Scientists at University College London (UCL) have discovered new clues about why people with Alzheimer’s disease may suffer from memory loss.
Their study, done in mice, shows that memory problems may be linked to how the brain replays our recent experiences while we are resting. These findings may lead to better ways to diagnose or treat Alzheimer’s disease in the future.
Alzheimer’s disease is known to be caused by harmful proteins and plaques building up in the brain. This damage leads to memory loss, confusion, and trouble navigating or recognizing familiar places. But it hasn’t been fully clear how these changes in the brain cause problems with memory.
The UCL researchers focused on a process called “replay,” which happens in the hippocampus, a part of the brain important for memory. When we rest, our brains normally replay recent experiences. This helps us form and keep memories. The team wanted to see if this replay process is affected by Alzheimer’s.
The replay involves special brain cells called “place cells.” These cells become active when we move through a space. As we go through different locations, the cells fire in a sequence. When we later rest, the brain replays these same sequences. This replay helps memories become stronger.
To study this, the scientists used mice that were genetically modified to develop amyloid plaques in the brain, which are a hallmark of Alzheimer’s. They had the mice complete a simple maze task and used electrodes to record the activity of around 100 place cells at the same time.
The researchers found that the replay process still happened in mice with amyloid plaques—but something was wrong. The sequences of place cell activity were no longer in the correct order. The brain was trying to replay the memories, but the patterns were scrambled.
Another issue was that the place cells became less stable. In healthy mice, the same cells would fire when visiting the same places. But in the mice with amyloid plaques, the cells didn’t behave as reliably, especially after rest. This is the time when replay should be making the memory stronger.
These changes had a real effect on the mice. The affected mice didn’t do as well in the maze. They often forgot which parts they had already visited and made mistakes that healthy mice avoided. This suggests that the scrambled replay was making it harder for them to remember where they had been.
Professor Caswell Barry, one of the lead researchers, explained that this study shows the brain still tries to replay experiences, but the process breaks down in Alzheimer’s. Instead of stopping completely, replay events become disorganized and stop working properly.
The team hopes this research can lead to better tools to detect Alzheimer’s early—before too much damage has occurred. It may also help improve treatments that already target parts of this replay system. For example, they are looking into how a brain chemical called acetylcholine, already used in some Alzheimer’s drugs, might help fix these replay problems.
The study was published in the journal Current Biology and gives scientists a clearer view of what may be going wrong in the brain during the early stages of Alzheimer’s. Understanding how memory replay is affected could open new doors for early diagnosis and better treatments.
If you care about Alzheimer’s, please read studies about Vitamin D deficiency linked to Alzheimer’s, vascular dementia, and Oral cannabis extract may help reduce Alzheimer’s symptoms.
For more information about brain health, please see recent studies about Vitamin B9 deficiency linked to higher dementia risk, and results showing flavonoid-rich foods could improve survival in Parkinson’s disease.
Copyright © 2025 Knowridge Science Report. All rights reserved.
