Around 50 million people worldwide live with dementia today. About 10 million new cases are documented each year, and it is estimated that this number will reach 80 million by 2030. Up to 152 million people could suffer from dementia by 2050.
The most common form of dementia is Alzheimer’s disease. Of the above 50 million people with dementia, 60-70% were diagnosed with Alzheimer’s. This progressive neurological disorder is notorious for its ability to rob individuals of their identity. It is a terrible condition characterized by loss of lifelong memories, decreased thinking skills, personality changes, and a general inability to function independently.
If you want to strengthen your brain’s protection against dementia, we have known for some time that a consistent exercise plan is just as good for the brain as it is for the body. For example, this study published in Neuroimage found that exercise actually stimulates the formation and maintenance of new neurons in the hippocampus, which is considered the “memory command center” of the mind.
More specifically, there are also scientific reasons to believe that exercise specifically helps prevent Alzheimer’s disease. A comprehensive review of ten studies of over 23,000 people published in the Mayo Clinic Proceedings concludes that more active people are much less likely to develop Alzheimer’s disease than those who lead a largely sedentary lifestyle.
Still, how the brain works on the brain has remained a mystery – until now. Groundbreaking new research from Massachusetts General Hospital published in Nature Metabolism tentatively shows what happens in the brain at the molecular level when we work up a sweat. Read on to learn more about the secret cognitive side effect of exercise. And to learn more about how you can take advantage of exercise in your older years, read The One Exercise That Is Best for Fighting Alzheimer’s Disease.
Scientists report that when we exercise, our muscles produce more of the hormone irisin (named after the Greek god Iris). Once created, irisin enters the brain, where it increases both general health and the functionality of neurons. This leads to improved thinking skills and memory. In fact, study authors go so far as to say that irisin promotes the cognitive benefits of exercise. Given these results, they believe that irisin could be useful as a form of therapeutic Alzheimer’s treatment.
“Maintaining cognitive function is a major challenge in an increasingly aging population,” says lead study author Christiane Wrann, DVM, PhD, head of the program for neuroprotection in movement at MGH. “Exercise is known to have beneficial effects on brain health, which is why identifying key mediators of these neuroprotective benefits such as irisin has become such a critical goal of research.”
This research was done in mice, but the results persisted in healthy rodents as well as mice diagnosed with the rodent version of Alzheimer’s. Importantly, both humans and mice produce irisin in response to exercise. For some great exercises you can do, check out these 5 minute exercises for a flatter stomach.
The study’s authors bred a group of mice that were unable to produce irisin. Then they brought another group of normal mice and set up both cohorts with an exercise bike. After a few days of cardio, the normal mice showed marked improvements on a number of cognitive tests. However, the rodents with irisine deficiency did not experience any significant cognitive boost from their training.
When the research team took a closer look at rodent brains, they discovered that even the irisin-deficient mice actually produced new neurons in response to exercise. But – and it’s a big but – the new neurons in the rodents without irisin showed far fewer synapses and dendrites, which are essential for interneuronal communication. In other words, these new brain cells won’t be nearly as useful cognitively as if irisin were involved.
Where were these new neurons located? The hippocampus, which happens to be one of the first areas of the brain to be affected by Alzheimer’s.
When researchers used chemicals to artificially deliver irisin to the deficient rodents, mice of all ages showed instant cognitive improvements. Notably, even irisin-deficient mice suffering from some form of rodent Alzheimer’s did better on cognitive and memory tests. In addition, the mice diagnosed with dementia even showed signs of reduced encephalitis, which is also beneficial in terms of combating memory loss.
When mice without irisin were injected with some of the hormone into their bloodstream, it didn’t take long for irisin to appear in their brains. This confirms that irisin can cross the blood-brain barrier and interacts directly with brain cells. “What makes this study particularly strong is that we show the effect of irisin on cognitive function in four different mouse models, rather than one,” explains co-author of the study Bruce Spiegelman from the Dana-Farber Cancer Institute and Harvard Medical School. Dr. Spiegelman discovered Irisin in 2012.
Nor can it be emphasized enough how promising the effects of irisin are in rodents suffering from advanced Alzheimer’s disease. “This could have implications for intervention in people with Alzheimer’s disease, where therapy typically begins after the patient develops symptoms,” adds Dr. Wrann added.
“It’s hard to imagine anything better for brain health than daily exercise, and our results shed new light on the mechanism involved: protection against neuroinflammation, perhaps the biggest killer of brain neurons in old age,” says Rudy Tanzi, Co -Author of the study -Director of the McCance Center for Brain Health at MGH.
Although much research is still needed, especially in humans, researchers say irisin could one day be developed as a drug to treat Alzheimer’s disease. They hope to be able to test a pharmaceutical version of the hormone in both mice and humans in the future.
“Since Irisin does not specifically target amyloid plaques, but directly targets neuroinflammation, we are optimistic that it could have positive effects on neurodegenerative diseases beyond Alzheimer’s,” concludes Dr. Wrann.
All in all, this study is another reason why we should all exercise regularly. It keeps the mind young! And for more training news to use, here is the One Walking Exercise That Can Predict Your Risk Of Death, Study says.