Wearable devices may help identify multiple sclerosis patients at greater risk of worsening disability and loss of brain volume, a study suggests.
Researchers found people whose activity patterns changed were more likely to have worsening disability and loss of brain volume than those whose patterns changed less or not at all.
The study shows an association but does not prove activity changes cause MS progression.
Wrist-worn sensors measured levels of light, moderate and vigorous physical activity, time spent sitting or inactive and circadian rhythms, the body’s sleep-wake cycle.
The research was led by Kathryn C. Fitzgerald of Johns Hopkins University in Baltimore, Maryland.
Fitzgerald said: “Timely identification of patients at risk for disease progression is essential to reduce long-term disability, but the current tests for measuring MS disability are not designed to detect small changes.
“Using a relatively inexpensive and accessible device around the wrist may help us identify early changes in the disease.”
The study involved 238 people with multiple sclerosis, a condition in which the immune system attacks the protective covering of nerves and disrupts communication between the brain and body. Participants had an average age of 55 and had lived with the condition for about 13 years.
At the start of the study, participants had an average disability score of three on the Expanded Disability Status Scale, a clinical scale used to measure disability in MS.
This score indicates no problems with walking but moderate disability in one area such as muscle weakness, balance problems or thinking and memory difficulties, or mild disability in several areas.
Participants had no other serious health conditions affecting physical activity and had not experienced an MS relapse in the six months before the study.
They wore the devices around their wrists for two weeks at a time, repeating this monitoring every three months for an average of three years.
Participants also completed disability assessments every six months and had brain scans at the start of the study and again after two years.
During the study, 120 participants experienced disease progression. Those with decreases in daytime activity were more likely to have progression.
People whose activity levels dropped in the first half of the day were about 20 per cent more likely to experience progression than those whose activity levels did not decline.
Declines in activity between 8am and 10am were also linked to loss of brain volume.
Each standard deviation drop in activity was associated with a 0.18 per cent decrease in whole brain volume, a 0.34 per cent decrease in deep grey matter and a 0.35 per cent decrease in the volume of the thalamus.
A limitation of the study was that it did not include a comparison group of people without MS, which could help researchers understand how activity levels may change as part of normal ageing.
Participants were also relatively older and more disabled, meaning the findings may not apply to younger people with MS or those with milder disability.
The study was supported by the US National Institutes of Health.
