Associations between Prior Head Injury and Physical Functioning and Frailty in Older Adults: Results from the Atherosclerosis Risk in Communities (ARIC) Study

Abstract Text:

Background: Older adults have the highest incidence of traumatic brain injury (TBI) and are at the greatest risk for subsequent short-term impairments of postural control and gait. Relationships of TBI with physical function and frailty in older adults is not well described.

Purpose: To examine the cross-temporal and prospective associations between prior head injury and physical function and frailty among community dwelling older adults.

Methods: 5,598 Atherosclerosis Risk in Communities (ARIC) Study participants who attended the fifth study visit in 2011-2013 and underwent the initial assessment of physical function and frailty were included. Head injury history was defined via self-report questions asked at study visits and via ICD-9/10 codes from hospitalizations occurring prior to visit 5. Repeat physical functioning and frailty were assessed at visit 6 (2016-2017) and visit 7 (2018-2019). Physical functioning was assessed by the Short Physical Performance Battery (SPPB), which is comprised of assessments of balance, gait speed, and repeated chair stands (each component score ranged 0-4 and summed for a total SPPB score of 0-12). Frailty was defined using a validated approach comprising weight loss, physical activity, walking speed, exhaustion, and weakness, and categorized as pre-frail (1-2 components)/frail (3-5 components) versus robust (0 components). Linear regression models and linear mixed models were used to investigate cross-temporal and prospective associations respectively, between head injury and SBBP component and total scores. Logistic regression models investigated cross-temporal and prospective associations between head injury and frailty/pre-frailty. Models were adjusted for sociodemographic factors (age, sex, race-center, education, smoking status, alcohol consumption, military veteran status), vascular risk factors (diabetes, hypertension), and cognitive status. Prospective models incorporated inverse probability of attrition weighting to account for death/attrition.

Results: Overall, 27% (n=1,533) of participants (mean age 75.4+5.1 years, 58.0% women, 21.7% Black) had a prior head injury. The median time between first head injury and physical functioning and frailty assessment was 32.1 years (25th-75th percentile: 14.6-58.2 years). Cross-temporally, individuals with prior head injury had lower SPPB total score (-coefficient=-0.22, 95%CI=-0.35,-0.09) and lower SPPB component scores (-coefficient=-0.07, 95%CI=-0.13, -0.01 for balance, -coefficient=-0.06, 95%CI=-0.12, -0.04 for gait speed, and -coefficient=-0.09, 95%CI=-0.16,-0.02 for chair stands) compared to individuals without head injury. Individuals with prior head injury were also more likely to be pre-frail/frail (OR=1.20, 95%CI=1.06,1.37) compared to individuals without prior head injury. Prospectively from Visit 5 to Visit 7, prior head injury compared to no head injury was associated with -0.22 (95%CI= -0.35,-0.09) greater decrease in SPPB total, -0.07 (95%CI=-0.13,-0.01) greater decrease in SPPB balance score, -0.06 (95%CI=-0.10,-0.02) greater decrease in SPPB gait speed score, and a -0.09 (95%CI=-0.16,-0.02) greater decrease in SPPB chair stand score over a median of 5 years (25th-75th percentile: 3.4-8.4 years). Among individuals who were robust at Visit 5, prior head injury was associated with increased odds of becoming pre-frail/frail at Visit 6 or 7 (OR=1.34, 95%CI=1.06-1.69) compared to those without head injury.

Conclusions: Prior head injury is associated with later-life poorer physical function performance, prevalent pre-frailty/frailty, with steeper decline in physical function and higher risk of incident pre-frailty/frailty in older adults.

Keywords: mild traumatic brain injury, long term health, exercise, weight loss, grip strength