Differences in social adjustment during adulthood between adoptees with high and low risk for schizophrenia spectrum disorders - the Finnish adoptive family study of schizophrenia.

Objective: To investigate differences in social adjustment during adulthood between adoptees with high genetic risk (HR) and low genetic risk (LR) for schizophrenia spectrum disorders.

Methods: This study is a subsample of the Finnish Adoptive Family Study of Schizophrenia. The study sample consisted of 120  adoptees whose biological mothers had DSM-III-R verified schizophrenia spectrum disorders, and 142 socio-demographically matched control adoptees. The social adjustment of the adoptees was assessed using the interview-based Adult Adjustment Scale (AAS).

Results: A lower proportion of the HR adoptees (61.7%) fell into the category of good adaptation compared to LR adoptees (74.6%) (p = 0.024). In addition, the median AAS score among HR adoptees was lower compared to LR adoptees (p = 0.023). Poorer results among HR adoptees were also found regarding some individual items and the social health -domain within the AAS. The psychiatric morbidity, excluding schizophrenia spectrum disorders, was higher among HR adoptees. Psychiatric morbidity was shown to mediate the association of genetic status to total AAS, and, also to the domain of social health.

Conclusion: According to our results, genetic susceptibility to schizophrenia is associated with weakened social adjustment during adulthood. Although our results demonstrated that psychiatric morbidity has notable effect on the association of genetic status to adult adjustment scores, the impact of other determinants, like psychosocial factors or health-related behaviour, cannot be ruled out. The comparable rearing environment provided by the adoption design in conjunction with reliable diagnostics provide new information on the relation of genetic susceptibility and social adjustment.