The authors’ observations
When considering Mr. R’s diagnosis, our treatment team considered the possibility of OCD with absent insight/delusional beliefs, OCD with comorbid schizophrenia, bipolar disorder, and psychotic disorder due to another medical condition.
Overlap between OCD and schizophrenia
There appears to be both an epidemiologic and biologic overlap between OCD and schizophrenia. The Table1 summarizes the DSM-5 criteria for OCD and for schizophrenia. Schirmbeck et al2 reported that the estimated prevalence of OCD in patients with schizophrenia is 12%, which is higher than in the general population. Obsessive-compulsive symptoms (OCS) in patients with schizophrenia have been reported to be even more prevalent (30.7%).2 In a prospective cohort study, de Haan et al3 assessed 172 patients with first-episode schizophrenia, schizophreniform disorder, or schizoaffective disorder for the development of OCS over a 5-year follow-up period. Symptoms were tracked over time and included OCS on first assessment, persistent OCS, subsequent emergence of OCS, and intermittent OCS. A striking 51.1% of the patient sample screened positive.3 Obsessions and delusions are similar because they are both irrational thoughts, the former with insight and the latter without insight. The fact that OCS were present in up to 14% of drug-naïve patients with schizophrenia in this study suggests that this was not merely an adverse effect of antipsychotic medication.
Much of the literature about OCD examines its functional impairment in adults, with findings extrapolated to pediatric patients. Children differ from adults in a variety of meaningful ways. Baytunca et al4 examined adolescents with early-onset schizophrenia, with and without comorbid OCD. Patients with comorbid OCD required higher doses of antipsychotic medication to treat acute psychotic symptoms and maintain a reduction in symptoms. The study controlled for the severity of schizophrenia, and its findings suggest that schizophrenia with comorbid OCD is more treatment-resistant than schizophrenia alone.4
Some researchers have theorized that in adolescents, OCD and psychosis are integrally related such that one disorder could represent a prodrome or a cause of the other disorder. Niendam et al5 studied OCS in the psychosis prodrome. They found that OCS can present as a part of the prodromal picture in youth at high risk for psychosis. However, because none of the patients experiencing OCS converted to full-blown psychosis, these results suggest that OCS may not represent a prodrome to psychosis per se. Instead, these individuals may represent a subset of false positives over the follow-up period.5 Another possible explanation for the increased emergence of pre-psychotic symptoms in adolescents with OCD could be a difference in their threshold of perception. OCS compels adolescents with OCD to self-analyze more critically and frequently. As a result, these patients may more often report depressive symptoms, distress, and exacerbations of pre-psychotic symptoms. These findings highlight that comorbid OCD can amplify the psychosocial distress among higher-risk youth. It is therefore essential for physicians to perform a thorough interview in this population because subtle psychotic symptoms may be present.
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