For most of us, flickering lights and clicking sounds would drive us to distraction. But for people with Alzheimer’s, they could be a life saver.

Studies in mice with Alzheimer’s suggest delivering these sensations in a specific way improves learning, memory, and brain function. Would it have the same effect in human patients? MIT scientists were eager to find out.

In normal brain function, brain cells generate electrical signals that combine to create brain waves at various frequencies.

For example, the gamma frequency band 30–80Hz (cycles per second) contributes to normal brain function and is involved with attention, perception, and memory. However, these signals are impaired in both mice genetically programmed to develop Alzheimer’s and in human Alzheimer’s patients.

As we first told you back in 2019, experiments to improve these oscillations in demented mice have shown enormous promise.

In the initial studies we reported on, scientists at MIT made genetic modifications to stimulate certain brain frequencies in mice. They experimented with various frequencies but the only one that was effective at improving cognitive function and overall brain health was 40 hertz.

Shrinks Damaging Proteins by Half 

When the MIT researchers subjected mice to this 40 hertz frequency for one hour it led to a whopping 50 percent reduction in levels of beta amyloid – the protein linked to Alzheimer’s disease – in the area of the hippocampus.

The researchers went on to conduct a series of experiments between 2016 and 2019 where they tested a simpler, non-invasive method to stimulate 40 hertz by using flickering lights and clicking sounds. They first tested light followed by sound and then the two combined.

These studies produced widespread benefits in cognitive function and brain health. For instance, researchers found that mice with Alzheimer’s who were treated experienced improvements in learning and memory, a reduction in brain atrophy and a reduction in the loss of brain cell and nerve impulses. These treated mice also had lower levels of beta amyloid proteins as well as tau tangles, another hallmark of Alzheimer’s disease.

What’s more, the combined therapy produced better results than using light and sound alone. When researchers combined light and sound, plaques disappeared in large areas of the brain, including brain areas critical for learning and memory.

With these promising findings in rodents, researchers turned to human tests.

The MIT research involved two trials. The first tested safety, with researchers finding the combined light and sound therapy resulted in only minor side effects, the most common being drowsiness. The other trial enrolled 15 people with early-stage Alzheimer’s who received either 40Hz light and sound therapy or sham treatment for an hour a day in their own homes.

The results were extremely encouraging.

Holds Back Disease Progression 

After three months the seven patients in the sham group showed two signs of disease progression: reduced volume of the hippocampus, a key memory area, and increased volume of ventricles or brain cavities. However, treated patients did not experience significant changes in these measures.

Treated patients also exhibited better connectivity across brain regions related to cognition and visual processing and had better sleep patterns when compared to controls. After just three months the researchers didn’t expect any difference in cognitive test results. Even so, the treatment group performed markedly better on a face-name association test, a memory task with a strong visual component.

Senior author Li-Huei Tsai, commenting on the paper published in the journal Plos One in December said, “…we were pleased to see that volunteers did not experience any safety issues and used our experimental light and sound devices in their homes consistently.

“While we are also encouraged to see some significant positive effects on the brain and behavior, we are interpreting them cautiously given our study’s small sample size and brief duration. These results are not sufficient evidence of efficacy, but we believe they clearly support proceeding with more extensive study of 40Hz sensory stimulation as a potential non-invasive therapeutic for Alzheimer’s disease.”

Even more exciting, earlier research suggests that these improvements in cognitive function and brain health can make the lives of patients better.

Stabilizes Activities of Daily Living 

Earlier studies showed that flickering lights and sound at 40Hz in patients with mild cognitive impairment and mild to moderate Alzheimer’s resulted in many positive benefits. These benefits included everything from improved sleep and better brain function to maintaining peoples’ functional abilities over the six-month study period when compared to a significant decline in the control group. Best of all, this treatment was safe, tolerable, affordable, and easy to perform at home.


  1. https://news.mit.edu/2019/brain-wave-stimulation-improve-alzheimers-0314
  2. https://alz-journals.onlinelibrary.wiley.com/doi/10.1002/trc2.12178 
  3. https://pubmed.ncbi.nlm.nih.gov/34630050/ 
  4. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0278412 
  5. https://picower.mit.edu/news/small-studies-40hz-sensory-stimulation-confirm-safety-suggest-
    alzheimers-benefits 

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