Repetitive Behaviors: A Comparison of Obsessive Compulsive Disorder with and without Autism Spectrum Disorder

Background: Restricted, repetitive and stereotyped behaviors (RRSB)  are among the core symptoms of Autism Spectrum Disorders (ASD) and share features in common with the compulsions of  Obsessive-Compulsive disorder (OCD), as well as mental retardation. The behaviors often impede daily functioning for patients.  Little research has been done comparing these symptoms, with a single report finding no differences in parent reports (Zandt, Prior, & Kyrios, 2007).
Objectives: This study examined the differences in RRSB in participants with OCD only (OCD) as they compared to participants with a diagnosis of both OCD and an ASD (OCD+ASD). The relationship of RRSB scores to cognitive ability is investigated in both groups.
Methods: 47 participants: 31  OCD (Mean age = 14.40 +/- 2.3 yrs), and 16 OCD+ASD (14.11+/- 2.64 yrs) completed the Repetitive Behavior Scale-Revised (RBS-R, Bodfish, Symons, Parker & Lewis, 2000), a parent rating of repetitive behaviors, consisting of 5 subscales: Stereotypic Behavior , Self-Injurious Behavior , Compulsive Behavior, Rituals/Sameness Behavior, and Restricted Interests. Overall scores as well as subscale scores were analyzed using the Lam scoring system (Lam and Aman, 2007). The Children’s Yale-Brown Obsessive Compulsive Scale (CY-BOCS, Goodman, 1986) was also used, with compulsions ratings obtained for the whole group and obsessions ratings for 15 of 16 OCD+ASD participants.   44 participants completed a cognitive assessment, Weschler Abbreviated Scale of Intelligence (WASI), (n=41), the Mullen Scales of Early Learning (n=1), and the Differential Abilities Scale (n=2).  We examined differences between the two groups on both the RBS-R and CY-BOCS, and on each RBS-R subscale. We also examined correlations between the RBS-R and both the CY-BOCS and scores of cognitive ability.
Results: Preliminary results indicate no significant differences in the overall scores on the RBS-R between the OCD (X=23.00 +/- 17.22) and OCD+ASD groups (X=29.00+/- 13.28; t = -1.32, p=.19). However, the Restricted Interests subscale differed significantly between groups (OCD:  2.06 +/- 2.78; OCD+ASD: 4.75 +/- 1.81; t = -3.99, p < .00). No significant differences were found between groups on either obsessions or compulsion scales of the CY-BOCS. Scores on the RBS-R and CY-BOCS compulsions were positively correlated (r =.316, p = .05).
Seven percent (n= 2) of individuals in the OCD and 27% (n = 4) OCD+ASD scored below 70 on a cognitive test.  Mean cognitive scores (OCD: 101.90 +/-16.52, OCD+ASD: 80.87 +/-28.35) were negatively correlated with scores on the overall score of the RBS-R and on all of the subscales of the RBS-R with the exception of the Compulsive Behavior subscale.
Conclusions: Analyses indicate no differences between groups on the RBS-R overall score, but the OCD+ASD group had higher scores on the Restricted Interests subscale than the OCD group. The results suggest that the RBS-R is capturing obsessive-compulsive symptoms of both OCD and autism, and individuals with OCD and an ASD appear to have other types of significant repetitive behavior. Since cognitive ability influences these behaviors as well, assessments must be administered in the context of a more complete evaluation.