40Hz brain stimulation may treat Alzheimer’s disease

For the past decade, scientists have been exploring a unique way to treat Alzheimer’s disease using gentle sensory stimulation at 40Hz, a brainwave frequency known as “gamma” rhythm. This idea, first tested at MIT’s Picower Institute for Learning and Memory, has gained increasing support from researchers worldwide.

Studies suggest that exposing the brain to this rhythm through light, sound, or touch may help protect against Alzheimer’s and even improve brain health in both animals and humans.

A new review article in PLOS Biology summarizes the current state of research and highlights key questions for the future of this promising therapy.

How 40Hz Stimulation Works

In 2016, MIT researchers led by Professor Li-Huei Tsai published their first study showing that exposing mice to flickering light at 40Hz reduced the buildup of harmful proteins linked to Alzheimer’s, such as amyloid and tau.

Since then, their research has expanded to include sound and touch-based stimulation, with each method showing similar positive effects. Their findings suggest that 40Hz stimulation helps clear toxic proteins, protects brain cells from dying, and improves memory and cognitive function.

Further studies have identified some of the key processes behind these benefits. One important discovery, published last year, showed that 40Hz light and sound stimulation triggers the release of a brain peptide called VIP, which helps clear waste from the brain through the glymphatic system—a kind of “plumbing” that flushes out toxins.

From Mice to Humans: Clinical Trials Show Promise

Encouraged by their findings in animals, MIT researchers, along with their spinoff company Cognito Therapeutics, began testing 40Hz stimulation in humans.

Their Phase II clinical trials found that Alzheimer’s patients exposed to 40Hz light and sound showed slower brain shrinkage and some cognitive improvements compared to those who were not treated. They also found that the treatment helped protect the brain’s white matter, which is essential for communication between different brain regions.

Now, a larger nationwide Phase III clinical trial is underway to determine if this therapy could become a widely available treatment for Alzheimer’s. If successful, it could provide a safe, non-invasive way to slow down or even prevent the disease.

Growing Global Interest in Gamma Stimulation

Since MIT’s early discoveries, other research teams around the world have confirmed and expanded on these findings. In 2024, scientists in China found that 40Hz stimulation improved the brain’s fluid-clearing system in mice.

A Harvard Medical School study in 2022 showed that a method called Transcranial Alternating Current Stimulation (which applies mild electrical stimulation to the scalp) significantly reduced tau protein buildup in three out of four human volunteers. Meanwhile, researchers in Scotland used audio and visual stimulation at a slightly different frequency (37.5Hz) to improve memory in over 100 participants.

Unanswered Questions and Future Research

Despite the promising results, many questions remain about how 40Hz stimulation works on a deeper level. Researchers are still investigating how different brain cells respond to gamma stimulation and how these responses affect Alzheimer’s pathology.

Professor Tsai and her team are particularly interested in understanding how neuropeptides (chemicals that help brain cells communicate) and immune cells called microglia react to this therapy. They believe that uncovering these mechanisms could help improve the treatment and make it more effective.

Even beyond Alzheimer’s, researchers are beginning to explore whether 40Hz stimulation could help with other neurological conditions.

Early studies suggest that it may have potential benefits for Parkinson’s disease, stroke recovery, anxiety, epilepsy, and even the cognitive side effects of chemotherapy. MIT researchers are also studying whether it could help people with Down syndrome.

The Road Ahead

The next decade of research on 40Hz brain stimulation will focus on answering these open questions and optimizing the therapy. As scientists continue to refine their understanding of how gamma rhythms impact the brain, this approach could lead to new treatments for multiple brain disorders.

If future clinical trials confirm its effectiveness, 40Hz sensory stimulation could become a groundbreaking, non-invasive way to improve brain health and protect against neurodegenerative diseases like Alzheimer’s.

The research findings can be found in PLOS Biology.