From Grip Strength to Digital Hand Kinematics: A Narrative Review of Hand Motor Markers for Mild Cognitive Impairment and Dementia

OBJECTIVES To evaluate whether hand motor measures, from grip strength to digital hand kinematics, predict incident MCI or dementia, discriminate MCI or dementia from healthy aging, and are associated with disease severity.METHODS This narrative review, prepared in line with the SANRA items, updates that evidence with original studies published in 2016-2026 (PubMed, Web of Science, EMBASE, Cochrane Library). Fourteen representative original studies were selected, and each was classified by evidence type: longitudinal risk prediction, cross-sectional discrimination, or severity association.RESULTS Fourteen original studies (<i>n</i> = 33-340,212) were synthesized: four provided longitudinal riskprediction evidence, eight cross-sectional discrimination evidence and two severity-association evidence. Lower grip strength predicted incident dementia in large cohorts (e.g., HR 0.86 per 5-kg higher grip in UK Biobank), and pegboard dexterity retained some prospective value but separated MCI from controls inconsistently. Finger-tapping and digital kinematic measures (computer mouse, tablet, digitizer) differed between MCI and control groups in several studies; only two reported MCI-detection accuracy (AUC 0.79-0.945), both derived and tested in the same sample, and none was externally validated.CONCLUSIONS Grip strength is the best-supported low-cost marker of future dementia risk, although the association is not specific to cognition and may partly reflect shared aging processes or reverse causation. Digital hand-kinematic measures differ between MCI and control groups, but their specific sensitivity to the MCI stage is unproven. Standardized protocols, STARD-compliant accuracy reporting, external validation and longitudinal MCI cohorts are required before clinical or exercise-practice use.