A 1% Decrease in Deep Sleep Increases Dementia Risk by 27%
A recent study revealed that individuals aged 60 and above who experience an annual 1% decline in deep sleep are associated with a 27% higher dementia risk. These results indicate that preserving or improving deep sleep might serve as a preventive measure against the disease.
Referred to as deep sleep, slow-wave sleep typically spans 70 to 90 minutes and predominantly takes place in the initial hours of the night. Besides being the sleep phase responsible for a refreshed awakening, deep sleep plays a crucial role in the body’s repair of muscles, bones, tissues, and fortification of the immune system.
Link Between Deep Sleep and Dementia Risk
Earlier research has proposed that the brain disposes of harmful proteins associated with dementia during deep sleep, but the connection between deep sleep and dementia development has remained unclear. However, a recent study conducted by Monash University researchers indicates that a decline in deep sleep is linked to an increased risk of dementia in individuals over the age of 60.
Matthew Pase, a co-author of the study, stated, “Slow-wave sleep, or deep sleep, provides various forms of support to the aging brain, and we are aware that sleep aids in the removal of metabolic waste from the brain, including the clearance of proteins that accumulate in Alzheimer’s disease. Nevertheless, the role of slow-wave sleep in the development of dementia has been uncertain until now. Our findings suggest that the loss of slow-wave sleep might be a modifiable risk factor for dementia.”
Sleep Assessments and Participant Demographics
The study involved 346 participants who had undergone two overnight sleep assessments during the periods 1995-1998 and 1998-2001. The average age of these participants was 69, and roughly half (52%) were female.
“We utilized these sleep studies to investigate the impact of aging on slow-wave sleep and whether alterations in the percentage of slow-wave sleep were linked to the risk of dementia in later life, spanning up to 17 years,” explained Pase.
The researchers discovered that, on average, there was a decline in the amount of sleep between the two sleep studies, indicating that the aging process was linked to a reduction in deep sleep.
Dementia Incidence and Deep Sleep
During the 17-year follow-up period, there were 52 reported cases of dementia. After accounting for age, gender, genetic factors, smoking habits, and the use of sleep, anti-anxiety, and antidepressant medications, it was revealed that a decrease of one percentage point in deep sleep per year was linked to a 27% rise in the risk of dementia.
The researchers also determined that the decline in deep sleep associated with aging was expedited in the presence of the genetic risk factor for Alzheimer’s disease, known as the APOE e4 allele. However, alterations in brain volume did not exhibit a similar correlation.
“We also explored whether genetic susceptibility to Alzheimer’s disease or early signs of neurodegeneration in brain volume were related to a reduction in slow-wave sleep,” noted Pase. “Our findings indicated that a genetic risk factor for Alzheimer’s disease, rather than changes in brain volume, was linked to an accelerated decline in slow-wave sleep.”
Read the original article on: New Atlas
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