Brain, neurons are formed even at the age of 90. New hopes against Alzheimer's

The human brain continues to renew itself by developing new neurons even up to the age of 90.

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The brain does not age and neurogenesis continues even in old age: even at 90, in fact, new neurons are created in our brain. Discovered in the dentate gyrus of the hippocampus, an area of the brain linked to memory, their identification could lead to new treatments for Alzheimer's disease and other neurodegenerative diseases.

This is what emerges from a new study published in the journal Nature Medicine and conducted by Spanish researchers from the Center for Molecular Biology "Severo Ochoa" in Madrid, according to which healthy people maintain a genuine regenerative capacity. An ability of neurons to regenerate which, however, appears reduced in Alzheimer's patients: this is why in turn its block would be at the basis of memory loss.

A systematic review

Coordinated by Professor María Llorens-Martín, the scientists analyzed the brains of 58 deceased people. 13 of them, aged 43 to 87, had died from various causes - such as cancer and stroke - but were neurologically healthy, while the other 45 (aged 52 to 97) were death from Alzheimer's. In the brain of the neurologically healthy group, the presence of thousands of neurons expressing doublecortin (DCX +), a factor indicating the presence of neurogenesis. Specifically, neurons were identified in the dentate gyrus of the hippocampus, and their number decreased slightly with advancing age. As for the brains of Alzheimer's patients, the number of these immature neurons was greatly reduced, and the more advanced the disease stage, the fewer nerve cells detected.

"These data support the idea that Alzheimer's disease is a condition that differs from physiological aging and suggest that, although there is an age-related physiological decline in the DCX + cell population, independent neuropathological mechanisms contribute to reaping the population of immature neurons in Alzheimer's disease, ”the Spanish researchers write.

These results rekindle a long debate that began in 1998, when American scholars at the Salk Institute announced that new neurons are also forming in the human brain. Since then, many studies have followed up to a research published in Nature in March 2018 in which researchers seemed to deny the possibility of regeneration in adults; a month later, however, another study appeared in the journal Cell Stem Cell confirming the hypothesis that the brain does not age and continues to create neurons. It was estimated that about 700 neurons replaced each day regardless of age.

In short, a long debate that will lead to the definition of how to stimulate neurogenesis to have important therapeutic implications against Alzheimer's.