Mood Disorders (Depressive and Bipolar Spectrum)
Depressive disorders
Know the core symptom clusters: mood, anhedonia, energy, sleep, appetite, psychomotor change, guilt/worthlessness, concentration, suicidal ideation. Duration thresholds matter: major depressive episode (2 weeks), persistent depressive disorder (2 years), premenstrual dysphoric disorder, disruptive mood dysregulation disorder in children. Exclude substance/medical causes and screen for bipolarity before starting antidepressants.
Bipolar spectrum
Bipolar I requires a manic episode (≥1 week or hospitalisation, marked impairment, psychosis possible); bipolar II requires hypomania (≥4 days, no marked impairment, no psychosis) plus depression. Mixed features, rapid cycling (≥4 episodes/year), and cyclothymia must be recognised. Traps: missing hypomania because the patient presents depressed; attributing irritability to personality; forgetting postpartum psychosis as a bipolar-spectrum emergency.
Treatment principles
Acute mania: antipsychotic ± mood stabiliser; avoid antidepressant monotherapy. Bipolar depression: quetiapine, lamotrigine or lithium, cautious antidepressant use with mood stabiliser cover. Unipolar depression: psychotherapy, SSRI/SNRI, augmentation (lithium, aripiprazole), ECT for severe or treatment-resistant illness.
Worked rule of thumb
Before diagnosing unipolar depression, ask about any lifetime period of elevated mood, increased energy and reduced need for sleep lasting at least 4 days. A positive screen changes drug choice and prognosis.