An hour a day of light therapy has been found to break down Alzheimer’s-like brain deposits in mice. That’s a long way from it working on people, but because it seems to be such a completely harmless therapy, it could move quickly into human trials. “This is really intriguing because it’s such an unexpected and brand new method for tackling the disease,” says professor Ed Boyden of the Massachusetts Institute of Technology (US), who led the research team. The mice were exposed to a light flickering at 40 hertz for one hour a day, and this triggered brain cells to vibrate together. This vibration created increased gamma waves - a type of brain activity that is weaker in people with Alzheimer’s. After the mice had been exposed to the light for a week their brains contained fewer of the amyloid plaques which are present in patients with Alzheimer’s. The light seemed to boost the activity of the cells that clear away these plaques and reduce their production.

Most of the drugs that have been developed for Alzheimer’s aim to reduce these same amyloid plaques, but some scientists feel that this is the wrong target. They think that ‘tangles of tau protein’ in brain cells could be the real cause of the disease. An interesting and unique result of the light therapy is that, in addition to reducing the plaques, it also reduced the number of these ‘tau tangles’ in the rodents’ brains. So it worked on both of the suspected causes. Up until now some of the drugs developed for Alzheimer’s have produced promising results in mice, but they have failed to halt mental deterioration in people. But professor Boyden feels that this could be a breakthrough, and, since the light therapy is harmless, he plans to try it on people - perhaps using a phone or a computer screen.