BIOLOGICAL EXPLANATIONS (G,B,N,P)
Genetic relatives with schiz = higer risk of developing it in later life.
A twin study conducted by Gottesman and Shields found that 58% of MZ identical twins were concordant for schiz, there was no comparison to DZ non-identical twins.
Cardno found a concordant rate of 40% for MZ twins compared to 5.8% for DZ twins. Suggesting that there is a genetic link, although there is a small sample size, it is difficult to generalise as MZ twins tend to be treated simmilarly.
Family study conducted by Kety et al looked at 207 10-18yr old offsprings of schizophrenic mothers (high risk group) and 104 offsprings of healthy mothers (low risk group). A follow up was conducted after 10/20years which showed schizo was diagnosed in 16% of the high risk group and only 2% of the low risk group. This shows that not every offspring develops schiz, however there is a relationship between the mother and child, it might not be genetic but they could have learnt the behaviour.
Prospective study - doesn't rely on any restropective data, Longitudinal which is important and schiz can develop in people over 40 aswell. The mother's of these children were diagnosed with schiz long before modern systems were available, further genetic engineering could remvove the gene causing schizo as application.
Both twin and family studies lack extraneous variables as they are in the same enviroment therefore adoption studies help.
Tienan found 7% of adoptees who had biological mother's that had schiz later devleoped it compared to 1.5% of the matched control group who's biological mothers didn't.
Kety found high rates in adoptees whose biological parents had schiz even when adopted by healthy parents, they were not sharing the same enviroment, suggesting there is a genetic link.
Drugs that adjust dopamine levels appear to reduce symptoms of schiz, therefore it might be related to the cause. Could be the amount of dopamine receptors and not the amount of Dopamine, drugs that block dopamine receptors reduces positive symptoms, therefore ther might be a type 1 link between schiz and dopamine.
MRI scans show englarged ventricles in the brain in those that have schizo.
Young compared schiz and non schiz clients together and found ventricle differences varied with the degree of severity of the illness, the larger the ventricle the more severe the illness however those with brain damage is associated with -ve symptoms rather than +ve.
Torrey found schizo sufferes have 15% larger ventricles, especially type 2 sufferers. It's not the…