The relationship of age with the autism-spectrum quotient scale in a large sample of adults

Background: The historical focus on autism as a childhood disorder means that evidence regarding autism in adulthood lags significantly behind research in other age groups. Emerging studies on the relationship of age with autism characteristics do not target older adult samples, which presents a barrier to studying the important variability that exists in life span developmental research. This study aims to further our understanding of the relationship between the Autism-Spectrum Quotient Scale and age in a large adult sample. Methods: The present study examines the relationship of Autism-Spectrum Quotient Scale (AQ) scores with age in 1139 adults, ages 18-97 years. Participants came from three distinct samples-a sample of primarily students, a sample of MTurk participants, and a sample of primarily community dwelling older adults. The majority of the participants did not self-report an autism diagnosis (91%), were female (67%), and identified as White (81%). Participants completed the AQ primarily via online surveys. Researchers scored the AQ following six common scoring practices. Results: Results of preregistered analyses indicate that autism characteristics measured by the AQ are not strongly associated with age (r values from -0.01 to -0.11). Further findings indicate that the measurement of autism characteristics is consistent across age into late life using both multiple groups and local structural equation modeling approaches to measurement invariance (comparative fit indices = 0.82-0.83, root mean square error = 0.06) as well as reliability analysis. Finally, demographic and autism-related variables (sex, race, self-identified autism spectrum disorder diagnosis, and degree of autism characteristics) did not moderate the relationship between age and autism characteristics. Conclusion: These results suggest that self-reports of autism characteristics using the AQ do not vary strongly by age in this large age-representative sample. Findings suggest that the AQ can potentially serve as a useful tool for future research on autism across the life span. Important limitations on what we can learn from these findings point toward critical avenues for future research in this area.