New PNAS study: 40 Hz sound stimulation caused large, long-lasting Alzheimer’s biomarker changes in primates
A newly published PNAS paper caught my attention because it goes beyond the usual mouse studies. Researchers exposed aged rhesus monkeys to a 40 Hz auditory stimulus for one hour a day over seven days. The sound wasn’t music or binaural beats—it was a 1 kHz sine tone delivered in hard on/off pulses (~1 ms each) at 40 times per second.
The results were striking. Levels of amyloid-β in cerebrospinal fluid increased by more than 200% and stayed elevated for over five weeks after the stimulation stopped. That sustained effect in a primate model is what makes this notable, since primates are much closer to humans than rodents.
This builds on earlier gamma-frequency research but suggests the effect may be stronger and longer-lasting than previously shown. It’s still early and not a treatment claim, but it’s a compelling step toward understanding how rhythmic sensory stimulation might influence neurodegenerative disease pathways.
Here is the link to the paper (and details on the sound used in the study):
This audio is a 40 Hz gamma auditory stimulation sound inspired by neuroscience research, featuring a 1,000 Hz pure tone delivered in short pulses at 40 cycles per second. It is intended for educational and experimental interest only, not as a medical treatment. Suggested use includes moderate volume, short sessions, and external speakers, but it should not be used by individuals with a history of seizures, sound sensitivity, or neurological conditions without medical guidance.
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