Autism: Why Do Some Develop Then Regress?

The largest known study of its kind offers a host of new details on autism with regression, including a link between regression and a family history of autoimmune thyroid disease, an association with gastrointestinal symptoms and more findings offering a better picture of autism's causes.

While previous research used data collected from school age and older children, the new study included mostly children in their pre-school years. The U-M Autism & Communication Disorders Center used data collected from 13 sites across the nation as part of a larger project within the Collaborative Program for Excellence in Autism.

The studies are detailed in three upcoming medical journal papers by U-M researchers Jennifer Richler and Rhiannon Luyster and University of Cincinnati researcher Cindy Molloy. They looked at numerous factors contributing to Autism Spectrum Disorder (ASD).

The researchers found:

• Nearly 77 percent of children experiencing language loss also lost communication skills in non-verbal areas. Children who used words and then stopped talking showed a pattern of developing and losing non-verbal communication skills, including responding to their name, imitation, direct eye gazing, gestures, participation in social games and receptive language skills before speech. They went from having more of these skills before the loss than other children with ASD to having fewer of these non-verbal communication skills after the word loss.

• The mean age of loss was 19 months. Although children with regression had less obvious autism symptoms before the loss, most of them already had begun to demonstrate subtle delays before the word loss.

• There are mixed results indicating there could be a possible regressive phenotype of autism. For the most part, children with ASD who had regression overlapped in symptoms with children who had never lost skills. The patterns of development described by parents of children with regression, however, were very similar across different sites and children. Most saw real losses in the children and not gradual realization by the parents that something was wrong.

• There is no evidence that regression in ASD is associated with the measles-mumps-rubella (MMR) vaccine. Most children receive the MMR vaccine between 15 and 18 months, which is around the same time that the losses occurred. But variations in when children received vaccinations were not related to variations in timing of regression, and children who received a vaccination before parents reported that they became concerned were just as likely to already have delays as children who received vaccinations after the onset of ASD.

The study, gathering information through collaboration with many of the nation's top universities, brought together data from 1,592 children diagnosed with ASD across the 13 sites during a five-year period. Researchers gave greater analysis to 351 cases, to include 163 with regression and 188 with no regression.

Autism is a complex developmental disability that typically appears during the first three years of life. ASD impacts the normal development of the brain processes related to social interaction and communication skills. Children and adults with autism typically have difficulties with verbal and non-verbal communication, social interaction, and leisure or play activities.

Center Director Catherine Lord, a nationally known pioneer in autism research, played a key role in learning how to properly diagnose 2-year-olds a decade ago. She is confident the University's research will make it routine to diagnose autism for children 18 months old, and perhaps younger.

The number of children diagnosed with the disorder has increased tenfold during the past decade. The center has been conducting a sweeping longitudinal study of children with ASD that started when participants were age 2. Most of the subjects now are in their teens.

More on the Autism & Communication Disorders Center:http://www.umaccweb.com/ >