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The Potent Brain Benefits of Regular Physical Activity

Research shows the potential for exercise to delay the onset and slow the progression of disorders such as MS, Alzheimer's and Parkinson's, and even depression, but could we get the benefits without working out?

It's no secret exercise makes us feel better. A jog around the neighbourhood, a vigorous cycling session, or even a calming yoga class all result in an overall uplifted mood. This is because of the release of natural "feel-good" chemicals such as endorphins and endocannabinoids during exercise. These chemicals, often associated with the "runner's high", bring about feelings of euphoria, reduce stress and increase pain tolerance. But the benefits of exercise go beyond the immediate emotional uplift. Regular physical activity is a gift that keeps giving, contributing to long-term physical and mental well-being.

Increasingly, research is demonstrating the potential of exercise in delaying the onset and slowing the progression of disorders such as multiple sclerosis, Alzheimer's and Parkinson's disease, and even depression, with active people becoming depressed at much lower rates than sedentary people. Integrating physical activity as an add-on therapy alongside existing medications shows promising potential in managing these chronic illnesses.

The most beneficial type of exercise is still a matter of ongoing research. Some studies suggest that high-intensity exercise, even as brief as six minutes, could help delay the onset of Alzheimer's and Parkinson's. Though the symptoms of multiple sclerosis – such as fatigue, weakness, and poor coordination – may make exercise seem daunting, studies show the benefits of regular exercise outweigh the challenges, with aerobic exercise increasing strength and balance, improving bowel and bladder control, and decreasing spasticity related to multiple sclerosis. Other research findings highlight the effectiveness of cycling and stretching in reducing age- and disease-related cognitive decline. What is clear is that any protective effects, whether cognitive or motor-related, subside when regular exercise is not maintained.

Despite the robust evidence supporting the benefits of exercise, the underlying mechanisms behind these benefits remain elusive. However, a significant breakthrough in this quest came with the discovery of irisin, an 'exercise hormone'

Irisin, an exercise-induced hormone produced by skeletal muscle tissue, was discovered in 2012 in rodents and plays roles in metabolism modulation and body fat reduction. Recent discoveries show it also affects the brain. Notably, it also crosses the blood-brain barrier, potentially mediating the benefits of exercise on brain function. This discovery presents a fascinating possibility – could we replicate the benefits of exercise without working out?

A study by Johns Hopkins and Harvard Medical Schools scientists in 2022 provides some intriguing insights. The researchers found that irisin administration in animal studies had a similar effect on exercise. Irisin reduced the brain pathology associated with Parkinson's and the loss of neurons responsible for regulating dopamine.

These neurons are essential. As the levels of dopamine decrease, people with Parkinson's experience tremors, stiffness, and difficulty with coordination and balance. Irisin improved these motor outcomes in preclinical models and reduced neuron loss by a remarkable 35%. Regular exercise may not always be feasible in Parkinson's patients so irisin supplement treatment could be a game-changer. The findings surrounding irisin also provide a glimpse into why exercise is so beneficial and present a potential 'exercise-mimicking' intervention for Parkinson's.

These insights could extend beyond Parkinson's and possibly apply to other neurodegenerative disorders, such as Alzheimer's, multiple sclerosis, and Huntington's, as these diseases share common pathogenic mechanisms. Notably, in Alzheimer's, the beneficial effect of irisin seems to be mediated by Irisin and Brain-Derived Neurotrophic Factor. This protein also plays a pivotal role in brain health and increases after exercise. This reveals an interconnected network of exercise-induced molecules that work in tandem to promote brain health.

The age-old adage that 'exercise is medicine' holds more truth than ever in the context of maintaining cognitive health and potentially decelerating the progression of neurodegenerative diseases. The discovery of irisin is an essential piece of the puzzle on why exercise is so good for our brains and the remarkable potential of exercise in mitigating neurodegenerative diseases. Our approach to exercise and to understand its physiological responses will continue evolving, forging new pathways to maintain cognitive health and quality of life.

Dr Victor Dieriks



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