Resistance training leads to increased levels of irisin, a hormone that may play a role in the cognitive benefits of exercise.
Researchers at Massachusetts General Hospital have uncovered evidence suggesting that irisin, a hormone produced by muscles during exercise, may hold promise as a therapeutic approach for Alzheimer’s disease. Irisin has been shown to regulate glucose and lipid metabolism in fat tissue and increase energy expenditure, and its presence has been detected in both human and mouse brains. However, studies have indicated that irisin levels are reduced in individuals with Alzheimer’s and in mouse models of the disease.
The research team, whose findings were published in the journal Neuron, has previously developed the first 3D human cell culture models of Alzheimer’s disease that exhibit two characteristic features of the condition: the accumulation of amyloid beta deposits (plaques) and neurofibrillary degeneration (tangles) of the protein tau, which is found in brain cells (neurons). Amyloid beta is an abnormal protein that, if left unchecked, can damage brain cells.
The study demonstrated that irisin treatment significantly reduced amyloid beta levels in the 3D cell culture models, suggesting that it may have the potential to protect brain cells from damage associated with Alzheimer’s disease. Further research is warranted to explore the therapeutic potential of irisin-based therapies for Alzheimer’s disease.
The researchers identified a specific receptor that irisin binds to, triggering cells to increase neprilysin levels, an enzyme that breaks down amyloid beta. Additionally, they discovered that irisin’s binding to this receptor suppresses signaling of two key proteins, extracellular signal-regulated kinase (ERK) and signal activator of transcription 3 (STAT3), which is essential for enhancing neprilysin activity and combating amyloid beta.
These findings suggest that irisin may serve as a promising therapeutic agent for preventing and treating Alzheimer’s disease. Previous studies have shown that irisin injected into the bloodstream of mice can reach the brain, opening up new avenues for targeted therapies.
Current investigations on the role of irisin and exercise in brain health are in their early stages and require further research.
Prior studies in human adults have demonstrated that certain forms of exercise, particularly resistance training, can lead to increased levels of irisin, a hormone that may play a role in the cognitive benefits of exercise. To fully understand how irisin contributes to brain health, more research is needed, including studies that compare the effects of irisin to other growth factors such as insulin-like growth factor-1 (IGF-1) and brain derived neurotrophic factor (BDNF).
Future research should also clarify the specific types of exercise (e.g., aerobic versus resistance training), intensities, and durations that lead to optimal levels of irisin in the brain. Additionally, further research is needed to compare the responses of adults with and without cognitive impairment to exercise and to better understand the cognitive outcomes associated with the expression of myokines such as irisin.
Exercise is essential for maintaining physical and mental health, and its benefits extend to people with Alzheimer’s disease as well. According to Nick Voci, a doctor of physical therapy at Manchester Physical Therapy in Vermont, exercise can help improve balance, strength, and activity tolerance in people with Alzheimer’s. This is because regular physical activity increases blood flow to the brain, which helps to protect brain cells from damage and supports cognitive function.
Voci also noted that the study’s findings could lead to the development of medications that mimic the effects of exercise, potentially providing an alternative approach to managing Alzheimer’s symptoms.
While more research is needed to fully understand the impact of exercise on people with Alzheimer’s, the available evidence suggests that it can play a valuable role in maintaining overall health and well-being.
Abstract
Alzheimer’s disease (AD) is characterized by progressive memory dysfunction, oxidative stress, and presence of senile plaques formed by amyloid beta (Aβ) accumulation in the brain. AD is one of the most important causes of morbidity and mortality worldwide. AD has a variety of risk factors, including environmental factors, metabolic dysfunction, and genetic background. Recent research has highlighted the relationship between AD and systemic metabolic changes such as glucose and lipid imbalance and insulin resistance. Irisin, a myokine closely linked to exercise, has been associated with glucose metabolism, insulin sensitivity, and fat browning. Recent studies have suggested that irisin is involved in the process in central nervous system (CNS) such as neurogenesis and has reported the effects of irisin on AD as one of the neurodegenerative disease. Here, we review the roles of irisin with respect to AD and suggest that irisin highlight therapeutic important roles in AD. Thus, we propose that irisin could be a potential future target for ameliorating AD pathology and preventing AD onset.