Validity and Reliability of the Turkish Version of the Adult Autism Subthreshold Spectrum Scale

Considering autism as a spectrum, dimensional measures such as the Adult Autism Subthreshold Spectrum (AdAS Spectrum) have been increasingly emphasized. The AdAS Spectrum is a self-report questionnaire designed to characterize autistic traits and subthreshold manifestations rather than establish an autism diagnosis. This study aimed to culturally adapt the AdAS Spectrum for the Turkish population and evaluate its validity and reliability. A total of 99 individuals with autism spectrum disorder and 348 typically developing participants were enrolled in the study. Participants completed the AdAS Spectrum, Autism Spectrum Quotient (AQ), and Empathy Quotient (EQ) scales. Confirmatory factor analysis supported the seven-domain structure of the original AdAS Spectrum (χ²/df = 2.058, root mean square error of approximation [RMSEA] = 0.048, comparative fit index [CFI] = 0.952, Tucker-Lewis index [TLI] = 0.946, standardized root mean square residual [SRMR] = 0.038). The scale showed high internal consistency (Kuder-Richardson coefficient [KR-20] = 0.964), good-to-excellent test-retest reliability (intraclass correlation coefficient [ICC] = 0.800 through 0.961), and expected associations with another dimensional measure of autistic traits. These findings support the Turkish AdAS Spectrum as a self-report measure for the dimensional characterization of autistic traits in research.