Biological Approach Flashcards
What are the three biological explanations for schizophrenia?
- Genetic explanation 🧬
- dopamine hypothesis brain 🧠 (neurochemical)
- neural correlates to schizophrenia
What is the genetic explanation for schizophrenia?
That it is caused by polygenic sets of candidate genes
What are candidate genes?
Individual genes that have direct link to genetic transmission
What did Ripke et al (2014) find? (Genetic explanation for scizophrenia)
Found 108 gene sets within 37,000 schizophrenics
These genes were connected to functioning of the neurochemicals, particularly dopamine
What did Gottesman (1991) find? 👨👩👧👦
Genetic explanation for scizophrenia
Looked at occurrence rates of scizophrenia with families….
With one biological parent having scizo, concordance rate of for children is 13%
Both parents having scizophrenia, 46%
And sibling 9%
What did Joseph (2004) find? 👯♀️
Genetic explanation for schizophrenia
Meta analysis of all reported studies prior to 2001
Dizygotic twins had 7.4% concordance rate
👩🏼👩🏻
Monozygotic had 40.4%
👩🏼👩🏼
What did Tienan (2004) find?
Genetic explanation for schizophrenia
In findland, studied 154 adoptees who’s biological mother has been diagnosed with scizophrenia. 👩👦
6.7% developed scizophrenia compared to control group of 194 at just 2%
What is the dopamine hypothesis?
Over sensitivity to dopamine leads to frequent firing of neurons in the brain resulting in schizophrenic type symptoms 🔫
What did synder (1974) and comer (2003) find?
Dopamine hypothesis
Schizophrenics have higher level of D2 reception neurons, these neurons effect perception and attention
What did Davis et al (1991) find?
Dopamine hypothesis
Positive symptoms associated with high levels in MESOLIMBIC dopamine system
Negative symptoms associated with high levels in MESOCORTICAL dopamine system
Where in the brain is HYPERdopaminergia found and what is it linked to?
Subcortex - Broca’s area
Speech poverty and avolation
Where in the brain is HYPOdopaminergina found, and what is it linked to?
In the prefrontal cortex
Exaplin how ‘drug research into amphetamines’ is a support for the dopamine hypothesis
Randup and Munkvad
Created schizophrenia in rats by giving them amphetamines 🐀
They work by stimulating dopamine causing schizophrenia episodes
This increases reliability as people to take these drugs are more controlled due to not having schizophrenia
Explain how ‘drug research into antipsychotics’ is a support for the dopamine hypothesis 💊
Antipsychotics block receptors of dopamine which causes a decrease in positive symptoms
Davies et al proved this effectiveness and not placebo as patients relapsed on placebo 55% of the while treatment was 19%
Higher levels of dopamine correlate with positive symptoms
Increased reliability by adding further research
What are neural correlates?
Structures in the brain that are directly correlated with a certain experience 🧠
What part of the brain causes negative symptom ‘avolition’ ? 🧠
What is this area in control of?
And so damage would cause….
Ventral striatum
Anticipation of reward 🏆
A lack of motivation due to lack of anticipation
What two parts of the brain causes positive symptom ‘hallucinations’?
And does low or high activity levels cause this?
Superior temporal gyrus
Anterior cingulate gyrus
Low ⬇️
What did Allen et al find?
Neural correlates
Scanned the brains of patients experiencing auditory hallucinations, and compared to control group
Whilst scan took place, they had to identify prerecorded speech as theirs or others 🗣
Hallucination group made more errors and had lower activity levels in STG and ACG 🧠
Explain how ‘biochemistry cause or effect?’ is a criticism for neural correlates.
🐔🥚
Is it the schizophrenia that causes the brain abnormalities, or the abnormalities that causes the schizophrenia
Lack of motivation caused by less activity in ventral striatum, or less activity in this area caused by lack of motivation?
Unclear and not controlled
