Copenhagen High Risk Study
1994

Kety conducted a longitudinal study in Denmark 1962.
Kety and colleagues identified 207 offspring mothers diagnosed with schizophrenia high risk group), along with this matched a control of 104 children with “healthy mothers” All children were aged between 10-18 years at the start of the study (in 1962– hence a matched pairs design
Children (schizophrenic mother children vs healthy mother children) were matched on age, genders, parental socio-economic status, ruban/rural residence
Due to the longitudinal nature of the study- children were followed up in 1974, and further in 1989

• Schizophrenic was diagnosed 16.2% in the high risk group, compared to 1.9% in the low risk group
• Identified a Schizotypal personality disorder- which is a disorder characterised by ecentric behaviour and anomalies of thinking resembling symptoms of schizophrenia. Kety infact diagnosed a schizotypal personality disorder in 18.8% of the high risk group, compared to only 5% of the low risk group.
• Combining figures for the two disorders i.e. Schizophrenia itself and the Schizotypal personality disorder- found that the high risk group had 35% of participants with either/or, in comparison to the low risk group with only 6.9% of participants.

• The high risk group (children with schizophrenic mothers) are more likely to develop schizophrenia compared to the low risk group (control group of healthy mothers).
Therefore, this shows that genetics play a role in the development of schizophrenia.
However Kety only concluded with a correlation, not infact a causal relationship.

• A strength of Ketys study is that she matched the children (schizophrenic mother children vs control group) on relevant variables including parental socio-economic status, and urban/rural residence. Matched upon these variables because low socio-economic status and urban environments are known to be risk factors in developing schizophrenia. Therefore, by controlling these factors, it shows that the relationship observed of children having schizophrenia/schizotypal disorder was primarily due to the genetic component (of mothers having schizophrenia)
• Nature vs Nurture debate- despite Kety’s study being a large well controlled study, and longitudinal, we still encounter problems. The main difficulty with family studies is that we cannot differentiate the genetic and environmental influences, because children share the same environment as their mother
• Reliability of diagnosis- the diagnosis of schizophrenia is not always reliable.
The mothers of schizophrenia had all been diagnosed with schizophrenia before modern diagnostic systems were available, so it is possible that they varied widely in their symptoms. It might even be the case that they would not have been given this diagnosis at all if later criteria had been used.