Hormone Produced During Exercise Jogs Memory, Maintains Brain Health

By | February 13th, 2019

If we told you there was a magic pill to feel less tired, more alert and younger, you’d take it, right? What if we told you the pill doesn’t require a prescription or payment and is available to everyone whenever they want it? And on top of all that, research points to this pill preserving brain health and limiting the effect of dementia on the brain. You’re in, right?

You know what’s coming—this “magic pill” isn’t a pill at all. But if ever there was a pill for health, exercise would be it. Studies show that people who exercise are vastly healthier than their more sedentary counterparts. And a new study published in the journal Nature is shedding light on the hormone that makes exercise good for our brains. 

What Is Irisin?

Irisin, known as the exercise hormone, has been found to potentially preserve our brain’s memory and thinking skills—even when a culprit like dementia is actively degrading them. It’s produced in our muscles during exercise and is thought to jumpstart many metabolic processes—how we convert food to energy—in the body. There is also evidence that it promotes neural growth in the hippocampus, the brain’s memory center.

“This raised the possibility that irisin may help explain why physical activity improves memory and seems to play a protective role in brain disorders such as Alzheimer’s disease” said Ottavio Arancio, M.D., Ph.D., co-leader of the study and a professor of pathology and cell biology and of medicine at Columbia University Vagelos College of Physicians and Surgeons.

Because there is evidence that Alzheimer’s might be a metabolic disease that has to do with how the body utilizes glucose, the brain’s main energy source, Arancio and a group of international scientists decided to test the effect of irisin in the brain.

The idea was that higher levels of irisin might keep the brain functioning for a longer period of time after dementia starts to creep in. People with dementia, scientists found, have lower levels of irisin in the brain.

Higher Levels of Irisin Translated to Better Memory Performance

The scientists used mice—half with normal cognition and half genetically engineered to have Alzheimer’s in the brain—to test how higher levels of irisin affect memory performance. When they injected the Alzheimer’s mice with the hormone, they started to perform better on memory tests and strengthened their synapses, which allow neurons to communicate.

When they blocked irisin in the brains of healthy mice, the synapses weakened, and mice did worse on memory tests.

Without Irisin, Exercise Wasn’t Effective

Then scientists decided to test the effect of naturally produced levels of the exercise hormone by introducing swimming into the routines of the mice. Some of those mice were injected with beta-amyloid, the toxic protein that accumulates in Alzheimer’s disease and others were given the irisin-blocking substance. They swam for an hour each day for five weeks. The mice that were given beta-amyloid did no worse on the memory tests, but those who could not produce irisin did not better on tests than the animals who did not swim and were given infusions of the memory-robbing beta-amyloid.

The experiment suggests that the magic pill is not just exercise, but the production of irisin in the body that protects the brain and fights off the effects of beta-amyloid. But these studies were conducted using mice, so it cannot be determined how humans would react under the same conditions.

A Magic Pill for Real?

Arancio and his colleagues are now looking for a drug that could raise levels of irisin or mimic its effects in the brain.

“In the meantime, I would certainly encourage everyone to exercise, to promote brain function and overall health,” he said. “But that’s not possible for many people, especially those with age-related conditions like heart disease, arthritis, or dementia. For those individuals, there’s a particular need for drugs that can mimic the effects of irisin and protect synapses and prevent cognitive decline.”


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