Grip strength and gait speed as early biomarkers of brain amyloid and tau deposition: Biomarkers (non‐neuroimaging) / Novel biomarkers. (7th December 2020) - Jacob, Mini Elizabeth
Abstract: Background: Screening biomarkers, accessible and measurable at a primary care clinic, may hold the key to risk stratification and prevention efforts in Alzheimer's and related dementias. Among potential candidates that could fulfill this role, gait speed and grip strength have garnered strong evidence as early predictive factors. The pathophysiologic basis for this association is not clear; it is possible that functional performance is impaired by early tau/amyloid deposition. To test this, we examined the cross‐sectional relationship between gait speed and grip strength measures with amyloid and tau PET in middle‐aged Generation 3 participants in the Framingham Heart Study. Method: Among 190 participants, examined in 2016‐2019, average age was 55.1 (SD 7.7), and 44% were women. Fast walk speed was measured over 4 meters, and grip strength was assessed using a hand‐held Jamar dynamometer. PET amyloid imaging was done using [11C]PiB tracer and tau using [18F]AV‐1451. We tested associations between fast walk speed (FWS) and grip strength (GS) with amyloid in the frontal and lateral retrosplenial (FLR) regions and tau in parahippocampal, entorhinal, inferior temporal regions. Linear regression models were performed with adjustment for sex, time from exam to PET scan, total cholesterol, diabetes, cardiovascular disease, smoking status, systolic blood pressure, waist‐hip ratio, APOEe4 status and physical activity. We also tested interactions between FWS/GS and APOE status /gender. Result: FWS and GS did not demonstrate independent associations with tau or amyloid PET imaging in the full sample, however significant interactions were noted between FWS/GS and both gender and APOE. In the APOE status stratified analysis, higher FWS was associated with higher parahippocampal tau levels among e4 negative, while higher GS was associated with lower parahippocampal tau among e4 positive individuals. Additionally, higher GS was associated with lower parahippocampal Tau in men, but not in women. Conclusion: Grip strength and gait speed may be early markers of tau deposition in cognitively normal middle‐aged individuals. Further studies with larger samples are required to confirm the relationship and identify sub‐groups who may benefit from screening and preventive interventions.