Psychiatric Morbidity in Parents and Sibs of Schizophrenics and Non-Schizophrenics

The aims of this study were to compare the psychiatric morbidity occurring in the close relatives (N = 332) of patients showing nuclear forms of schizophrenia with that of a control group (N = 201), and to consider the findings in relation to the concept of the schizophrenic "spectrum' and to some genetic theories of schizophrenia. About one third of each group were interviewed by a psychiatrist using defined diagnostic criteria, and information of varying degrees of completeness was obtained about the remainder. After considering possible biases, it was concluded that the "spectrum disorders' most likely to be biologically related to schizophrenia were personality disorders of non-neurotic type, either alone or in combination with another diagnosis. The results, however, did not fit well with the model of dominant inheritance of schizophrenia and schizoid disease proposed by Heston (1970).