Elderly persons who experience excessive daytime drowsiness or lack of enthusiasm for activities have a three-times-higher likelihood of developing dementia as they become older, according to a study published in the journal Neurology.
The peer-reviewed study suggests that older individuals who struggle with sleep-related issues—such as trouble falling asleep or a lack of deep, uninterrupted sleep—may be more prone to motoric cognitive risk syndrome (MCR), a condition that is often experienced before dementia develops.
People with MCR exhibit a slow walking speed and experience some memory issues, although not to the extent of mobility disability or dementia.
The study did not prove that the syndrome is caused by sleep-related issues, but revealed a sufficient association between sleep disturbances and cognitive decline to suggest preventative action.
Dr. Victoire Leroy, a researcher from the Albert Einstein College of Medicine in New York who led the study, emphasized the significance of sleep from a potentially preventative standpoint.
“Our findings emphasize the need for screening for sleep issues,” she said. “There’s potential that people could get help with their sleep issues and prevent cognitive decline later in life.”
The study followed 445 participants with an average age of 76, none of which had dementia.
At the start of the study, participants completed a sleep assessment that included questions about trouble falling asleep, staying asleep, disturbances related to temperature while in bed, and their use of sleep-inducing medication, if any.
They were also asked about indicators for excessive daytime sleepiness and their level of enthusiasm for daily activities, such as difficulty staying awake while driving or engaging in social activities, and maintaining enough enthusiasm to get things done. Lastly, participants were questioned on memory issues, and their walking speed was tested on a treadmill at the start of the study, and then again each year—with the study following the participants for three years on average.
The study categorized 177 participants as poor sleepers and 268 as good sleepers. At the outset, 42 individuals already met the criteria for MCR syndrome, while during the study period, 36 more developed the syndrome.
The study results showed that people experiencing both excessive daytime sleepiness and low enthusiasm for activities were significantly more likely to develop motoric cognitive risk syndrome.
Approximately 35.5 percent of participants with excessive daytime sleepiness and low enthusiasm developed MCR, compared to only 6.7 percent of those not experiencing these issues.
After adjusting for other potential risk factors, such as age, depression, and other health conditions, researchers found that individuals with daytime sleepiness and low enthusiasm were more than three times as likely to develop the syndrome than those who did not have sleep-related problems.
“More research needs to be done to look at the relationship between sleep issues and cognitive decline and the role played by motoric cognitive risk syndrome,” Leroy said. “We also need studies to explain the mechanisms that link these sleep disturbances to motoric cognitive risk syndrome and cognitive decline.”
A limitation of the study is that participants reported their own sleep information, so they may not have remembered everything accurately, the authors note.