Repetitive behaviors in autism: relationships with associated clinical features.

Relationships between repetitive behaviors (RBs) and associated clinical features (i.e., cognitive and adaptive functioning levels, sleep problems, medication use, and other behavioral problems) were examined in two groups (High nonverbal IQ > or = 97 versus Low nonverbal IQ < or = 56) of children with autism spectrum disorders (n = 14; mean age = 10 years, 7 months). For the group as a whole, nonverbal cognitive ability (NVIQ) (as measured by the Leiter-R), adaptive functioning level, the presence of sleep problems, and three scales of the Aberrant Behavior Checklist (ABC) (Irritability, Lethargy, and Hyperactivity) were highly correlated with total RB scores on the Repetitive Behavior Scale-Revised (RBS-R). After controlling for NVIQ, adaptive level, sleep problems, and two scales of the ABC (Irritability and Lethargy) were not significantly associated with RB scores. However, there remained a significant positive correlation between the presence of RBs and the Hyperactivity scale of the ABC. Parent ratings of their stress levels and the presence of RBs in their children were highly correlated. The relationship between RBs and associated clinical features in autism is complex and future studies should control for cognitive ability when examining the direct and indirect relationships of these variables with RBs.