Scientists significantly reduced toxic proteins in mice brains by stimulating neurons with flashing lights

The Human Brain / Flickering Lights May Lead to Innovative New Treatment for Alzheimer’s Disease
Image: Pixabay
December 09, 2016

Researchers working at MIT have discovered a way to reduce the plaques seen in the brains of Alzheimer's disease patients by at least 50 percent using only flashing lights.

MIT News reports that the method seems to work by stimulating a type of brain wave known as a gamma oscillation, which the scientists found help the brain to suppress the production of the plaques and to galvanize the cells responsible for eliminating them.

"The potential is just enormous"

The study was performed using mice that had the disease, so it is not yet known if the method will have the same effect on human Alzheimer's patients. It is also unknown, writes The Guardian, whether or not cognitive deficits would be improved as well as the plaques, which are the most visible symptom of the disease. There is, however, reason to hope.

Li-Huei Tsai is the director of the Picower Institute for Learning and Memory at MIT as well as the senior author of the paper.

"If humans behave similarly to mice in response to this treatment, I would say the potential is just enormous, because it's so non-invasive, and it's so accessible," she said.

The new approach is important for several reasons. One is the number of major setbacks recently experienced in the area of Alzheimer's research after human patients did not experience the same level of clinical improvement as rodents in previous studies. Another is the non-invasive nature of the technique.

"This is still preliminary work," writes The Atlantic, "But it heralds a completely new approach to dealing with Alzheimer's—changing neural activity, rather than delivering drugs or chemicals."

Tsai and the other scientists are well aware of the innovative quality of the method.

"It's so different from what people have tried, but we are very excited about the possibility of bringing this to human testing," she said.

Of Mice and (Maybe) Men

The study started off simply, according to MIT News. The first mice to be studied were those that had been genetically wired to develop Alzheimer's disease but were not yet showing any symptoms in behavior or any plaque accumulation. The researchers put these mice into a maze and monitored their brains as they went through it.

The scientists discovered that specific brain waves—gamma oscillations—necessary for learning and memory were impaired in the hippocampus area of the mice's brains. The Atlantic explains that mice usually experience a "short, sharp burst" of gamma waves when they reach a dead end in a maze. However, when these particular mice got to a dead end, they experienced weaker bursts of the waves, and their neurons also did not fire at the same time as often as they usually do.

The next step was to figure out how to solve the mice's gamma wave problems. The team decided to use a technique called optogenetics, a method in which they put light-sensitive proteins into neurons so that the neurons can be activated with flashes of light. The scientists found that they were able to actually create gamma waves in the mices' brains by sending them 40 of these flashes per second. After one hour of doing this, they discovered that the levels of plaque had been reduced by roughly 50 percent—a stunning result.

"We were very, very surprised," said Tsai.

How do the gamma waves destroy the plaque? They stimulate a type of cleaning cell known as microglia. These cells patrol around the brain, keeping it clean by ingesting dead cells and toxic proteins. The gamma waves caused them to double in number and in size, and they promptly began to clean up the surrounding plaque in the brains of the mice.

However, the optogenetics technique used by the scientists is not practical for human patients, as it is both complex and invasive. Fortunately, the researchers have developed a far simpler procedure, and all it requires is light.

LEDs: Stimulating the Gamma Wave of the Future

The scientists got around the optogenetics problem with relatively little difficulty, constructing a simple device that contained a strip of LED lights able to be programmed to flash at different frequencies. When the researchers programmed the lights to flicker at 40 hertz and exposed the mice to them for one hour, they found that the mice experienced enhanced gamma waves and a 50 percent reduction of plaque levels. However, they also discovered that the plaque levels had risen again to their original levels just 24 hours later.

What to do? They decided to try a longer course of treatment, this time on mice that had more accumulated plaque. They exposed these mice to the lights at the same frequency for one hour per day for a period of seven days.

The result?

In what Tsai calls "the most exciting part of this entire study," says The Atlantic, both the size and the number of plaques were reduced by two thirds.

"We need to do more work"

The treatment is not perfect: so far the light only induces waves in the visual cortex, the part of the brain that gets signals from the eyes, which suffers relatively little from the effects of Alzheimer's. Scientists need to figure out how to stimulate gamma waves in the deeper areas of the brain that are more affected by the disease.

To that end, Tsai and Ed Boyden—one of the creators of optogenetics and one of the study's contributors—have founded Cognito Therapeutics, a company dedicated to developing devices for stimulating gamma waves using the eyes. Tsai says that she is thinking of "goggles, or something similar."

Meanwhile, though, she cautions against going overboard in enthusiasm for the treatments.

"I worry that people will think they can use a homemade device to treat themselves, and the correct frequency is extremely important," she says. "If people use an incorrect one, we don't know if it could be harmful. For human use, we need to do more work."

References: MIT News, The Guardian, The Atlantic