Biological Explanations for schizophrenia(A01) Topic 2

TOPIC 2 - biological explanation for schizophrenia

What are biological explanations?

Biological explanations suggest schizophrenia has a strong genetic basis.

Family studies

Family studies show the closer the genetic relationship, the higher the risk.

Research on Family studies

Gottesman found a 2% chance if an aunt had schizophrenia, 9% for a sibling and 48% for an identical twin, compared to 1% of the population. This supports a genetic contribution, although family members share environments.

Polygenetic 

Schizophrenia is polygenic(caused by many genes) and aetiologically heterogenous(different combinations of genes lead to vulnerability).

Ripke study

Ripke et al found 108 genetic variations linked with a slightly increased risk, supporting this view. Additionally, new mutations in parental DNA may explain cases without family history, with parental age being a risk factor.

Dopamine hypothesis explanation(another major explanation)

The original version argued that hyperdopaminerga in subcortical brain regions causes positive symptoms such as hallucinations/speech poverty. The updated hypothesis suggests hypodopaminergia in the prefrontal cortex underlies negative symptoms such as avolition, with both genetic vulnerabilities and early stress increasing dopamine sensitivity.