Alzheimer's disease does not interfere with neurogenesis
Scientists have found new nerve cells in old people with Alzheimer's
Sergey Vasiliev, Naked Science
The study of postmortem brain samples of elderly people found new nerve cells even in those of them who reached the age of 99 and suffered from neurodegenerative diseases like Alzheimer's disease. Orly Lazarov and her colleagues from the University of Illinois at Chicago write about this in an article published in the journal Cell Stem Cell (Tobin et al., Human Hippocampal Neurogenesis Persists in Aged Adults and Alzheimer's Disease Patients).
The saying "nerve cells do not regenerate" is based on the idea that the brain ends growing in adolescence and, unlike other organs of our body, is not able to grow new cells instead of old ones. Recent studies have refuted these ideas, demonstrating that neurogenesis continues in the adult brain. Moreover, there is evidence that it occurs even in the elderly, albeit on a very modest scale.
However, the scale of neurogenesis in old age may be underestimated. In the course of their new work, American doctors found quite a lot of nerve stem cells and young growing neurons in the hippocampus in extremely elderly people, including those who were diagnosed with the terrible diagnosis of Alzheimer's disease. The hippocampus is a key structure in the work of emotions and memory, in such patients it can also be deeply affected. However, the more young cells were found in brain tissue samples, the more points these people scored in cognitive function tests.
Orly Lazarov and her co-authors took post mortem tissue samples from people aged 79 to 99 years. The samples were stained to isolate young neurons and stem cells. Of course, at such a respectable age, there are not as many of them as in youth, nevertheless, scientists managed to count on average about 2,000 stem cells and about 150,000 young neurons per brain; in Alzheimer's patients, this number was lower.
"The fact that we have discovered both stem nerve cells and new neurons in the hippocampus of the elderly means that we only need to find a way to enhance the neurogenesis that is already taking place," says Orly Lazarov. "Using, for example, a small signaling molecule, it would be possible to slow down or even stop the decline of cognitive abilities in old age, especially at the beginning of this process, when any intervention is more effective."
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