Bipolar affective disorder in late life

Definition and terminology. Older-age bipolar disorder (OABD) refers to bipolar disorder in those aged ≥50–60 years. Two groups exist — early-onset illness ageing into old age (about two-thirds) and late-onset disease with first episode after 50 (about one-third).

Epidemiology. Community prevalence is only 0.5–1% above 65 years, but bipolar disorder accounts for 5–10% of geriatric psychiatry outpatients and a large share of psychiatric emergency presentations. It is one of the three conditions classed as severe mental illness (SMI), along with schizophrenia and schizoaffective disorder.

Late-onset mania is "secondary mania" until proved otherwise. Strong association with cerebrovascular disease ("vascular mania"), right frontal or basotemporal stroke, head injury, frontotemporal dementia, hyperthyroidism, and drugs — corticosteroids, levodopa, antidepressants.

Clinical features. Mania is attenuated with age — irritability, dysphoria, confusion and paranoia rather than classic euphoria. Mixed states are common; depressive episodes are more frequent and longer; cognitive impairment is prominent and may mimic dementia ("pseudo-dementia of mania").

Differential diagnosis. Unipolar depression (the commonest misdiagnosis), delirium, frontotemporal dementia, agitation of dementia, alcohol/substance misuse, hyperthyroidism, and steroid-induced mood change.

Assessment. Full physical and neurological examination, complete drug review, TSH, sodium (mEq/L), calcium (mg/dL), renal and liver function, B12, ECG, cognitive testing, and neuroimaging in every first-ever manic episode. Always assess suicide risk — cardiovascular disease is the leading cause of death in SMI, but suicide remains a major contributor.

Acute mania — management. Lithium or valproate is first-line. The GERI-BD trial (the only RCT in those ≥60 years) found lithium and divalproex comparably effective, with lithium marginally superior on symptom reduction. Atypical antipsychotics (quetiapine, aripiprazole, risperidone) at one-third to one-half adult dose. ECT for severe, refractory or catatonic mania.

Lithium in the elderly. Remains the gold standard for maintenance and the only agent with a proven anti-suicidal effect. Use 30–50% lower doses and lower target levels. Monitor creatinine (mg/dL), eGFR, TSH, calcium, ECG. Toxicity is precipitated by thiazides, ACE inhibitors/ARBs, NSAIDs, dehydration, diarrhoea and fever; neurotoxicity can occur at apparently therapeutic levels.

Alternative mood stabilisers. Valproate — monitor LFT, platelets, ammonia (hyperammonaemic encephalopathy), parkinsonism, weight gain. Lamotrigine — best for bipolar depression maintenance; needs slow titration because of rash and Stevens–Johnson syndrome. Carbamazepine — best avoided (enzyme induction, hyponatraemia, interactions). Antidepressant monotherapy is contraindicated — risk of switch and rapid cycling.

Course, comorbidity and outcome. High burden of metabolic syndrome and cardiovascular disease, greater risk of cognitive decline and dementia, poor medication adherence, functional impairment and excess mortality (CVD death 2–3 times general population). Management must include psychoeducation, adherence support, carer involvement, and aggressive cardiovascular risk factor control.

ISBD Older-Age Bipolar Disorder Task Force (2025–26 systematic review, Bipolar Disorders). Supports age-stratified lithium targets rather than the adult range of 0.6–1.2 mEq/L: 0.4–0.8 mEq/L for ages 60–79 years and 0.4–0.7 mEq/L for those ≥80 years, with more frequent renal monitoring.

AGS Beers Criteria 2023 and current reviews (2024–25). Beers flags lithium with loop diuretics or ACE inhibitors as potentially inappropriate unless levels are closely monitored. Contemporary reviews confirm quetiapine and aripiprazole as the preferred antipsychotics in OABD (least EPS and metabolic burden), and note a possible neuroprotective / dementia-risk-reducing signal for lithium.