Adults who still have robust neuron production in their brains have better memory and cognitive function than those whose ability is diminished, a study published today shows. Nature. The authors examined brain samples from young adults and deceased donors. ‘Super Agers’ – People over 80 years of age with exceptional memory.
They found that young and old adults with healthy cognition produced neurons at high levels for their age, a process called neurogenesis. The team estimated that the new neurons make up only a small portion – 0.01% – of the neurons present in the hippocampus, a brain region that is essential for memory. In contrast, in people experiencing cognitive decline, including individuals with Alzheimer’s disease, neurogenesis appears to falter: Researchers saw fewer developing, or immature, neurons in those brain samples.
Surprisingly, a group of ‘super agers’ had even higher numbers of immature neurons than the other groups, and significantly more than people with Alzheimer’s. However, the group size was small, so not all findings were statistically significant.
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Maura Boldrini DuPont, a neuroscientist and psychiatrist at Columbia University in New York City, says the small size of the groups—each had ten or fewer individuals—is a reason to take the results with a grain of salt.
Understanding the tools the brain uses to generate neurons and maintain cognitive function into old age could help researchers develop drugs that induce neurogenesis in people with cognitive decline, says neuroscientist and co-author Orly Lazarov of the University of Illinois at Chicago.
Controversy over neurogenesis
The findings support the idea that people’s brains continue to generate neurons well into adulthood. But that idea was not always accepted.
In the early 1900s, neuroscientist Santiago Ramón y Cajal suggested that the human brain could not create neurons after birth. Ultimately, researchers found that neurogenesis occurred in childhood, but they still thought that was the end point.
“When I went to medical school, this is what they taught,” says DuPont.
However, over the past few decades, this dogma has been challenged by new evidence supporting neurogenesis in the adult hippocampus, giving rise to the Ongoing debate in neurobiology.
Although researchers know that neurogenesis occurs in some adult animals, including rats and primates, they have not agreed whether it occurs in the brains of human adults. The main reason for this is that there are more tools to study neurogenesis in animals than in humans. For example, in mice, researchers can inject chemicals that trace the birth and development of neurons. Lazarov says this cannot be done in living people and research in human brain samples is limited.
However, one tool that researchers have used to study neurogenesis in humans is protein markers. Antibodies can be used to detect certain proteins expressed by neural stem cells – which can turn into neurons – and immature neurons in donated brain samples. But Lazarov points to critics’ arguments “that these proteins are not specific enough and may be expressed not only in neurogenesis, but also in other cell types”.
Scientists have therefore turned to single-cell RNA sequencing to find more specific genetic markers of neural stem cells and immature neurons in the human hippocampus.
in the future
Lazarov and colleagues went one step further in their latest study. They not only used RNA sequencing to identify the genetic signatures of these cell types, but also uncovered their epigenetic signatures. Epigenetic markers are DNA modifications that regulate gene expression. The team used an assay that pinpoints parts of a cell’s DNA that are ready for expression to determine these signatures. DuPont says the assay is a strong point of the study.
Lazarov says the next step will be to understand the function of neurons generated in the adult brain. “We need functional validation of these cells to tell what they are doing in the human brain,” she says, adding that this will require new imaging techniques that are sensitive enough to detect this activity.
This article is reproduced with permission and was first published On 25 January 2026.
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