One of the first signs of ageing is memory loss. Many studies linked memory loss with the ageing brain, but could not explain why exactly we start having difficulty remembering things as we get older. The latest research published in the recent issue of the Nature Neuroscience found that it is poor sleep that the older people are suffering from that is causing memory loss and brain deterioration.
Sleep and memory
The researchers from the UC Berkeley found that certain important brain waves, which play a crucial role in long-term memory storage, are produced while we are asleep. During sleep, brain waves move memories from one part of the brain (the hippocampus) to another (the prefrontal cortex). While new, short-term memories are stored in the hippocampus, the prefrontal cortex stores long-term memories. If a person has long-term poor quality sleep, the memories get stuck in the hippocampus, and do not get to the long-term storage in the prefrontal cortex. The result is notable forgetfulness and difficulty remembering common things such as names and numbers.
In the kind of sleep called non rapid-eye movement, our brain creates waves from the middle frontal lobe. This part of the brain is known to deteriorate as we age, causing us to have problems entering deep sleep, which is necessary for long-term memory storage.
This explains why when we are young and easily enter into a deep sleep, retaining memories and facts is easy and gets more difficult as we age.
The study included 18 people in their 20s and 15 participants in their 70s. They were tested on their ability to remember certain number of words before they went to sleep. During sleep, an electroencephalographic machine was attached to their heads to monitor their brain activity. They were tested again after they woke up. However, while being tested the second time, they were attached to the Magnetic Resonance Imaging (fMRI) scans.
The results show that older participants had 75 percents lower quality of deep sleep than the younger people. In consequence, their memory was 55 percents worse the next day. This suggests that the frontal lobe deterioration is linked with poorer wave activity.
Potential practical implications
The scientists hope that their new findings are highly promising for the development of potential new treatments for memory loss in the elderly. What they are hoping to do is “jumpstart” slow wave sleep in order to help people remember better.
One German study was already able to boost deep sleep in the participants, using stimulation with electricity. The noticeably improved sleep helped with retaining memory overnight.