Revisiting the Construct Validity of the DASS-21 in Thai Young People: Evidence for a General Distress Factor from a Cross-Sectional Psychometric Study

Abstract

Background/Objectives: The Depression, Anxiety, and Stress Scales–21 (DASS-21) is widely used to assess psychological distress, but its factor structure may vary across contexts. This study evaluated the factor structure and construct validity of the Thai DASS-21 among Thai young people. Methods: In this cross-sectional study, 220 Thai young people aged 12–24 years completed the DASS-21 and measures of psychological well-being, mindfulness, and suicide risk. Exploratory factor analysis used principal axis factoring with unrestricted, two-factor, and three-factor solutions; oblimin rotation was used for the specified solutions. FA-based parallel analysis was conducted. Confirmatory factor analysis of ordinal items compared one-factor, two-factor, and original three-factor models in the same sample. Results: EFA showed substantial common variance across items. Mean-eigenvalue parallel analysis suggested five factors, with a dominant first factor. Among the specified EFA solutions, the two-factor solution was more interpretable and explained 44.09% of the variance. CFA fit indices favored the two-factor Distress and Depression model over the one-factor model; fit was comparable to the original three-factor model, with fewer free parameters. Distress and Depression scores correlated negatively with psychological well-being (r = −0.54 and −0.71, respectively) and mindfulness (r = −0.73 and −0.64, respectively), and positively with suicide risk (r = 0.46 and 0.45, respectively; n = 71). Conclusions: The Thai DASS-21 showed a strong general distress component with partial differentiation into related Distress and Depression factors. Findings do not establish strict unidimensionality or justify replacing subscale scores with the total score. Independent replication is required.