A standardized research protocol was implemented at each of the nine centers to assure uniformity of diagnosis. All ASD subjects had to meet the following criteria: (a) a clinical DSM-IV-TR diagnosis of autistic or Asperger’s disorder, (b) an ADI/ADOS or at least an ADOS module 4 scale to assure they met the cut off for ASD, and (c) a Full Scale IQ score of 80 or above. If prior formal IQ test results were not available, a WAIS or a WASI was administered. Constantino’s Social Responsiveness Scale-Adult Research Version (SRS-A) was obtained if a suitable informant accompanied the subject, as it is a second party rating scale (a second party rating scale is administered to a person other than the subject who answers questions about the subject, such as a family member or a friend). The SRS was selected because it is easy to administer and is reported to have good psychometric properties: internal consistency 0.91–0.97, test–retest reliability 0.84–0.97 and interrater reliability 0.74–0.95 (Bolte et al. 2008 (link)). The respondents completing the measure in this study were spouses, parents and siblings. A subset of subjects at UCLA was retested after an average of 1 year to determine test–retest reliability.
Two groups of comparison subjects were selected. The first consisted of 276 volunteers who did not have, and never had a DSM-IV-TR diagnosis. They were recruited from clinic staff members and students, and were individually administered the scale by a research staff member. The second group consisted of 302 volunteers recruited at an adult psychiatric out-patient clinic. They were formally diagnosed as having a DSM-IV-TR diagnosis other than ASD by an experienced board certified psychiatrist or a licensed psychologist who administered the scale individually to each. The majority of the comparison cases were recruited by the principal investigator and UCLA.
Two groups of comparison subjects were selected. The first consisted of 276 volunteers who did not have, and never had a DSM-IV-TR diagnosis. They were recruited from clinic staff members and students, and were individually administered the scale by a research staff member. The second group consisted of 302 volunteers recruited at an adult psychiatric out-patient clinic. They were formally diagnosed as having a DSM-IV-TR diagnosis other than ASD by an experienced board certified psychiatrist or a licensed psychologist who administered the scale individually to each. The majority of the comparison cases were recruited by the principal investigator and UCLA.