Schizophrenia

Basics

A chronic psychotic disorder characterized by delusions, hallucinations, disorganization, negative symptoms, and cognitive deficits:
- Premorbid phase:
  - Development of negative symptoms: Apathy, anhedonia, avolition, alogia, affect blunting
  - Deterioration of personal, social, and cognitive functioning
- Active phase:
  - Development of positive symptoms: Paranoia, ideas of reference, delusions, hallucinations, disorganized speech, disorganized behavior
  - May be precipitated by a stressful event or substance use
- Residual phase:
  - Patients are left with negative symptoms, impaired social and cognitive abilities
  - Psychotic symptoms may persist
Onset typically early in adulthood
- Men: Ages 18–25; Women: Ages 25–35
- Rarely occurs in childhood or age >45
Common comorbidities: Depression, anxiety, substance abuse, neurological symptoms, metabolic disturbances
Life expectancy on average is 28.5 yr lower than the general population:
- Cardiovascular disease is the most common cause of death
- 5% of patients commit suicide
- Patients may have difficulty accessing or adhering to medical treatment
- Disorganized thinking, abnormal behavior, and delusions may obscure the detection of medical illness when patients present for care
Medication nonadherence is a common reason for psychiatric decompensation and presentation to the ED

Pathophysiology unclear but dopamine and glutamate pathways are implicated
Genetic component (concordance rate of 50% in monozygotic twins)
- Likely polygenetic disorder: Impact of multiple genes with small, additive effect
- Complement component C4: Increased expression associated with increased synaptic pruning during neurodevelopment
- Higher risk in patients with DiGeorge syndrome (22q11.2 deletion)
Perinatal risk factors:
- Influenza during second trimester
- Maternal and postnatal infections
- Advanced paternal age
Environmental risk factors:
- Immigration
- Urban living environment
Use of cannabis may unmask psychosis in predisposed individuals

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