Evidence for three subtypes of repetitive behavior in autism that differ in familiality and association with other symptoms

• Published in: Journal of child psychology and psychiatry Vol. 49; no. 11; pp. 1193 - 1200
• Main Authors: Lam, Kristen S.L., Bodfish, James W., Piven, Joseph
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.11.2008; Blackwell Publishing; Blackwell
• Subjects: Adolescent; Adult; Age Distribution; Autism; Autism Diagnostic Interview-Revised; Autistic Disorder - classification; Autistic Disorder - epidemiology; Autistic Disorder - genetics; Autistic Disorder - psychology; Behavior Patterns; Biological and medical sciences; Child; Child clinical studies; Child, Preschool; Classification; Communication Problems; Correlation; Correlation analysis; Developmental disorders; Diagnostic Tests; Disabilities; Discriminant analysis; Exploratory factor analysis; Factor Analysis; Factor Analysis, Statistical; Familiarity; Female; Genetic Predisposition to Disease - epidemiology; Genetic Predisposition to Disease - genetics; Genetic Predisposition to Disease - psychology; Humans; Infant; Infantile autism; Intelligence; Intelligence Quotient; Interpersonal Competence; Interview, Psychological - methods; Language Disorders - epidemiology; Language Disorders - psychology; Male; Measures (Individuals); Medical sciences; Motor Reactions; North Carolina - epidemiology; Psychology. Psychoanalysis. Psychiatry; Psychopathology. Psychiatry; repetitive behavior; Repetitive behaviour; Severity of Illness Index; Social Behavior; Stereotypes; Stereotypic Movement Disorder - epidemiology; Stereotypic Movement Disorder - genetics; Stereotypic Movement Disorder - psychology; Subtypes; Symptoms; Symptoms (Individual Disorders); Validity; Young Adult; North Carolina; Human; Factor analysis; Autism Diagnostic Interview-Revised; Developmental disorder; Repetitive behavior; Interview; Autism; Symptomatology; Adolescent; Young adult; Diagnosis; Child; Subtype
• ISSN: 0021-9630; 1469-7610
• DOI: 10.1111/j.1469-7610.2008.01944.x

Background:  Restricted repetitive behaviors (RRBs) are a core feature of autism and consist of a variety of behaviors, ranging from motor stereotypies to complex circumscribed interests. The objective of the current study was to examine the structure of RRBs in autism using relevant items from the Autism Diagnostic Interview‐Revised in a sample of 316 individuals with autistic disorder. Methods/Results:  Using exploratory factor analysis, three distinct factors were identified: Repetitive Motor Behaviors (RMB), Insistence on Sameness (IS), and Circumscribed Interests (CI). RMB were found to be associated with a variety of subject characteristics such as IQ, age, social/communication impairments, and the presence of regression. IS was associated with social and communication impairments whereas CI appeared to be independent of subject characteristics, suggesting CI may be particularly useful in subsetting samples. Based on sib‐pair correlations, IS and CI (but not RMB) appear to be familial. Analysis of the data at the case level suggests that the presence of multiple forms of RRB in an individual is associated with more impairment in the social and communication domains, suggesting a more severe presentation of autistic disorder. Conclusions:  There appears to be considerable structure within repetitive behavior in autism. The finding that these behaviors are differentially related to subject characteristics and familiality adds to their validity.