Association of handgrip strength asymmetry with prodromal and incident Parkinson's disease: A prospective cohort study.
Level 3 - non-randomized controlled study
Prospective cohort study
PubMed 42623021 · doi:10.1177/1877718X261479507
What was done
Prospective cohort study analyzing 497,100 participants free of Parkinson's disease (PD) at baseline from the UK Biobank. Handgrip strength (HGS) asymmetry index was calculated by dividing the absolute inter-hand difference by the average HGS of both hands. The primary outcome was incident PD identified through hospital admissions, death registries, and self-reported data over a median follow-up of >13 years. The secondary outcome was prodromal PD (presence of ≥3 of 8 prodromal features). Associations were evaluated using Cox regression models and lag analyses.
What was found
Over a median follow-up exceeding 13 years, 2,868 participants developed incident PD. The highest versus lowest quartile of HGS asymmetry was associated with a higher risk of PD (HR = 1.23; 95% CI: 1.10, 1.37; P-trend < 0.001). Lag analysis showed HGS asymmetry predicted incident PD up to 8 years in advance. A significant association with prodromal PD risk was also reported (no numerical risk estimate provided in the abstract). Associations persisted after excluding individuals with low HGS or prodromal PD at baseline.
Why it matters
Asymmetry in handgrip strength is an accessible physical measurement that may serve as an early, non-invasive indicator of Parkinson's disease risk up to 8 years prior to clinical diagnosis.
Limits
UK Biobank participants are predominantly of European descent and subject to healthy volunteer selection bias. Incident PD and prodromal features relied on administrative codes, hospital records, and self-reports rather than standardized in-person clinical examinations. The abstract does not report numerical effect estimates for the prodromal outcome or account for baseline handedness or unilateral upper-extremity injuries.