5.09 Schizophrenia
Psychiatry review for the USMLE Step 1 Exam
- Epidemiology:
- Slight male predilection (1.4:1 male to female ratio).
- Men present between 18-25, women between 28-35.
- Affects about 0.5% of the population.
- Symptoms:
- Positive symptoms: hallucinations, delusions, disorganized behavior and speech.
- Negative symptoms: flat affect, anhedonia, apathy, alogia, lack of interest in socialization.
- Cognitive symptoms: impairments in attention, executive function, working memory.
- Diagnosis:
- Criteria: two or more symptoms lasting over a month.
- Schizophreniform disorder if symptoms last less than 1 month.
- Pathophysiology:
- Excess dopamine in prefrontal cortical pathway (negative symptoms).
- Excess dopamine in mesolimbic pathway (positive symptoms).
- Other neurotransmitters may also play a role (especially serotonin excess).
- Treatments:
- Antipsychotics (D2 receptor antagonists).
- First-generation antipsychotics: haloperidol, chlorpromazine (more side effects).
- Second-generation antipsychotics (atypical antipsychotics): aripiprazole, olanzapine, quetiapine, risperidone (lower extrapyramidal side effects, higher metabolic side effects).
- Outcomes:
- Rule of thirds: one-third full recovery, one-third improved with mild symptoms, one-third require high-level care.
