Definition: a mental disorder that includes a broad range of perceptual, cognitive and behavioral disturbances.

• Brief Psychotic disorder: >1 day and < 1 month 

• Schizopheniform disorder: >1 month and < 6 month 

• Schizophrenia: > 6 months 

• Schizoaffective disorder: Schizophrenia + major affective disorder

 

Epidemiology: 

• Point prevalence of the condition is 0.5-1% throughout the world

• The peak age of onset is the early 20s 

 

 

Causes: 

• Genetic and multiple environmental factors that affect brain development.

• Schizophrenia has a heritability of about 60%. (47% in monozygotic twins, 12% in dizygotic twins)

• Early use of Cannabis may be a risk factor.

• Dopamine excess (D2) in mesolimbic pathways is the oldest and most widely accepted neurochemical hypothesis.

 

Pathophysiology:  

• Anatomical abnormalities:

  • Ventricular enlargement: mainly with negative symptoms.

  • Reduced brain size.

  • Reduced connectivity between the frontal and temporal lobes.

• Neurotransmitter abnormalities:

  • ↑dopamine, serotonin, and alpha-adrenergic activity.

  • ↓GABA and glutamate activity.

  • Mainly seen in the mediodorsal thalamic nucleus in the prefrontal cortex. 

 

Signs and Symptoms: 

• Auditory hallucinations in the third person, and/or voices commenting on their behavior 

• Thought withdrawal, insertion and broadcast 

• Primary delusion (arising out of nothing)

• Delusional perception

• Somatic passivity and feelings – patients believe that thoughts, feelings or acts are controlled by others