In a study published to Nature.com on December 7, 2016, researchers found that exposing subject mice to flicker for one hour each day for seven days reduced the buildup of amyloid proteins consistent with Alzheimer’s disease by 43.7-63.6%.  Particulars of the flicker used is 1ms pulses at 40 Hz utilizing light at the 473nm wavelength (cyan color).  Other frequencies above and below 40 Hz were ineffective.  TheGuardian summarized the study as follows:

The study, in mice, found that exposure to flickering light stimulated brain waves, called gamma oscillations, that are known to be disturbed in Alzheimer’s patients. Boosting this synchronous brain activity appeared to act as a cue for the brain’s immune cells, prompting them to absorb the sticky amyloid proteins that are the most visible hallmarks of the disease in the brain’s of people with Alzheimer’s.

Source:
Study @ Nature.com
TheGuardian