The sample included data from 393 different individual participants. Some participants had repeated assessments, yielding a total of 437 cases. Each case was defined by an ADOS and best estimate clinical diagnosis; 29 participants provided data for multiple cases (M=2.52, SD=1.06, range=2–6) based on evaluations conducted at different points in time. The majority of participants (n=319) were research participants and clinic referrals for assessment of possible autism to the University of Chicago Developmental Disorders Clinic (UCDDC), the University of Michigan Autism and Communication Disorders Center (UMACC), or the New York Presbyterian Center for Autism and the Developing Brain (CADB) at Weill-Cornell. Seventy-four participants were evaluated as part of the Simons Simplex Collection (SSC; Fischbach & Lord 2011), a multi-site genetic study. Approximately 80% of the sample was male and 83% Caucasian. Inclusion/Exclusion criteria varied by research study. However, individuals with significant hearing, vision or motor problems that interfered with standardized testing or who were exhibiting active psychosis or uncontrolled seizures at the time of assessment were excluded from each study. Participants in the SSC were also required to meet Collaborative Programs for Excellence in Autism criteria for ASD (see Hus et al., 2013 (link) for details) and were excluded if the individual had a diagnosis of Fragile X syndrome, tuberous sclerosis, Down syndrome or significant early medical history. Additionally, SSC participants could not have any first, second or third degree relatives with ASD or a sibling with substantial language or psychological problems related to ASD. Ages ranged from 9.92 to 62.25 years at the time of assessment (mean=21.56, standard deviation=8.62 years).
Of the 437 cases, 177 had clinical diagnoses of autism (40% of entire sample), 170 Other-ASD (i.e., PDD-NOS or Asperger’s; 39%), and 90 Non-ASD diagnoses (21%). The Non-ASD sample was comprised of both clinical referrals and individuals recruited to research studies as controls. In addition to having first ruled-out an ASD diagnosis, 84% of non-ASD participants received a primary diagnosis of a non-ASD DSM-IV-TR disorder; 30% had a primary diagnosis of mood and/or anxiety disorders, 26% had non-specific intellectual disability, 14% had externalizing behavioral disorders (e.g., ADHD/ODD), 5% had Down syndrome or Fragile X, 4% had language disorders, 1% had Fetal Alcohol syndrome, 1% had Cerebral Palsy and 3% of cases had unspecified difficulties. The remaining 16% of Non-ASD sample did not meet criteria for a DSM-IV-TR diagnosis at the time of assessment; 64% of these individuals (n=9) had had a previous diagnosis of ASD and 36% (n=5) had had a previous Non-ASD diagnosis. There was no significant difference in ADOS totals between the 9 individuals with previous ASD diagnoses and the remaining non-ASD group (data available from authors upon request).Table 1 provides a more detailed sample description.
Of the 437 cases, 177 had clinical diagnoses of autism (40% of entire sample), 170 Other-ASD (i.e., PDD-NOS or Asperger’s; 39%), and 90 Non-ASD diagnoses (21%). The Non-ASD sample was comprised of both clinical referrals and individuals recruited to research studies as controls. In addition to having first ruled-out an ASD diagnosis, 84% of non-ASD participants received a primary diagnosis of a non-ASD DSM-IV-TR disorder; 30% had a primary diagnosis of mood and/or anxiety disorders, 26% had non-specific intellectual disability, 14% had externalizing behavioral disorders (e.g., ADHD/ODD), 5% had Down syndrome or Fragile X, 4% had language disorders, 1% had Fetal Alcohol syndrome, 1% had Cerebral Palsy and 3% of cases had unspecified difficulties. The remaining 16% of Non-ASD sample did not meet criteria for a DSM-IV-TR diagnosis at the time of assessment; 64% of these individuals (n=9) had had a previous diagnosis of ASD and 36% (n=5) had had a previous Non-ASD diagnosis. There was no significant difference in ADOS totals between the 9 individuals with previous ASD diagnoses and the remaining non-ASD group (data available from authors upon request).