Lost memories may be recoverable … one day

Alzheimer's diseaseAs is well known, memory loss is one of the most common symptoms of Alzheimer’s disease, and one of the most tragic. Sufferers can effectively lose their personality as their memories start to fade and disappear, leaving them almost hollow shells of the vibrant people they once were.

They can forget all their achievements, the friendships they’ve made over a lifetime, even their own families. It is indeed a tragedy nobody would wish on their worst enemy. And for decades it has been believed that those memories have not just faded away but have somehow been destroyed forever.

Second good news on Alzheimer’s in recent weeks

Alzheimer's research at the Massachusetts Institute of Technology

The Dome at the Massachusetts Institute of Technology

Hot on the heels of some good news about Alzheimer’s research comes something else to smile about.

Nobel prize winner Susuma Tonegawa of the Massachusetts Institute of Technology has just published an optimistic new paper. It raises new hope that one day there could be a treatment for Alzheimer’s that would actually restore those lost memories. It’s not likely to happen in the near future, but it’s a speck of bright light at the end of a very dark tunnel.

The research involved two groups of mice, and is described in the journal Nature. One group was composed of perfectly normal mice (the control group), while the other consisted of mice who had been genetically engineered to have Alzheimer’s-like symptoms. In order to test their memory, both groups were given a mild electric shock to their feet. The first group, unsurprisingly, showed that they remembered the experience by shying away from the area where they’d received the shock.

The second group, the ones with Alzheimer’s-like symptoms, seemed unconcerned. They had soon forgotten the experience and were oblivious to the situation.

Optogenetics … the blue light treatment

However, their reaction changed quite dramatically once the researchers stimulated certain cells in their brains. The researchers used a special blue light to stimulate cells in the hippocampus (the area in the brain that seems to be involved in creating and retreiving memories). Once put in the same situation that had earlier left them unconcerned, they, like the control group, displayed fear, showing that they had remembered the uncomfortable experience they’d undergone previously.

According to the researchers, the treatment seems to have boosted neurones to regrow dendritic spines (like small buds) on the brain cells, allowing more successful connection with neighbouring brain cells.

In an interview with the Boston Herald, Rudy Tanzi, a Harvard neurology professor, said that these results “shattered a 20-year paradigm of how we’re thinking about the disease”. Since the 1980s, he said, researchers believed the memories just weren’t getting stored properly.

To prepare for the treatment, a gene was inserted into parts of the brain so make them photosensitive. Then the blue light was used in a treatment called optogenetics, which is the optical stimulation of brain cells.

Caution is advised

Doug Brown, director of research at the Alzheimer’s Society, was less jubilant. He cautioned that the technique wouldn’t easily be translated into a precedure that is safe for the millions of people worldwide who suffer from dementia.

Although the research was interesting, he said, the practicalities of this approach means we’re still a long way from knowing if restoring people’s memories is a real possibility.

Some researchers are optimistic

Christine Denny, a neurobiologist at Columbia University, thinks that electrical stimulation of the brain may be an alternative for scientists to pursue. Nature reports that early trials showed deep-brain stimulation of the hippocampus may improve memory in some Alzheimer’s patients.

Last word goes to Prerana Shrestha and Eric Klann of the Center for Neural Science at New York University. In a commentary accompanying the research paper they said that the research employed a “clever strategy” and that “the potential to rescue long-term memory in dementia is exciting.”

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