Ethnoracial Differences In The Association Between Physical Functioning And Brain Imaging Outcomes From Habs-hd

Physical functioning (PF) tests are potential screening tools for brain diseases. PF differs by race and ethnicity, possibly reflecting the effect of upstream social inequities on brain diseases. We have found PF to be differentially related to blood biomarkers for Alzheimer’s disease by race and ethnicity. It is unclear if similar differential ethnoracial associations exist between PF and structural brain outcomes. PURPOSE: To determine the association between PF and structural brain imaging markers (white matter hyperintensities [WMH], total brain volume [TBV], hippocampal volume [HV]) across an ethnoracially diverse sample. METHODS: Participants from the HABS-HD study included cognitively unimpaired non-Hispanic African Americans (AA, n = 420), non-Hispanic whites (NHW, n = 917), and Hispanics (n = 828) aged 64.7 (SD = 8.4) years on average. Functional data (Timed Up and Go [TUG] and Short Physical Performance Battery [SPPB]) were collected by trained personnel and brain imaging data were collected via 3 T MRI. Multivariable linear regressions modeled TUG and SPPB on WMH, BV, and HV with interaction terms for ethnoracial group and adjustment for covariates (age, sex, education) and intracranial brain volume. RESULTS: Significant linear associations were found between PV and BV (TUG: β = -0.63 [-0.76, -0.50]; SPPB: β = 0.38 [0.26, 0.50]) and HV (TUG: β = -0.33 [-0.46, -0.20]; SPPB: β = 0.17 [0.05, 0.29]), but not WMH. Significant interactions with ethnoracial group were observed for SPPB and HV. Stratified analyses suggested potential effect modification by ethnoracial group; however, differences were not statistically significant. CONCLUSION: PF was consistently associated with structural brain changes across ethnoracial groups. Given the potential for social determinants to influence both PF and brain health, further mechanistic research is needed to help tailor preventive and therapeutic interventions to improve brain health equitably across racial and ethnic groups. Supported by: NIH-NIA to SB: R01AG054073, R01AG058533