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January 16, 2019

New Evidence for Shared Risk Architecture of Mental Disorders

Author Affiliations
  • 1Stanley Center for Psychiatric Research, Broad Institute of MIT and Harvard, Cambridge, Massachusetts
  • 2Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts
JAMA Psychiatry. 2019;76(3):235-236. doi:10.1001/jamapsychiatry.2018.4269

In this issue of JAMA Psychiatry, Plana-Ripoll et al1 provide compelling insights into the frequency, nature, and temporal patterns of comorbidity among mental disorders. Comorbidity—the contemporaneous or successive occurrence of at least 1 additional mental disorder given an index diagnosis—has been well documented by prior research2 and bedevils clinical practice.3 What Plana-Ripoll et al1 emphatically bring home by analyzing very large, high-quality administrative databases is the pervasiveness of comorbidity across all domains of psychopathology. Their large sample gives them the statistical power to demonstrate that given any index mental disorder, there is increased risk of developing an additional mental disorder of any type, including a disorder that is outside the broad diagnostic category of the index condition. Moreover, the comorbidity that they document is bidirectional; for almost all pairs of disorders, the hazard ratio is increased independent of their temporal order of onset. As the authors recognize, this bidirectionality provides new evidence for the sharing of risk architecture across mental disorders.