Key to Age-Related Memory Decline Explored

It is during sleep, while we are young, that our brains convert fresh memories into long-term memories, but as we age that process declines and with it our memory of things that happened just recently. Carol Barnes, Ph.D., lead scientist, and colleagues from the University of Arizona recently explored and gained insight into why this happens.

The team studied the brain scans of 22 rats; recording their daily activities, waking and sleeping. Half of the rats in the study were old; half were young. Studying the area of the brain thought to be involved in learning and memory, called the hippocampal area, the scientists observed the rats’ brain activities wandering through mazes while searching for food during the day, and sleeping during the night.

It was found that the young rats’ brain wave patterns during sleep closely resembled the brain wave patterns they had exhibited during the day while scurrying through their maze. These young rats seemed to be replaying the events of their day, consolidating the memory of it, while they slept.

A similar brain activity in the majority of the older rats was decidedly missing. The scientists surmised that because most of the older rats lacked this ability to replay daily activities while they slept, their memories of the day’s activities were not being stored properly, a step thought necessary to convert recent memory into long-term memory.

A second experiment found that all of the rats, regardless of age, who were able to replay their daily activities during sleep scored better on learning and memory tests than any of the rats who did not replay their day’s activities during sleep.

The scientists concluded from the study that as we age, the decreasing ability of our brains to convert fresh memories into long-term memories through the process of replaying recent daily activities during sleep very likely contributes to age-related, long-term memory decline.

Studies such as this one will one day perhaps be able to identify the specific cause of memory loss in aging brains and lead to way to prevent it. Studies such as this might also encourage the development of new drugs designed to improve memory recall while we sleep which could prove to be an additional aid in preventing age-related long-term memory loss.

The results of this study can be found in the July 30, 2008 issue of The Journal of Neuroscience.