According to the Alzheimer’s Association, one in three Americans over the age of 65 is living with Alzheimer’s or another form of dementia—more than five million seniors in all. Until now, there has been no known prevention or cure for these illnesses.
But a group of researchers in Scotland may have found a way to treat these mysterious memory diseases.
A new study by scientists at the University of Edinburgh, and published in The Journal of Neuroscience, found that long-term memories (which are often affected by dementia) are naturally forgotten, rather than simply erased as had been previously thought. However, this process can also seemingly be reversed.
The brain’s natural processes are the cause of forgetting: Brain cells communicate and connect with each other through synapses. Each synapse contains proteins called AMPA receptors, which float on the brain’s membrane—the more AMPA receptors, the stronger the memory.
But the Edinburgh study found that (for reasons that are still being determined) brain cells can actively remove AMPA receptors from synapses, causing memories to be forgotten.
Scientists have long observed that even fully established long-term memories can fade over time—German psychologist Hermann Ebbinghaus called this phenomenon the “forgetting curve.”
“There’s no more signal transmission, and the memory is forgotten,” Dr. Oliver Hardt, who led the Edinburgh team, told the Observer. “We wanted to find mechanisms for keeping the memory.”
“Forgetting long term memories is an active process, but we were able to eliminate the forgetting.”
To that end, the researchers placed rats into a box that contained two objects in fixed locations every day for seven days. Throughout the week, the rats naturally formed memories of the objects and their surroundings.
After this exercise, the scientists administered several tests to the rats. In one experiment, they gave the animals a drug designed to stop them from forgetting the object locations every day for two weeks starting the day after the exercise. In another, they waited a week before giving the drug to the rats, and then only administered it for six days (rats’ long term memory lasts about eight days).
In both cases, the rats were able to remember the objects’ locations in the room, even after a two week break.
“They had perfect memory on day one,” Dr. Hardt said. “Forgetting long term, consolidated memories is an active process, but we were able to eliminate the forgetting.”
The drug given to the rats (its clinical name is GluA2-3Y) gave the antibodies a new target and steered them away from the AMPA receptors, leaving memories intact.
While the rats’ drug could feasibly be adapted for people with Alzheimer’s or dementia, Dr. Hardt stressed that there had not yet been any concrete human research.
“We don’t know if the same mechanism is at work,” he said. “How it’s implemented could vary.”
But Dr. Hardt said these results could eventually provide insight into how the human brain forgets, and how pathological forgetting could be prevented.
“Whatever we found is in principle valid for the human process,” he said. “It’s highly likely that our experiment could be applied to other species.”