A Prospective, Longitudinal Evaluation of Early Temperament Indicators of Autism in Males with Fragile X Syndrome
Through prospective, longitudinal designs studies in idiopathic autism have identified several temperament indicators present within the first year of life that are indicative of later autism diagnoses in infants at high-risk due to having an older sibling with a diagnosis of autism. However, no studies have been conducted to examine the relationship between temperament and the emergence of autism in infants and young children with fragile X syndrome over time, a sample also at high-risk for developing autism. Using extant data, 11 males with fragile X syndrome were followed from 9 months to 106 months of age to examine temperament characteristics as a predictor of the severity of autistic behavior. Both parent ratings and an experimental measure of temperament were assessed, specifically dimensions of anger, attention, and soothability. Using multi-level modeling, results indicated that higher levels of initial anger ratings as well as increases in anger ratings over time significantly predicted more severe autistic behavior. Initial levels of soothability were not significant; however, less soothability over time was indicative of more severe autistic behavior. Contrary to hypotheses, attention ratings were not a significant predictor of autistic behavior. Findings regarding the experimental measure of anger indicated that children with more severe autistic behavior showed decreased facial anger over time. The current study extends the literature by demonstrating increased anger and decreased soothability are predictive of the severity of autistic behavior in a longitudinal sample of males with fragile X syndrome to elucidate early indicators of autistic behavior.