Senior man walking by the riverside to symbolize gait changes seen in people with mild cognitive impairment
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Changes to the body clock’s rest and activity patterns detectable through wearable devices are associated with frailty in older people, research suggests.

Disturbances to circadian rest-activity rhythms were associated with the age-related worsening of grip strength, body mass index and fatigue and its faster progression.

The findings, published in Nature Communications, show the potential value of wearable technology in monitoring long-term health.

“Wearable technology provides a holistic approach for detecting common indicators of disease,” said corresponding author Peng Li, PhD, from Brigham and Women’s Hospital division of sleep and circadian disorders.

“Combining circadian rest-activity data with other clinical measures could help with early identification and intervention in susceptible populations.”

Frailty is defined as an age-related decline in multiple physiological systems, with affected older individuals vulnerable to stressor events and having a poorer quality of life.

They are also at increased risk of major adverse health outcomes, including Alzheimer’s disease.

The researchers examined how frailty related to the internal circadian clock, the 24-hour rhythms present in nearly all biological and physiological processes that have developed as an evolutionary adaptation to daily environmental change.

The study included 1022 participants from the Rush Memory and Aging Project, aged 59 to 100 years. The mean age at baseline was 81 years old, and approximately three-quarters were women.

Over a mean of 6.6 years of follow-up, 34.9% of the participants developed frailty.

The researchers report that disturbances in circadian rest-activity rhythms, especially reduced rhythm strength, reduced stability, and increased variation of cycle length were associated with an increased risk of frailty and increased speed of frailty progression.

After adjusting for age, sex, education, sleep duration, sleep fragmentation, vascular disease burden, vascular risk factors, and their interactions with time, the increase in the continuous frailty measure was much faster in participants with a smaller relative amplitude or lower average activity level during the most active 10-hour period (M10).

For every standard deviation decrease in amplitude or M10, the annual increase significantly accelerated by 0.005. This effect was equivalent to being two and a half years older than the mean age of participants at baseline.

This was true for three of the four frailty components assessed—grip strength, body mass index, fatigue. None of the circadian metrics was associated with the rate of change in gait speed, which was based on the time to walk eight feet.

The association of circadian rest-activity metrics with frailty persisted after accounting for Alzheimer’s and Parkinson’s disease at baseline, and its effect was mostly unchanged.

“It is known that circadian function plays an important role in many age-related diseases, such as cardiometabolic disorders, delirium, cognitive impairment, and Alzheimer’s disease,” the researchers reported.

“Our results add a significant pillar to this important role of circadian function in aging by showing that it is associated with the risk of developing frailty in the future.”

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