This study aims to compare the incidence of neuropsychiatric symptoms (NPS) in research participants with mild cognitive impairment (MCI) secondary to Alzheimer’s disease (AD) with and without a history of traumatic brain injury (TBI).

TBI is well-understood to be a risk factor for AD dementia and is also a separate risk factor for NPS. In turn, NPS are associated with faster progression from MCI to dementia along the AD spectrum. Using a research cohort, we explored if and how a reported history of TBI influenced NPS in participants with MCI due to AD.

Utilizing the National Alzheimer’s Coordinating Center data set, a cross-sectional analysis was performed on participants with Global Clinical Dementia Rating of 0.5, indicating MCI, with an etiology of AD. Exposure was defined as a binary yes/no response regarding TBI history. Outcomes were NPS as evaluated by the informant-based Neuropsychiatric Inventory Questionnaire (NPIQ). Covariates included demographics (sex, age, race, Hispanic ethnicity, education) and ApoE4 status. Multiple logistic regression analysis was performed, with the primary outcome being each NPS evaluated in the NPIQ.  

At the MCI stage of AD, a reported history of TBI was positively correlated with depression [OR 1.201; 95% CI 1.055-1.366], anxiety [OR 1.211; 95% CI 1.060-1.380] and motor disturbance [OR 1.279; 95% CI 1.023-1.586].   

TBI history is connected to an increased prevalence of depression, anxiety and motor disturbance at the MCI stage of AD. This promotes further work to examine if the impact of TBI on dementia risk is partially mediated by NPS and if early intervention on these NPS could improve cognitive outcomes.