Abstract
The Autism Spectrum Screening Questionnaire (ASSQ) is equipped with good properties for screening the broader phenotype of autistic traits, but it is standardized for a limited age range-from 7 to 16 years. To contribute to the early detection of Autism Spectrum Disorder (ASD), particularly in high functioning children with ASD, likely to cause maladjustments during school age, the present study examined psychometric properties to apply the ASSQ to a younger age. We tested parents' ASSQ ratings for preschool children in clinical (N = 154, average age 60.77 months, range 55-72 months) and community settings (N = 1390, average age 60.53 months, range 57-68 months) in Japan. The results showed, just as in school-aged children, the ASSQ had reliability and validity as a screening instrument for preschool children in community settings. A cut-off of 7 with sensitivity of 0.93 and specificity of 0.84 is recommended for community screening. Still, based on the current study with a clinical group, an optimal cut-off score with high sensitivity and high specificity for parents' ASSQ ratings could not be established. The clinicians should be reminded that the ASSQ is a screening instrument, not a diagnosing instrument. Also, this result suggest multi-faceted evaluation is necessary in clinical settings, for example, the addition of teachers' ratings.