Lack of deep sleep in older people increases their risk of getting dementia, a recent study reveals.
Insufficient slow-wave sleep in persons over 60 may raise dementia risk by 27% for every 1% loss of deep sleep yearly, according to Monash University neuroscientist Matthew Pase.
Slow-wave sleep, the third stage of a 90-minute sleep cycle, strengthens muscles, bones, and the immune system by slowing brain waves, heart rate, and blood pressure.
As reported by Science Alert, Pase noted: "Slow-wave sleep, or deep sleep, supports the aging brain in many ways, and we know that sleep augments the clearance of metabolic waste from the brain, including facilitating the clearance of proteins that aggregate in Alzheimer's disease."
In this picture taken on January 10, 2017, dementia-stricken Kimiko Ito takes a nap while waiting for her husband to bring her lunch at their house in Kawasaki.
He added that though the function of slow-wave sleep in dementia development remains unknown, " Our findings suggest that slow-wave sleep loss may be a modifiable dementia risk factor."
Researchers from Australia, Canada, and the US evaluated Framingham Heart Study data from 346 people. Two overnight sleep examinations were performed on these people between 1995 and 1998 and 2001 and 2003, with an average five-year delay. Sleep variables across time were examined in the community-based sample, all over 60 in 2020 and dementia-free in 2001-2003.
The researchers examined results from two polysomnography sleep studies and tracked dementia until 2018. Slow-wave sleep decreased after 60, peaked between 75 and 80, then stabilized. Comparing participants' first and second sleep studies revealed a link between each percentage point decrease in slow-wave sleep per year and a 27% increased risk of developing dementia. This risk rose to 32 percent when focusing on Alzheimer's disease.
These connections are evident, but the study does not prove a causative link, requiring further research to properly understand slow-wave sleep loss and dementia. The results suggest that slow-wave sleep may reduce dementia risk, which should guide sleep quality measures for older adults.
The Enduring Research on Sleep-Memory Link
The relationship between sleep and memory has been studied for generations, according to a CBC article. In the mid-1700s, philosopher David Hartley mused about dream-filled sleep and memory development. By the 1900s, modern researchers began confirming this idea, illustrating how different sleep stages influence memory development. Neuroscientist Matthew Walker highlighted the importance of sleep in processing newly acquired information and long-term memory storage in 2009.
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Over the last two decades, studies have indicated that just a day and a half without sleep can disrupt memory game performance and slow reaction times. Research involving American nurses revealed that both insufficient and excessive sleep—less than five hours or more than nine hours per night—correlated with poorer cognitive test results, suggesting mental aging beyond their years. Some studies compare sleep deprivation to the cognitive damage caused by 0.10% blood alcohol after one day.
In 2013, the CDC declared poor sleep a "public health epidemic," especially in older persons, associating it with a decline in cognition and dementia.
Strawberry May Help Fight Dementia
In a recent study, University of Cincinnati (UC) researchers examined the cognitive benefits of strawberry-infused supplement powder. The research included 30 moderate cognitive decline patients aged 50-65. Participants were instructed to abstain from consuming any berry fruits and instead added a daily packet of supplement powder to their water, with half containing strawberries.
Cognitive tests, mood assessments, signs of depression, and metabolic data were collected. The findings indicated that those who consumed the strawberry-infused powder showed "reduced memory interference," suggesting better executive control during memory testing. Additionally, this group exhibited lower depressive symptoms, improved emotional control, and enhanced problem-solving abilities compared to the placebo group, according to lead researcher Robert Krikorian from UC.
"There is epidemiological data suggesting that people who consume strawberries or blueberries regularly have a slower rate of cognitive decline with aging," the expert noted, as quoted by Fox News.
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