Alzheimer’s Disrupts Brain’s Memory Replay Process, Study Finds
Alzheimer’s disease may be scrambling memories even during rest, according to new research revealing a breakdown in the brain’s memory consolidation process. A study from University College London (UCL) observed that mice engineered to develop amyloid plaques characteristic of Alzheimer’s exhibit disrupted hippocampal replay of memories during rest periods.
This process, which normally stabilizes spatial memories, becomes scrambled and poorly coordinated in affected animals.
The research team used implanted electrodes to monitor 100 place cells simultaneously in the hippocampus of mice.
These neurons typically fire in sequences corresponding to specific locations, enabling the brain to replay spatial experiences during rest. In mice with Alzheimer’s-like pathology, the stability of these place cells diminished, leading to inconsistent spatial representations after rest.
Behavioral tests confirmed this disruption: affected mice repeatedly revisited previously explored paths in maze navigation tasks, suggesting impaired memory consolidation.
"We found this replay process is disrupted in mice engineered to develop the amyloid plaques characteristic of Alzheimer’s, and this disruption is associated with how badly animals perform on memory tasks," the authors reported in Current Biology (DOI: 10.1016/j.cub.2025.12.061). The study clarifies that the disruption does not eliminate replay entirely but alters its timing and coherence, preventing effective memory reinforcement.
The findings suggest that targeting acetylcholine pathways could improve memory replay in Alzheimer’s.
Current treatments for the disease often focus on modulating acetylcholine levels, but this study proposes a mechanism to enhance their efficacy by restoring the temporal structure of hippocampal replay. The research was supported by the Cambridge Trust, Wellcome, and the Masonic Charitable Foundation.
