To examine the relationship between environmental pollutants and cognition in subacute-chronic mild traumatic brain injury (TBI).

Environmental pollutants like fine particulate matter (PM2.5) and ozone are associated with neurodegenerative diseases. The Montreal Cognitive Assessment (MoCA) is a validated measure to assess cognitive impairment in TBI. CalEnviroScreen 4.0 provides census-tract pollution data that can be used to explore pollutant impact on cognitive health post-TBI, an underexplored topic.

A retrospective (7/2024-8/2025) cohort study of a single-center TBI clinic was performed. Inclusion: ≥18 years old, mild TBI diagnosis per American-Congress-Rehabilitation-Medicine criteria, time from TBI to clinic as ≤12 months, MoCA at first visit, Glasgow Outcome Scale–Extended (GOSE) for functional outcome, complete home address. PM2.5 and ozone scores were extracted from CalEnviroScreen 4.0. MoCA determined cognitive functioning, with <26 defined as cognitive impairment. Performed descriptive statistics, Spearman’s correlation, and multivariable logistic regression to compare normal vs suboptimal MoCA. 

Of 48 patients studied (mean age=46, 76.7% female, 70% non-white), 21 (43.8%) had normal MoCA. Compared to patients with normal MoCA, those with suboptimal MoCA had lower GOSE (5.67 vs 6.43, p=.038), were more likely to have intracranial blood on CT (44.4% vs 9.5%, p=.020), and were from more disadvantaged areas as measured by state area deprivation index (4.70 vs 3.62, p=.040). Patients with suboptimal MoCA came from regions with greater PM2.5 exposure (77.22 vs 60.67, p=.009). This was not seen for ozone exposure. There was a negative correlation between MoCA and PM2.5 (rho=-0.358, p=.013). Accounting for age, sex, race, and high school education, greater PM2.5 exposure (OR=1.058, 95% CI=1.010-1.122, p=.033) and intracranial blood on CT (OR=9.141, 95% CI=1.415-96.754, p=.034) were independently associated with suboptimal (vs normal) MoCA.

Areas with greater environmental pollutants are associated with worse cognitive performance in subacute-chronic mild TBI, making air pollution a potential environmental risk factor in post-TBI cognitive decline.