The Late Contributions of Repetitive Head Impacts and TBI to Depression Symptoms and Cognition.

Objective: To test the hypothesis that repetitive head impacts (RHI), like those from contact sport play, and traumatic brain injury (TBI) have long-term neuropsychiatric and cognitive consequences, we compared middle-age and older adult participants who reported a history of RHI and/or TBI to those without this history on measures of depression and cognition. Methods: This cross-sectional study included 13,323 individuals (mean age=61.95, 72.5% female) from the Brain Health Registry who completed online assessments, including the Ohio State University TBI Identification Method; the Geriatric Depression Scale (GDS-15); and the CogState Brief Battery and Lumos Labs NeuroCognitive Performance Tests. Inverse propensity weighted linear regressions accounting for age, sex, race/ethnicity, and education tested the effects of RHI and TBI compared to a non-RHI/TBI group. Results: 725 reported RHI exposure (mostly contact sport play and abuse) and 7,277 reported TBI (n=2,604 with LOC). RHI (beta=1.24, 95% CI=0.36,2.12), TBI without LOC (beta=0.43, 95% CI=0.31,0.54), and TBI with LOC (beta=0.75, 95% CI=0.59,0.91) corresponded to higher GDS-15 scores. While TBI with LOC had the most neuropsychological associations, TBI without LOC had a negative effect on CogState Identification (beta=0.004, 95% CI=0.001,0.01) and CogState One Back Test (beta=0.004, 95% CI=0.0002,0.01). RHI predicted worse CogState One Back Test scores (beta=0.02, 95% CI =-0.01,0.05). There were RHIxTBI interaction effects on several neuropsychological subtests, and participants who had a history of both RHI and TBI with LOC had the worse depression symptoms and cognition. Conclusions: RHI and TBI independently contributed to mid- to worse mid- to later-life neuropsychiatric and cognitive functioning.