Mood disorders (depressive and bipolar spectrum)
Questions here turn on episode definition, specifiers, and the switch-risk logic that decides whether an antidepressant is allowed.
Core rules
- Major depressive episode: five of nine symptoms for two weeks, including depressed mood or anhedonia, with functional change; exclude mania and hypomania before prescribing.
- Mania: elevated, expansive or irritable mood with increased energy for at least one week, or any duration if hospitalization is required, plus three of seven symptoms (four if mood is only irritable): grandiosity, decreased sleep need, pressured speech, flight of ideas, distractibility, increased goal-directed activity, risky behaviour.
- Hypomania: same symptom set for at least four consecutive days, observable by others, without marked impairment, psychosis or hospitalization.
- Bipolar I requires a manic episode; bipolar II requires hypomania plus a major depressive episode; never upgrade for irritability alone.
- Specifiers that examiners love: mixed features (three opposite-pole symptoms nearly every day), rapid cycling (four or more episodes in twelve months), psychotic features, melancholic, atypical (hyperphagia, hypersomnia, leaden paralysis, rejection sensitivity), peripartum, seasonal.
- Lithium remains the reference mood stabilizer: it reduces suicide and relapse, needs renal, thyroid and calcium monitoring, and is toxic above about 1.2 mEq/L; thiazides, NSAIDs and ACE inhibitors raise levels, while sodium depletion does too.
- Antidepressant monotherapy in bipolar disorder risks switch and rapid cycling; pair with a mood stabilizer or avoid.
Worked example
A 28-year-old woman has had four depressive episodes and one period of four days with reduced sleep, fast speech and shopping sprees that her family noticed but that did not impair her work. The four-day episode is hypomania; with recurrent depression this is bipolar II, so the answer is a mood stabilizer (lithium, lamotrigine or quetiapine) rather than antidepressant monotherapy.
Traps
Calling bipolar II a milder form of bipolar I; missing hypomania by relying on the current episode only; using antidepressants as monotherapy in bipolar depression; ignoring mixed features when assessing suicide risk.