Mid infrared light treatment attenuates cognitive decline and alters the gut microbiota community in APP/PS1 mouse model.

Alzheimer's disease (AD) as the first most neurodegenerative disease in the elderly still has no effective therapy, suggesting that the intervention toolbox for AD should be expanded. One newly developed strategy involves the use of photobiomodulation, such as near infrared or far infrared light, which has proven to attenuate AD-associated pathology. However, the efficacy of mid infrared light (MIR) in treating AD is under investigated. With this in mind, we assessed the benefits of MIR light of peak wavelength 7.7-10 µm treatment on APP/PS1 transgenic mice. We found that APP/PS1 mice treated with MIR light had improved learning and memory abilities and reduced amyloid-ß (Aß) plaque load in the brain. We also surprisingly found that the gut microbiota composition in APP/PS1 mice treated with MIR light returned to normal (wild type mice) levels. Together, these findings suggested a novel non-invasive and promising avenue for AD treatment via photobiomodulation, and also proposed that future target for AD might be the gut microbiota via the brain-gut-skin axis.