Psychiatry and Behavioral Sciences
Core concepts
Psychiatry questions test pattern recognition across time course and function. Know the diagnostic anchors: major depressive disorder (2 weeks, five or more symptoms, functional impairment), bipolar disorder (mania: elevated mood or irritability plus increased energy, decreased need for sleep, grandiosity, risky behavior), schizophrenia (6 months, positive and negative symptoms, functional decline), and anxiety disorders by trigger and duration. Understand substance withdrawal timelines (alcohol and benzodiazepine withdrawal can be fatal), delirium versus dementia (acute fluctuating attention deficit versus chronic progressive cognitive decline), and suicide risk assessment. Know first-line pharmacology and its monitoring.
Traps
The most common trap is missing bipolar disorder in a depressed patient - screening for prior manic or hypomanic episodes before starting an antidepressant is essential, since antidepressants can precipitate mania or rapid cycling. Another is confusing delirium with dementia; delirium is acute, fluctuating, and attention-predominant. Questions also test that psychosis in the elderly or new-onset psychosis warrants medical workup. Watch for the difference between dysthymia (persistent, milder) and major depression, and remember that capacity and involuntary commitment are legal-clinical judgments, not diagnoses.
Worked rule of thumb
For any mood stem, ask three questions: (1) Has there ever been a manic or hypomanic episode? If yes, the diagnosis is bipolar spectrum, and the treatment is a mood stabilizer, not antidepressant monotherapy. (2) Is there psychosis, suicidality, or grave disability? If yes, safety planning and possible involuntary evaluation take priority. (3) Is there a medical or substance cause? Example: a 25-year-old with 3 weeks of low mood, insomnia, and anhedonia who reports a prior week of little sleep with racing thoughts and spending sprees - bipolar disorder; start a mood stabilizer and avoid antidepressant monotherapy.