Predicting mood outcome following traumatic brain injury (TBI): PTA & demographic variables

Alexithymia as a risk factor for poor emotional outcomes in adults with acquired brain injury

Emotional disorders are pervasive in the acquired brain injury (ABI) population, adversely affecting quality of life and rehabilitation. This study aimed to explore the unique associative effects of alexithymia as measured by the Perth Alexithymia Questionnaire (PAQ; i.e., difficulty identifying positive/negative feelings, difficulty describing positive/negative feelings, and externally orientated thinking), on emotional outcomes as measured by the Depression Anxiety Stress Scale-21 (DASS-21) and Mayo-Portland Adaptability Inventory (MPAI-4) Adjustment index, in 83 adults with ABI. The addition of alexithymia to hierarchical multiple regression models (controlling for demographic, injury-related, and functional outcome variables) yielded statistically significant changes in R2 for all emotional outcome measures (i.e., Depression, Anxiety, Stress, and Adjustment). Difficulty identifying negative feelings was found to be a significant unique predictor of Depression (β = .43 p = <.001), Anxiety (β = .40, p <.001), Stress (β = .49, p <.001), and Adjustment (β = .26, p = .001). Externally oriented thinking was found to be a significant unique predictor of Adjustment (β = -.15, p = .033). These findings strengthen the argument that alexithymia, especially difficulties identifying negative feelings, may be an important risk factor for psychological distress in ABI and should be considered during early rehabilitation.

The structure of the Hospital Anxiety and Depression Scale: Theoretical and methodological considerations

The Hospital Anxiety and Depression Scale (HADS; Zigmond - Snaith, 1983) is widely used; however, its factor structure is unclear, with studies reporting differing unidimensional, two-factor and three-factor models. We aimed to address some key theoretical and methodological issues contributing to inconsistencies in HADS structures across samples. We reviewed existing HADS models and compared their fit using confirmatory factor analysis (CFA). We also investigated methodological effects by comparing factor structures derived from Rasch and Principal Components Analysis (PCA) methods, as well as effects of a negative wording factor. An Australian community-dwelling sample consisting of 189 females and 158 males aged 17-86 (M = 35.73, SD = 17.41) completed the 14-item HADS. The Rasch Analysis, PCA and CFA all supported the original two-factor structure. Although some three-factor models had good fit, they had unacceptable reliability. In the CFA, a hierarchical bifactor model with a general distress factor and uncorrelated depression and anxiety subscales produced the best fit, but the general factor was not unidimensional. The addition of a negative wording factor improved model fit. These findings highlight the effects of differing methodologies in producing inconsistent HADS factor structures across studies. Further replication of model fit across samples and refinement of the HADS items is warranted.

Interaction between APOE ɛ4 and Age Is Associated with Emotional Distress One Year after Moderate-Severe Traumatic Brain Injury

Emotional distress is common following moderate-severe traumatic brain injury (TBI) and is associated with poorer post-injury outcomes. Previously investigated sociodemographic, psychological, and injury-related factors account for only a small proportion of variance in post-TBI emotional distress, highlighting a need to consider other factors such as genetic factors. The apolipoprotein E gene (APOE) has been commonly studied in the TBI literature, with the ɛ4 allele linked to worse neuronal repair and recovery. Few studies have investigated the potential relationship between APOE ɛ4 and emotional distress after moderate-severe TBI, and results have been varied. We examined whether APOE ɛ4 was associated with emotional distress 1 year following moderate-severe TBI, and whether this relationship was moderated by age, sex, and TBI severity (as indexed by the duration of post-traumatic amnesia [PTA]). Moderate-severe TBI survivors provided saliva samples following inpatient admission to a TBI rehabilitation hospital. They completed a self-report measure of emotional distress, the Hospital Anxiety and Depression Scale (HADS), at a follow-up interview ∼1 year post-injury. Complete genetic and follow-up data were available for 441 moderate-severe TBI survivors (mean age = 39.42 years; 75% male). We constructed a linear regression model that included APOE ɛ4 carriage status (carrier vs. non-carrier) and interactions with age, sex, and TBI severity (APOE × age, APOE × sex, APOE × age × sex, and APOE × PTA duration) to predict total score on the HADS, while covarying for the main effects of age, sex, PTA duration, and previous head injury. There was a significant main effect of APOE ɛ4, whereby ɛ4 carriers reported less emotional distress than non-carriers (p = 0.04). However, we also found a significant interaction with age such that APOE ɛ4 carriers reported increasingly greater emotional distress with older age compared with non-carriers (p = 0.01). A sensitivity analysis (n = 306) suggested that the APOE × age interaction, and main effects of age and previous head injury, were not unique to individuals with pre-injury mental health problems (n = 136). However, the main effect of APOE ɛ4 was no longer significant when individuals with pre-injury mental health problems were removed. Our findings highlight the importance of considering moderation of genetic associations, suggesting that APOE ɛ4 may be a risk factor for emotional distress specifically among older survivors of moderate-severe TBI. If these findings can be independently replicated, APOE ɛ4 carriage status, interpreted in the context of age, could be incorporated into risk prediction models of emotional distress after moderate-severe TBI, enhancing targeted early detection and intervention efforts.