Accelerometry-derived activity fragmentation as a predictor of brain atrophy and disability progression in multiple...

Area of Science:

• Neurology
• Biomedical Engineering
• Rehabilitation Science

Background:

• Activity fragmentation, a measure of interrupted physical activity, is linked to adverse health outcomes in the general population.
• Its prognostic value in multiple sclerosis (MS) is currently unknown.

Purpose of the Study:

• To investigate the association between activity fragmentation and neurological decline in people with MS (PwMS).
• To determine if activity fragmentation predicts disability progression and brain atrophy in MS.

Main Methods:

• PwMS (n=239) used wrist accelerometers over time and underwent regular disability and MRI assessments.
• Active-to-sedentary transition probability (ASTP) and sedentary-to-active transition probability (SATP) were calculated during the 10 most active hours (M10).
• Statistical models assessed within-person and between-person effects on disability progression and brain substructure atrophy.

Main Results:

• A within-person increase in ASTP slope (greater activity fragmentation) correlated with a higher risk of confirmed Expanded Disability Status Scale (EDSS)-plus progression (HR 1.22).
• Increased activity fragmentation was also associated with reduced deep gray matter and thalamic volumes over time.
• No significant associations were found for SATP with these outcomes.

Conclusions:

• Worsening activity fragmentation predicts increased risk of neurological decline in MS.
• Activity fragmentation may indicate reduced physiological reserve and serve as an early marker for MS progression.