Did you know? When you exercise, endorphins are released into your bloodstream. The “feel-good” hormones can elevate your mood, which is why many people regularly exercise. However, a new study found that exercising also produces another hormone, one that may improve memory and protect against Alzheimer’s disease.
The study was published in Nature Medicine and was co-led by Ottavio Arancio, MD, PhD, a researcher at Columbia University’s Vagelos College of Physicians and Surgeons and Taub Institute for Research on Alzheimer’s Disease and the Aging Brain.
Several years ago, exercise researchers discovered the hormone irisin. This hormone is released into the circulatory system during physical activity. The early studies suggested that irisin primarily plays a role in energy metabolism. However, new research has discovered that the hormone may also promote neuronal growth in the hippocampus, or the area of the brain responsible 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 Arancio.
Arancio and his colleagues first looked for a link between irisin and Alzheimer’s in people. After studying tissue samples from brain banks, they found that irisin is present in the human hippocampus. They also learned that the hippocampai levels of the hormone are reduced in people with Alzheimer’s.
Their next task was to explore what irisin does in the brain, so they turned to mice. The experiments revealed that irisin, in mice, protects the synapses in the brain and the animals’ memory. When irisin was disabled in the hippocampus of healthy mice, the animals’ synapses and memory weakened. The opposite occurred when the team boosted brain levels of irisin.
After discerning the importance of irisin, the researchers studied the effects of exercise on irisin and the brain. Science Daily reports:
“In the study's most compelling experiments, the researchers 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.
Blocking irisin with a drug completely eliminated the benefits of swimming, the researchers also found. 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 point to the conclusion that irisin could be exploited as a therapy for preventing or even treating dementia in humans. Arancio and his team are now searching for pharmaceutical compounds that can increase brain levels of the hormone. Or, at the very least, they hope to find a compound that can mimic its action.
"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."
h/t Science Daily