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OCD diagnosis increased risk for schizophrenia

Recent data published in JAMA Psychiatry suggest that an obsessive-compulsive disorder diagnosis appears associated with increased risk for schizophrenia and schizophrenia spectrum disorders.

“Despite the fact that our results indicate putative overlapping etiological factors of OCD and schizophrenia or schizophrenia spectrum disorders, they do not necessarily suggest that these disorders should be aggregated into one global diagnosis,” the researchers wrote. “However, given these findings and the fact that OCD and schizophrenia co-occur with one another at a higher rate than would be expected in the general population, the phenotypes of these disorders are potentially more similar than currently acknowledged.”

Sandra M. Meier, PhD, of Aarhus University in Denmark, and colleagues conducted a prospective cohort study of 3 million people born between 1955 and Nov. 30, 2006, and followed up from 1995 to Dec. 21, 2012, to determine whether an OCD diagnosis increased the risk for developing schizophrenia and schizophrenia spectrum disorders. Researchers also evaluated whether a family history of OCD increased the risk.

Overall, 16,231 participants developed schizophrenia, 447 of whom had a prior OCD diagnosis, and 30,556 developed a schizophrenia spectrum disorders, 700 of whom had a prior OCD diagnosis.

A prior diagnosis of OCD was associated with an increased risk for schizophrenia (incidence rate ratio [IRR]=4.99; 95% CI, 4.53-5.48), which was significantly more than a previous diagnosis of other childhood-onset disorders, including autism (IRR=2.35; 95% CI, 2.08-2.64), attention-deficit/hyperactivity disorder (IRR=2.12; 95% CI, 1.89-2.37) or bulimia nervosa (IRR=2.29; 95% CI, 1.9-2.72). Similarly, a previous OCD diagnosis in the father (IRR=4.86; 95% CI, 2.09-9.41) and mother (IRR=3.57; 95% CI, 2.01-5.79) increased the risk for schizophrenia.

A prior diagnosis of OCD was associated with an increased risk for a schizophrenia spectrum disorder (IRR=5.18; 95% CI, 4.8-5.58), which was significantly more than a previous diagnosis of other childhood onset disorders, including autism (IRR=2.5; 95% CI, 2.28-2.73), ADHD (IRR=2.29; 95% CI, 2.11-2.49) or bulimia nervosa (IRR=2.2; 95% CI, 1.9-2.53). Previous OCD diagnosis of the father (IRR=3.04; 95% CI, 1.52-5.33) and mother (IRR=2.78; 95% CI, 1.81-4.05) also increased the risk.

“Our findings indicate that OCD, schizophrenia and schizophrenia spectrum disorders might share etiological risk factors,” the researchers wrote. “A significantly elevated risk of schizophrenia and schizophrenia spectrum disorders was observed in association with a prior diagnosis of OCD in the patients or their parents. Future research is needed to disentangle which genetic and environmental risk factors are truly common to OCD and schizophrenia or schizophrenia spectrum disorders.”

Disclosure: The study was funded in part by the Lundbeck Foundation Initiative for Integrative Psychiatric Research, iPSYCH. One researcher reports financial ties with the Stanley Medical Research Institute.