Schizophrenia

Symptoms #

• Delusions (beliefs that are false, and not amenable to change)
• Hallucinations (perceptions that are not associated with an external stimulus, and cannot be experienced by others)
• Disorganized speech (frequent derailment, incoherence)
• Grossly disorganized or catatonic (unresponsive) behavior
• Negative symptoms (normal behaviors are reduced)
  • Avolition: decreased motivation
  • Alogia: decreased speech
  • Anhedonia: decreased pleasure
  • Lack of sociality

Prevalence #

Childhood-onset schizophrenia (COS) is defined as onset before 13th birthday. This is relatively rare (1 in 10000).

Late-onset schizophrenia is more common (5-7 in 1000).

Etiology #

Precursors to COS include:

• hallucinations and delusions
• social withdrawal
• symptoms of autism and ADHD
• speech, language, motor problems

COS has a slow onset, and is nonremitting and chronic. The best predictor of COS is the premorbid functions.

Genetics #

High heritability factor for COS: >80%

• more heritable than late-onset schizophrenia

Molecular gene studies have identified some candidate genes associated with COS (such as G72, DTNBP1, and GAD1). There are also some copy number variants (deletions/duplications of DNA segments) associated with COS.

Risk Factors #

• Pregnancy complications
• Abnormal fetal growth/development
• Delivery complications

The main endophenotype resulting from these factors is abnormal brain development.

Since COS is a neurodevelopmental disorder, it is the behavioral outcome of a development process that begins long before expression of symptoms.

Cortical Development #

In typical development, cortical development continues into adolescence and young adulthood. Grey matter volumes usually increase in late childhood, then decrease (GM thinning) during puberty.

However, in COS, studies have observed a progressive grey matter loss that is more rapid than typical. GM loss normalizes by age 24, and is localized to prefrontal and temporal cortices.