Over the last 20 years, there has been growing evidence that adults can produce hundreds of new nerve cells per day, raising hopes that this effect could be therapeutically useful. By promoting neurogenesis depression, dementia and other brain diseases could be preventable or treatable, speculated physicians. However, a study published in the journal “Nature” has shattered these hopes as it concluded that the brain is not producing new neurons in adults.
The formation of new nerve cells decreases rapidly as we age
The team of researchers led by Arturo Alvarez-Buylla of the University of California San Francisco (USA) has recently examined the theory to which the production of neurons is also persisting during the adulthood. The scientists analyzed brain tissue samples taken from deceased subjects.
“We found that the number of proliferating progenitor cells and young neurons in the dentate gyrus decreases dramatically in the first year of life and only a few isolated young neurons can be observed at ages 7 and 13,” the researchers write in the study’s report.
In adult populations, the researchers were unable to detect any young nerve cells in the tissue samples.
Disappointing study results
Investigations on the hippocampus of the Macaca mulatta monkeys have also shown that the proliferation of neurons in the subgranular zone occurs in early postnatal life but this decreases greatly during juvenile development, according to the researchers.
“We conclude that neurogenesis in the dentate gyrus does not exist or is only very rarely occurring in adult humans,” the researchers added.
The current study results will disappoint many, emphasizes Paul Frankland, a neuroscientist at the Hospital for Sick Children in Toronto, in Canada, in a supplementary contribution to the study published in the journal “Nature”.
Although other scientists doubt regarding the new study, Arturo Alvarez-Buylla and his colleagues are convinced that the brain is not producing new neuron in adults.