THE FINNISH ADOPTIVE FAMILY STUDY OF SCHIZOPHRENIA - IMPLICATIONS FORFAMILY RESEARCH

A nationwide Finnish sample of schizophrenics' offspring given up for adoption was compared blindly with matched controls, who were adopted offspring of non-schizophrenic biological parents. The adoptive famili es were investigated thoroughly using joint and individual interviews and psychological tests. The biological parents were also interviewed and tested. Among the 155 index offspring, the percentage of both psyc hoses and other severe diagnoses (borderline syndrome and severe perso nality disorders) was significantly higher than in the 186 matched con trol adoptees. This supports a genetic hypothesis. However, notable di fferences between these two groups only emerged in the families which were rated as disturbed. Thus the genetic effect (i.e. the differences between high and low genetic propensity) was only manifested as a psy chiatric disorderin the presence of a disturbed family environment. Th e impact of disturbed family relations was strongest in the presence o f the appropriate genotype.