Gottesman and Shields 1966
Gottesman and Shields aimed at looking at how far schizophrenia was genetic and they also tried to replicate other studies that had already found a genetic link with schizophrenia.
Secondary data was also gathered from a hospital in USA about twins who had been diagnosed with schizophrenia. To collect data they gathered information for 16 years. At the beginning they had 392 patients who seemed to fit the criteria; however 68 patients were one of two twins and had either been diagnosed with schizophrenia or had some sort of related psychosis. At the end only 62 patients were left. 5 cases showed that both MZ twins had been diagnosed with schizophrenia. The remaining 57 pairs had at least one twin who had schizophrenia.
There were 31 males and 31 females in the group of patients who were aged 19 to 64, where the average age was 37. Tests included blood and visual ones to check whether the twins were MZ or DZ. Data collected included notes from the hospital, case histories for the twins, tape recordings of 30 minute samples of verbal behaviour which were gathered by doing semi structured interviews, personality testing etc.
Gottesman and Shields wanted to find out if whether one twin who had schizophrenia, would the second twin develop Schizophrenia too as well as whether the pairs of twins were MZ or DZ twins.
Gottesman and Shields looked at concordance rates within MZ twins to see the percentages of cases where both of the twins had been diagnosed with Schizophrenia. They did the same with DZ twins where they had found a higher concordance rate for MZ twins for schizophrenia or other related disorders. They found a much lower concordance rate for DZ twins.
Results were reported in terms of concordance rates which looked at the following features:
· Pairs where…