These findings offer new hope for potential physical treatments for Alzheimer's disease.
The research, published in the latest edition of the journal Proceedings of the National Academy of Sciences (PNAS), was led by researchers from the Kunming Institute of Zoology (KIZ), under the auspices of the Chinese Academy of Sciences .
This research effort focused on the use of auditory tones with a frequency of 40 hertz, which is equivalent to a low hum in the human hearing range.
Previous research in mice has shown that 40 hertz stimulation can help remove toxic Alzheimer's-related proteins from the brain, and this latest study provides the first significant evidence from nonhuman primates.
In Alzheimer's disease, a protein known as beta-amyloid tends to accumulate and form plaques, damaging brain cells and impairing memory and cognitive function. Normally, the brain clears such waste through cerebrospinal fluid ( CSF ).
The team studied nine elderly rhesus monkeys, whose brains naturally develop plaques similar to Alzheimer's, making them a highly relevant model for studying the condition in humans. The monkeys were exposed to a 40-hertz tone for one hour every day of the week.
The results were astonishing. Levels of a key protein linked to Alzheimer's in the CSF of the elderly monkeys more than doubled after the treatment period. This indicates more waste products were being removed.
"The most amazing thing is that the effects were long-lasting. When we took measurements five weeks after the sound treatment ended, the beneficial changes had not faded," explained Hu Xintian, a researcher at KIZ.
Current drug therapies approved for Alzheimer's disease, while effective for some patients, carry potential risks such as brain swelling and are also expensive. In contrast, 40-hertz auditory stimulation represents a safe and low-cost physical intervention, Hu explained.
"The long-term effects we observed in primates support the development of this soft approach as a future therapy for Alzheimer's," Hu added.
