Poor Sleep and Memory Issues Linked Among Seniors, Study Finds
(BERKELEY, Calif.) -- An experiment conducted by researchers at the University of California, Berkeley, found that seniors enjoy less quality sleep than younger individuals, which hinders long-term retention of episodic memories.
Though it has been recognized that sleep bolsters newly formed memories, the study is the first of its kind linking some of the well-known characteristics of aging with one another.
"We've known of the hallmarks of old age," Matt Walker, a professor of neuroscience and psychology at the University of California, Berkeley, and senior author of the study, told ABC News. "Your brain deteriorates, sleep deteriorates, memory deteriorates -- but we hadn't found if they're independent or interrelated."
Of the 33 participants in the study, 18 of them were in their 20s, and 15 were in their 60s and 70s. Each one of the participants studied 120 word pairs for roughly 30 minutes and then performed two separate recognition memory tests -- one after 10 minutes and the other after a night's rest. Researchers used ordinary words paired with non-words, in line with a theory that your ability to retain previously unknown information declines with age.
After 10 minutes, the younger group's members scored 25 percent higher than their elderly peers. The results after a night's rest were even more staggering; older participants' ability to recall the word pairs was 55 percent less accurate than their younger counterparts.
In order to establish a link between quality of sleep and memory loss, researchers scanned brain activity of the participants throughout the night and found the older group's quality of sleep was 75 percent less than the younger subjects.
Researchers have found that the middle frontal lobe of the brain, responsible for creating slow waves, shrinks with age and interferes with a senior's ability to enjoy deep sleep.
The brain scans of the participants showed the older group had disrupted NREM waves -- or non-rapid-eye-movement waves -- which impeded subsequent REM waves, the stage of sleep physiologically different from others and an essential part of a good night's rest.
On average, healthy adults spend 25 percent of their slumber in deep, REM sleep -- and researchers discovered that the disruptions occurring in the older group impacted the transfer from the brain's temporary storehouse, the hippocampus, to the pre-frontal cortex, the long-term memory center in the brain. The interruption resulted in a diminished development of episodic or short-term memory, but not long-term memory.
"Because we have identified sleep as an underappreciated factor that contributes to memory problems, it becomes a treatable target," said Walker.
Research is still needed in order to discover new steps that can be taken by seniors to improve memory, including therapeutic or prescription remedies. Some are experimenting with direct electrical stimulation to the brain with the goal of improving deep sleep for the elderly.
"Sleep in seniors changes in many ways," Dr. Osorio, research assistant professor at the Centre for Brain Health at NYU School of Medicine told ABC News. "Everyone accepts that sleep will change for the worse when you get older. Seventy years ago we thought as you got older, you would develop senile dementia as a normal part of aging. Having studied this more thoroughly, we can conclude it is not. The same may be true of our understanding of sleep in seniors, but we are not there yet."
It is recommended that adults enjoy eight hours of sleep per night.
Individuals may decrease consumption of alcohol and caffeine to improve their quality of sleep and, of course, regular exercise is widely cited as beneficial for many things, including catching more regenerative z's.
The study was published by the journal Nature Neuroscience.
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