Outcomes for Adults with Autism Spectrum Disorder and Intellectual Disability

Abstract

Autism spectrum disorder (ASD) and intellectual disability commonly occur together. As the diagnostic criteria for ASD have widened, the proportion of people with ‘high-functioning’ ASD has increased, and current estimates of the prevalence of intellectual disability among those with ASD are much lower than they were in the past. On the other hand, improvements in recognition and assessment have led to an increase in the proportion of people with intellectual disability who have a diagnosis of ASD. It is now thought that individuals with ‘low-functioning’ ASD (i.e. adults with ASD and intellectual disability) comprise around 50 % of the ASD population. This chapter is about adults with ASD and intellectual disability. The focus is on social functioning outcomes rather than health or psychopathological issues which are covered by other chapters in this book. The chapter begins with an evaluation of the methods that have been used to measure outcomes in adults with ASD and intellectual disability. This is followed by a review of the evidence on outcomes for this group. Finally, we discuss the clinical and research implications of this evidence.