Autism Spectrum Disorders & Regression: Findings From a Population Based Study

Background: Developmental regression is among the hallmarks of Autism Spectrum Disorder (ASD). Estimates of the prevalence of regression have varied, ranging from 10% to 50%. In part, this variation may be due to the definition of regression itself. Several studies have suggested that a more specific definition of regression is associated with lower prevalence of regression.

Objectives: This study investigated regression in a population of ASD children residing in New Jersey to determine the occurrence of regression, average age of prevalence, and whether if there are systematic differences in characteristics of ASD children with regression as compared to ASD children without regression, with respect to age of sex, race, ASD diagnosis age, and DSM-IV-TR features.

Methods: Data were collected as part of a population-based ASD surveillance investigation carried out in Essex, Union, Hudson and Ocean Counties.  ASD ascertainment was by an active, retrospective, multiple-source, case-finding method, developed by the Centers for Disease Control and Prevention (CDC), based on review and analysis of information contained in health and education records.  Demographic variables and case-specific data, including information on regression were analyzed. Current findings represent 8-year olds (1998-born), in 2006. Regression was defined as loss of either language or social skills, or both. T tests, Chi-square, and ANOVA were used to test associations.

Results: In a sample of 533 ASD children, 72 children (13.5%) were found to have experienced developmental regression in early development by parent report.  Average age of regression was 25.3 month. Overall, regression distribution in this group did not vary significantly by race or sex. There was no significant association between the occurrence of regression and intellectual disability (ID).  68 children with a history of regression (94.4%) met the criteria for Autistic Disorder (AD), and 4 children with a history of regression (5.6%) met the criteria for ASD-NOS. In contrast, 345 children with no history of regression (74.8%) met the criteria for AD, and 116 children with no history of regression (25.1%) met the criteria for ASD-NOS (p<.001). On average, children with a history of regression were diagnosed with ASD by one year earlier than children with no history of regression (43 months and 55 months respectively, p<.001). Interestingly, 11 children with a history of regression (14.9%) had no clinical ASD diagnosis.

Conclusions: Our estimate of regressive ASD falls in the lower end of previously reported estimate of regression prevalence. A history of regression may lead to earlier identification of ASD, and that children with a history of regression are more likely to satisfy the criteria for AD than ASD-NOS.  Further research is necessary to understand the causes of regression.