Our regenerating brains

For decades, neuroscientists have argued over whether or not humans can make new neurons after their brains stop developing in adolescence. Now a team of Spanish scientists has found evidence that we do keep making fresh neurons well into our 90s, reports BBC.com, and that production drops rapidly in people with Alzheimer’s—even when the disease has only recently taken hold. The researchers examined the brains of 58 people who died at ages 43 to 97, focusing on the hippocampus, a part of the brain involved in memory and emotion. The researchers were able to spot immature, or “new,” neurons and noted that their production declined slightly with age in healthy brains. “I believe we would be generating new neurons as long as we need to learn new things,” says co-author Maria Llorens-Martín, from the Autonomous University of Madrid. “And that occurs during every single second of our life.” But the brains of people at the very beginning of Alzheimer’s—when symptoms have not yet manifested—had 30 percent fewer new neurons than healthy brains of the same age. By measuring levels of new brain cells, doctors might eventually be able to diagnose Alzheimer’s at an earlier stage than currently possible and recommend exercise and other interventions to boost neuron production.

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