ASSOCIATION OF ADOPTIVE FAMILY FUNCTIONING AND GENETIC LIABILITY FOR BROAD SCHIZOPHRENIA SPECTRUM DISORDERS WITH ADOPTEES’ PSYCHIATRIC MORBIDITY ACTA UNIVERSITATIS OULUENSIS D Medica 1715
Earlier research has solidified the role of genetic contributions in the etiology of schizophrenia and
other psychiatric disorders. However, complex socio-environmental factors have also long been
recognized to have an influence on the processes leading to the onset of psychiatric disorders.
According to the vulnerability-stress model, the interaction of biological and environmental risk
factors is suggested to play a key part in the development of psychiatric disorders.
The study used data from the Finnish Adoptive Family Study of Schizophrenia. The data
comprises adoptive families with adoptees who were, by their biological mother, at high (HR) and
low (LR) genetic risk for broadly defined schizophrenia spectrum disorders. The ultimate purpose
of this doctoral dissertation was to examine the impacts of HR for broad schizophrenia spectrum
disorders and family-related environmental factors on the psychiatric morbidity of the adoptees.
The environmental factors included duration of preadoption out-of-home care, adoptive family
functioning, death and divorce of adoptive parents occurring before the offspring reached the age
of 18, and socioeconomic status (SES) of adoptive families.
The findings showed that among adoptees with longer time in preadoption out-of-home care
(> 6 months), an increased risk for later psychiatric disorders was observed in the HR adoptees.
Contrarily, among adoptees with shorter time in preadoption out-of-home care (≤ 6 months), later
psychiatric disorders associated with adoptive family functioning. The findings also showed that
the likelihood for psychiatric disorders was increased in adoptees raised in adoptive families with
dysfunctional processes, especially among the HR adoptees. Furthermore, the findings indicated
that dysfunctional family processes and HR for broad schizophrenia spectrum disorders were
related to increased likelihood of psychiatric disorders of the adoptees only in families with high
In conclusion, the results imply that dysfunctional family processes and HR for broad
schizophrenia spectrum disorders may increase the likelihood for psychiatric disorders in
offspring both independently and in interaction. Furthermore, the results support the significance
of familial SES and early caregiving circumstances in the development of psychiatric disorders.
Keywords: family functioning, gene-environment interaction, genetic risk, preadoption
out-of-home care, psychiatric disorders, schizophrenia, socioeconomic status