Landmark Study Shows Improving Deep Sleep May Protect Against Dementia

A Monash University research suggests that enhancing deep sleep could significantly reduce the risk of dementia in the elderly. The study tracked 346 individuals over 60 and found a 27% increased risk of dementia per 1% annual reduction in deep sleep. The findings highlight deep sleep's potential as a modifiable risk factor for dementia prevention.

The study, led by Associate Professor Matthew Pase and published in the prestigious JAMA Neurology journal, meticulously followed 346 individuals over the age of 60 who were part of the Framingham Heart Study. These participants underwent two detailed overnight sleep studies approximately five years apart, between 1995 and 2003. Researchers then tracked the incidence of dementia until 2018, noting that a mere 1 percent reduction in deep sleep per annum was linked to a worrying 27 percent escalation in dementia risk.

“Slow-wave sleep, or deep sleep, supports the ageing 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. However, to date we have been unsure of the role of slow-wave sleep in the development of dementia. Our findings suggest that slow wave sleep loss may be a modifiable dementia risk factor,” Pase said.

Moreover, the analysis considered various influential factors such as age, gender, genetic predispositions, and medication use. Notably, the presence of the APOE e4 gene, a known genetic marker for Alzheimer's, was correlated with a more rapid decline in SWS, although brain volume was not.

“We used these to examine how slow-wave sleep changed with ageing and whether changes in slow-wave sleep percentage were associated with the risk of later-life dementia up to 17 years later. We also examined whether genetic risk for Alzheimer’s Disease or brain volumes suggestive of early neurodegeneration were associated with a reduction in slow-wave sleep. We found that a genetic risk factor for Alzheimer’s disease, but not brain volume, was associated with accelerated declines in slow wave sleep.” he said.

These findings echo the broader scientific consensus on the restorative powers of sleep, emphasizing its role in flushing out toxic proteins that accumulate during waking hours. The glymphatic system, responsible for this clearance, is most active during sleep, highlighting the potential long-term consequences of insufficient rest.

Given the observational nature of the study, causality cannot be firmly established. However, the evidence underscores the need for older adults, who are already prone to sleep disturbances, to prioritize sleep quality.

This research not only bolsters our understanding of the complex interplay between sleep and cognitive health but also signals a call to action for individuals and healthcare providers alike to view deep sleep maintenance as a potential strategy for dementia prevention.