Tests at MIT have shown a boost to the activity of the brain’s immune cells

Doctors in the US have launched a clinical trial to see whether exposure to flickering lights and low frequency sounds can slow the progression of Alzheimer’s disease.

A dozen patients enrolled in the trial will have daily one-hour sessions of the radical therapy which researchers hope will induce brain activity that protects against the disorder.

Animal tests have shown that exposure to light and sound waves at 40Hz reinforces so-called gamma waves in the brain, with knock-on effects across the organ. In mice used to model the disease, the therapy appears to boost the activity of the brain’s immune cells, making them clear the aberrant proteins that build up in Alzheimer’s.

Li-Huei Tsai, a neuroscientist who is leading the trial at MIT, told the Society for Neuroscience meeting in Chicago on Tuesday that the therapy improved the survival and health of the animals’ neurons, boosted their connectivity, and dilated blood vessels, all of which may benefit patients. “We would like to see if our approach slows Alzheimer’s disease,” Tsai told the Guardian.

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The patients enrolled on the trial will have cognitive tests every three months to assess their brain function and regular scans to measure their brain activity and the connectivity of neurons across the organ.

Tsai told the conference that the light and sound sessions had boosted the amplitude and synchrony of 40Hz brain waves in the trial patients, but that it would take a year to gather data on whether the sessions helped to keep the disease at bay. The researchers call the exposure “gamma entrainment using sensory stimuli”, or Genus.

A further 40 patients are to be recruited for a second trial that will examine directly whether the light and sound waves reduce levels of amyloid protein plaques and tau protein tangles – the hallmarks of Alzheimer’s disease – in the patients’ brains and cerebrospinal fluid.

The unusual approach to combating Alzheimer’s draws on the ability of light and sound waves to affect electrical activity in the brain. In a series of papers published since 2016, Tsai and her colleagues have shown that light and sound waves oscillating at 40Hz strengthen waves of the same “gamma” frequency in the brain.

In mice, at least, this appears to have multiple effects on cells in the brain, including ramping up the activity of the organ’s immune cells, making them more effective at clearing protein plaques and tangles.

“We hope our findings in mice will translate to helping people with Alzheimer’s disease, though it’s certainly too soon to tell and many things that have worked in mice have not worked in people,” Tsai said.

James Pickett, head of research at the Alzheimer’s Society, said: “Brain rhythms and their role in conditions like dementia are still mysterious, but this work begins to outline their impact on different types of brain cells and the mechanisms involved.

“It’s very early days, but we look forward to seeing how this area of research develops.”

In a separate development, a US company that declared its experimental Alzheimer’s therapy a failure in March has revived the drug after a fresh analysis found that it helped some patients. Biogen said it will ask the US drug regulators to approve aducanumab after it identified a statistically significant slowing in the decline of cognitive ability and basic activities of daily living in a subset of patients on high doses of the drug.

Pickett said: “This is hugely exciting news. After the trial being stopped earlier this year because it appeared not to work, further analysis suggests that it does benefit people with dementia in the earliest stages.”

“We’re waiting for further data but this could be the first new treatment for Alzheimer’s disease in over 15 years, and as such, has the potential to be a transformative discovery.”