Most strategies for treating Alzheimer’s disease center on finding a drug that will reverse the disease pathology biochemically. Drugs, however, can be expensive and have side effects, and so far none have worked.

In 2016, the labs of Li-Huei Tsai, Emery Brown and Ed Boyden teamed up to try a completely different approach: After observing that gamma frequency (40Hz) brain wave power is substantially weaker in Alzheimer’s patients, they experimented in mouse models with instilling the rhythms with stimulation – first with optogenetics – and then with completely non-invasive 40Hz) flashes of visible light. In a paper in Nature in December 2016, they showed that the flashes had several beneficial effects on the mice: it reduced harmful amyloid beta plaques in the visual cortex both by reducing their production and by stimulating microglia to clear the plaques away. Cognitive performance improved, too.

The trio called this non-invasive, inexpensive potential treatment for neurodegeneration: GENUS, for Gamma ENtrainment Using Sensory stimuli. They have since begun testing it in humans and are also studying the effects of other modes of stimulation such as sound and touch. Tsai and Boyden founded the company Cognito Therapeutics to accelerate this translational work. They are also studying whether non-invasive entrainment of rhythms can positively impact other diseases and partnering with engineers and designers to invent new modes for delivering the stimuli.

Above: A rendering of a microglia-like cell, stimulated to action by GENUS, absorbing amyloid plaques.