A new study has shown that exposure to strobe lighting can, in mice, reduce levels of toxic amyloid proteins associated with Alzheimer’s disease. Gamma oscillations, which are brain waves that are stimulated by flickering light, have been found to be disturbed in patients with Alzheimer’s. The flashing lights appeared to cue brain activity that increased the ability of the brain’s immune cells to absorb the amyloid proteins.
The research was published in last Wednesday’s issue of the journal Nature, and was based in observations that Alzheimer’s patients display a loss of the synchronized brain activity known as gamma oscillations. This activity is also linked to attention and memory.
Researchers were cautiously optimistic as to whether such a treatment would have the intended effect on humans and their Alzheimer’s symptoms.
Li-Huei Tsai, director of the Picower Institute for Learning and Memory at MIT, and the senior author of the study, said:
“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.”
The study comes after the failure of clinical trials in November to translate success of new drugs in rodents to success in humans. However, scientists are at least optimistic that the success of such light-based treatments will be much quicker and cheaper to confirm in human patients, compared to pharmaceutical treatments.
Using mice who had been genetically engineered so that neurons in the brain that generate gamma activity were sensitive to light, the research used a technique called optogenetics to pulse light directly into the brains of the mice, causing neurons to fire in unison. The scientists found a 50 percent reduction in the levels of beta amyloid proteins in the hippocampus after one hour of the stimulation. They found that the proteins had been absorbed by microglia, the immune cells of the brain. Microglia often lose their immune functionality in Alzheimer’s patients, secreting toxic compounds themselves instead of clearing them from the brain. The strengthening of gamma oscillations seemed to restore the immune functionality of the microglia.
The researchers then went on to prove that the gamma oscillations could be stimulated non-invasively, with the use of a flickering strobe light. They used a 40Hz flicker that would be hard to discern and “not offensive at all” for a human patient. After exposing the mice to the flickering light for an hour a day for a week, the brains of the mice showed a 60 percent decline in amyloid plaques.
It remains unclear whether such a process would improve memory or overall cognitive abilities.
According to David Reynolds, chief scientific officer at Alzheimer’s Research UK:
“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.”