Change in sarcopenia and the risk of dementia: evidence from the English Longitudinal Study of Ageing with a 10-year follow-up

Background The study aimed to investigate the association between changes in sarcopenia and the risk of dementia, and whether cumulative levels of physical activity (PA) mediate the association of changes in sarcopenia with dementia. Methods Our data are from the English Longitudinal Study of Aging (2004-2019). Robust, probable sarcopenia and sarcopenia were assessed according to European Working Group of Sarcopenia in Older People (EWGSOP2) criteria. Kaplan-Meier cumulative risk curves were used to explore the association between changes in sarcopenia and the risk of dementia. Cox proportional hazard models were used to calculate the hazard ratios (HR) and 95% confidence intervals (95% CI). Causal mediation analysis was used to assess the mediating effects of cumulative levels of PA. Results A total of 3610 participants were included in the analysis. At a median follow-up time of 9.83 years, 296 participants developed dementia. Compared with participants with stable robust, participants with robust to probable sarcopenia/sarcopenia had an increased risk of dementia (HR = 1.49, 95% CI = 1.05-2.10); conversely, compared with participants with stable sarcopenia, participants with sarcopenia to probable sarcopenia/robust did not have a reduced risk of dementia (HR = 0.79, 95% CI = 0.51-1.52). The cumulative levels of PA mediate the association with robust to probable sarcopenia/sarcopenia and the risk of dementia with a natural indirect effect HR (95% CI) of 1.06 (1.01-1.13), proportion mediated = 15.4%. Conclusions Different changes in sarcopenia were associated with different dementia risks, with continued progression of sarcopenia, increased dementia risk, and cumulative levels of PA mediated the association between the progression of sarcopenia and the risk of dementia.