Do we grow new brain cells as adults? The answer seems to be yes

Scientists have found evidence of new brain cells sprouting in adults – a process that many thought only occurred in children

By Carissa Wong

3 July 2025

Developing brain cells from the hippocampus growing in culture

ARTHUR CHIEN/SCIENCE PHOTO LIBRARY

Whether or not we grow new brain cells as adults has been the subject of an ongoing and often contentious debate. Now, evidence suggests that we can. This could help answer one of neuroscience’s most controversial questions and has sparked some speculation that the process could be exploited to treat conditions like depression and Alzheimer’s disease.

New neurons form via a process called neurogenesis in children, as well as in adult mice and macaques. This involves stem cells repeatedly giving rise to so-called progenitor cells that proliferate to form immature neurons that later become fully developed.

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Prior studies on human adults have identified stem cells and immature neurons in the hippocampus. This brain region, which is crucial for learning and memory, is a prime spot for neurogenesis in children and some adult animals, but progenitor cells have yet to be seen here in adult humans. “We were missing this link, and that’s one of the main arguments against new neurons forming in the adult human brain,” says Evgenia Salta at the Netherlands Institute for Neuroscience, who wasn’t involved in the new research.

To find this link, Jonas Frisén at the Karolinska Institute in Sweden and his colleagues first set about creating machine learning models that can accurately identify progenitor cells. This involved collecting hippocampus samples from six young children whose brains were donated by their parents for research when they died.

The researchers trained the artificial intelligence models to identify progenitor cells based on the activity of around 10,000 genes, using data extracted from the samples. “In childhood, progenitor cells look similar to what they do in mice, so we can easily identify these,” says Frisén. “[The idea is] we can take the molecular fingerprints of childhood progenitors and use that to identify these cells in adults.”