Reconceptualizing the Factor Structure of the Depression Anxiety Stress Scales (DASS) for Traumatic Brain Injury

Paper accepted In Press at Journal of Emotion and Psychopathology, which will be published open-access. Alexia Samiotis and Jai Carmichael are equal First Authors.

Abstract:
We used contemporary factor analytic procedures to assess whether the Depression Anxiety Stress Scales (DASS) can reliably differentiate depression, anxiety, and stress in individuals with TBI. One-hundred and thirty-six adults (M_age = 38.51 years; 77.94% male) with moderate-severe TBI completed the DASS42. Various confirmatory factor models were estimated for both the DASS21 and DASS42, with a focus on novel statistical indices derived from bifactor modeling. Bifactor modeling revealed a dominant general distress factor, accounting for 89% of the systematic variance in DASS21 total scores. Specific depression, anxiety, and stress factors added little specific information when holding the general factor constant, accounting for only 11–27% of residual systematic variance in the subscale scores. Omitting the specific factors and instead treating the DASS21 as a unidimensional measure introduced minimal bias in parameter estimates. However, some multidimensionality was apparent when considering individual items, particularly from the depression scale. Additionally, first- and second-order factor models indicated that the specific factors were not well-differentiated from one another or from the general factor. These findings extended to the DASS42. In conclusion, scores on the DASS after TBI predominately reflect a single underlying latent variable of general distress, providing support for using the total score over the three conventional scales.