There have been long questions about the relationship of schizophrenia to other mental disorders. Lifetime DSM-III-R diagnoses of mood and anxiety disorders in twins with clinically diagnosed schizophrenia (n = 24) and their non-affected co-twins (n = 24) were compared with twins from pairs without schizophrenia (n = 3327) using a sample from the Vietnam Era Twin Registry. Schizophrenic probands had significantly elevated rates of all included disorders (bipolar disorder, major depression, dysthymia, generalized anxiety disorder, panic disorder, and PTSD) compared with controls (P < 0.01). The odd ratios comparing co-twins of schizophrenic probands with controls was greater than three for every disorder, but did not attain statistical significance. A similar pattern was observed when analyses were restricted to only monozygotic twins (n = 12). Consistent with other studies, schizophrenics appeared to have higher rates of a range of mental disorders. Our results suggest that schizophrenia per se represents a risk factor for other psychiatric disorders, but the absence of significantly elevated risk among non-schizophrenic co-twins suggested that family environmental and/or genetic factors that contribute to risk of schizophrenia do not increase the risk of mood and anxiety disorders to the same extent that the risk of these other disorders is increased by the presence of schizophrenia.
Bibliographical noteFunding Information:
Supported by NIH grants DA04604 and AA10586 and the Department of Veterans Affairs Health Services Research and Development Service (Study 992). Department of Veterans Affairs Health Services and Development Service: Chief Research and Development Officer, John R Feussner MD; Administrative Officer, Janet Gold. Cooperative Studies in Health Services: Program Manager, Charles Welch III PhD; Health Services Research & Development: Deputy Director, Shirley Meehan MBA, PhD; Hines VA Cooperative Studies Program Coordinating Center, Vietnam Era Twin Registry: Director, Willian G Henderson PhD; Registry Coordinator, Mary Ellen Vitek; Programmer, Kenneth Bukowski; Statistical Assistant, Mary Biondic; Vietnam Era Twin Registry Advisory Committee: Theodore Colton ScD, Ralph Paffenbarger MD, Walter Nance MD, Myrna Weissman PhD, Roger Williams MD. Drs Irving Gottesman and Jag Khalsa also made important contributions to the success of this study. Most importantly, the authors wish to acknowledge and thank the members of the Vietnam Era Twin Registry for their participation and cooperation. They willingly provided sensitive information and considerable time in responding to the survey. Without their contribution this research project would not have been possible.
- Anxiety disorders
- Mood disorders