Researchers found people with changes in their activity patterns were more likely to have worsening disability and loss of brain volume than people whose patterns did not change as much or at all. Wearable sensors may help identify individuals with multiple sclerosis who are more likely to have worsening disability and loss of brain volume, according to a new study.

The study by researchers at Johns Hopkins University, in Baltimore, involved 238 people with MS with an average age of 55 who had been living with MS for an average of 13 years. At the start of the study, they had an average disability level of 3 on the Expanded Disability Status Scale, a scale that measures disability in MS. A level of 3 indicates no problems with walking, but moderate disability in one of eight functional systems such as muscle weakness, problems with balance or problems with thinking and memory or mild disability in three or four areas. 

People had no other serious health problems that could affect their physical activity and had not had an MS relapse within six months prior to the study. 

Wearable sensors measure how much light, moderate, or vigorous physical activity people had during the day; how much time they spent sitting or inactive; and their circadian rhythms, or sleep-wake patterns. The participants wore devices around their wrists 24 hours a day to measure their activity levels for two weeks. They did this every three months for an average of three years. They also took tests every six months to check their disability levels. They had brain scans at the start of the study and after two years to look for any changes in the brain. 

During the study, 120 people had progression of the disease. People who had decreases in their daytime activity levels were more likely to have disease progression. People who had decreases in their activity levels in the first half of the day were about 20 percent more likely to have disease progression than people who did not have decreases in their activity level.

People who had declines in their activity levels in the morning, from 8 to 10 a.m., were more likely to have loss of volume in their brains. Every standard deviation decline in activity level was linked to a 0.18 percent decrease in whole brain volume as well as a 0.34 percent decrease in deep gray matter and a 0.35 percent loss in the volume of the thalamus area of the brain. 

A limitation of the study is that a group of people who did not have MS were not included, which would have help researchers understand how activity levels may change as a part of normal aging. Also, the participants of this study were relatively older and more disabled, so the results may not apply to younger people with MS or those with less disability.

The findings were published in the journal Neurology.