Genetic vulnerability and premature death in schizophrenia spectrum disorders: a 28-year follow-up of adoptees in the Finnish Adoptive Family Study of Schizophrenia.

BACKGROUND

Excess mortality is widely reported among schizophrenia patients, but rarely examined in adoption study settings.

AIM

We investigated whether genetic background plays a role in the premature death of adoptees with schizophrenia.

METHODS

Mortality among 382 adoptees in the Finnish Adoptive Family Study of Schizophrenia was monitored from 1977 to 2005 through the national causes-of-death register. The sample covered 190 adoptees with a high genetic risk of schizophrenia (HR) and 192 with a low risk (LR).

RESULTS

Overall mortality among the adoptees did not differ between the HR and LR groups, as 10% and 9% respectively had died during the follow-up, at mean ages of 45 and 46 years. Schizophrenia spectrum disorder was the most significant predictor of premature death in both groups, with dysfunction in the rearing family environment associated with mortality, unnatural deaths and suicides in the HR but not in the LR group. All the suicides involved HR cases.

CONCLUSIONS

Mortality among the adoptees was not related to genetic factors but to environmental ones. The association of unnatural deaths and suicides with dysfunction in the rearing environment among the HR adoptees may indicate that they had a greater genetically determined vulnerability to environmental effects than their LR counterparts. The genetic and rearing environments can be disentangled in this setting because the biological parents give the offspring their genes and the adoptive parents give them their rearing environment. Our findings add to knowledge of the factors associated with the premature death of adoptees in mid-life.