Moderate-to-severe traumatic brain injury (msTBI) is now understood to have chronic consequences that persist into late life. Depression and apathy represent common psychiatric consequences of msTBI. These conditions are important to understand in the context of recovery given their associations with quality of life (QoL) and other important recovery and health metrics. Although these syndromes have been solidified in the literature as separate and unique constructs, there exist notable overlapping symptoms and dimensions. We propose that consequently, important nuance is lost when examining depression and apathy as unique, separate constructs, which has important implications for how we study and treat these disorders. The goal of this research is to examine these overlapping symptom dimensions and establish whether symptom clusters may be more representative of the overarching constructs.

112 older adults with a lifetime history of msTBI (M=9.5 years post-injury) were included as part of a cross-sectional study. The Geriatric Depression Scale (GDS), Brief Symptom Inventory (BSI) depression subscale, and Frontal Systems and Behaviors (FrSBe) apathy subscale were included as measures of apathy and depression. We use KMO and Bartlett’s test of sphericity analyses to confirm the factorability of our data. Parallel analysis and eigenvalues were used to determine the number of factors. Given the ordinal nature of this data, we ran two exploratory factor analyses (EFA), one with Pearson’s Correlation and the other utilizing Spearman’s Rank Correlation. Both EFAs were otherwise identical, with a maximum likelihood estimator and oblimin rotation. Items loading at ≥ |.40| were retained for each factor. We then tested whether these clusters served to predict overall QoL ratings.

Both EFAs demonstrated an ideal three factor structure, and all factors were highly correlated with one another (r > .90 for each factor). Based on loading items, these factors were described as Affect/Identity symptoms (e.g., feelings of worthlessness and hopelessness), Social Approach behaviors (e.g., doing things without reminders, caring about appearance, becoming involved spontaneously), and Behavioral Avoidance (e.g., doing nothing, lacking energy). This model significantly predicted overall QoL ratings, with the Affective cluster accounting for the greatest variance in the model (EtaSq =.21, p < .001). Social Approach behaviors (EtaSq=.02, p=.01) and Behavioral Avoidance (EtaSq=.01, p=.03) were also significantly associated with QoL.

Our study reveals important related domains involved in depressive and apathetic symptomatology in individuals recovering from msTBI. As hypothesized, these factors did not fall into an Apathy/Depression divide, but rather, into domains that are commonly disrupted across both apathy and depression. Additionally, Affective cluster symptoms were those most predictive of QoL, explaining the greatest proportion of variance. Our approach suggests that examining specific symptom clusters in the context of post-injury mood disturbance may be a worthwhile approach in individuals recovering long-term from msTBI that provides greater specificity than traditional models of apathy and depression as unitary constructs.