Although the process repeats and repeats, it is not without limit. Which is one of the reasons we age and it’s particularly relevant for cognitive function too – as we age our cognitive function slows naturally too. Once cells stop reproducing, they become “senescent”, during which they still work in the body, but just don’t reproduce.
Now, there’s a growing body of evidence that suggest that senescent cells may cause lots problems for the body – and especially for cognitive function. Some studies have linked senescent cells in the heart and kidneys with tissue degradation in surrounding areas, as well as atherosclerosis (plaque build-up in your arteries) and arthritis (joint pain and/or stiffness).[ii]
In a study just published in Nature one biologist, Dr. Darren J. Baker, working at the Mayo Clinic has found that a build up of senescent cells in mice causes degenerative neurological conditions, like Alzheimer’s. However, in a striking development, he also found that clearing away the senescent cells prevented the conditions from developing.
By developing genetically engineered mice that rapidly developed fibrous proteins in their brains (which are associated with declining cognitive function and diseases like Alzheimer’s), Dr. Baker was able to identify senescent cells in the hippocampus (a critical part of the brain responsible for memory and learning) and the cerebral cortex (which underpins memory, attention, perception, consciousness, awareness, language and many more fundamental elements of our lives), as well as lots of the protein tangles associated with diseases.
In order to see what affect the senescent cells were having, Dr. Baker tested some mice to see what happened when the senescent cells were removed. This resulted in a group of mice that were predisposed to neurological disease, although did not have senescent cells present in their brains.
As the mice aged, the protein tangles associated with Alzheimer’s seemed to have disappeared. The mice did not appear cognitively impaired. Control groups, who had retained senescent cells, showed signs of severe cognitive decline.
Clearly there are lots of differences between people and mice and, as it is not possible to genetically engineer people, some other approach to removing senescent cells will be required to see if the protein tangles associated with Alzheimer’s can be removed in the same way.
The findings are years away from clinical application, however, they do give a window into one potential new avenue for treating Alzheimer’s and cognitive decline in the future.
[i] Quammen, David (April 2008). "Contagious cancer: The evolution of a killer". Harper's. 316 (1895): 42. Retrieved 24 September 2012.
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