Circadian rhythms describe the body’s natural 24-hour clock. These rhythms regulate changes that occur throughout the day and impact a multitude of day-to-day aspects, including sleep, appetite, and waking up. A recently published study investigated rest and activity rhythms (RARs), which are markers of circadian rhythms, and how they relate to dementia. The findings of the study suggest that individuals with disrupted RARs have a higher likelihood of developing dementia.
The researchers of the study wanted to specifically investigate how RARs were linked to the development of incident dementia, which is the development of new cases of dementia within a population group over a specific time. The average age of the participants was 79 years old, while the average follow-up time after the initial experiment was 3.3 years. After the conclusion of the experiment, it was found that 8% of the participants developed dementia.
The researchers adjusted for various factors in three models and also conducted sensitivity analyses. Weaker rhythm strength in individuals was associated with an increased risk for dementia, with each standard deviation decrease in rhythm strength being linked to a 54% greater risk for dementia. However, each standard deviation increase in “within-day” rhythm was linked to a 19% higher risk for developing dementia. The participants who had more fragmented rhythms experienced symptoms like daytime sleepiness or waking up in the middle of the night.
An unusual finding that the researchers came across was that lower day-to-day rhythm consistency is associated with a greater dementia risk for Black individuals but not white individuals. However, the researchers have advised caution regarding this finding as not enough evidence has surfaced. Additionally, a later peak time of activity, such as later in the day, was associated with a 69% higher chance of dementia in individuals compared with those who had a normal peak time of activity.
The researchers noted that the overall results indicate that alterations in circadian RARs, specifically those of weaker rhythm strength, more fragmented rhythm, and later peak activity time, may be risk factors for incident dementia. However, this study does have its limitations. Since the study was only on black and white participants, it may not be generalizable to other groups. In addition to that, this study focused only on older individuals, so it is currently unknown whether the findings can be applied to middle-aged people. More research is needed in this area, but the early findings indicate that disrupting your body clock can result in a higher likelihood of developing dementia.
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