A few years ago scientists discovered that directing flashing light at 40 Hertz (cycles per second) into the eyes and noises into the ears of mice with Alzheimer’s disease led to a marked decline in amyloid plaques in their brains. The mechanism making this happen was pretty much a matter of speculation, so researchers at Georgia Tech and Emory universities set out to understand why the therapy seems to work on mice and what that means for how we fight Alzheimer’s.

Amyloid plaques are one of the main suspects underlying the development of Alzheimer’s disease. The researchers in this study exposed healthy mice to up to an hour of 40 Hz light flicker. A control group of mice exposed to a different flicker mode was used as a control.

Studying the chemistry of the treated mouse brains, the researchers noted a higher concentration of cytokines that result in microglial phagocytic states, that clean up the plaque material, including IL-6 and IL-4, and more microglial chemokines, including M-CSF and MIG.

This is being performed in parallel with a current in-human study evaluating the effectiveness of light flickers on Alzheimer’s patients and helps to explain the underlying mechanism, which could be the same in humans. As the researchers noted, cytokine effects varied depending on the frequency of the light stimulation, potentially expanding the capability of this kind of therapy for other conditions.

Here’s a Georgia Tech video about the research: