gotesman and shields 1966

Question 1

aim

Answer 1

to find out if there is a genetic basis for sz and to also replicate previous twin studies into sz to test their reliability.

Question 2

sample

Answer 2

-62 sz patients half male and female and all had a twin.

Question 3

procedure

Answer 3

the researchers had to assign each twin pair to either MZ or DZ conditions. zygocity was determined by:
finger printing testing
blood testing
physical resemblance

mental health in the twin was measured by a range of tests:
- hospital notes
- questionnaires and semi structured interviews
- 30 min tape recording of speech to identify language problem ( negative symptom)
- personality testing
- psychometric testing to measure disorganised thinking ( positive)

Question 4

results

Answer 4

55% of the DZ pro bands had a healthy twin, compared to only 21% of MZ.
54% of MZ pro bands had a twin with either sz or a related psychotic disorder.
- for severe sz, the concordance rate for MZ was 75% but only 24 for DZ.

Question 5

conclusion

Answer 5

the closer the genetic link, the more likely both twins are to show schizophrenic symptoms. however the MZ concordance rate was significantly lower than 100%. this means that despite their shared genotype they do not always share symptoms. genetics is not only cause of sz