biological explanations for schizophrenia Flashcards
what are family studies
confirmed risk of schizophrenia increases in line with genetic similarity to relative with disorder
2% chance developing it with aunt
9% if sibling and 48% if idential twin
family members tend to share aspects of environment as well as genes
correlation represents both nature and nurture
what are candidate genes
number different genes involved
most likely genes would be those coding for neurotransmitters including dopamine
ripke- combined previous data from genome wide studies, genetic makeup of 37,000 people with diagnosis compared to 113,000 controls, 108 separate genetic variations associated with slightly increased risk
different studies different candidate genes- aetiologically heterogeneous
what is the role of mutation
genetic origin in absence of family history
mutation in parental dna- caused by radiation poison or viral infection
positive correlations between parental age and risk of schizophrenia increasing from 0.7% with fathers under 35 to 2% in fathers over 50
what is the original dopamine hypothesis
based on discovery drugs used to treat schizophrenia caused symptoms similar to those in people with parkinsons- low da levels
schizophrenia might be result of high levels of da in subcortial areas of brain
what is updated versions of dopamiine hypothesis
davis- addition of cortical hypodopaminergia (low da in brains cortex) and can explain symptoms of schizophrenia
suggested cortical hypodeopaminergia leads to subcortical hyperdopaminergia- high and low levels of da in different brain regions part of updated version
explain origins of abnormal da function- both genetic variations and early experiences of stress psychological and physical- make people more sensitive to cortical hypodopaminergia and subcortical hyperdopaminergia
what is research support (genetic evaluation)
strong evidence base
gottesman- risk increases with genetic similarity to family member with disorder
tienari adoption studies- iological children of parents are at heightened risk even if grow up in adoptive family
hilker twin studies- concordance rate of 33% for identical twins and 7% for non identical twins
shows some more vulnerable to disorder as result of genetic makeup
what is environmental factors (genetic evaluation)
clear evidence show environmental factors increase the risk
include both biological and psychological influences
biological risk facors include birth complications and smoking thc rich cannabis in teenage years
psychological risk factors- childhood trauma leaves people more vulnerable to adult mental health problems in general- particular link with schizophrenia
researcher- 67% people with schizophrenia and related psychotic disorders reported at least one childhood trauma as opposed to 38% of matched group with non psychotic mental health issues
genetic factors alone cant provide complete explanation for schizophrenia
what is the evidence for dopamine (neural evaluation)
idea dopamine involved in schizophrenia
amphetamines increase da and worsen symptoms in people with schizophrenia and induce symptoms in people without
antipsychotic drugs reduce da activity and intensity of symptoms
candidate genes act on production of da or da receptors
dopamine involved in symptoms of schizophrenia
what is glutamate (neural evaluation)
dopamine hypothesis evidence for central role of glutamate
post morten and live scanning studies found raised levels of neurotransmitter glutamate in several brain regions of people with schizophrenia
candidate genes believed to be involved in glutamate production or processing
equally strong case can be made for role of other neurotransmitters
