Researchers have unveiled a novel method to detect Alzheimer's disease at an early stage by monitoring daily activity patterns using wrist-worn activity-tracking devices.

With over 6 million Americans impacted by Alzheimer's across all age groups, the researchers hope their innovative approach could help identify the condition promptly, enabling early intervention for timely help and support.

In a recent study led by researchers at the Johns Hopkins Bloomberg School of Public Health, the team analyzed 82 cognitively healthy older adults who were participants in a long-running study of aging. The movement data of the participants were examined from wristwatch-like devices called actigraphs worn by them.

While doing a PET scan, 25 participants had detectable brain amyloid buildup, the protein build-up linked to Alzheimer's disease.

Using a sensitive statistical technique called FOSR (function-on-scalar regression), the researchers detected that the amyloid-positive participants had higher mean activity during the early afternoon (1:00 to 3:30 p.m.) and less day-to-day variability in activity from 1:30 to 4:00 p.m. and 7:30 to 10:30 p.m. compared to the amyloid-negative participants. The findings were published in the journal Sleep.

Although some of these time windows with differences were not statistically significant in more conservative analysis, researchers noted that higher afternoon activity and lower afternoon variability in the amyloid-positive participants still echoed their prior findings.

"We need to replicate these findings in larger studies, but it is interesting that we've now seen a similar difference between amyloid-positive and amyloid-negative older adults in two independent studies," said Adam Spira, who led the study, in a news release.

"The new study's results partly confirm findings from an earlier study in a smaller sample, also led by Spira, and suggest that actigraphs someday could be a tool to help detect incipient Alzheimer's disease before significant cognitive impairment sets in," the news release stated.

"It's conceivable that the higher afternoon activity we observed is a signal of 'preclinical sundowning'. At the same time, it's important to note that these findings represent averages among a small sample of older people over a short period of time. We can't predict whether an individual will develop amyloid plaques based on the timing of their activity. So, it would be premature for older people to be concerned because their fitness trackers say they are particularly active in the afternoon, for example," Spira said.