Biological explanations of Sz Flashcards
Kendlar
those with a 1st degree relative with sz were 18x more likely to develop it.
Gottesman
family study
identical twins- 48%
sibling 9%
1 parent 6%
2 parents 46%
Impact of Gottesman
Shows genetic impact but must be influenced by environment as not 100%
Adoption studies
Tienari- 7% risk in children with Sz mothers but in a healthy environment
2% for adopted children with healthy mothers.
Candidate genes
Deletion from chromosome 22 associated with Sz but also other disorders.
DRD2- control of dopamine
Issues with genes
Polygenic so hard to identify a cause
Rikpe found 108 genetic variations which provide a slight risk to Sz.
Lots of causes to Sz.
Genetic mutation
Moreno et al- prenatal exposure to influenza can cause mutations and elevate risk for sz.
Brown- paternal age changes risk of sperm mutation.
fathers under 25- 0.7% risk, over 50- 2% risk
evidence for biological and psychological factors from the environment
Smoking THC cannibis in teens and birth complications have been found to increase risk for Sz.
Childhood trauma- Morvkved et al. 67% of sz patients had trauma
Hyperdopaminergia in the subcortex
high dopamine in central areas of the brain
exitatory NT- recieving neurons fire excessively.
Dopamine agonists
Agonists- increase neural activity by binding to receptor cell. MDMA is a dopamine agonist
Can cause Sz symptoms in normal people.
Parkinsons treatments.
Antipsychotics
Dopamine antagonists block uptake of Da in the brain to reduce activity
Hypodopaminergia in the cortex
Abnormal dopamine systems in the brains cortex.
Goldman- rakic et al. Low levels of dopamine in the pre-frontal cortex- avolition
Unclear cause and effect.
Evidence for dopamines role in Sz
Drugs like amphetamines- induces Sz in non- sz individuals by activating dopamine systems.
Symptom reduction not as good as first seen
on 20% reduced with antipsychotis
