Biological explanations

• Gottesman's large scale family study- found evidence that schizophrenia runs in families and is in part genetic. Found much higher concordance rates in MZ twins (48%) in comparison to DZ twins (17%)
• Kety's High risk study 1962- 207 children (mother with schizophrenia:high risk) 104 children (healthy mother:low risk) start age 10-18y. Matched for age, gender, socio-economic, urban or rural. Follow up in 1974 and 1989 (Parnas et al) schizophrenia diagnosis: high risk- 16.2% and low risk-1.9%
• Shields- MZ twins raised separately showed 50% concordance for schizophrenia. Adoption studies where 1/2 parents have schizophrenia also 50% concordance. Showed environment may inflate the affect through learning of 'schizophrenia' behaviours from relatives
• Tienari- showed schizophrenia genetic risk only materialises if adoptive environment includes psychological disturbance