A severe and persistent mental illness characterized by delusions, hallucinations, disorganization of thought and behavior, cognitive dysfunction, and impairment in reality testing


  • Major psychiatric disorder with a variable course, typically involving prodromal, active, and residual psychotic symptoms with disturbances in thought, speech, affect, behavior, and perception
  • DSM-5 eliminated subcategories of schizophrenia (paranoid, disorganized, catatonic, etc.).
  • System(s) affected: central nervous system (CNS)



  • 0.3–0.7% of the population >18 years old
  • Age of onset: typically <30 years, earlier in males (late teens to mid-20s) than females (early 20s to early 30s)

Etiology and Pathophysiology

  • A complex interaction between genetic and environmental factors
  • Overstimulation of mesolimbic dopamine D2 receptors, deficient prefrontal dopamine, and aberrant prefrontal glutamate (NMDA) activity result in perceptual disturbances, disordered thought process, and cognitive impairments.

If first-degree biologic relative has schizophrenia, risk is 8–10%.

Risk Factors

  • Antenatal risk factors include prenatal infection or malnutrition, obstetric complications leading to hypoxia, winter births, postnatal infections requiring hospitalization, urban birth, and advanced paternal age.
  • Risk factors across the lifespan include adolescent cannabis use, childhood trauma, urban residence, autoimmune disorders, severe and repeated stress, lower socioeconomic status, minority status, being a first- or second-generation immigrant, and inadequate social support.

General Prevention

Educate all patients on the risks around cannabis use, especially those in a potential prodromal period or those with a family history of psychosis.

Commonly Associated Conditions

  • Nicotine dependence (>50%) and substance use disorders
  • Metabolic syndrome, diabetes mellitus, and obesity

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