Can adults grow new brain cells?

Summary

The developing human brain gains billions of neurons while in the womb, and tacks on some more during childhood. For most of the 20th century, the conventional wisdom was that the brain cells grown before adulthood would be the only ones we would have for the rest of our lives. But over the past few decades, more and more research is challenging that belief.So is it actually possible for adults to grow neurons? While some experts believe there's strong evidence that we can gain brain cells after childhood, others are still skeptical of this notion.The process of creating new brain cells is called neurogenesis. Researchers first observed neurogenesis after birth in lab animals of various ages, including mice, rats and songbirds. In adult mice, they found new neurons growing in parts of the brain collectively called the subventricular zone, an area closely linked with sense of smell, as well as in the hippocampus, a structure that’s central to memory.Researchers think that neurogenesis in these brain regions is important for plasticity, or the brain's ability to adapt and change over time. Plasticity underlies the ability to learn and form memories, for instance.In mice, it's clear that lifestyle factors such as living in a stimulating environment and exercising can promote the growth of new neurons. Conversely, in mouse models of diseases like Alzheimer's, neurogenesis is hampered. What's still up for debate is whether these findings extend beyond mice and other lab animals.Neurogenesis in human adults?"Most of our knowledge about adult neurogenesis came from studies in animal models," Hongjun Song, a professor of neuroscience at the University of Pennsylvania Perelman School of Medicine, told Live Science in an email. "Whether such knowledge can be directly translated to human studies is a challenge."That's because many of the studies that have established the existence of adult neurogenesis in animals used methods that aren't possible in human studies, such as inje...