LED light therapy reduces hallmark Alzheimer’s protein in mice

Nature: Gamma frequency entrainment attenuates amyloid load and modifies microglia

A study by researchers in the US has found that shining a flickering LED light at mice reduces the levels of a key Alzheimer’s protein called amyloid in the visual area of the brain. The research is published on 7 December in the journal Nature.

In the brain, nerve cells are interconnected to form circuits and the activity of the nerve cells in these circuits creates electrical rhythms in the brain called ‘neural oscillations’. Previous research has shown these electrical rhythms to be disrupted in neurodegenerative diseases such as Alzheimer’s, particularly gamma oscillations that happen at a specific frequency in the brain. These electrical rhythms are associated with processes such as attention, learning and memory – all of which are affected by Alzheimer’s.

Disruption of the electrical rhythms in the brain has been shown in mice to be associated with the build-up of a protein called amyloid. Amyloid occurs naturally in the brain, but can start to clump together to form amyloid plaques during Alzheimer’s disease.

To investigate the link between these changes in electrical activity and amyloid in the brain, the team at the Massachusetts Institute of Technology studied mice bred to develop a build-up of amyloid. These mice also had reduced gamma oscillations in the brain. The researcher used a combination of genetic technology and light pulses to re-tune electrical activity in the brain and found that this was able to reduce amyloid levels. Researchers also found changes in the behaviour of a subset of immune cells in the brains of these mice called microglia. These are known to be responsible for coordinating the inflammatory response to amyloid, which involves removing amyloid from the brain.

The researchers then attempted to alter the electrical rhythms using a non-invasive procedure involving an LED light. The scientists shone a blinking LED light at the mice for one hour, and this caused an alteration in the electrical rhythms in the visual cortex of the mice brains. The researchers observed a reduction in amyloid both 12 and 24 hours after this initial one hour session. They then repeated this process of one hour sessions every day for a week, but in older mice who had amyloid plaques and in the area of the brain which responds to stimuli from the eyes the visual cortex, amyloid levels were reduced by up to 60%.

Dr David Reynolds, Chief Scientific Officer at Alzheimer’s Research UK, said:

“This latest study in mice provides more evidence on the complex biology of Alzheimer’s and highlights the importance of changes in electrical rhythms in the disease. It is conceivable that changing brain cell rhythms could be a future target for therapies, but researchers will need to explore how light flickering approaches could not only reduce amyloid in the visual area of the brain but in those areas more commonly affected in Alzheimer’s.”

“Studies like this are valuable in revealing new processes implicated in Alzheimer’s disease and opening new avenues for further research. While mice used in this study showed some key features of Alzheimer’s, it is always important to follow up these findings in people. Researchers will now need to explore changes in these brain waves in people to explore their contribution to the disease and how any treatment approach could be practically and successfully implemented in people with Alzheimer’s disease.”