Study: Brain Substance May Halt Alzheimer's

A study in the journal Nature Medicine shows infusions of a substance called BDNF can halt Alzheimer's disease — at least in rodents and monkeys.

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JACKI LYDEN, host:

Welcome back to All Things Considered from NPR News. I'm Jacki Lyden. A substance made by the brain itself could offer a better way to treat Alzheimer's disease. New research shows that the substance, known as BDNF, halts the disease in animals. And there's indirect evidence that it works in human brains, too. NPR's Jon Hamilton has the story.

JON HAMILTON: Alzheimer's kills brain cells or neurons. The substance BDNF is part of a family of so-called growth factors. They keep brain cells alive.

Dr. MARK TUSZYNSKI (Neuroscience, University of California, San Diego): No matter how you try to kill a neuron, growth factors appear to prevent death cascades.

HAMILTON: Mark Tuszynski is a brain scientist at the University of California San Diego. He says BDNF is different from other growth factors because it works in the hippocampus and other areas of the brain attacked by Alzheimer's.

Dr. TUSZYNSKI: So that led us to explore the idea, well, gee, if we gave therapeutic quantities of BDNF to this degenerating circuitry in Alzheimer's disease animal models, might it have a beneficial effect?

HAMILTON: The answer to that question appears in a sweeping scientific paper that includes six separate studies. It's all in the current issue of the journal Nature Medicine. Tuszynski and a large team from several research institutions tested BDNF in cell cultures, in mice, in rats and in monkeys.

In some experiments, the substance was injected directly into the brain. In others, scientists used a technique that induced the brain to make more on its own. And in each experiment, BDNF kept brain cells from dying.

Dr. TUSZYNSKI: So based on those collective six studies, we concluded that BDNF really has quite potent properties. And what was particularly intriguing to us is that BDNF enhanced connections between cells in the brain, the so-called synapses.

HAMILTON: In animals and people, it's the degeneration of these connections that usually causes memory problems associated with age. But the new studies found that BDNF could actually reverse the effects that aging usually has on the brains of rats and monkeys.

Nicole Berchtold, a brain scientist at the University of California Irvine, says that result got her attention.

Dr. NICOLE BERCHTOLD (Assistant Specialist, Brain Aging Research Unit, University of California Irvine): It's definitely a wow - cool, exciting because if you look at the behavioral changes in learning, it seem like it almost brought them back to about what they were when they were young.

HAMILTON: Berchtold says the new research also helps explain something found in earlier studies, that people who exercise are less likely to develop Alzheimer's.

Dr. BERCHTOLD: We know that exercise very quickly increases the levels of BDNF and that it's associated with improvements in learning and memory. And that these are long-term changes.

HAMILTON: There's at least one other way to increase BDNF - a technique called deep brain stimulation. Caryl Sortwell from the University of Cincinnati says researchers discovered this after noticing a surprising effect among patients who get deep brain stimulation for Parkinson's disease.

Dr. CARYL SORTWELL (Neurology, University of Cincinnati): They didn't seem to be as debilitated as they would expect giving how much time had passed.

HAMILTON: Sortwell says animal studies suggest that's because deep brain stimulation triples the amount of BDNF in critical areas of the brain.

Experiments that actually give extra BDNF to people are probably several years off. And scientists say they probably won't be limited to people with Alzheimer's. BDNF levels also have been linked to depression, schizophrenia and Huntington's disease. Jon Hamilton, NPR News.

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