Plasma Aβ and neurofilament light chain are associated with cognitive and physical function decline in non-dementia older adults

BackgroundCognition is closely associated with physical function. Although high brain amyloid-beta (A beta) deposition and neurofilament light chain (NfL) are associated with cognitive and gait speed decline, relationships of combined plasma A beta and NfL profiles with cognitive and physical functions in older adults remain unknown. The research aim of this study was to investigate the prospective associations of combined plasma A beta and NfL profiles with cognitive and physical functions in older adults.MethodsParticipants (n=452, aged 765years) who had both plasma A beta and NfL data collected from the Multidomain Alzheimer's Preventive Trial (MAPT, May 2008 to April 2016) were included in the current study. These participants were from four MAPT groups (multidomain interventions [physical activity and nutritional counselling, and cognitive training], omega-3 supplementation, multidomain plus omega-3 supplementation and control group) and had received a 3-year intervention, followed by a 2-year observational follow-up. Cognitive function was evaluated as Mini-Mental State Examination and composite cognitive score (CCS, a mean Z-score combining four cognitive tests). Physical function was evaluated as gait speed (4-m usual-pace walk test) and chair-stand time (5-time maximal chair-stand test). Cognitive and physical function data measured at the time of and after blood A beta and NfL tests were used for analysis. Participants with plasma A beta (42)/A beta (40) ratios lower than 0.107 and NfL levels greater than 93.04pg/ml were classified as A beta+ and NfL+. Multivariable regressions and mixed-effects linear models were used for the analysis.ResultsAt the cross-sectional level, no significant association was found between A beta +NfL+ and cognitive or physical function after controlling for age, sex, body mass index, education level and MAPT group. Evaluating longitudinal changes, participants with A beta +NfL+ had greater annual declines in the CCS (beta=-0.11, 95%CI [-0.17, -0.05]) and gait speed (beta=-0.03, 95%CI [-0.05, -0.005]). After adjusting for APOE 4 genotype, A beta +NfL+ was associated with a greater decline only in the CCS (beta=-0.09, 95%CI [-0.15, -0.02]).ConclusionsCombined low plasma A beta (42)/A beta (40) ratio and high plasma NfL level was associated with greater declines in cognition and gait speed over time, providing further evidence of the links between cognitive and physical function.Trial registration www.clinicaltrials.gov [NCT00672685].