Amostra

Participants were selected from an ongoing study of 406 individuals with ASD (Seltzer et al., 2003) and a completed study of 169 individuals with DS (Krauss & Seltzer, 1999). In both studies, the maternal respondent was interviewed at 18 month intervals regarding her son or daughter's health, behavior problems, functional abilities, and daily activities. In both studies, about half of the families lived in Massachusetts and the other half in Wisconsin. The criteria for inclusion in the DS study were that the mother was between the ages of 55 and 85, and the son or daughter lived at home with her at the beginning of the study. The criteria for inclusion in the ASD study were that the son or daughter with ASD was age 10 or older, had received an independent diagnosis of ASD (Autistic Disorder, Asperger Disorder, or PDD-NOS) from an educational or health professional, and had a research-administered Autism Diagnostic Interview-Revised (ADI-R; Lord, Rutter & Le Couteur, 1994) profile consistent with the diagnosis. Unlike the inclusion criteria for the DS study, individuals with ASD were selected for the ASD study either if they lived with their families or if they lived in non-family settings. Families in both studies volunteered to participate