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Basics
Description
Syndrome seen with schizophrenia, schizoaffective disorder, mood disorder, substance use, medical problems, delirium, and dementia; symptoms include:
- Positive symptoms: Hallucinations and delusions (fixed false and often paranoid beliefs created as the patient loses the ability to correct errors in thinking)
- Negative symptoms: Apathy, avolition, withdrawal, paucity of speech
- Disorganized speech/behavior
Epidemiology
Prevalence
- Schizophrenia: Peak onset 18–25 years in men; women peak onset 25–35 years
- Schizophrenia: 1% of the US population; thought to be similar worldwide
- Delusional disorder: 0.03% of population
- Bipolar type I: 1% of population
- Prevalence in major depression not known
Risk Factors
Substance abuse (particularly marijuana), family history of psychosis, lower socioeconomic status
Genetics
Schizophrenia: 50% concordance for monozygotic twins, little or no shared environmental effect; multiple candidate genes involving disruption of neurodevelopment
General Prevention
Community interventions for early detection and treatment of prodromal symptoms show promise.
Pathophysiology
Neurodevelopmental predisposition + 1st/3rd trimester in utero insult (e.g., 1st trimester infection or 3rd trimester birth hypoxia) leads to exaggerated neuronal apoptosis in late adolescence with subsequent thalamic sensory overload. Increased dopaminergic mesolimbic transmission may contribute to delusions and hallucinations in schizophrenia. Dopamine deficiency in mesocortical pathways may contribute to frontal lobe hypoactivity often associated with apathy and withdrawal in schizophrenia. Glutamate, neurosteroids, and neurodevelopmental abnormalities are active areas of research.
Etiology
Postulated stress-diathesis model: Individuals biologically at risk develop psychosis when under stress.
Commonly Associated Conditions
- Serious mental illness is associated with metabolic syndrome, autonomic dysfunction, sudden cardiac death.
- Cancer mortality: Particularly breast and lung cancer
- Substance abuse disorders, including nicotine dependence
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