Overview
- Researchers in PNAS exposed nine aged rhesus macaques to one hour per day of 40-hertz tones for seven days.
- Cerebrospinal-fluid Aβ42 rose about 205.6% and Aβ40 about 201% from baseline, with levels still elevated five weeks later.
- Tau showed no measurable change, and post-mortem analysis found prevalent amyloid plaques with weak or negative tau tangles.
- The authors hypothesize the stimulation activates the brain’s glymphatic waste-clearance pathway, moving amyloid into CSF.
- Commentators describe the approach as a non-invasive, low-cost prospect compared with anti-amyloid drugs but emphasize the evidence is preclinical and advise against relying on home 40-hertz audio tracks.