And it has been a banner year in brain science. We've learned that lifestyle changes really can keep your brain young and that electrical pulses can help with rheumatoid arthritis, and that LSD can relieve anxiety and depression. Scientists even managed to replicate a human brain network that carries pain signals. NPR science correspondent Jon Hamilton joins us. Jon, thanks so much for being with us.
JON HAMILTON, BYLINE: Hi, Scott.
SIMON: Well, let's start with that brain network. What does it do?
HAMILTON: Well, it recreates the pathway that carries brain signals from, say, your fingertip to the part of the brain that says, you know, ouch, that hurts. And that pathway has several sort of relay stations along the way. So a team at Stanford decided to recreate those stations using brain organoids, which are these pea-sized clumps of human brain cells that can mimic different types of brain tissue. In this case, the scientists used four different organoids representing the four types of nerve cells that relay pain signals. And when they put these organoids together in a dish, they spontaneously wired up to form the entire pain pathway.
SIMON: That sounds extraordinary, but I have to ask - can you tell if the organoids in a dish felt anything?
HAMILTON: You can, and the way you can tell is with red hot chile peppers. The scientists took the organoid that was acting like a nerve ending, and they exposed it to chemicals like the ones in hot chile peppers, you know, that burn your mouth. Here is Dr. Sergiu Pasca explaining what happened.
SERGIU PASCA: We discovered that if you start adding some of these compounds that are inducing inflammatory responses of pain, then you start seeing that information traveling. The neurons that sends these signals get activated. And they transmit that information to the next station and the next station, all the way to the cortex.
HAMILTON: There's good reason for this research, too. It's part of an effort to help people with chronic pain.
SIMON: Let's move on to the whole question of trying to keep your brain young. Like, can you really do that?
HAMILTON: Why, yes, you can. At least according to a really big study funded by the Alzheimer's Association. This study involved about 2,000 people in their 60s and 70s, and they were all pretty sedentary, at least at the beginning. Half of these people spent two years getting aerobic exercise at the gym, eating a Mediterranean diet, watching their blood pressure and taking part in this really demanding cognitive training program. The other people - they were just told to eat better and exercise more. At the end of the study, the people in the hardcore program did better on tests of thinking and memory. And their scores were actually as good as those from people a year or two younger than they were.
SIMON: Now, we got help (ph) for other things that catch up to us as we get older, like rheumatoid arthritis. There's a new treatment for that, right?
HAMILTON: There is, and it's pretty surprising. So rheumatoid arthritis happens when the immune system starts damaging your joints. People who have it are usually treated with drugs that reduce pain and inflammation. Unfortunately, some of those drugs are really expensive. They can leave people more vulnerable to infections. So in July, the Food and Drug Administration approved a device that uses pulses of electricity to keep the immune system from going after a person's joints.
SIMON: It sounds like one of the commercials you see on late-night TV. Does it work? How does it work?
HAMILTON: It actually does. This device is the passion project of Dr. Kevin Tracey. He's president of the Feinstein Institutes for Medical Research on Long Island. More than 20 years ago, Tracey became fascinated by this discovery that a signal from the brain could suppress inflammation in the body. He and a team of scientists began studying how the system worked, and here's Tracey explaining what they found.
KEVIN TRACEY: We realized that the signal was traveling down the vagus nerve, and the vagus nerve was like the brake lines in your car. It was the brakes on inflammation. And this started this entire idea of, can we make devices that turn on the brakes and then treat patients with excessive inflammation?
HAMILTON: The vagus nerve, of course, connects your brain to your gut and other internal organs, but along the way, it passes through your neck. And a company founded by Tracey was able to implant a device in a person's neck that could actually deliver electrical pulses to the vagus nerve. And sure enough, it actually reduced inflammation in people's joints. Some of them say it even changed their lives, and now this device is on the market.
SIMON: I've been saving this. Tell us about LSD used to treat anxiety and depression.
HAMILTON: Happy to, Scott. This is part of a big trend in brain science in the past few years, where researchers are testing psychoactive drugs for a range of mental illnesses, including depression and PTSD. And now we have the first large, rigorous trial of LSD for anxiety. It involved nearly 200 people with a disabling condition called generalized anxiety disorder, which is often accompanied by depression. And the study found that people who got just one single large dose of LSD felt better almost immediately, and they were still better three months after they got the drug.
SIMON: With all this good news about brain research in 2025, can we expect to build on that in the year ahead?
HAMILTON: Well, a lot of the research we've been talking about was funded by the National Institutes of Health and other federal agencies. Some of that funding has been delayed or eliminated by the Trump administration. The administration said the cuts were needed to reduce waste and better align research with the president's priorities. So maybe don't expect quite as many advances in the new year.
SIMON: NPR's Jon Hamilton. Thanks so much.
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