Archives of General Psychiatry
Approximately 1 percent of adults in England have autism spectrum disorder, based on one of the first studies of adult prevalence in the country. Previous studies have relied primarily on self-report which can be unreliable. To determine what proportion of the English population age 16 years and older is affected by autism, researchers conducted a multiphase study to screen adults in the community. They hypothesized that the rate of autism would be much lower in older adults than in children and that adults on the spectrum would be predominately male and socially disadvantaged. In the first phase of the study, participants selected from the 2007 Adult Psychiatric Morbidity Survey in England completed the Autism-Spectrum Quotient self-questionnaire. The answers to this and other self-assessments helped the investigators select 618 individuals from the initial 7,461 respondents to interview using the Autism Diagnostic Observation Schedule (ADOS-4). Based on the results of screening using the tool, 19 people met the criteria for autism spectrum disorder representing a prevalence rate of 9.8 per 1,000 individuals, or nearly 1 percent. While only a small number of individuals were identified, many were living in social housing and had the lowest levels of education, reinforcing the authors' hypothesis that those with autism are more likely to be socially disadvantaged. None of these associations, however, were statistically significant. The authors note that the prevalence rate identified in this study is similar to the rate reported among children, supporting the idea that autism rates have not changed significantly over time. Due to the small sample of adults with ASD, they were unable to examine differences in adult prevalence by age. The findings suggest that adults with ASD may be undiagnosed and socially disadvantaged, which has significant public health implications.
--IACC 2011 Summary of Advances in ASD Research