Dr. Sanjay Gupta (9:49)
All right, Sahar, first of all, as a fellow runner, I hear you. The idea that something as healthy as exercise could have this dark side, that's alarming, obviously. But like most things in medicine, the answer is not a simple yes or no. Think about the dose and think about your own biology. So let's look at the evidence because I think this is actually quite fascinating. First of all, you're quite right. We have a lot of evidence that exercise in general is, is a good thing, a really good thing when it comes to preventing or slowing down neurodegenerative diseases. Take Parkinson's disease. A 2024 study out of Yale showed that high intensity aerobic exercise could help preserve what are known as dopamine producing neurons. When you develop Parkinson's, you lose those neurons. Exercise can help preserve that. That doesn't just slow down the disease, it could actually help the brain repair itself. Now, let's talk about distance training. Specifically, 2020 study out of Sweden compared the Parkinson's disease risk of long distance skiers who participated in a big race to the general public's risk. The skiers initially had a close to 30% reduced risk, but over time, that gap Narrowed that benefit became smaller. After 15 years, their risk basically looked similar to everyone else's. So that suggests that the exercise provides what scientists call a quote unquote, motor reserve to ward off the disease for a time, rather than permanently protecting the brain. So think of that as delaying the onset of a problem as opposed to preventing it completely. We also see the massive benefit of exercise when it comes to Alzheimer's. Recent study out of Hopkins found as little as 35 minutes of moderate exercise per week was linked to a 41% lower risk of dementia. This is really, really inspiring stuff. I mean, if you think about what's happening in the brain, we know we can create new brain cells throughout our lives. And we also know that exercise is one of the things that helps make that happen. It helps create these specific neurotrophic factors, which, as one neuroscientist said to me, is kind of like miracle growth for the brain. Now, most of the concern I think you're talking about stems from something known as als. Amyotrophic lateral sclerosis, or you may know it as Lou Gehrig's disease. For years, we've seen higher rates of ALS in certain professional athletes, soccer, football players. But even then, researchers note that one risk factor for soccer and football players is that they're taking repetitive hits to the head. Right? So studies suggest that for the vast majority of people, that's not gonna be the case, and strenuous exercise is. Is not only gonna be safe, but actually beneficial. Now, I will say, and this is rare, but for individuals with a specific variant of something known as the CNORF72 gene, I'm gonna repeat that just in case you wanna write it down. C9orf72 gene. And people who have a specific variant of that gene, intense physical stress might. Might act as a trigger for als. I just want to throw that out there. It's rare. The research is still emerging, but I think it's important for you to know the science around this is pretty new, just within the last five years. So we don't know, for example, if other environmental factors may be playing a role here as well. So what's the bottom line, Sahar? I think, number one, listen to your body. If you have a family history of motor neuron disease, it might be worth having a deeper conversation with a specialist. Number two, remember that most of the risks, they tend to appear at the extreme ends of human endurance, so don't overdo it. And number three, for the vast majority of us, the cardiovascular benefits, the cognitive benefits of training for a marathon or any kind of exercise for that matter, far outweigh the risks. So I hope that gives you some peace of mind next time you're out on the trail. No need to feel guilty about that runner's high. I'm right there with you. And if you do decide to go for it, Sahara, make sure you follow a training program and add the miles on slowly. I don't want you to be calling back with some question about a new runner's injury. Thanks for all the great questions this week. I love going down the rabbit holes with you. If you have something on your mind, record a voice memo. Email it to pagingdr.gupta.com that's paging Dr.gupta.com or give us a call 470-396-0832 and leave a message. I'm Dr. Sanjay Gupta. Talk to you soon.