Health Australia (Commonwealth Union) – Dementia, an umbrella term for a range of cognitive impairments, has captured the attention of scientists, healthcare professionals, and families worldwide. As our population ages, the prevalence of dementia is on the rise, making it one of the most pressing public health challenges of our time.
Dementia is often a result of abnormal changes in the brain. In Alzheimer’s disease, it’s the accumulation of beta-amyloid plaques and tau tangles that disrupt communication between brain cells. In vascular dementia, reduced blood flow to the brain due to strokes or other vascular issues is the culprit. Understanding the underlying causes is crucial for developing effective treatments and interventions.
A recent study conducted by Monash University has shed light on the critical role of deep sleep, also known as slow wave sleep, in the cognitive health of individuals over 60 years of age. The findings reveal that even a minimal annual reduction of just 1 percent in deep sleep can translate to a substantial 27 percent heightened risk of dementia. This discovery suggests that preserving or enhancing deep sleep-in older individuals could potentially serve as a safeguard against the onset of dementia.
The research, spearheaded by Associate Professor Matthew Pase from the Monash School of Psychological Sciences and the Turner Institute for Brain and Mental Health in Melbourne, Australia, has been published in JAMA Neurology. The study involved 346 participants, all aged over 60, who were part of the Framingham Heart Study. These individuals underwent two overnight sleep studies between 1995-1998 and 2001-2003, with an average gap of 5 years between the 2 assessments.
Subsequently, these participants were meticulously monitored for the development of dementia from the time of the second sleep study until 2018. The study’s results revealed an average decline in the amount of deep sleep between the two time periods, signifying a loss of slow wave sleep associated with aging. Over the 17-year follow-up period, 52 cases of dementia were identified. Even after adjusting for various factors like age, gender, genetic influences, smoking habits, medication use, and more, the research found that each yearly percentage decrease in deep sleep was linked to a significant 27 percent increase in the risk of dementia.
Associate Professor Pase indicated that slow-wave sleep, or deep sleep, supports the aging brain in many ways, and they know that sleep augments the clearance of metabolic waste from the brain, including facilitating the clearance of proteins that aggregate in Alzheimer’s disease. These findings underscore the profound significance of deep sleep in the overall health and cognitive well-being of older individuals and the potential for its preservation in the prevention of dementia.
“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.”
Associate Professor Pase highlighted the distinctive nature of the Framingham Heart Study, characterized by its community-based cohort. This study incorporated recurrent overnight polysomnographic (PSG) sleep assessments and sustained monitoring for the emergence of dementia cases.
He further indicated that they harnessed these resources to investigate the alterations in slow-wave sleep as individuals aged and whether variations in the percentage of slow-wave sleep were linked to the risk of developing dementia later in life, extending up to 17 years.
“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.”
Poor sleep has often been linked to a wide variety of detrimental effects; hence these findings can shed better light on the more specific impacts of poor sleep.
