A new research paper documents the outcomes of five volunteers who continued to receive 40Hz light and sound stimulation for around two years after participating in an MIT early-stage clinical study of the potential Alzheimer’s disease (AD) therapy. The results show that for the three participants with late-onset Alzheimer’s disease, several measures of cognition remained significantly higher than comparable Alzheimer’s patients in national databases. Moreover, in the two late-onset volunteers who donated plasma samples, levels of Alzheimer’s biomarker tau proteins were significantly decreased.

The three volunteers who experienced these benefits were all female. The two other participants, each of whom were males with early-onset forms of the disease, did not exhibit significant benefits after two years. The dataset, while small, represents the longest-term test so far of the safe, noninvasive treatment method (called GENUS, for gamma entrainment using sensory stimuli), which is also being evaluated in a nationwide clinical trial run by MIT-spinoff company Cognito Therapeutics.

“This pilot study assessed the long-term effects of daily 40Hz multimodal GENUS in patients with mild AD,” the authors wrote in an open-access paper in Alzheimer’s & Dementia: The Journal of the Alzheimer’s Association. “We found that daily 40Hz audiovisual stimulation over 2 years is safe, feasible, and may slow cognitive decline and biomarker progression, especially in late-onset AD patients.”