An independent analysis of the Danish Adoption Study of Schizophrenia. VI. The relationship between psychiatric disorders as defined by DSM-III in the relatives and adoptees.

In this report, modified DSM-III criteria were applied to all the available interviews with adoptees from the greater Copenhagen sample of the Danish Adoption Study of Schizophrenia. In the adoptees, reasonable agreement was found between our DSM-III diagnoses and the original diagnoses using global DSM-II-based criteria by Kety et al for their categories of chronic and acute, but not borderline, schizophrenia. Comparing DSM-III-based diagnoses in adoptees and relatives, schizophrenia, schizotypal personality disorder, and paranoid personality disorder were all significantly more common in the biologic relatives of schizophrenic v screened control adoptees. These three diagnoses, which together form a tentative "schizophrenia spectrum," were also significantly concentrated in the biologic relatives of adoptees with schizoaffective disorder, mainly schizophrenic subtype, and schizotypal personality disorder, but not in biologic relatives of adoptees with schizophreniform disorder or atypical psychosis.