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A research team has demonstrated for the first time in non-human primates that auditory stimulation at 40 Hz significantly elevates β-amyloid levels in the cerebrospinal fluid (CSF) of aged rhesus monkeys, with this effect persisting for over five weeks. The study provides the first non-human primate experimental evidence supporting the use of 40-Hz stimulation as a noninvasive physical therapy for Alzheimer's disease (AD), revealing significant differences between primate and rodent models. Researchers conducted the study using nine aged rhesus macaques (Macaca mulatta) aged 26–31 years. These aged individuals developed widespread spontaneous amyloid plaques in their brains, effectively mimicking the Aβ...

In research, scientists found that 40Hz sensory stimulation improved cognition and circuit connectivity and encouraged the growth of new neurons in mice genetically engineered to model Down syndrome. The method, called GENUS (for Gamma Entrainment Using Sensory Stimulation), could provide clinical benefits. In the first set of experiments, the team shows that an hour a day of 40Hz light and sound exposure for three weeks was associated with significant improvements on three standard short-term memory tests—two involving distinguishing novelty from familiarity and one involving spatial navigation. Because these kinds of memory tasks involve a brain region called the hippocampus, the...

Clinical studies testing the safety and efficacy of 40Hz sensory stimulation to treat Alzheimer's disease have found the therapy was well tolerated, produced no serious adverse effects and was associated with some significant neurological and behavioral benefits. Tsai's lab discovered exposing mice to light flickering or sound clicking at the gamma-band brain rhythm frequency of 40Hz produced improvements in learning and memory; reduced brain atrophy, neuron and synapse loss; and showed lower levels of hallmark Alzheimer's proteins amyloid beta and phosphorylated tau. In the Phase 1 study, volunteers filled out a questionnaire. Meanwhile, measurements taken with EEG scalp electrodes clustered...

Studies are producing mounting evidence that light flickering and sound clicking at the gamma brain rhythm frequency of 40 Hz can reduce Alzheimer's disease (AD) progression and treat symptoms in human volunteers as well as lab mice. In a mouse model, researchers reveal a key mechanism that may contribute to these beneficial effects: clearance of amyloid proteins, a hallmark of AD pathology, via the brain's glymphatic system, a recently discovered "plumbing" network. The paper describes a series of experiments showing that when sensory gamma stimulation increases 40 Hz power and synchrony in the brains of mice, that prompts a particular...