Genetic - Gottesman & Shields, 1972

Carried out a twin study which looked into the genetic inheritance of schizophrenia. This explanation believes that mental disorders such as schizophrenia can be explained by genes or particular combinations of genes that are passed on to offspring. Schizophrenia patients has sensory dysfunction such as psychosis, which has genetic origins. The study uses identical or monozygotic (MZ) twins who share all their DNA, whereas non-identical or dizygotic DZ) twins only share around 50% of their DNA. This is helpful because of the the disorder is the same in both identical and non-identical twins then it can be concluded that there is probably little genetic connection as in theory the more of the same DNA the more likely it would be for them to both have schizophrenia rather than just one. Twins allow the detailed study of nature vs nurture debate. The sample of this study was 467 twins that were registered at the Maudsley psychiatric hospital in London. They selected 57 pairs of twins 24 MZ and 33 DZ twins (they were identified as MZ or DZ by blood tests and finger print tests. The researchers interviewed the patient and their twin (some of the patients already had a diagnosis of schizophrenia). Participants also took part in cognitive tests such as object sorting. To make sure the diagnosis was valid case studies of each participants were independently evaluated by judges not involved in the research. This study found that around 50% of MZ twins shared schizophrenia, it was found to be much lower in DZ twins (9%) It was also found that severe cases were much likely to share the disorder with their their twin, less severe cases were way less likely to share it with their twin.

Strengths- Used a large sample of MZ and DZ twins, the independent judges that were used to assess cases reduced researcher bias greatly, they also collected data via qualitative methods such as interviews.

Weaknesses- The information isn't very representative of people without twins the sample was drawn from one hospital only making it less generalisable, the interviews and qualitative data they use could be considered subjective and open to bias.

	Created by Millie O about 3 years ago

Genetic, Biochemical, Cognitive