Therapy helps mice; long way from helping humans.
Star Tribune 18 Dec 2016 By MELISSA HEALY Los Angeles Times
New research demonstrates that, in mice under attack by Alzheimer’s dementia, exposure to lights that flicker at a precise frequency can right the brain’s faulty signaling and energize its immune cells to fight off the disease.
Light therapy for Alzheimer’s is miles from being ready to treat patients. But the research has prompted creation of a start-up company — Cognito Therapeutics — to approach the FDA about clinical trials, and to explore ways to deliver precisely calibrated light flickers to human research subjects.
Even if the new research does not yield a treatment for Alzheimer’s, it is expected to deepen understanding of a key player in the disease — the brain’s dedicated immune system — and point to ways it can be used to fight the disease.
In a study published last week in the journal Nature, neuroscientists demonstrated that microglia — immune cells that are a key part of the brain’s cleanup crew — can be activated by inducing rhythmic electrical impulses in the brain called gamma oscillations.
In the region of the brain that processes sight, at least, researchers at MIT showed they could induce cells to fire in synchronous gamma oscillation without so much as a needle stick: When they set mice in a box illuminated by LED lights flickering precisely at 40 Hz, the neurons of each animal’s visual cortex began humming along at the same frequency.
The effect was dramatic in mice bred to develop the sticky brain plaques and tangles that are a hallmark of Alzheimer’s in humans. After only an hour in front of the lights, the scientists found reduced levels of amyloid protein in the visual cortices. They detected a noticeable uptick in the size and activity of microglia, suggesting that these immune cells were vacuuming up more amyloid protein and stepping up their trash-disposal efforts.
Noting that this effect lasted less than a full day, the scientists then gave some of the mice a week of daily sessions. Compared with mice who did not get the weeklong light therapy, those that did had 67 percent fewer amyloid plaques — the clumps of amyloid protein that appear to gum up the function of a brain in the grips of Alzheimer’s. And the plaques that they had were, on average, 64 percent smaller.
Keith Fargo, of the Alzheimer’s Association, cautioned that it’s not time for those worried about Alzheimer’s to go looking for LED lights. The value of the new research, he said, lies mostly in what it reveals about the role of the immune system in Alzheimer’s disease.