- The ARC - California Edition -

Research Indicates Autism Rate is Higher

Researchers from England recently published a study that identified autistic disorders may be occurring much more frequently than previously thought. This finding is in light of speculation during recent years that the incidence of what is known as Autism Spectrum Disorders (ASD) is increasing. The study undertook a detailed look at 15,500 children who resided in the Staffordshire area of central England during 1998 and 1999.

The report of their findings, published June 27, 2001 in the Journal of the American Medical Association (JAMA), included estimates that the prevalence of autism in the study group was 16.8 cases out of every 10,000 children, and estimates that there was a prevalence of 45.8 cases per 10,000 children for other Pervasive Developmental Disorders (PDD). 

The authors noted that these numbers are three times the findings of earlier studies of these disorders. Previous estimates of PDD placed the prevalence at approximately 20 cases per 10,000.

In their comments, the researchers state they could not ascertain whether their findings were reflecting a true rise in the incidence of autism. “Whether the higher prevalence rates reported recently arise from a secular increase in the incidence of the disorder or merely reflect a broadening of the concept of PDD together with improved detection and recognition cannot be assessed from these data,” according to the report.

Other surveys have also indicated that the rapidly rising incidence of autism may be the result of better case finding procedures and improved awareness by both the parents/lay public, and within the professional groups as well. 

This point was discussed in their report. The research found that children subjected to this study had an average rate of mental retardation of only 26%. Earlier studies have reported nearly 75% of the children with PDD as presenting mental retardation. The rate has been falling in studies conducted during recent years. 

(Pervasive Developmental Disorders in Preschool Children: Chakrabarti and Fombonne; JAMA 2001; 285)