Feeling drowsy during the day at an older age might be more than just a minor annoyance. According to recent research, daytime Sleep could indicate a higher risk of developing motoric cognitive risk (MCR) syndrome, a condition that often precedes dementia.
The study, published in Neurology, found that among participants who experienced excessive daytime sleepiness and low enthusiasm for activities, 35.5% developed MCR, in contrast to just 6.7% of those without these symptoms. MCR is a newly identified syndrome characterized by a slow walking pace and memory complaints among older individuals who do not yet have dementia or mobility limitations. Those with MCR are more than twice as likely to eventually develop dementia, adding urgency to research into preventive strategies.
Understanding daytime sleepiness and Dementia Risk
Dr. Victoire Leroy, a geriatric medicine professor at Tours University Hospital, explained that previous studies had linked sleep disorders and dementia risk, but they often focused on single points in time rather than ongoing patterns. The researchers aimed to expand knowledge by exploring the relationship between specific sleep quality factors and pre-dementia conditions like MCR.
Establishing the relationship between sleep dysfunction and MCR risk is crucial because early intervention may offer the best hope for preventing dementia, the researchers stated.
Tracking Sleep Patterns and Cognitive Decline
The study involved 445 adults with an average age of 76, recruited from New York’s Westchester County for the Central Control of Mobility and Aging study. Participants walked on treadmills to record their baseline gait and were assessed annually from 2011 to 2018. Each year, they also reported their sleep quality over the prior two weeks, detailing factors such as sleep duration, time taken to fall asleep, efficiency, disturbances, use of sleep medication, and any daytime dysfunction like trouble staying awake during activities.
Over a follow-up period of about three years, 36 participants developed MCR. Interestingly, while poor sleep slightly increased the risk of MCR, the research found that only daytime dysfunction was significantly associated with MCR risk—those experiencing daytime fatigue had a 3.3 times greater likelihood of developing the syndrome.
Dr. Richard Isaacson, director of research at the Institute for Neurodegenerative Diseases in Florida, noted that these findings might encourage physicians and patients to examine sleep habits and walking speed closely when assessing early signs of cognitive decline.
Exploring the Brain and Sleep Connection
The study has some limitations, acknowledged Dr. Tara Spires-Jones, a neurodegeneration specialist at the University of Edinburgh. For one, sleep measurements were self-reported rather than scientifically verified, which could lead to biased results, especially among people with memory issues. Additionally, the study group was largely white and smaller than similar studies, meaning that further research is needed to confirm the findings.
Despite these constraints, the research offers valuable insights into the links between sleep and brain health. While MCR is newly identified, experts are working to better understand its causes and effects. Without clear biomarkers, it’s challenging to diagnose and monitor MCR, but various theories exist. Sleep plays a role in clearing neurotoxins from the brain, and previous studies have shown that sleep-deprived individuals accumulate proteins associated with Alzheimer’s disease. Inflammation in the brain, commonly seen in Alzheimer’s and related dementias, may also play a role.
While one might expect that poor sleep quality and duration would influence daytime dysfunction, daytime sleepiness alone appeared significantly linked to MCR. This raises questions about the direction of causation: it’s possible that early dementia disrupts sleep rather than poor sleep directly causing dementia. Evidence suggests that disruptions in sleep, including REM sleep behavior disorders, are often early predictors of diseases like Lewy body dementia or Parkinson’s disease.
The Importance of Monitoring Sleep Health
The study underscores the critical role of sleep in maintaining brain health, especially in aging populations. Dr. Leroy emphasized the need for individuals with sleep issues to consult their doctors. Dr. Isaacson also noted that sleep questionnaires or even home sleep studies could be beneficial. There are now many treatments, both drug and non-drug, that may help depending on the specific daytime sleepiness issue, he explained. Addressing sleep problems could benefit overall brain health and help delay dementia onset.
Taking other proactive measures can also support brain resilience. Dr. Spires-Jones recommended a healthy lifestyle, balanced diet, physical and mental activity, and addressing hearing loss as ways to reduce dementia risk. However, she added that lifestyle factors only account for part of the risk, as genes play a substantial role.
Spires-Jones concluded that with advances in research and treatment, there is hope for reducing dementia risk. If mobility issues are already a concern, fall prevention strategies, such as using home adaptations or consulting with physical and occupational therapists, can help maintain safety and quality of life as one age.
