ch 15.15 & 15.16- Biology of Schizoprenia + Genetic & Environmental Influences

Schizoprenia & the Brain

Decreased frontal lobe activation: important for executive functions, can’t organize speech and behaviour like a normal individual

Enlarged ventricles due to widespread loss of brain matter: persistent illusions

• likely stress related

Progressive deterioration over repeat brain scans: reduction in function after more and more psychotic episodes

Schizophrenia & Neurotransmitters

Overactive dopamine associated with positive symptoms, ex: delusions and hallucinations

Glutamate-blocking drugs produce negative symptoms that mimic those in schizoprenia: unable to properly generate signals and behaviour contribute to producing certain behaviours and thought patterns ( lots of glutamate goes to frontal lobe)

Schizoprenia & Genetics

if one identical twin has schizophrenia, the other twin has a 25-50% chance of also developing it, but not 100% (monozygotic twins have most) (large role for environmental introducing the trait)

Estimated that 10% of the population has a gene sequence that puts them at risk (role for environment)

Environmental Influences on Schizophrenia

Maternal exposure to influenza virus: born in later winter months are more at risk of developing as adults

Fetal exposure to stress: mothers coming from famine or loss of loved one

Marijuana use: people already with susceptibility can induce symptoms

Head injuries: before age of 10 can increase risk for those with genetic underlying

Stressful rearing environments: higher rates in urban environments such as poverty & air pollution

Supportive family environment protects against relapse: important social environment are 3-4x less likely to relapse

Neuro developmental hypothesis

Emergence of schizophrenia in early adulthood due to outgrowth of neurological systems previously disrupted- disruption to our environment

2 predicting periods: maternal infection (1st trimester), adolescent period (frontal lobe and prefrontal cortex development)

Prognosis

Despite common perception, prognosis is not entirely poor

Early treatment and proper social support vastly improved prognosis - can minimize number of episodes someone experiences

Relapses common, though most people make functional recoveries