Characteristic Symptoms of Schizophrenia

1. Overview & Epidemiology

Schizophrenia — from the Greek roots schizein ("to split") and phren ("mind"). A chronic psychotic disorder characterised by auditory hallucinations, paranoid or bizarre delusions, and disorganised speech and thinking, in the context of significant social or occupational dysfunction. Onset is typically in young adulthood.

Who named what — the historical figures (examiner's favourite)

Epidemiology (→ PSY-1.2)

• Lifetime prevalence ~1% (about 1 in 100). Annual incidence per Gajdos/DSM-IV-TR ≈ 0.5–5.0 / 10,000; higher in those born in urban areas of industrialised nations.
• Equal prevalence in males and females, but onset differs:
  • Males: ~15–25 years (peak 20–28).
  • Females: ~25–35 years (peak 26–32) — later, with a smaller second peak around menopause.
• Comorbidity: after smoking (the single most prevalent comorbidity, 75–90%), the most prevalent comorbid disorder is alcohol dependence. Cannabis use can contribute to psychosis and earlier onset in vulnerable individuals.
• Genetics: complex/polygenic inheritance; risk genes are non-specific and overlap with other psychotic disorders (e.g. bipolar disorder).

Epidemiology cross-check (→ PSY-1.5): OCD lifetime prevalence ≈ 2–3% (not 10%); PTSD ≈ 1–2%; eating disorders are 10–20× more common in females (not males); gambling disorder is more common in males.

---