The Association Between Childhood Trauma and Motor Structure in Obsessive-Compulsive Rituals: An Ethological and Evolutionary Approach

Objective: Ethological models have highlighted a specific motor structure of compulsions in obsessive-compulsive disorder (OCD), based on the rigid repetitions of acts, and with the adaptive significance of facing unpredictable conditions. Such an evolutionary mechanism might explain the robust association between childhood traumatic experiences (CTEs) and OCD. However, a relationship between CTEs and the motor structure of compulsions has not been investigated yet. The first objective of the study was to confirm a specific motor structure of OCD compulsions with respect to control behaviors; the second objective was to assess a possible association between the motor structure of compulsions and CTEs severity. Method: Thirty-two OCD outpatients (13 female, M-age = 44.50 years, SE = 19.71) and 27 healthy controls (10 female, M-age = 37.62 years, SE = 16.20), matched for sex and age, provided a videotape of their compulsions and corresponding ordinary acts, respectively. Behavior was scored with the software "Observer." Participants were administered the Yale-Brown Obsessive Compulsive Scale and the Childhood Trauma Questionnaire. A dependent t test was used to compare the motor structure of behavior between the groups; Pearson's correlations to investigate associations between motor parameters and CTEs. Results: Compulsions showed a specific motor structure due to the repetition of functional and nonfunctional acts. CTEs severity was especially associated with the repetition of functional acts, independently from OCD severity. Conclusion: Our findings, in confirming a peculiar motor structure for OCD compulsions, hint for the first time at a link between CTEs and compulsive repetition of functional acts, which would represent a plastic developmental response to CTEs unpredictability.