Validation of the 21-item Depression, Anxiety, and Stress Scales (DASS-21) in individuals with autism spectrum disorder

The purpose of the study was to examine the internal consistency and validity of the 21-item Depression Anxiety Stress Scale (DASS-21) in individuals with Autism Spectrum Disorder (ASD) and without intellectual disability (IQ >= 70). Participants (NN = 123) were consecutively recruited from the Brain and Mind Centre in New South Wales, Australia. Internal consistency was determined using Cronbach's alpha. Item-total correlations were evaluated by Pearson's product-moment correlation coefficient. The convergent validity of the DASS-21 was examined by measuring its associations with quality of life and other measures of depression and anxiety. Factorial validity was assessed using confirmatory factor analysis. The DASS-21 demonstrated good internal consistency, adequate convergent validity, and all items exhibited satisfactory item-total correlations. Considering fit indices and factor loadings, the confirmatory factor analysis results provided support for the original 3-factor oblique model consisting of depression, anxiety, and stress factors. The model fit could be further improved with some modifications. Overall, the results indicate that the DASS-21 is a viable self-report screening measure for depression, anxiety, and stress in individuals with ASD and without intellectual disability.