Memories Lost to Alzheimer’s Disease May Actually Be Recoverable

Scientists once thought that the memories Alzheimer’s patients lost were gone forever. Now, new research indicates that they might just be hiding somewhere in the deep recesses of the brain—and that they can be reactivated with light.

The experts used a technique called optogenetics, which uses light to trigger nerve cells that are tagged with a special protein. They found that when mice with Alzheimer’s-like symptoms were subjected to this approach, their prior fear responses—which had been obliterated—returned. The light had prompted the neurons to grow dendritic spines, which form synaptic connections with other cells.

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By stimulating nerve cells with light, people with Alzheimer’s might be able to retrieve lost memories.

While the technique can’t yet be replicated in humans, the positive results in mice suggest that it could someday be possible. But even then, patients might only reap short-term benefits; in the long-term, the severity of the disease might negate those short-term improvements.

The Guardian reports:

Lead scientist Prof Susumu Tonegawa, from the Picower Institute for Learning and Memory at the Massachusetts Institute of Technology (MIT) in the U.S., said: “The important point is, this a proof of concept. That is, even if a memory seems to be gone, it is still there. It’s a matter of how to retrieve it.”

The research, published in the journal Nature, specifically targeted memory cells in the hippocampus region of the brain previously identified by Tonegawa’s team.

Specifically, Tonegawa and his colleagues pulsed the light (mimicking processes that happen in the brain when it repeatedly calls up old memories), which helped foster new connections between the hippocampus and entorhinal cortex region of the brain. These two areas are the most vulnerable to Alzheimer’s disease—the latter becoming more and more damaged as the disease wears on.

Prosthetic memory devices would function similarly in their stimulation of the hippocampus. Overall, though, these advances will take quite some time to become practical or even mainstream. But the promise of rescued memories is one that could bring hope—and accelerated research goals.