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Light Therapy for Alzheimer’s Disease?

Light Therapy for Alzheimer’s Disease?

Last week, researchers at MIT reported on a new treatment idea for Alzheimer's disease. The claim was based on a study from Li-Huei Tsai and her team, which suggested that lights flashing at a certain frequency could reduce beta-amyloid plaques. The novelty of the research has generated a lot of press—could something as simple as light therapy help patients with Alzheimer's disease?

Before you set up strobe lights around your room, let's look more closely at the research. For aspects of cognition, including memory, groups of neurons fire together at a specific frequency. Gamma frequencies (i.e., roughly 40 Hz) appear to be important for cognition, and your brain's ability to fire large groups of neurons this way decreases in Alzheimer's and other diseases. In preclinical studies, Dr. Tsai found that the "gamma power" of neurons decreased before beta-amyloid plaques or cognitive impairment developed. So, increasing it may help protect against Alzheimer's disease.

To help more neurons fire together at gamma frequencies, Dr. Tsai stimulated the neurons of genetically engineered mice for one hour using LED lights that flickered at 40 Hz. This did succeed at increasing gamma power in the brain, and, more notably, it reduced beta-amyloid plaques by more than 50 percent. Even when older mice were treated at later stages of Alzheimer's disease, just one week of light therapy reduced beta-amyloid levels and other features of the disease. The researchers aren't yet sure why the effects occurred, but inducing gamma frequencies appeared to help to recruit immune cells that remove toxic proteins and other "garbage" in the brain.

Though this sounds incredibly promising, there are several caveats. First, the studies were done in mice, and no research has yet demonstrated that the effects will hold in humans. And more importantly, it is unlikely that light therapy would be effective. The light therapy did not affect the hippocampus, a major area of the brain affected in Alzheimer's disease. In the mice, the reduction in beta-amyloid was only found in the brain's visual cortex. If this type of frequency stimulation is to help patients, other technologies must be developed to non-invasively increase gamma power in more vulnerable brain regions like the hippocampus.

More information on this study is available in a Radiolab podcast with Li-Heui Tsai and her colleagues from MIT.

Nick McKeehan is Assistant Director, Aging and Alzheimer's Prevention at the Alzheimer’s Drug Discovery Foundation. He served as Chief Intern at Mid Atlantic Bio Angels (MABA) and was a research technician at Albert Einstein College of Medicine investigating repair capabilities of the brain. He received a bachelor of science degree in biology from Purdue University, where he was awarded a Howard Hughes Scholarship. Mr. McKeehan also writes about the biotechnology industry for 1st Pitch Life Science.

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