Association of tongue, handgrip, and pinch strength with blood-based phosphorylated-tau 181 in cognitively healthy older adults.

The development of blood-based phosphorylated tau (p-tau) biomarkers to identify Alzheimer's disease risk before cognitive decline offers a valuable opportunity for early intervention. Handgrip strength appears as a complementary non-invasive biomarker of dementia risk. Measurement of tongue strength may contribute further insight into the risk of cognitive decline and dementia. We examined associations between tongue strength, handgrip strength, three-finger pinch strength, and plasma p-tau181 in cognitively healthy older adults. A total of 158 cognitively healthy participants aged 50+ years (75.31% female; mean 69.32 years) were recruited. Participants' p-tau181 levels were sourced from a longitudinal study in which they were involved. Pearson correlation coefficients, independent t-tests, and multivariable linear regression analyses were performed to examine the association between strength measures and p-tau181 levels. Tongue strength was positively associated with handgrip (β = 0.53, 95% CI (0.25,0.81), p < 0.001) and pinch strength (β = 2.30, 95% CI (0.92,3.68), p = 0.001), with models adjusted for age, sex, body mass index, and educational level. Based on p-tau181 tertiles, the associations between tongue, handgrip, and pinch strength measures were evident only in the middle and highest tertiles. Handgrip (in adults 69 years and older) and pinch, but not tongue strength, were negatively associated with log-transformed p-tau181 levels. Although preliminary, findings support strength-based non-invasive biomarkers for risk stratification. Future studies are needed to investigate the relation between changes in strength measures with established measures of AD risk as well as frailty.