The more we know about Alzheimer’s, the more progress we make in terms of effective long-term treatment options. Mice have allowed researchers, to uncover and discover a wide range of clues — with a recent study showing that the memories of Alzheimer’s patients may not be ‘lost’ forever.
What this study suggests, is that individuals with Alzheimer’s, may not forget who their loved ones are or where they’re going, their brains simply cannot find where those memories are stored. Published in Nature, it appears that this degenerative disease may not prevent the brain from making new memories after all.
What’s even more exciting, is that patients within the early stages, may actually improve their symptoms when exposed to brain stimulation. Here’s what the study found, and how these findings may improve the future of Alzheimer’s treatment.
Memory Manipulation in Mice Shows Promise for Alzheimer’s
Last year, Susumu Tonegawa, a neuroscientist from the Massachusetts Institute of Technology in Cambridge, and his colleagues, found that when suffering from certain forms of amnesia, memories were stored — they just could not be retrieved.
When studying humans, it’s difficult to distinguish the difference between a retrieved and stored memory based on the ability to recall information. In mice, however, memories can be manipulated. Tonegawa and his colleagues focused on two strains of mutated mice, whose genes were linked to Alzheimer’s.
Developing amyloid plaques, these mice are just like humans in that they eventually lose their memories. When placing the mice in a box that gave them an electric shock, the normal learned response is fear. In terms of the mutated mice, they did not fear the box, simply because they didn’t remember being shocked.
Stimulation of the hippocampus showed promising results —
In order to stimulate the area of the brain that encodes short-term memories, the experimental mice were engineered to produce light-sensitive proteins within the neurons in their hippocampus. Once these mice were placed back into the box in which they should fear, shining a light on their brains caused the mice to freeze.
By administering light, the modified neurons fired, causing the mice to remember being shocked. This told the researchers that the memory had, in fact, been encoded. The following day, the mice had once again forgotten that they feared the box.
The researchers then pulsed the light, essentially mimicking a naturally occurring process — as a memory is repeatedly accessed over time. What they found, was that the connection that relates to long-term memory storage was strengthened. The memory was processed and embedded, resulting in the mice fearing the box, even if they were not exposed to light.
Two steps forward and one step back
Although these findings are exciting, it’s believed that this technique would only work for approximately two to three years in humans. As the disease progresses, advancing symptoms would erase any gains. Of course, there’s also the possibility that these findings will not translate to human brains.
Although mutated mice do exhibit amyloid plaques, they do not develop in the same way that humans do. Since researchers have not determined how to stimulate human brains with light, testing these findings could also be challenging. Instead, electrical stimulation may be the answer — but there are still a lot of unknowns.
For now, these findings have provided researchers with more beneficial clues related to Alzheimer’s — allowing them to be more specific and focused when developing future studies. It is their hope that they can provide some relief for the patients and their families who are currently suffering.
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