Epidemiology of Head Injury and Associations with Clinical and Neuropsychological Test Scores in Older American Indians: Data from the Strong Heart Study.

Background: American Indians have the highest mortality and hospitalizations from head injury of all US groups; however, little is known about prevalence, risk, or outcomes in this population.

Methods: The Strong Heart Study recruited American Indians representing 11 tribes and communities across three regions for two sequential examinations in 2010-2019. Participants were asked to self-report prior head injury, loss of consciousness (LOC), cause, sociodemographics, and behaviors (age, sex, education, bilingual, smoking, alcohol use, stroke). Cognitive testing covered executive function, phonemic fluency, processing speed, and memory. Analyses tabulated summaries and multivariate logistic regressions estimated risk associations.

Results: This older cohort of American Indians (visit 1 N = 818, follow-up visit 2 N = 403) was mean age 73 at intake, with mean 6.7 years between exams. At visit 1, 40% reported prior head injury, majority with LOC; 4-6% reported injury with LOC > 20 min. Incidence analysis estimated 3.5 cases per 100 person-years. Primary causes were falls, motor vehicles, sports, fight or assault, military (bullet, blast, fragment), and horse-riding incidents. Male sex and prior stroke were independently associated with higher risk, but age, education, bilingual, smoking, and alcohol use were not associated with risk. Those with previous head injury had significantly worse depressive symptoms, quality of life, fatigue, social functioning, pain, general health, and processing speed.

Conclusion: These findings suggest very high prevalence, incidence, and risk of head injury in older American Indians, with substantial impacts on quality of life and well-being. Future research should prospectively evaluate risk and prevention opportunities in this population.