Reconceptualising the factor structure of the Depression Anxiety Stress Scales (DASS) for traumatic brain injury.

OBJECTIVE

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 traumatic brain injury.

METHODS

A total of 136 adults (Mage = 38.51 years; 77.94% male) with moderate-to-severe traumatic brain injury 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 modelling.

RESULTS

Bifactor modelling 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.

CONCLUSION

In conclusion, scores on the DASS after traumatic brain injury predominately reflect a single underlying latent variable of general distress, providing support for using the total score over the three conventional scales.