Vigorous exercise could help enhance a hormone that protects the body against Alzheimer’s disease.
When an individual performs a workout, a flood of endorphins is released to boost the person’s mood. However, researchers from the Columbia University’s Vagelos College of Physicians and Surgeons and Taub Institute for Research on Alzheimer’s disease and the Aging Brain found that exercise produces another hormone along with the endorphins that can both improve memory and protect against neurological diseases.
For the last few years, researchers have known that a hormone called irisin that plays a role in energy metabolism is released into the circulation during physical activity. However, the researchers now discovered that irisin also promotes neuronal growth in the brain’s hippocampus, a region that is crucial for both 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,” Ottavio Arancio, MD, PhD, who is a professor of pathology and cell biology and of medicine at Columbia University Vagelos College of Physicians and Surgeons, said in a statement.
According to the study, irisin is an exercise-induced myokine released on cleavage of the membrane-bound precursor protein fibronectin type III domain-containing protein 5 (FNDC5), which is also expressed in the hippocampus.
After examining tissue samples from brain banks, the researchers found that the hormone is present in the hippocampus region and that hippocampal levels of irisin are reduced in Alzheimer’s patients.
The team, which also included scientists from the Federal University of Rio de Janeiro in Brazil and Queens University in Canada, then found that irisin protects mice brain synapses and improved their memory, which are both used to classify Alzheimer’s disease. When irisin was disabled in the hippocampus of a healthly mouse, its synapses and memory weakened, but when the levels of irisin was boosted, both memory and synapses improved.
Next, the research team examined how exercise effects both irisin and the brain and identified swimming as an activity that could be beneficial thwarting neurological diseases like Alzheimer’s. In experiments, the researchers found that mice who swam most days for five weeks did not develop memory impairment despite receiving beta amyloid infusions, which are commonly associated with Alzheimer’s.
By blocking the hormone with a drug, the researchers eliminated the benefits of swimming and the mice performed no better on memory tests than sedentary animals after infusions with beta amyloid.
The findings suggest that irisin could be used to find new therapies that prevent or treat dementia.
“In the meantime, I would certainly encourage everyone to exercise, to promote brain function and overall health,” Arancio 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.”
The study was published in Nature Medicine.