The distinctions that define management
- Bipolar I = ≥1 manic episode (depression common, not required).
- Bipolar II = ≥1 hypomanic + ≥1 major depressive episode, never mania. (Not "milder" — the depressive burden is often greater.)
- Rapid cycling = ≥4 mood episodes in 12 months; a course specifier, often antidepressant‑aggravated.
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Why the diagnosis dominates treatment
- Antidepressant monotherapy is contraindicated in bipolar depression — switch/cycling risk. Anchor on a mood stabiliser (lithium, valproate, lamotrigine for depression‑predominant) ± an atypical antipsychotic; treat bipolar depression with agents with evidence (e.g., quetiapine, lurasidone, lithium, lamotrigine).
- Lithium — narrow therapeutic index (0.6–0.8 mmol/L maintenance): monitor levels, renal and thyroid function; the strongest anti‑suicidal evidence base. Toxicity (tremor→ataxia→confusion→seizure) is an emergency; beware NSAIDs, ACE‑inhibitors, diuretics, dehydration.
- Valproate — teratogen; avoid in people of childbearing potential without a pregnancy‑prevention programme.
- Lamotrigine — titrate slowly (SJS/TEN risk).
The clinical detection problem
Bipolar II is routinely missed because patients present in depression and don't volunteer hypomania (they liked it). In every recurrent/treatment‑resistant/early‑onset/postpartum depression, actively screen: "Have you had days needing little sleep but full of energy, unusually talkative, confident, or doing things out of character?"
Pitfalls
- Diagnosing "treatment‑resistant depression" that is actually undetected bipolar disorder.
- Starting valproate in a woman of childbearing potential.
Pearls
- 🎯 Mania = Bipolar I; hypomania + depression (no mania) = Bipolar II.
- 🩺 The most important question in recurrent depression: "Have you ever had a period of abnormally high energy with reduced need for sleep?"
Next → From mood to the anxiety/fear‑related disorders (Concept 20).