Diagnosing ASD in Children Aged 6–18: Gender Differences and the Diagnostic Process

Background/Objectives: Diagnosing ASD becomes more difficult with age, especially in girls. This study explores developmental factors and diagnostic tools that affect ASD diagnoses after age six. The study also integrates the neurodiversity paradigm to evaluate how diagnostic tools like the ADOS-2 and Social Attribution Test (SAT) capture the heterogeneous presentation of ASD across genders. Methods: This retrospective study analyzed data from 91 children (73 boys, 18 girls) assessed for ASD between ages 6–18. Multivariate Generalized Linear Models (GLMs) were employed to identify independent predictors of diagnosis, controlling for age, gender, and language difficulties. Results: Notable gender differences emerged: boys showed more atypical development and restricted interests, while girls showed higher sensory sensitivity. Multivariate analysis confirmed that Social Affect (SA), age of initial concern, and the absence of structural language difficulties significantly impacted diagnosis likelihood. Conclusions: This study emphasizes the need for gender-sensitive criteria and implicit measures like the SAT to identify “masking” phenotypes. It emphasizes current tool limitations, the risk of diagnostic overshadowing, and the importance of longitudinal studies with comprehensive assessments to better capture ASD diversity, especially in social and language skills.