Researchers from MIT found that when mice engineered to exhibit Alzheimer’s-like qualities were exposed to flickering lights and 40Hz sounds for one hour a day, their brain functions improved and toxic levels of Alzheimer’s-related proteins diminished. In addition, the 40Hz sound appeared to improve cognitive and memory skills.
Light and sound delivered at a certain frequency —40 flashes or clicks per second — appear to restart the natural 40Hz gamma rhythm of the brain, which is disrupted in patients with Alzheimer’s. This gamma rhythm is essential for local neuronal communication and is associated with concentration and cognitive activity. Neurons in the cortex usually work in groups and are a bit analogous to a musical orchestra. When music instruments synchronize we hear a pleasant melody, but when they desynchronize we hear a cacophony of sounds a little like the tuning up of an orchestra. Similarly, when there is no normal brain rhythm, neurons fire out of sync and cannot generate coherent group decisions.
The improved 40Hz brain gamma waves appear to increase activation of immune cells that became more efficient at chewing up the harmful proteins that form plaques and tangles in Alzheimer’s brain. The 40Hz sound also improved brain blood vessels, further helping clear the toxic proteins. Most importantly, these combined effects of light and sound extended to the prefrontal cortex, which probably explains significant improvement of the cognitive functions.
Experiments also showed that without the light or sound stimulation, results faded in about a week, indicating that Alzheimer’s patients might need to be treated regularly.
Experimental drugs from some of the world’s top pharmaceutical companies have so far failed to halt the march of Alzheimer’s disease, a neurodegenerative disorder that gradually robs people of their memory and cognition.
Now MIT scientists are trying an audacious approach that doesn’t involve medicines of any kind: They’re using LED beams to disrupt gamma waves in the brains of lab mice, hoping to reduce the buildup of beta amyloid plaque — a substance widely thought to contribute to Alzheimer’s.
When brain cells fire rhythmically and in sync, they produce waves, which are categorized by their firing frequencies. Delta waves (1.5 Hz to 4 Hz), for example, are produced during deep sleep, theta waves (4 Hz to 12 Hz) occur during running and deep meditation, and gamma waves (25 Hz to 100 Hz) are associated with excitement and concentration. Disruption of gamma waves could be a key contributor to Alzheimer’s disease pathology, according to a mouse study published today (December 7) in Nature. And the restoration of these waves, researchers propose, may one day be an option for Alzheimer’s disease treatment.