Poor Sleep Linked to Memory Loss in Older Adults
Poor quality of sleep during old age prevents memories from being stored in the brain, according to a new study. Researchers say that the study helps understand the link between memory, the aging brain and sleep quality, and add that the new findings will pave the way for new therapeutics designed to strengthen memory and improve the quality of life in older adults.
Researchers from University of California, Berkeley, found that memories in the brains of old people rarely get into the brain's "hard drive" or the prefrontal cortex, and instead stay in the hippocampus. Researchers say this is the reason that old people tend to forget things.
"When we are young, we have deep sleep that helps the brain store and retain new facts and information. But as we get older, the quality of our sleep deteriorates and prevents those memories from being saved by the brain at night," said Matthew Walker from UC Berkeley, senior author of the study.
The study included 18 young adults (around age 20) and 15 older adults (around age 70). Researchers tested how good these participants were in remembering information after a night's sleep. All the participants were given a test on memory ability before they went to bed. Their sleep quality was assessed using an electroencephalographic (EEG) machine that measured their brain wave activity.
Next morning, they were tested on their memory ability and this time researchers assessed their brain activity through functional and structural Magnetic Resonance Imaging (fMRI) scans.
Healthy adults spend about a quarter of their sleep in deep and restorative sleep called non-rapid-eye-movement (REM) sleep, during which the brain's middle frontal lobe generates slow waves. In old people, this part of the brain is damaged, preventive them from getting a deep sleep.
In the study, activity loss in the frontal lobe was associated with poor sleep, which in turn reflected in the way older people scored in the memory ability tests. Study results showed that older people suffered from sleep quality that was lower than 75 percent compared with sleep in younger study participants.
Researchers from UC Berkeley will be further studying whether or not enhancing sleep quality will lead to improvements in the memory of older adults.
"What we have discovered is a dysfunctional pathway that helps explain the relationship between brain deterioration, sleep disruption and memory loss as we get older - and with that, a potentially new treatment avenue," Walker said in a news release.
The study is published in the journal Nature Neuroscience.