Diagnose: Applying DSM Criteria Precisely
What the Diagnose domain rewards
This domain tests criterion-level accuracy. Know duration thresholds, required symptom counts, exclusion criteria, and specifiers for high-yield disorders: major depressive disorder (2 weeks, 5 of 9 symptoms, one must be depressed mood or anhedonia), bipolar I (7 days or hospitalization for mania; 4 days for hypomania in bipolar II), schizophrenia (6 months total, 1 month active symptoms, functional decline), GAD (6 months), panic disorder (recurrent unexpected attacks plus 1 month of worry/behavior change), PTSD (1 month, trauma exposure, four symptom clusters), OCD, ADHD (symptoms before age 12, two settings), and personality disorders.
Traps to expect
- Substance/medical exclusion: mania or psychosis induced by a stimulant or steroid is not primary bipolar or schizophrenia.
- Unipolar vs. bipolar: any history of mania or hypomania converts the diagnosis to bipolar; treating with an antidepressant alone is the classic wrong answer.
- Grief vs. MDD: normal bereavement can include sadness but persistent functional impairment or psychosis points to MDD.
- Specifiers matter: with anxious distress, with mixed features, with peripartum onset, in partial remission.
- Differential by time course: brief psychotic disorder (1 day–1 month), schizophreniform (1–6 months), schizophrenia (6+ months).
Rule of thumb
Count symptoms against the criterion, check duration, then check exclusions. If the vignette shows a substance or medical condition that better explains the picture, that exclusion wins.
Worked example
A 24-year-old has 5 days of elevated mood, decreased sleep, pressured speech, and grandiosity after starting a high-dose stimulant. Answer: substance-induced bipolar-like presentation, not bipolar I disorder, until symptoms persist beyond the expected physiologic effect.