic if patient refuses oral medication or is severely agitated

Acute Depression Management

• Mood stabilizers (lithium, valproate, lamotrigine)—lamotrigine preferred for depression
• Avoid antidepressants monotherapy: Risk of mood switch to mania; if needed, combine with mood stabilizer
• Atypical antipsychotics: Quetiapine has evidence for bipolar depression; aripiprazole augmentation
• ECT (electroconvulsive therapy): Rapid, effective for severe depression or mixed features, especially if suicidal

Maintenance/Long-term Management

• Lithium: Prevents both manic and depressive recurrence; reduces suicide risk
• Valproate/lamotrigine/atypical antipsychotics: Monotherapy or combination regimens; individualizing based on previous episode predominance (lithium or valproate if more manic; lamotrigine if more depressed)
• Psychosocial interventions: Cognitive-behavioral therapy, family-focused therapy, interpersonal social rhythm therapy (IPSRT) to stabilize sleep-wake cycle; essential for adherence and relapse prevention

Special Populations

Complications of the illness

• Suicide (emergency): risk is among the highest of any psychiatric disorder (lifetime ~10–15% as stated above); highest during depressive and mixed episodes, when depressive hopelessness coexists with the energy and impulsivity to act. Any new agitation plus suicidal ideation warrants immediate safety assessment and often hospitalization.
• Substance use disorders: self-medication plus shared impulsivity circuitry; worsens cycling and adherence.
• Premature cardiovascular death: the leading cause of mortality — from metabolic syndrome, smoking, sedentary behavior, and antipsychotic exposure, not from mania itself.
• Psychosocial ruin: bankruptcy, arrests, sexually transmitted infection, and job loss from manic risk-taking; cognitive deficits may persist into euthymia.

Complications of treatment

• Lithium toxicity (emergency): coarse tremor, ataxia, confusion, myoclonus, seizures, and arrhythmia. Lithium is handled like sodium and cleared entirely by the kidney, so anything that lowers renal lithium clearance raises the level:
• Volume depletion (vomiting, diarrhea, dehydration) and thiazides: distal sodium loss triggers compensatory proximal tubular sodium — and therefore lithium — reabsorption.
• NSAIDs: blocking renal prostaglandins reduces renal blood flow and enhances proximal reabsorption.
• ACE inhibitors/ARBs: reduce efferent arteriolar tone and GFR, lowering filtered lithium clearance.
• Management is aggressive isotonic fluids; hemodialysis for severe neurotoxicity, renal failure, or very high levels.
• Chronic lithium effects: nephrogenic diabetes insipidus (collecting-duct ADH resistance → polyuria/polydipsia), chronic tubulointerstitial nephritis, hypothyroidism/goiter, and hyperparathyroidism with hypercalcemia. Monitor renal and thyroid function periodically.
• Valproate: hepatotoxicity, pancreatitis, thrombocytopenia, and hyperammonemic encephalopathy (urea-cycle interference → lethargy/confusion with normal LFTs) — check ammonia, not just transaminases. Also weight gain and PCOS-like hyperandrogenism.
• Lamotrigine: Stevens–Johnson syndrome/TEN (emergency) — any rash during titration means stop the drug; risk rises with fast titration or valproate co-administration (valproate inhibits lamotrigine glucuronidation).
• Carbamazepine: agranulocytosis/aplastic anemia, SIADH-type hyponatremia, and autoinduction; FDA labeling advises **HLA-B*1502** screening in patients of Asian ancestry before use.
• Antipsychotics: metabolic syndrome, akathisia, tardive dyskinesia, and neuroleptic malignant syndrome (emergency) — fever, rigidity, autonomic instability, elevated CK.
• Antidepressant-induced switch or rapid cycling: the iatrogenic complication examiners love.
• Teratogenicity: valproate (neural tube defects, reduced childhood IQ) is avoided in pregnancy per ACOG and neurology guidance; lithium carries first-trimester Ebstein anomaly risk.

• Decreased need for sleep is the highest-yield discriminator: feeling rested after 3 hours (not insomnia with fatigue) points to mania. A stem describing a patient who "hasn't slept in days and feels great" is bipolar until proven otherwise.
• One manic episode = bipolar I, forever: no depressive episode is required. Bipolar II requires both a hypomanic and a major depressive episode and, by definition, never a full manic episode — a single manic episode reclassifies the patient as bipolar I.
• First presentation of mania — sequence matters:
• If the patient is severely agitated or dangerous, safety and behavioral control come first (de-escalation, an antipsychotic ± a benzodiazepine, involuntary hold if needed).
• In parallel, exclude mimics: urine drug screen, TSH, and pregnancy test, with baseline renal function, electrolytes, and ECG before starting lithium. DSM-5-TR (APA) requires that a manic episode not be attributable to a substance or another medical condition; the specific panel above is standard clinical practice rather than a DSM-listed workup.
• Antidepressant monotherapy is the classic distractor in a patient with "treatment-resistant depression" who later becomes euphoric and hypersexual. Always screen for past hypomania before starting an SSRI; treatment-emergent mania that persists beyond the drug's physiologic effect counts toward a bipolar diagnosis under DSM-5-TR.
• Lithium has the strongest evidence for reducing suicide risk in bipolar disorder — largely from observational cohorts and meta-analyses rather than dedicated randomized trials — so pick it when the stem emphasizes recurrent suicidality. Safety planning, means restriction, and treating the mood episode itself remain part of the answer.
• Know the lithium interaction triad: NSAIDs, thiazides, and ACE inhibitors/ARBs all reduce renal lithium clearance and raise levels; a patient started on one of these who develops coarse tremor and ataxia has toxicity, not worsening illness.
• Rash on lamotrigine = stop the drug, do not dose-reduce; and remember valproate raises lamotrigine levels, mandating slower titration.
• Mania vs. mimics: cocaine/amphetamine intoxication (positive tox screen, shorter course), hyperthyroidism (tremor, weight loss, suppressed TSH), and steroid-induced mood change all reproduce the syndrome. In schizoaffective disorder, psychosis persists ≥2 weeks without prominent mood symptoms — that time relationship is the tested distinction.