Biological explanation for schizophrenia Flashcards
Genetic explanation
-The genetic explanation suggests that schizophrenia is the result of biological processes that are driven by certain genes
-Such as the development of brain structures or the activity of neurotransmitters
Why is schizophrenia considered a polygenetic disorder
-Schizophrenia is considered a polygenetic disorder because there is a collection of genes that are associated with a higher risk of schizophrenia
Evaluation for the polygenetic nature of schizophrenia (Ripke)
Ripke et al (2014) conducted a genetic review of over 36,000 schizophrenia cases
-They found 118 genetic loci associated with schizophrenia
-This suggests that schizophrenia is aetiologically heterogenous, as different combinations of diseases are correlated with having the disorder
Why are MZ twin studies used when looking at genetic explanations of schizophrenia
- Monozygotic twins share the same genetic information and often share environments
-If schizophrenia is a genetic disorder, then we would expect to see a higher concordance rate of schizophrenia between people that are closely related, if one person has the disorder
Evaluation for the genetic explanation of schizophrenia (Gottesman)
-Gottesman reviewed cases of schizophrenia in families and found a 48% concordance rate between MZ twins, compared to a 17% concordance rate for DZ twins, compared to the prevalence of the general population (1%)
-This suggests that schizophrenia has a genetic component, as there were large differences in concordance rates between the two sets of twins
-However, this also suggests that there are other factors involved, as if schizophrenia were entirely genetic, the concordance rate for MZ twins would be 100%
Neural Correlates
-Neural correlates are the variations in neural structure and brain chemistry that are correlated with an increased risk of schizophrenia
Dopamine Hypothesis
-The dopamine hypothesis suggests that schizophrenia symptoms are the result of dopamine neurotransmitter imbalances across the brain
Hyperdopaminergia
-Excessive amounts of dopamine (hyperdopaminergia) in speech area such as the Broca’s area, may lead to auditory hallucinations
Hypodopaminergia
-Lower levels of dopamine (hypodopaminergia) in areas such as the frontal cortex are thought to be associated with negative symptoms such as avolition or speech poverty
How did the dopamine hypothesis come about
-The dopamine hypothesis came about from psychologists giving healthy patients dopamine-releasing drugs such as L-DOPA, causing schizophrenic symptoms in these healthy patients
Alternate neurotransmitter associated with schizophrenia
-Glutamate, which is an excitatory neurotransmitter associated with learning, attention and memory and is often found in low quantities in individuals with schizophrenia
Research evaluation point for the dopamine hypothesis/ biological explanation as a whole (positive)
-A researcher conducted a meta-analysis on 212 studies looking into the effectiveness of anti psychotic drugs targeting the dopamine system on the symptoms of schizophrenia
-They found that the anti psychotics were much more effective than a placebo
-This suggests that the biological explanation/ dopamine hypothesis has some validity as otherwise the drugs would not have an effect
Ventricles as part of the biological explanation of schizophrenia
-Enlarged ventricles in the brain are thought to be associated with people with schizophrenia
Evaluation of enlarged ventricles as part of the biological explanation (neural correlates)
-Research using CT scans identified that people with schizophrenia had a larger ventricle in the brain compared to the average, suggesting that this correlation may be linked to the cause of schizophrenia
-However, as this research on ventricles is correlational, it is difficult to establish a causal relationship between schizophrenia and enlarged ventricles, as the enlarged ventricles could be a side effect of medication
General evaluation for the biological explanation of schizophrenia (negative)
-A biological explanation of schizophrenia assumes that schizophrenia is inevitable
-This biologically deterministic approach may make sufferers feel disempowered after being diagnosed with schizophrenia
-Other more psychological approaches, such as the cognitive approach, have a soft deterministic perspective, suggesting that mental processes can be managed or controlled via free will
