biologial explanations for schizophrenia Flashcards
How does the biological explanation suggest that schizophrenia is developed?
-transmitted through hereditary means, i.e though the genes passed on to individuals from their families
True or false? schizophrenia is believed to be caused by one main ‘schizo-gene’
false
What does polygenic mean?
-several genes are involved in the development of the disorder
How many genetic variations are believed to cause schizophrenia?
108
What was Gottesman (1991)’s study and what did it find about schizophrenia? (APFC)
-aims:
-procedure: large scale family study
-findings: someone with a sibling that has sz has a 9% chance, increasing to 17% in DZ twins, and 48% in MZ twins
-conclusion: the risk of schizophrenia increases in like with the genetic similarity to a relative with the disorder
What were the findings of Gottesmans research?
-someone with a sibling that has sz has a 9% chance of developing it, increasing to 17% if they are a DZ twin, and 48% if they are an MZ twin
What study found that someone with a sibling that has sz has a 9% chance of developing it, increasing to 17% if they are a DZ twin, and 48% if they are an MZ twin?
Gottesman 1991
True or false? schizophrenia can also have a genetic origin in the absence of a family history of the disorder?
-True
-Genetic mutation supports this idea
Explain genetic mutation as a genetic explanation for schizophrenia?
-mutation in parental DNA which can be caused by radiation, poison or viral infection
Where does evidence for genetic mutation as a genetic cause of schizophrenia come from?
-Brown et al (2012) found positive correlations between paternal age, which is associated with increased risk of sperm mutation, and risk of schizophrenia
-0.7% with fathers under 25
-over 2% in those with fathers over 50%
What neural correlates are part of the biological explanation of schizophrenia?
-dopamine
-brain structure
-glutamate
What is the dopamine hypothesis/ what does it say about dopamine and schizophrenia?
-focuses on the link between dopamine and schizophrenia
-dopamine increases the rate of the firing of neurons, enhancing communications between them
-the release of too much dopamine can lead to positive symptoms such as hallucinations and delusions
-excess of dopamine receptors in Broca’s area may be associated with poverty of speech and/ or auditory hallucinations
What is the link between brain structure and schizophrenia?
-Torrey (2002) analyzed brain structure through brain scans of both schizophrenic and non-schizophrenic individuals
-it was found that the ventricles in a schizophrenics brain are 15% larger than the average persons
-this suggests a link between schizophrenia and brain structure
What is the link between glutamate and schizophrenia?
-post mortem and live scanning studies have consistently found raise levels of the neurotransmitter glutamate in several brain regions of people with schizophrenia (McCutcheon, 2020)
-several candidate genes for SZ are believed to be involved in glutamate production or processing
What are the strengths of biological explanations for schizophrenia?
-success of treatments that block dopamine receptors
-research support from adoption studies
What are the limitations of biological explanations for schizophrenia?
-research into neural correlates is correlational
-could be caused by psychological explanations
Explain the strength of biological explanations for schizophrenia that treatments that block dopamine receptors are successful?
-Crosseley et al (2010) found in a meta-analysis that medication that blocks dopamine receptors typically leads to a significant reduction in the positive symptoms of schizophrenia
-if these drugs reduce symptoms, it suggests that dopamine is an important factor in the symptoms
-this supports the dopamine hypothesis
Explain the strength of biological explanations for schizophrenia that there is research support from adoption studies?
-Tienari et al (2004) conducted adoption studies that found that biological children of parents with SZ are at heightened risk even if they grow up in an adoptive family
-of the adoptees whose biological mother had a diagnosis. 6.7% also received a diagnosis, compared to 2% of controls
-this shows that you are more likely to have schizophrenia if a biological relative does too
Explain the limitation of biological explanations for schizophrenia that research into neural correlates is correlational?
-research into neural correlates ins useful in flagging up particular brain systems that may not be working normally, however there is a correlation-causation problem
-does the unusual activity in a region of the brain cause the symptom, or does the symptom cause the unusual activity?
-e.g does dopamine cause symptoms of schizophrenia, or does schizophrenia cause an increase in dopamine?
-the existence of neural correlates n schizophrenia therefore tells us relatively little in itself
Explain the limitation of biological explanations for schizophrenia that there is support for psychological explanations?
-there is overwhelming support in the role of biological factors in sz, however, psychological explanations offer an alternative explanation
-e.g psychological explanations including family dysfunction propose that schizophrenia is the result of having as mother who is cold, rejecting and controlling aka schizophrenogenic
-according to this explanation, this leads to distrust that later develops to paranoid delusions, and ultimately sz
-furthermore, a diathesis-stress model has been put forwards suggesting that sz is caused by a genetic vulnerability AND psychological trigger, combining both explanations into an interactionist one
-it could be argued that this is a more convincing explanation of the disorder.
