To Your Health: exercise may protect against Alzheimer’s disease

Researchers have found new evidence that a vigorous workout, which can release a flood of endorphins, those “feel-good” hormones that boost mood, also produce another hormone that may improve memory and protect against Alzheimer’s disease.

Researchers at the Columbia University Irving Research Center, who published their findings in Nature Medicine, a peer-reviewed medical journal, are still trying to understand how this happens, they said.

Exercise researchers earlier had discovered a hormone called irisin that is released into circulation during physical activity. Initial studies suggested that irisin mainly played a role in energy metabolism, but newer research has found that Irisin may also promote neuronal growth in the brain’s hippocampus, which is critical for learning and memory.

“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 researcher Ottavio Arancio, a professor of pathology and cell biology and medicine at Columbia’s Vagelos College of Physicians and Surgeons.

In the new study Arancio and his colleagues in Brazil and Canada found irisin present in the human hippocampus and that hippocampal levels of the hormone are reduced in individuals with Alzheimer’s.

They also did experiments with mice, on the effect of exercise on irisin and the brain, and found that mice who swam nearly every day for five weeks did not develop memory impairment despite getting infusions of beta amyloid – the neuron-clogging, memory-robbing protein implicated in Alzheimer’s. Mice who swam and were treated with irisin-blocking substances performed no better on memory tests than sedentary animals after infusions with beta amyloid. The findings together suggest that irisin could be exploited to find a novel therapy for presenting or treating dementia in humans.

Arancio said his team is now searching for pharmaceutical compounds that can increase brain levels of the hormone or can mimic its action. Meanwhile, he said, he would certainly encourage everyone to exercise.

These findings were also reported in early February by EurekAlert, the online journal of the American Association for the Advancement of Science.