Clinical characteristics and treatment response of a possible self-contamination subtype of obsessive-compulsive disorder: a prospective investigation

Background Obsessive-compulsive disorder (OCD) present invasive thoughts and repetitive behaviors affecting 1–3% of the population, divided into 3–5 symptom dimensions. Self-contamination, a subtype within the contamination/washing dimension, remains poorly understood. This study aim is to investigate pathological features and treatment response in self-contamination subtype compared to other contamination subtype and checking symptoms. Method Seventy-one OCD patients were categorized into self-contamination (n = 15), contaminated (n = 25), and checking symptom (control, n = 31) groups. OCD symptom severity was assessed using the Japanese version of the Yale-Brown Obsessive-Compulsive Scale (Y-BOCS) Symptom Checklist. Comorbidities were evaluated using the Structured Clinical Interview for DSM-IV. Global functioning, anxiety, and depressive symptoms were measured using DSM-IV's Global Assessment of Functioning Scale (GAFS), State-Trait Anxiety Inventory, and Zung’s Self-rating Depression Scale, respectively. Treatment involved a standardized combination of selective serotonin reuptake inhibitors and cognitive-behavioral therapy, with treatment response assessed after 1 year. Results Subjects in the self-contamination group showed significantly lower quality of life, GAFS scores, and higher comorbidities including major depressive disorder, social anxiety disorder, body dysmorphic disorder, and olfactory reference disorder. Treatment response was notably poorer in the self-contamination group. Multiple regression analysis identified four poor treatment outcome predictors: score on the Y-BOCS and the SDS, duration of illness, and prevalence of ORD. Conclusion The identification of the self-contamination subtype in OCD patients is crucial for understanding the pathophysiological and treatment response. Further research is needed to clarify the socio-cultural effects on the development of this putative subtype of OCD.