MS: Reduced Daytime Activity Linked to Faster Disability Progression, Brain Atrophy

Wearable sensors, specifically accelerometers worn on the wrist, are showing promise in detecting subtle changes in daily activity that may precede noticeable disability progression in individuals with multiple sclerosis (MS), according to research published in Neurology on March 18, 2026. The study suggests that these devices could offer a more sensitive and continuous way to monitor disease progression than traditional methods, potentially accelerating clinical trials and enabling earlier intervention.

Early Signals of Change

Current methods for assessing disability in MS, such as the Expanded Disability Status Scale (EDSS), often rely on periodic clinical evaluations that may miss subtle changes over time. Researchers at Johns Hopkins School of Medicine sought to determine if continuous monitoring of real-world movement using wearable accelerometers could identify earlier signs of worsening disease. The study, led by Kathryn C. Fitzgerald, ScD, ScM, involved 238 patients with MS who were followed for an average of 2.9 years.

Participants wore an ActiGraph GT9X accelerometer on their non-dominant wrist for 24 hours a day, several times over a three-year period – averaging 9.6 times for 86.2 days total. The data collected included measures of total activity count (TAC), moderate-to-vigorous physical activity (MVPA), light intensity physical activity (LIPA), and patterns of sedentary behavior. Patients also underwent regular EDSS assessments every six months, along with MRI scans at baseline and in year two of the study.

The findings revealed that decreases in daytime activity, particularly between 8 a.m. And 2 p.m., were associated with a higher risk of confirmed disability progression. Specifically, the risk increased by 1.2 to 1.24 times for each standard deviation decrease in activity during those timeframes. Decreases in TAC, MVPA, and LIPA were also observed in patients who later experienced worsening disability. These changes in activity patterns were often detectable before clinical worsening was apparent on the EDSS.

Brain Atrophy and Activity Levels

Interestingly, the study also found a link between changes in activity patterns and brain atrophy, as measured by MRI. A decrease in TAC between 8 a.m. And 10 a.m. Was associated with a 0.18% decrease in whole-brain volume. Conversely, activity between 2 a.m. And 4 a.m. Was associated with increased brain volume. Decreases in activity were also linked to reductions in the volume of deep gray matter and the thalamus.

These findings suggest that disruptions in circadian rhythm and overall physical activity may contribute to neurodegeneration in MS. The researchers noted that patients with progressive MS exhibited greater decreases in TAC and LIPA, as well as increases in sedentary behavior, compared to those with stable or suspected progressive MS.

Implications for Monitoring and Treatment

Dr. Fitzgerald emphasized that these findings highlight the potential of wearable devices as a sensitive tool for monitoring disease progression in MS. She stated that the changes detected by accelerometers were often subtle and occurred before clinical worsening, suggesting that these devices could provide valuable insights into the early stages of disease progression.

The use of wearable sensors could also accelerate clinical trials by providing more frequent and objective measures of disease activity. Currently, clinical trials often rely on the EDSS, which can be subjective and time-consuming to administer. Continuous activity monitoring could provide a more efficient and reliable endpoint for assessing treatment efficacy.

However, Dr. Fitzgerald cautioned that these findings are preliminary and further research is needed to confirm the results in larger cohorts. She also noted that it is not yet clear whether modifying activity patterns can improve outcomes in people with MS. Ongoing research is focused on determining optimal thresholds for activity pattern changes and understanding how these changes relate to underlying biological processes.

Understanding Multiple Sclerosis

Multiple sclerosis is a chronic, often disabling disease that affects the central nervous system – the brain and spinal cord. It occurs when the immune system attacks the protective sheath (myelin) that covers nerve fibers, disrupting communication between the brain and the rest of the body. Symptoms of MS can vary widely, but often include fatigue, difficulty walking, numbness or weakness, vision problems, and cognitive difficulties. The disease course is unpredictable, with periods of remission and relapse.

The Role of Circadian Rhythms

The study’s findings regarding circadian rhythms and brain volume are particularly intriguing. Circadian rhythms are the natural, internal processes that regulate the sleep-wake cycle and other bodily functions. Disruptions in circadian rhythms have been linked to a variety of health problems, including neurological disorders. The association between activity patterns between 2 a.m. And 4 a.m. And increased brain volume suggests that maintaining a regular sleep-wake cycle may be beneficial for brain health in MS.

Future Directions

Researchers are now working to validate these findings in independent cohorts and to develop algorithms that can identify individuals at risk for progression based on their activity patterns. They are also exploring the potential of using wearable sensors to personalize treatment strategies and to monitor the effectiveness of interventions aimed at improving physical activity and circadian rhythm regulation. The National MS Society is actively supporting research in this area, recognizing the potential of wearable technology to improve the lives of people living with MS.

The next step in this research will be to determine whether interventions designed to increase physical activity and improve circadian rhythm patterns can slow disease progression and preserve brain volume in individuals with MS. This will require carefully designed clinical trials that incorporate wearable sensor technology to continuously monitor patient activity and assess treatment response.