Video telemetry and behavioral analysis discriminate between compulsive cleaning and compulsive checking in obsessive-compulsive disorder

Obsessive-compulsive disorder (OCD) patients exhibit compulsive acts that share key characteristics that discriminate them from normal behaviors. In OCD, factor analysis of symptomatology has identified separate clusters (contamination/cleaning; harming/checking; symmetry/ordering; hoarding). Here we used video analysis of the motor characteristics of OCD compulsions derived from two separate clusters, checking and cleaning, in order to determine whether behavioral differences exist in the way these two compulsions are performed. We compared 22 behavioral components (acts) of 12 OC-cleaning rituals and 25 OC-checking rituals. A normal activity with the identical theme was matched for each OC ritual as a control. For each ritual and control, we measured 22 parameters (such as the duration and frequency of act performance), and the levels of functionality, by evaluating the degree to which the act appears to contribute toward achieving its goal. We found that both OC-cleaning and OC-checking rituals differed from their respective control activity, and that they also differ between themselves in seven out of the 22 parameters. OC-cleaning involved increased repetition of functional activity whereas OC-checking involved a relatively increased non-functional activity. These results suggest that OCD cleaning and checking rituals are sufficiently different to justify their division into different subtypes and presumably are sub-served by different mechanisms. A better understanding of the relationship between those behavioral parameters derived from video-telemetry, and the parameters assessed by means of clinical and neurobiological tools, would improve our understanding of the nosological significance of compulsive symptoms and contribute to advancing endophenotypic exploration of the heterogeneity of OCD.