I. Genotype-environment interaction in the schizophrenia spectrum: genetic liability and global family ratings in the Finnish Adoption Study.

In the Finnish Adoption Study, a national sample of adoptees with high versus low genetic liability for schizophrenia spectrum disorders was indexed by DSM-III-R diagnoses of their biological, adopting-away mothers. The rearing-family environments of the adoptees were independently evaluated from global ratings of directly observed adoptive family relationships. The interaction of high genetic liability and dysfunction of the rearing families predicted highly significantly to schizophrenia spectrum disorder of the adoptees at 21-year follow-up.

Observing relationships in Finnish adoptive families: Oulu Family Rating Scale.

Adoption studies were intended to separate genetic from environmental "causal" factors. In earlier adoption studies, psychiatric diagnostic labels for the adoptive parents were used as a proxy for the multiple dimensions of the family rearing environment. In the Finnish Adoption Study, research design provided the opportunity to study directly the adoptive family rearing environment.

Genotype-environment interaction in schizophrenia-spectrum disorder. Long-term follow-up study of Finnish adoptees.

Background: Earlier adoption studies have convincingly confirmed the importance of a genetic contribution to schizophrenia. The designs, however, did not incorporate observations of the rearing-family environment.

Aims: To test the hypothesis that genetic factors moderate susceptibility to environmentally mediated risks associated with rearing-family functioning.