Psychometric properties of the Adult Autism Subthreshold Spectrum (AdAS Spectrum): A study with a non-clinical sample

Introduction: The Adult Autism Subthreshold Spectrum (AdAS Spectrum; Dell’Osso et al., 2017) has been developed to assess the wide spectrum of autistic-like clinical and non-clinical features in adults. Nevertheless, its psychometric properties have been analyzed with clinical individuals until now. This study was aimed at investigating the dimensionality, reliability, and validity of the instrument in a non-clinical sample. Method: Participants were 395 Spanish undergraduated students (60% males; mean age of 21.1 years, SD = 2.6), who completed the AdAS Spectrum, the Autism-Spectrum Quotient (AQ), and the Empathy Quotient (EQ). Results: A confirmatory factor analysis supported the seven-factor structure of the questionnaire. Internal consistency was excellent for the total score and acceptable for five factors. Test-retest reliability over a 4-week period was good. Higher AdAS Spectrum scores significantly correlated with higher AQ and lower EQ scores, supporting the validity of the scale. Conclusion: Overall, findings support the psychometric properties of the AdAS in a non-clinical sample. Future research is warranted to further examine the psychometric properties of the scale in the general population.