Measurement‐Dependent Sex‐Based Differences in Autistic Traits: Comparing Self‐Report, Informant‐Report, and Clinician Observation in Adults With Autism Spectrum Disorder

ABSTRACT Autistic traits are commonly assessed using self‐reported questionnaires, informant‐reported measures, and clinician‐administered diagnostic instruments; however, the convergence among these approaches and how they vary according to sex remain incompletely understood. We aimed to examine associations and discrepancies among self‐reported autistic traits (Autism‐Spectrum Quotient Japanese version [AQ‐J]), informant‐reported traits (Social Responsiveness Scale, Second Edition [SRS‐2]), and clinician‐rated autism trait intensity (Autism Diagnostic Observation Schedule, Second Edition [ADOS‐2], Module 4) in adults with autism spectrum disorder (ASD; n = 219) and typically developing (TD; n = 130) individuals. We also evaluated whether these patterns differed based on sex across measures. AQ‐J and SRS‐2 scores were higher in ASD than in TD participants. Questionnaire‐based measures showed minimal sex differences, whereas ADOS‐2 scores were higher in males within the ASD group. Repeated‐measures analyses revealed a significant measure‐by‐sex interaction ( p < 0.001, partial η 2 = 0.036). This reflected significantly lower clinician‐rated trait intensity in females, despite non‐significant questionnaire‐based sex differences, with no overall sex difference in mean trait intensity. Self‐reported, informant‐reported, and clinician‐rated assessments capture overlapping but distinct aspects of the autism phenotype, and the pattern of sex differences depends on the measurement modality used.