Psychiatry: Diagnosis, Risk Assessment, and Treatment Selection
Core concepts
Psychiatry questions test syndromic reasoning and safety. Know the defining features of major depressive disorder (≥2 weeks, depressed mood/anhedonia plus neurovegetative symptoms, impairment), bipolar I vs II (mania vs hypomania, no psychotic features in hypomania), schizophrenia (≥6 months with ≥1 month active symptoms, functional decline), and anxiety disorders. Understand substance withdrawal timelines (alcohol and benzodiazepine withdrawal can be life-threatening; opioid withdrawal is distressing but rarely fatal). Be comfortable with first-line pharmacotherapy and its risks: SSRIs for depression/anxiety (serotonin syndrome, hyponatremia, discontinuation), mood stabilizers for bipolar (lithium toxicity, renal/thyroid effects; valproate teratogenicity), and antipsychotics (metabolic effects, EPS, NMS).
Traps in questions
The most common trap is missing bipolar disorder in a depressed patient-screen for prior mania/hypomania before starting an antidepressant, which can precipitate mania or rapid cycling. Another trap is underestimating suicide risk: ask directly; prior attempts, plan, access to means, and hopelessness elevate risk. Distinguish delirium from psychosis (acute, fluctuating, disoriented). Do not confuse grief with major depression (grief is waves of sorrow with preserved self-esteem; depression is persistent with worthlessness).
Worked example / rule of thumb
A young adult with depressed mood, insomnia, and a history of a week of decreased need for sleep and grandiosity likely has bipolar depression; the rule of thumb is screen for mania before prescribing an antidepressant, and consider a mood stabilizer. Always pair diagnosis with a risk assessment.