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If you find yourself drowsy during your daily activities as you get older, you may need to consider it more than just a concern—as fatigue may indicate you’re at higher risk of developing a condition that can lead to dementia, a new study has found.
Among participants who experienced excessive daytime sleepiness and lack of enthusiasm, 35.5% developed cognitive-motor risk syndrome compared with 6.7% of people without these problems, according to the study published Wednesday in the journal Neurology.
Motor cognitive risk syndrome, or MCR, is characterized by slow walking speed and complaints of memory problems in older adults who do not already have dementia or mobility impairments. The risk of developing dementia more than doubles in those with the syndrome, which was first described in 2013.
“Previous studies have shown a link between sleep disorders and the risk of dementia,” said first study author Dr. Victoire Leroy, assistant professor of geriatric medicine at Tours University Hospital in France, via email.
But some of those scientific reports looked at that link mostly at just one point in time, according to the study. Not much is known about the link between certain aspects of poor-quality sleep and pre-dementia syndromes, Leroy and the research team wrote — so they wanted to expand research in this area.
“Establishing the relationship between sleep dysfunction and MCR risk is important because early intervention may offer the best hope for preventing dementia,” the authors said.
The findings are based on 445 adults who were an average of 76 years old and recruited from Westchester County, New York for the Center’s Mobility Control and Aging study, which assesses cognitive processes and brain mechanisms that regulate mobility in aging. Participants walked on treadmills so their initial gaits could be recorded, then were assessed annually from 2011 to 2018.
The study authors also collected annual data on the participants’ memories of their sleep quality and quantity in the two weeks before the assessments. Specifically, the team collected details within the seven components of the Pittsburgh Sleep Quality Index: subjective sleep quality, time taken to sleep, sleep duration, sleep efficiency (ratio of total hours slept to total hours in bed), sleep disturbances, use of sleep-inducing drugs, and daytime dysfunction, such as having trouble staying awake during activities or feeling less enthusiastic about getting things done.
Over a follow-up period of approximately three years on average, 36 participants developed cognitive motor risk syndrome. Compared to “good” sleepers, “poor” sleepers had only a slightly higher risk of MCR. But when the authors considered the seven components of sleep separately, only daytime dysfunction was associated with a 3.3-fold increased risk of MCR.
The study’s findings may help doctors and patients be more open to asking questions about sleep patterns and looking more closely at gait speed when making an early diagnosis, said Dr. Richard Isaacson, director of research at the Florida Institute for Neurodegenerative Diseases. Richardson was not involved in the study.
The study has some “serious” limitations, said Dr. Tara Spiers-Jones, professor of neurodegeneration and director of the Center for Discovery Brain Sciences at the University of Edinburgh in Scotland, via email.
“Sleep measures were self-reported, not measured by a scientist, and these self-reports could be biased by people with memory problems,” said Spiers-Jones, who was not involved in the study. “Participants in the study were also predominantly white, and the cohort was much smaller than similar studies at one time point, so the results will be stronger if confirmed in future studies.”
The authors acknowledged that while the duration of their study, approximately three years, is longer than some previous research, the follow-up period is still short.
Cognitive motor risk syndrome is newly identified, so experts still have a lot to learn before explaining in detail what causes it and how it affects the body, Isaacson said. That’s complicated by the lack of “definitive pathologic biomarkers” for MCR so far, Isaacson said.
But “several mechanisms may explain this association,” Leroy said. “Sleep plays a role in “cleaning” neurotoxins accumulated in the brain. In addition, previous studies have shown a greater accumulation of proteins associated with Alzheimer’s disease in sleep-deprived individuals.
“A possible alternative or additional way is through activation of the brain’s inflammatory response, which is seen in Alzheimer’s disease and related dementias,” Leroy said.
It is unclear why of the seven components of sleep, daytime dysfunction was the only one significantly associated with risk of MCR, when one might think that the other six components—which included sleep quality and quantity—would play a role. dysfunction of the day, experts said.
Spiers-Jones noted that for the possible link between daytime dysfunction and MCR, reverse causation is also possible.
“Scientific evidence suggests that when you’re in the early stages of dementia, pathological changes in the brain disrupt sleep,” she added — meaning “it’s likely that the early disease causes sleep disruption, not the disruption that causes disease.”
It’s well known that sleep disturbances like REM sleep behavior disorder can be early predictors of conditions including Lewy body dementia or Parkinson’s disease, Isaacson said.
The results of the study show how precious sleep is, Leroy said.
People who have problems with their sleep should talk to their doctors, consider filling out a sleep questionnaire and discuss whether a home or hospital sleep study might be helpful, Isaacson said.
“There are now many treatments, drug and non-drug approaches, that may be able to help depending on the exact problem found,” he added. “Treating sleep disorders should provide many years, even decades, of benefits in overall brain health and dementia prevention.”
You can take other measures to protect your brain as you age.
“Living a healthy lifestyle, including eating well, maintaining a healthy weight, keeping your body and brain active, and treating any hearing loss are all ways to increase brain resilience and reduce risk of madness,” Spiers-Jones said.
“This is not to blame people who have dementia for their lifestyle choices,” she added. “The best estimates show that less than half of the risk of dementia is due to this type of modifiable risk factor, while the rest of the risk is likely due to the genes we inherit.”
However, given the potential to modify your risk and the growth of medical research and treatments, Spiers-Jones added, there is reason for hope.
If you’re already experiencing mobility problems, fall prevention can help, Isaacson said — this can include physical and occupational therapy evaluations, and at-home adaptations such as installing grab bars in the shower, removing clutter and using nightlights. .