Understanding multidimensional apathy in traumatic brain injury.

Objective: To investigate whether individuals with moderate-to-severe chronic TBI exhibit higher levels of apathy-particularly in behavioural, cognitive, and emotional domains-compared to neurotypical controls, and examine the association between apathy severity and injury-related factors, productivity and quality of life.

Design: Cross-sectional, cohort study.

Setting: Community.

Participants: Participants were sampled from a larger longitudinal study of individuals recruited from consecutive inpatient TBI admissions to a rehabilitation hospital. We analysed data from 136 participants with moderate-to-severe TBI (53% male; M_Age = 51.8 years; M_{time post-injury} = 13.8 years, range 0.25-35.2) and 78 neurotypical controls (48.75% male; M_Age = 50.3 years).

Interventions: Not applicable.

Main outcome measures: Apathy Evaluation Scale, injury-related measures, Satisfaction with Life Scale, coded Productivity measure based on employment status.

Results: Results indicated that individuals with TBI had significantly higher overall apathy (p = 0.031) and behavioural apathy (p = 0.037) compared to neurotypical controls, but did not differ in the cognitive or emotional subtypes. Individuals with TBI were 1.98 times more likely to exhibit clinically significant apathy (OR = 1.98, 95% CI [0.98, 4.22]). Glasgow Coma Scale score, post-traumatic amnesia duration, age at the time of injury, time post-injury, and abnormal computed tomography scan were not significantly related to any apathy subtype. Higher global apathy scores were significantly associated with lower productive activities (p = 0.021), while higher global and behavioural apathy were significantly associated with lower life satisfaction (p <.001, p = 0.021, respectively).

Conclusions: These findings underscore the elevated prevalence of apathy following TBI, which may manifest primarily in the behavioural domain. The association between elevated apathy and lower functioning and reduced life satisfaction highlights that apathy is a key factor influencing long-term outcomes. Identifying and addressing apathy, especially its behavioural component, may therefore be critical for improving functional recovery and quality of life in this population.