Abstract
IMPORTANCE: Traumatic brain injury (TBI) and vascular risk factors are associated with cognitive impairment, but it is unknown if individuals with vascular risk factors experience worse cognitive outcomes after TBI. OBJECTIVE: To evaluate cognitive function among patients with TBI with vs without comorbid preinjury vascular risk factors. DESIGN, SETTING, AND PARTICIPANTS: This prospective cohort study examined individuals with TBI enrolled in the Transforming Research and Clinical Knowledge in TBI (TRACK-TBI) Study between February 26, 2014, and August 8, 2018, with a 1-year follow-up. Analyses were conducted February 26, 2024, to May 29, 2025. EXPOSURES: Vascular risk factors (ie, hypertension, diabetes, hyperlipidemia, and smoking). MAIN OUTCOMES AND MEASURES: Participants underwent a 5-test cognitive assessment at 2 weeks, 6 months, and 1 year postinjury; tests were combined into a global cognitive factor score in primary analyses and examined individually in secondary analyses. Inverse probability of attrition-weighted generalized estimating equations adjusted for age, sex, race, ethnicity, education, TBI severity, prior TBI, and psychiatric history were used to estimate the associations. RESULTS: The 1313 participants were a mean (SD) age of 38.7 (16.4) years, 428 were female (32.6%), 885 were male (67.4%), 393 had never smoked (29.9%), 221 had hypertension (16.8%), 98 had diabetes (7.5%), and 116 had hyperlipidemia (8.8%). Both participants with and without vascular risk factors had improvement in cognition over the first year postinjury. Compared with individuals without diabetes, participants with diabetes had lower global cognitive factor scores at 2 weeks postinjury (mean z-score difference, -0.25; 95% CI, -0.45 to -0.04), worse executive functioning at 2 weeks postinjury, and less improvement on processing speed over the first-year postinjury. There were no significant differences in cognitive performance comparing participants with vs without hypertension, hyperlipidemia, and smoking. Individuals with 2 or more vascular risk factors (compared with no vascular risk factors) had lower global factor score at 2 weeks postinjury (mean difference, -0.21; 95% CI, -0.19 to -0.07) and worse verbal episodic memory immediate recall, executive functioning, and processing speed at 2 weeks, but similar improvements in cognitive performance over the first-year postinjury. CONCLUSIONS AND RELEVANCE: In this cohort study of individuals with TBI, those with diabetes displayed poorer global cognitive function and executive functioning 2 weeks after TBI and recovered less in processing speed over the first-year postinjury. Given the modifiable nature of comorbid vascular risk factors, future work interrogating postinjury changes in vascular risk factor burden, over longer follow-up, is warranted.