Restores Brain Cell Connections and Memory Loss
In response to physical activity the muscles generate a hormone called irisin which releases stored fat and improves glucose tolerance. Here’s where the brain health angle comes in: This hormone is also found in the hippocampus, perhaps the most important area of the brain involved with memory and learning. It's one of the first areas affected in Alzheimer's. 25 researchers from the US, Canada and Brazil wanted to know whether the hormone had any role in the disease. So they looked at post-mortem specimens of brain tissue in 20 people in the early and advanced stages of Alzheimer's. These samples were age-matched with a control group without dementia. The researchers found the people who had died with advanced disease had lower levels of both irisin and FNDC5 -- the precursor protein that forms irisin -- in the hippocampus, compared to the other groups. Obviously they can’t check this by taking brain samples from living people, but in 20 living Alzheimer's patients, they also found reduced quantities of irisin/FNDC5 in the cerebrospinal fluid. That’s pretty good confirmation of the autopsy results. Having established that Alzheimer's patients carry less of the hormone, the next step was to check irisin levels in normal mice and compare them to those bred to develop an Alzheimer's-type disease. The latter were found to have lower amounts of irisin in the hippocampus, and this impeded the formation of new nerve connections. Boosting irisin levels either by injection or by extensive exercise restored new neuronal connections and memory deficits. Using a virus to block irisin signaling prevented the positive effects of exercise from taking place. In normal mice, cutting out irisin led to memory and learning deficits. These could be reversed when the hormone was restored. These are very exciting findings. Lead author Fernanda De Felice described exercise as a natural medication that increases irisin in the brain. She said, "Because irisin seems to be powerful in rescuing disrupted synapses that allow communication between brain cells and memory formation, it may become a medication to fight memory loss in Alzheimer’s disease.” Dr. De Felice is looking at ways of creating a pill version of the hormone to boost brain levels, assuming tests in humans prove viable.A Possible Milestone in Alzheimer's Research
This research has generated a warm response from the scientific community. Professor Lawrence Rajendran, Deputy Director of the UK Dementia Research Institute at King's College London, hailed the trial, saying, "If this well performed study...can be translated for human therapy, it indeed will be a milestone in Alzheimer's disease research." Martin Rossor, Professor of Clinical Neurology at University College London, said, “There is increasing evidence that exercise can improve thinking and memory and more recently that this can be seen in people with a diagnosis of Alzheimer’s disease. "This is an important study that explains how those beneficial effects of exercise might come about. Beneficial effects in animal models of Alzheimer’s disease often fail to translate to humans, but there are some encouraging avenues to explore.” Dr. James Pickett, head of research at the Alzheimer's Society UK commented, "This is a promising avenue for more research and potentially new therapies in future."- https://www.nature.com/articles/s41591-018-0275-4.epdf?referrer_access_token=L6u5Y0cFpFiRRRaOj9myD9RgN0jAjWel9jnR3ZoTv0OyawYOKwl2Yg9BbQAcbfR4mM8aUdviKB0d8aXJZFQTe9tRnrbd6DzXqZdNCRe19bizO0NV1x6hLUn8qL-xY3thVoVPDCxd5U130uIrlvL5UrR7cqsTQOUAKuGxAnOQBMpJT9ot5_tCwZnSp9slQHvk
- https://www.nhs.uk/news/neurology/exercise-hormone-may-play-role-combating-alzheimers-disease/
- https://www.queensu.ca/gazette/media/news-release-queens-university-researcher-discovers-potential-new-treatment-alzheimers-disease
