A CASE-CONTROLLED STUDY OF REPETITIVE THOUGHTS AND BEHAVIOR IN ADULTSWITH AUTISTIC DISORDER AND OBSESSIVE-COMPULSIVE DISORDER

Objective: The purpose of this study was to investigate the types of r epetitive thoughts and behavior demonstrated by adults with autistic d isorder and compare them with those of age- and sex-matched adults wit h obsessive-compulsive disorder. Method: Fifty consecutive patients ad mitted to the Yale Adult Pervasive Developmental Disorders (Autism) Cl inic with a primary diagnosis of autistic disorder (DSM-III-R and DSM- IV) completed the symptom checklist of the Yale-Brown Obsessive Compul sive Scale. Types of current obsessions and compulsions were evaluated . The comparison group consisted of 50 age- and sex-matched adults wit h obsessive-compulsive disorder (without ties) (DSM-III-R and DSM-IV). Results: Direct discriminant function analysis showed that the patien ts with autistic disorder could be distinguished from those with obses sive-compulsive disorder on the basis of the types of current repetiti ve thoughts and behavior that they demonstrated. Compared to the obses sive-compulsive group, the autistic patients were significantly less l ikely to experience thoughts with aggressive, contamination, sexual, r eligious, symmetry, and somatic content. Repetitive ordering; hoarding ; telling or asking (trend); touching, tapping, or rubbing; and self-d amaging or self-mutilating behavior occurred significantly more freque ntly in the autistic patients, whereas cleaning, checking, and countin g behavior was less common in the autistic group than in the patients with obsessive-compulsive disorder. In addition, a specific subset of seven obsessive-compulsive variables from the Yale-Brown Obsessive Com pulsive Scale symptom checklist was identified that reliably predicted membership in the autistic group. Conclusions: These results suggest that the repetitive thoughts and behavior characteristic of autism dif fer significantly from the obsessive-compulsive symptoms displayed by patients with obsessive-compulsive disorder. Future studies are warran ted to assess the treatment response and neurobiological underpinnings of repetitive thoughts and behavior in patients with autism and obses sive-compulsive disorder.