Describing an adoption study: Kety et al (1968) (Method (Independent…
Describing an adoption study: Kety et al (1968)
If there is a
genetic basis for schizophrenia
by comparing the
adoptive family and biological family
of a schizophrenic to see if there is a
of schizophrenia-related illness among
relatives than adoptive relatives.
463 adoptive and biological relatives tracked down in the Danish family records
A panel of 4 Danish psychiatrists used medical records to diagnose family members, their identities were revealed and they were assigned to adoptive family groups (IA and CA) or biological family groups (IB or CB)
C = control adoptees
Categories of diagnosis:
B1 to B3, like the index participants
D1 -> "uncertain chronic schizophrenia"
D2 -> "uncertain acute schizophrenia"
D3 -> "uncertain borderline schizophrenia"
C -> "inadequate personality"
(D1-D3 categories used due to psychiatrists being uncertain about diagnoses)
All relatives were grouped together in the B1-B3, D1-D3 and C categories as "schizophrenic spectrum disorders"
More signs of schizophrenic spectrum disorders in the index participants' biological family
More spectrum disorders in the index participants' biological families than in the Control's biological families
Large sample and covers a range of ages, from teenagers to men and women in their 40's. It should be representative of the Danes in general as they were taken from the Danish Adoption Register.
Application -> If schizophrenia has a genetic link, then even an adoptive family might not prevent a child from developing it in later life if they have a genetic predisposition for schizophrenia.
But the diathesis-stress model suggests a trigger is needed. If the family is aware the child has a genetic link to schizophrenia, they can guide the child away from drugs and watch for early symptoms.
The participants were not directly approached, the data was only analysed by researchers and this could be done under Danish laws without needing consent from the participants.
Issues of social responsibility, scientific integrity and harm. Finding out whether there was a genetic component to schizophrenia would have been a huge benefit for society, especially those adopted.
Independent groups design
as it looks as the difference between biological relatives and adoptive relatives of schizophrenics (index participants).
Looks at difference between schizophrenics and a control group with no history of mental illness.
Matched pairs design as the control participants were matched to the schizophrenic patients.
, adoption and schizophrenia are naturally occurring variables.
The prevalence of schizophrenia-related mental illness among family members.