In the early stages of Alzheimer’s disease, people often struggle with memories of personal experiences and events, known as episodic memory. However, it is unclear whether storing new episodic memories is the problem, or if the memories are made and stored as normal but cannot be recalled.
Researchers at the Massachusetts Institute of Technology found that mice showing signs similar to the early stages of Alzheimer’s disease were able to form and store new memories just as well as normal mice, but couldn’t recall them days later.
Using a technique called optogenetics, the researchers were able to artificially trigger recall of forgotten memories in mice. Optogenetics involves using light to stimulate cell activity in genetically modified animals. When the researchers optogenetically stimulated cells in the hippocampus, the area of the brain associated with memory, the mice were able recall the specific memories that they had previously forgotten. Once stimulated the mice showed the same level of memory recall as mice that did not have symptoms of Alzheimer’s disease.
Dr Doug Brown, Director of Research and Development at Alzheimer’s Society said:
“One of the key issues with understanding memory loss in Alzheimer’s is that we don’t know whether people are having problems storing memories or recalling them.
‘’This study in mice helps us to unpick the underlying processes and problems that lead to memory loss in the earliest stages of Alzheimer’s disease – this new evidence suggests that memory recall is the issue.
“While interesting, the practicalities of this approach – using a special blue light to stimulate memory – means that we’re still many years away from knowing if it would be possible to restore lost memories in people.”