Simons Simplex Collection at the Interactive Autism Network: An Online Follow-up Study

Background: The Simons Simplex Collection at the Interactive Autism Network (SSC@IAN) is an online cohort of families from the original SSC study who have agreed to be contacted about additional research opportunities. Participants in the SSC@IAN are members of simplex families, each of which has one child affected with an autism spectrum disorder, and unaffected parents and siblings. The online research environment at the SSC@IAN affords a unique, centralized platform to follow up with SSC families from all over the United States and Canada.

Objectives: The SSC@IAN follow-up study was an online study to gather medical, educational, diagnostic, and psychosocial updates on SSC probands and their families 5 to 8 years following their participation in the original SSC study. The original SSC cohort is a clinically and genetically well-characterized cohort that has proven valuable for research, and the follow-up study aimed to provide researchers with updated data on as many families as possible.

Methods: SSC@IAN families were provided the opportunity to complete 3 modules, accessible via their online research dashboard. Each module included a selection of update surveys (e.g. medical, pharmacological/treatment, educational, and diagnostic history) and standardized measures such as the Social Responsiveness Scale – Second Edition, Adult Behavior Checklist or Child Behavior Checklist, Aberrant Behavior Checklist, and Repetitive Behavior Scale-Revised.

Results: Four hundred (400) families with probands under age 18 completed some portion of the follow-up study. Ratios of males to females and IQ, are comparable between the original SSC cohort and the follow up participants. Mean full scale IQ for the original SSC cohort was 81, verbal IQ was 78 and nonverbal IQ was 84; for the follow-up study, the full scale IQ was 83, verbal IQ was 80, and non-verbal IQ was 86. Age ranged from 4 to 17 for the complete original SSC cohort (mean 9.0 years), and 8 to 17 years of age for the follow-up study cohort (mean 12.9 years). The age at baseline assessment in the present follow-up cohort was 4 to 11 years. Compared to the baseline SSC cohort data, probands showed lower scores in some specific areas, including RBS-R repetitive and sensory behaviors (total mean 27.0, 21.7), and CBCL6-18 externalizing behaviors (T mean 56.2, 52.7). Internalizing behavior and ADHD scores were similar between the follow-up study and baseline SSC cohort data (Internalizing T mean 60.0, 60.1; ADHD T mean 61.9, 60.6). In terms of comorbid diagnoses, parents reported high frequencies of diagnosis or treatment for ADHD (42%) and anxiety (26%) in probands at follow-up, with lower frequencies of seizure (6%), depression (4%), and bipolar disorders (2.5%).

Conclusions: The SSC@IAN follow-up study provides additional longitudinal data for researchers to investigate outcomes in this well-characterized ASD cohort. In general, the current sample shows a trend towards lower scores on some ASD and related behavioral measures compared with the SSC cohort’s original data, suggesting milder symptoms. However, consistent with other studies, anxiety disorders and ADHD are common comorbid conditions now reported in these older children and teens with ASD.