DSM-III schizophrenia: is there evidence for familial transmission

To resolve some recent controversies as to whether there is any evidence of familial transmission in DSM-III schizophrenia, a blind study of first degree relatives of 332 DSM-III schizophrenia was conducted. A comparison group of first degree relatives of 318 surgical patients who were free of psychiatric symptoms were also studied. The morbidity risks of schizophrenia and related illnesses were estimated among these relatives. The risk of DSM-III schizophrenia in the relatives of schizophrenics was 3.7 + 0.7 which was significantly higher (p less than .01) than among the relatives of surgical controls (0.2% + 0.2) with a relative risk of 18.5 (3.7/0.2). When broad criteria of schizophrenia were used by including all schizophrenia-related illnesses, the risks were approximately 9.0% and 1.0% respectively in the families of schizophrenics and controls with a relative risk of 9.0. These results will be discussed in the light of relevant literature. It is concluded that there is an evidence for familial transmission in DSM-III schizophrenia.