Biological explanation of schizophrenia Flashcards
What is the prevalence of Schizophrenia?
0.3-0.7% (less than 1%)
What happens to your rate of Schizophrenia if you are related to someone and what does this indicate?
It increases which indicates it has a genetic component
In Gottesman (1991) what are the rates of Schizophrenia if your non-identical twin (DZ) has Schizophrenia?
0.17
In Gottesman (1991) what are the rates of Schizophrenia if your identical twin (MZ) has Schizophrenia?
0.48
Which chromosomes and genes have been linked to Schizophrenia?
22 (via Digeorge syndrome),1, 18, 15, 14, 13, 12 . Sherrington suggests chromosome 5
The C4-A gene has been linked to Schizophrenia, what is it’s role?
It controls neural pruning
Why might this change in genes influence Schizophrenia?
It 1. Disrputs neural pathways. 2. alters brain sensitivity to chemicals e.g. dopamine and 3. might have been beneficial in creative thinking
What was a finding of Kety’s study?
The biological family members of those with schizophrenia had a higher rate of schizophrenia than the adopted family, and than the biological family of the control group
What did Tiernari et al (2000) study find?
That environment was also important, those who had a high risk of schizophrenia but lived in a ‘healthy’ home didn’t develop it but those in a disturbed household did- even many with a lower risk of Schizophrenia
What did Gottesman & Shield’s study find?
42% of the MZ twins both had a diagnosis of schizophrenia compared to 9% of the DZ twins
What did Tamminga and Schulz (1991) study find?
research has failed to isolate a single recessive or dominant gene which causes the illness. The disorder may be more complicated than that and may be the expression of many genes which cause it
Why is this a better theory than the cognitive and neurotransmitter one?
It has a better cause and effect relationship in suggesting that the genes cause the development of schizophrenia later in life
What is a problem with this theory?
It largely ignores environmental factors such as childhood trauma suggested by the Liverpool study
What is the diathesis-stress model?
It suggests you need both a genetic predisposition and environmental triggers in order to develop schizophrenia
What is an issue of using twin studies when saying that schizophrenia is genetic?
The concordance rate is never 100% which suggests that it is not fully genetic
