Adoptees at high genetic risk are significantly more sensitive to adverse v. 'healthy' rearing patterns in adoptive families than are adoptees at low genetic risk.

In adopted-away offspring of mothers with schizophrenia spectrum disorders, the genetic liability for schizophrenia-related illness (with the rearing contributions of the biological mothers disentangled) is broadly dispersed. Genetically oriented studies of schizophrenia-related disorders and studies of genotype-environment interaction should consider not only narrowly defined, typical schizophrenia but also schizotypal and schizoid personality disorders and nonschizophrenic nonaffective psychoses.

Schizophrenia is an aetiologically heterogeneous syndrome that usually becomes overtly manifest in adolescence and early adulthood, but in many cases subtle impairments in neurointegrative function are present from birth; hence it is considered to be a disorder with a neurodevelopmental component. The strongest risk factor that has been identified is familial risk with genetic loading. Other risk factors include pregnancy and delivery complications, infections during pregnancy, disturbances of early neuromotor and cognitive development and heavy cannabis use in adolescence. Unfortunately, to date it has not been possible to utilize the predictors of the disorder that have been identified in primary preventative interventions in a general population. However, some authors have claimed that in future it might be possible to reduce the risk for developing schizophrenia through general health policy. In clinical settings, it is helpful to map out possible early risk factors, at least familial risk for psychosis, especially in child, adolescent and young adult mental patients. Furthermore, in the future we may have predictive models combining data from genetic factors for schizophrenia, antenatal risk factors, childhood and adolescent development and clinical symptomatology, as well as brain structural and functional abnormalities.

The genetic liability to 'typical' DSM-III-R schizophrenia is decisively confirmed. Additionally, the liability also extends to a broad spectrum of other psychotic and non-psychotic disorders.