A common daytime habit many older adults do could be increasing their risk of developing dementia, a new study has found. Researchers at Johns Hopkins University said that daytime napping, specifically how often, how intentionally and how long, was found to influence a person's risk of developing dementia. However, the experts emphasized that the findings were observational and do not establish that napping directly causes dementia.
The study was published online in The Journals of Gerontology: Medical Sciences on October 5. These findings follow on from previous research in the field, some of which has indicated that sleepiness has been associated with an abnormal accumulation of proteins associated with dementia in the brains of otherwise healthy adults, Dr. Andrew Varga, a sleep neurologist and neuroscientist at the Icahn School of Medicine at Mount Sinai, told Newsweek.
The researchers reviewed the clinical data of almost 1,000 U.S. Medicare users who were at least 65 years old and who did not have dementia at the start of the study in 2013. They tracked the participants for up to 10 years.
They found that those who napped frequently, meaning either most days or every day, had a 48 percent higher risk of developing dementia compared to those who either rarely or never napped. The researchers said this was the case even after several demographic factors were accounted for, such as health conditions and nighttime sleep characteristics. Unintentional napping, so falling asleep without intending to, was linked to a 39 percent higher risk of developing dementia as well.
They also identified that duration of the nap had an impact too. Daytime sleeping for 30 minutes or less was associated with a 40 percent higher risk. The scientists noted that there could be a "two-way" nature to the association, meaning that cognitive decline can cause more frequent intentional and unintentional napping, as well as napping potentially increasing risk of the disease.
Varga said that as the proteins amyloid and tau – which are associated with dementia development – "start to accumulate and neurons start to become dysfunctional or die, some of the earliest neurons affected are ones that control the regulation of sleep and wake as well as the circadian rhythm." "So, this means that periods of sleep can come on during the day at inappropriate times," he said. However, as the researchers followed some participants for 10 years, who did not have dementia at the start of the study, they said that the findings seem to suggest that napping pattern could have an influence on dementia development, and not just be a reflection of the disease. In terms of how napping could affect dementia risk, Adam Spira, the study author and a professor of mental health at Johns Hopkins University, told Newsweek that one possibility is daytime napping may affect nighttime sleep.
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