In this solo presentation Dr. David Perlmutter debunks the outdated belief that humans are born with a fixed number of brain cells and cannot generate new ones. He explains that neurogenesis—the creation of new brain cells—continues throughout life and is driven by the brain‑derived neurotrophic factor (BDNF), a growth factor for neurons. Perlmutter identifies two primary ways to increase BDNF: aerobic physical exercise and the omega‑3 fatty acid DHA. He reviews a 2011 Proceedings of the National Academy of Sciences (PNAS) study of 120 adults that compared aerobic exercise to stretching over one year, showing that aerobic participants experienced higher BDNF levels, enlarged hippocampal volume, and improved memory, while the stretching group’s hippocampus shrank. He cites a Mayo Clinic commentary that frames aerobic exercise as a prescription for reducing cognitive risk and slowing decline, emphasizing that unlike drugs, exercise can be written on a prescription pad to protect and regrow brain cells. The talk concludes that regular aerobic activity (and DHA intake) are powerful, evidence‑based tools for enhancing neurogenesis and cognitive health.
Chapters
Back in the day when I was in medical school, we were told that each of us was given a certain number of brain cells, whether it was 100 billion or however many brain cells you were lucky enough to get, and that was pretty much it. That was what you were left with, and every time you drank a beer, you'd lose 30,000 brain cells or whatever the number was for some reason. I don't remember. But that said, The idea that humans don't grow new brain cells is actually now fully demonstrated to be wrong. How exciting it is that we possess the ability to regrow brain cells, a process called neurogenesis, and that we retain this ability throughout our entire lifetimes. So the question you may be wondering is, well, what can I do to increase neurogenesis? I'd like to grow back new brain cells And here's how to do it. Neurogenesis happens when your brain produces more BDNF. It stands for brain-derived neurotrophic factor. That's sort of the growth hormone for the brain, and we know that you can turn on the amount of BDNF in your brain with at least 2 things. Number one, physical exercise, specifically of the aerobic type, and number two, by taking into your body a specific omega-3 called DHA. Both of these things stimulate BDNF and therefore lead to increased amounts of BDNF. Let's take a look at how physical exercise makes that happen. Published in 2011 in the Proceedings of the National Academy of Sciences, a study called Exercise Training Increases the Size of the Hippocampus and Improves Memory. What the researchers looked at was the size of the brain's memory center called the hippocampus, which we know tends to shrink as we age in perfect correlation with our declining memory. And the study looked at 120 adults over a 1-year period. Half the group did some stretching exercise, the other half did some aerobic exercise. They measured the size of the hippocampus with MRI scans. They measured their blood levels of this brain-derived neurotrophic factor, or the brain's growth hormone. And even perhaps most importantly, They measured their memory function at the beginning, at 6 months, and in 1 year. And what they found was that those individuals who did the aerobic exercise in comparison to those who just did stretching had a marked increase in their BDNF levels, meaning more brain growth factor. And in addition, those individuals who did the aerobic part of the story had quote, substantial improvement in memory function. If you look at this graph, you'll see that the size of the brain's memory center, called the hippocampus, in the group doing the stretching actually declined during the 1 year, in comparison to those who did aerobic exercise, a dramatic increase in size of the brain's memory center. The authors indicated, and I quote, these results clearly indicate that aerobic exercise is neuroprotective. And that starting an exercise regimen later in life is not futile for either enhancing cognition or augmenting brain volume. I think it's an interesting finding to be actually found reported in the Proceedings of the Mayo Clinic, a very prestigious journal, which in 2011 commented that physical exercise. should be considered as a prescription for lowering cognitive risks and slowing cognitive decline across the age spectrum. And the reason the Mayo Clinic said that is because there is no other prescription. There is nothing that can be written on a prescription pad, although I tend to write that on a prescription pad, please exercise. There's nothing you can get at the pharmacy that will improve your memory and protect your brain, and now we know that the simple act of aerobic exercise will not only improve memory function, but actually allows you to regrow new cells in your brain's memory center. That's pretty powerful information. I'm Dr. David Perlmutter.
