Forgetfulness In Old Age May Be Caused By Poor Brain Wave Rhythms During Sleep
Most of us believe that forgetfulness just sort of happens as we age and that there’s very little we can do about it. This forgetfulness may not be nearly to the degree that Alzheimer’s and other forms of dementia affect the brain, but most of us think we will lose some of our ability to learn new things and record memories as we age.
A new study published in Neuron, however, may have the answer to why we forget things and lose the ability to learn new things quickly as we age, with the goal of perhaps reversing that age-old problem. The issue, the study reports, appears to have a lot to do with—you guessed it—sleep.
Matt Walker, one of the paper’s authors and a professor of neuroscience and psychology at the University of California, Berkeley, led a team of scientists in a study of 20 young adults and 32 older adults in their 60s and 70s. Both groups were asked to learn and remember 120 pairs of words. Then electrodes were attached to their heads during sleep to measure different brain waves. The next day, each participant was asked to take a test that showed how many of the word pairs they had remembered from the day before.
In both groups, the number of word pairs correctly remembered was in direct correlation with the participants’ brain wave activity during sleep. Slow waves occur about once per second, while faster waves called sleep spindles occur about 12 times per second. Good synchronization between these two types of waves results in better retention abilities.
“When those two brain waves were perfectly coinciding, that’s when you seem to get this fantastic transfer of memory within the brain from short term vulnerable storage sites to these more permanent, safe, long-term storage sites,” Walker says.
However, the group of older people had more trouble with their brain wave coordination, meaning their long and short brain waves were not properly synchronized as often. They also forgot more of the word pairs than the younger group, an issue that could be because of a mere 50 milliseconds of difference between brain waves.
“It’s like a drummer that’s perhaps just one beat off the rhythm,” says Walker. “The aging brain just doesn’t seem to be able to synchronize its brain waves effectively.”
The issue with aging people losing proper brain wave rhythm appears to have something to do with atrophy in an area of the brain that is responsible for deep sleep. In the study, increased levels of atrophy were associated with poor brain wave rhythm synchronization. Sadly, this atrophy is a normal part of aging. However, Walker believes it may be possible to restore correct brain rhythms to people with brain atrophy in order to improve learning and memory in the future.