Episodic obsessive-compulsive disorder and bipolar spectrum disorder: new evidence from a large Italian OCD sample.

Objectives: Obsessive-Compulsive Disorder (OCD) has been considered to be a chronic illness; however, some authors described a subtype of OCD characterised by symptom-free periods of time: Episodic-OCD (E-OCD). Only few studies focussed on this subtype of the disorder. The objectives of this research were to study the association between the episodic course of the disorder and lifetime psychiatric comorbidities and to investigate socio-demographic and other clinical features correlated to the episodic course.

Methods: The sample is composed of adult OCD patients. The course was defined episodic when at least one circumscribed symptom-free interval of at least 6 months was present. The sample was divided into two subgroups: Episodic-OCD and Chronic-OCD. Differences between groups were analysed with Student's t-test, χ2 tests, Fisher test and multivariate logistic regression.

Results: Data regarding 585 individuals were collected. 14.2% (N = 83) of our sample had an episodic course. Bipolar I comorbid disorder, abrupt onset, lower severity of illness and lower rates of repeating compulsions were associated with the likelihood of having an E-OCD.

Conclusions: Our findings confirm that a significant proportion of OCD patients have an episodic course and that E-OCD could represent a specific endophenotype.