Light and sound combined magnified the brain effects and extended them to the prefrontal cortex, a key area for planning and executing tasks.
“it’s stunning that the intervention had beneficial effects on so many different aspects of Alzheimer-like pathology,” said Dr. Mucke, who is also a professor of neurology and neuroscience at University of California San Francisco. “On the other hand, it shouldn’t be surprising that the brain is influenced by outside stimuli because what it was designed for was to adapt to a changing environment.”
The results also dovetail with findings by Dr. Mucke and his colleagues, who have genetically altered brain cells called interneurons, which he likened to conductors of the brain’s orchestra. The altered interneurons enhanced gamma rhythm activity, generating cognitive improvement in mice. “When there isn’t proper brain rhythm, there is disharmony and everyone is sort of playing when they want to, a little like the tuning up of an orchestra,” he said.
His colleagues are also developing a drug that would have similar effects. So there might be several ways to enhance gamma rhythms, he said.
Because the brain changes subsided somewhat after a week without the light or sound treatment, experts said it’s likely that people would need such stimulation consistently, essentially a sensory version of a daily pill to control a chronic condition.
Dr. Tsai’s team has tested light and sound on healthy people, using a four-by-three-foot light panel and high-quality stereo speakers, “so the sound is more tolerable to humans, because it’s not melody, it’s clicks,” she said. Electroencephalogram measurements show the desired gamma-wave effect, she said, and “nobody complains about any discomfort or headache or anything.”
They will soon start testing on people with mild Alzheimer’s. Dr. Tsai and a co-author, Edward Boyden, co-director of the M.I.T. Center for Neurobiological Engineering, have also co-founded a company, Cognito Therapeutics, which is testing a goggles-like light-and-sound device on Alzheimer’s patients, she said. Dr. Tsai said the company is not involved in her team’s academic research, which was funded by several foundations and the National Institutes of Health.