Biological explanation Flashcards
What does the genetic explanation for schizophrenia suggest?
Schizophrenia is an inherited disorder and results from a biological process driven by the activity of certain genes such as:
Brain structure development
Neurotransmitter levels
Schizophrenia is a….
Polygenetic disorder
What are the main studies of schizophrenia psychologists can use to study the genetic basis of schizophrenia?
(Linked to Gottesman 1991 Evaluation)
(Linked to Tienari 2004)
Twin studies
MZ twins are genetically identical and share environments
MZ Twins = 48%
DZ Twins = 17%
Evaluation (Ripke et al 2014)
There is no schizophrenia gene. However, a collection of genes locations have been located that are associated with a higher risk of developing schizophrenia. This means Schizophrenia is thought to be a polygenetic disorder.
Ripke et al (2014) Conducted a genetic analysis of over 36 thousand schizophrenia cases, this identified 108 genetic loci associated with the developments of Schizophrenia. This suggests a range of genes are responsible for Schizophrenia but also suggests the disorder is aetiologically heterogenous as different combinations of genes are correlated with having the disorder
Evaluation (Gottesman 1991)
Reviewed cases of schizophrenia in families and found a Concordance rate of 48% for identical twins (MZ) and 17% for non-identical twins (DZ). This compares to the general population rate of 1%. This suggest schizophrenia has a genetic aspect as there is such a large difference between the two sets of twins. Both DZ and MZ twins should share similar environments. However, Concordance rates are not 100% in MZ so it’s not fully genetic.
Evaluation (Tienari 2004)
Studied the biological children of Schizophrenia mothers who had been adopted. It was found that 5.8% of children adopted into psychologically healthy families developed Schizophrenia compared to 36.8% of children raise in dysfunctional families. As the risk for both groups is far above the 1% risk level of the general population this suggests Schizophrenia has a GB., However a difference between groups also suggests a role to play for psychological factors.
What is another Biological Explanation to Schizophrenia?
Neural Correlates: Neural structure and Biochemistry that are correlated with an increased risk of developing Schizophrenia.
What does the Dopamine Hypothesis suggest?
Dopamine releasing drugs such as L-dopa can produce Schizophrenia in health patients
Ant-psychotic drugs like Phenothiazine decreases symptoms of Schizophrenia and reduce symptoms of Schizophrenia and reduce dopamine levels.
Evaluation (Research) *The dopamine Hypothesis)
Levent et al conducted a meta-analysis review of 212 studies. These studies assessed the effectiveness of biological anti-psychotic drug treatments that work via normalising levels of dopamine. Results demonstrated these drugs were more effective than a placebo. The effectiveness of treatments that influence the dopamine system suggest that the underling biological theory of schizophrenia cause has validity, otherwise the drug would not be effective.
What are Ventricles?
Voids filled with cerebrospinal fluid deep within the brain
Thought to provide a cushioning effect for the brain
Enlarged Ventricles are associated with people with schizophrenia.
(What are Ventricles)
A03 Evaluation
Research using CT scans by JohnStone (1976) first identified people with Schizophrenia has larger than average Ventricles, suggesting this structural difference may be linked to the causes of Schizophrenia. However as these ventricle size studies are based on correlational research it is difficult to determine if there is a causal relationship or a third factor linked to both the enlarged ventricles and Schizophrenia such as enlarged ventricles being the side effect of medication
AO3 (General Evaluation, Strength)
Explaining Schizophrenia at the basic cellular and chemical level has the advantage of the scientific principles of parsimony. This biologically reductionist approach fails to consider evidence for the range of psychological aspects of Schizophrenia such as expressed emotion that seem to have a large influence on the development and relapse of the disorder
AO3 (General Evaluation, Limitation)
A full holistic explanation of Schizophrenia would consider the diathesis - stress approach in which the root cause of the disorder is a biological /genetic weakness (diathesis), however a environmental stressor such as family stress triggers the disorder
