Growth differences associated with compulsive and stereotyped behavior disorders in adults with mental retardation.

We have recently observed that compulsive behaviors in mentally retarded patients appear to be quite prevalent, can be reliably assessed, and have a high rate of co-occurrence with stereotyped and self-injurious behaviors in this population. As abnormal growth rate has been observed in obsessive-compulsive disorder (OCD) patients, we examined physical stature in adults with mental retardation who display repetitive movement disorders. Identification of cases with stereotypic movement disorder, and cases with compulsive behaviors was done using a symptom checklist and direct observation. Subjects with repetitive movement disorders were smaller in stature than control subjects, with gender differences observed across repetitive behavior disorders. Specifically, female subjects with compulsive behavior disorder, but not stereotypic movement disorder, were significantly shorter and weighted significantly less than same sex-matched controls. Conversely, male subjects with stereotypic movement disorder, but not compulsive disorder, were significantly shorter and weighed significantly less than same sex controls. These findings may point to a neuroendocrine abnormality associated with repetitive movement disorders.