# Decreased Physical Activity as an Early Digital Biomarker in Huntington's Disease: A One‐Year Observational Study

## TL;DR

This study shows that decreased physical activity, tracked by wearables, may be an early sign of functional decline in Huntington's disease patients.

## Contribution

The study identifies reduced physical activity as a potential early digital biomarker for Huntington's disease progression.

## Key findings

- Cluster 2 showed a significant decrease in physical activity over time compared to Cluster 1.
- Cluster 2 had a higher prevalence of sarcopenia at baseline.
- Physical activity reduction may indicate early functional changes in HD patients.

## Abstract

Huntington's disease (HD) is a neurodegenerative disorder characterised by motor dysfunction, cognitive impairment, and psychiatric disturbances. This study analyzed the relationship between clinical characteristics, sarcopenia, and physical activity (PA) levels in HD patients.

A 1‐year observational study was conducted with symptomatic, ambulatory HD patients, assessed at baseline and after 12 months. PA was monitored using a Fitbit Charge 4 activity tracker, and sarcopenia was determined through assessments of muscle strength, quantity, and physical performance. Participants were classified into two clusters based on age, motor (Unified HD Rating Scale), and cognitive function (Mini‐Mental State Examination).

We included 33 subjects with HD, mean age 53 (40–60) years, 45.5% males, median TFC 9.5 (7–13). At baseline, Cluster 1 had better motor function, functional capacity, and less apathy with a positive trend for higher PA, compared with Cluster 2, which had a negative trend for decreased PA over time (p = 0.006). After 1 year, Cluster 1 showed a decrease in PA (p = 0.035), similar to Cluster 2. At baseline, 53% of participants in Cluster 2 presented probable or confirmed sarcopenia, compared with 13% in Cluster 1. Significant differences (p < 0.05) were observed in muscle strength, bioelectrical impedance analysis (BIA), and SPPB scores, with higher values in Cluster 1.

These preliminary findings suggest that a reduction in PA using wearable technology may be a potential early indicator of functional changes in HD. Identifying when PA reduction begins can help determine the timing of interventions aimed at delaying disease progression.

Physical Activity: Early Biomarker in Huntington's Disease.