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Scientists say a hormone associated with longevity also appears to make people smarter. NPR's Jon Hamilton reports that the finding out today could someday lead to drugs that improve memory and learning.
JON HAMILTON, BYLINE: The hormone is called klotho, after the fate from Greek mythology who spins the thread of life. Scientists have known for more than a decade that people and animals tend to live longer if they have high levels of klotho in their bodies. And that led a team of researchers to wonder whether a hormone that protects the body against aging might also protect the brain.
Dena Dubal at the University of California, San Francisco, says their original goal was to answer a really intriguing question.
DENA DUBAL: Can we actually block or slow the aging process and prevent the cognitive decline that comes with aging?
HAMILTON: To find out, they studied hundreds of people who carry a form of the klotho gene that causes their bodies to produce high levels of the klotho hormone.
Dubal says what the team expected to find was that these people would experience less cognitive decline in their 60s and 70s and 80s than people with lower levels of klotho.
DUBAL: In fact, what we found was not consistent with our hypothesis. We were completely surprised by our findings.
HAMILTON: What they found was that the people with lots of klotho experienced just as much cognitive decline as other people. Their brains were not protected against aging. But Dubal says the results also showed that there was something different about their brains.
DUBAL: Those that carried that genetic variant that increased their klotho levels, they showed better cognitive performance across the lifespan.
HAMILTON: At any given age, people with lots of klotho scored higher on tests of learning and memory, language, attention, and spatial ability. So instead of discovering a way to protect the brain from aging, the team had found a hormone that appears to make people smarter.
To learn more, Dubal says, the team began studying mice that were genetically engineered to produce high levels of the mouse version of klotho. And this time, they weren't surprised by what they found.
DUBAL: Elevating klotho made the mice smarter across all the cognitive tests that we put them through.
HAMILTON: Tests like remembering how to get through a maze. And a look at the brains of these mice, suggested a reason. There was evidence that in areas involved in learning and memory, klotho was strengthening the connections between brain cells.
Dubal says all this suggests that a drug able to raise levels of klotho might be able to help people with Alzheimer's and other brain diseases, even if it doesn't stop the disease itself.
DUBAL: Our goal and vision is that there will be a therapy. We hope for a therapy that improves the lives of people that are suffering from diseases of the brain.
HAMILTON: But that's far from certain. Molly Wagster is from the National Institutes of Health, which helped fund the klotho research.
MOLLY WAGSTER: The beauty of this study is that the finding gives us another place to look, another path to take as we try to determine targets for development of drugs.
HAMILTON: Wagster says it also raises questions about whether klotho levels are affected by some of the things already known to be good for aging brains.
WAGSTER: Even diet or exercise or cognitive engagement, these things may stimulate klotho.
HAMILTON: But Wagster says there's a lot researchers still don't know about the hormone and how it interacts with other factors involved in both brain function and aging.
WAGSTER: The more pieces of the puzzle we have, the clearer the picture becomes as we're putting it together. And I find this to be another piece of that puzzle.
HAMILTON: The new research appears in the journal Cell Reports.
Jon Hamilton, NPR News.
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