Why Do Some 80 Year-Olds Have Extraordinary Memories?

The human brain tends to slow down as we age — even healthy brains shrink. That can make learning and memory harder as people age. But some people’s brains shrink more slowly than their peers. This lucky group is called “SuperAgers.” They’re people aged 80 or older. But they have the memory abilities of someone 50-to-60 years old. This week in the journal Alzheimer's & Dementia, researchers from Northwestern University’s SuperAging Program https://www.brain.northwestern.edu/superaging/index.html summarized some of the secrets they’ve learned in the last 2.5 decades. Want to hear about more stories about human health and aging? Email us and let us know at [email protected] mailto:[email protected]. Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave https://plus.npr.org/shortwave. See pcm.adswizz.com https://pcm.adswizz.com for information about our collection and use of personal data for sponsorship and to manage your podcast sponsorship preferences. NPR Privacy Policy https://www.npr.org/about-npr/179878450/privacy-policy

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Speaker 00

  This message comes from Capella University. That spark you feel, that's your drive for more. Capella University's FlexPath learning format lets you earn your degree at your pace without putting life on pause. Learn more at capella.edu. You're listening to Short Wave from NPR.

• 0:20Regina Barber?

  Hey, Short Wavers. Regina Barber here.

• 0:22Speaker 02

  And Rachel Carlson with our biweekly Science News roundup, featuring the hosts of All Things Considered. And today, we have Elsa Chang. Welcome.

• 0:31Regina Barber?

  West Coast representing.

• 0:32Speaker 03

  Woo! And I heard we've got some new research on how some people are aging extra well, hopefully including me, right?

• 0:39Regina Barber?

  Yeah, me too.

• 0:40Speaker 02

  Oh, yeah.

• 0:40Regina Barber?

  Plus endangered eagles feeding on toxic toads without harm.

• 0:44Speaker 02

  And a new discovery about life in some of the deepest parts of the ocean.

• 0:48Speaker 03

  Fascinating. I love mysterious deep sea stories.

• 0:52Regina Barber?

  Just like our whole, you know, summer series, Sea Camp.

• 0:54Speaker 03

  That's right.

• 0:56Regina Barber?

  You're listening to Short Wave, the science podcast from NPR.

• 1:13Speaker 00

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• 2:36Regina Barber?

  OK, Elsa, West Coast, Best Coast. Where do we start?

• 2:40Speaker 03

  OK, I definitely want to start with the people who age extraordinarily well. Super curious if we're talking about Asians. Rachel, kick us off.

• 2:48Speaker 02

  For 25 years, Northwestern University has studied these people who are in their 80s, but with the memory abilities of someone 50 to 60 years old. They're called superagers. And this week in the journal Alzheimer's and Dementia, researchers summarized some of the secrets superagers seem to have in common.

• 3:05Speaker 03

  I want to be a superager. What's their secret? Tell us.

• 3:10Speaker 02

  One commonality between superagers is they all have consistent social interaction, strong social relationships, and meaningful interactions with other people.

• 3:19Speaker 03

  OK, so keep partying. Go ahead.

• 3:21Regina Barber?

  Other factors may include getting good sleep, not just like being asleep for enough time, but getting high-quality sleep. A clinical neuropsychologist at Northwestern University, Dr. Sandra Weintraub, says movement and exercise may also play a key role, but those are more difficult to study objectively.

• 3:38Speaker 03

  OK, I feel like I'm screwed on sleep, but I have the social interaction piece down. What about genetics?

• 3:45Speaker 02

  I asked another researcher who wasn't involved in the paper, Amanda Marr. She's a clinical neuropsychologist at the University of Michigan. And she told me genetics do play a role in superaging. Surprise. But they're not the whole picture. Lots of people have genetic risk factors for Alzheimer's disease or dementia, but don't show any signs of those conditions.

• 4:04Regina Barber?

  So the question is, what helps those people's brains resist those conditions?

• 4:08Speaker 03

  Yeah, do they have any ideas from this research?

• 4:11Regina Barber?

  Yeah, those two things we already mentioned, like social interaction and sleep, probably play a role. Also, we know that the human brain tends to slow down as we age, like even healthy brains shrink, which can make learning and memory harder as people age. But super agers' brains shrink more slowly than the brains of their peers, and researchers think that that's involved in avoiding cognitive decline.

• 4:33Speaker 02

  Super agers also have a lot of this particular type of neuron compared to other people their age. It's called the von Economo neuron, and it's a big neuron found in humans and some other species like whales and elephants. And researchers think it's related to social relationships or social bonding.

• 4:49Regina Barber?

  And everyone we spoke to said these are all clues to help understand how those behavioral elements and neurological elements are connected to one another. Here's Sandra Reintraub again.

• 4:59Speaker 05

  Just because you're getting older doesn't mean you're losing it. I think we assume, oh, you know, they're just getting older, they're forgetful. That's not true.

• 5:06Speaker 02

  Sandra says there's a lot of variability amongst older people and that super agers offer insight into how we all might be able to keep our brains healthy as we age.

• 5:15Speaker 03

  Oh, I want that. Okay, so we go from super agers to eagles in Japan. They are somehow eating toxic toads and still doing okay? What?

• 5:27Regina Barber?

  Yeah, that's right. So these are the crested serpent eagles, which are critically endangered in Japan. A subspecies of these eagles live on two small islands there, and there are only about 200 of them.

• 5:38Speaker 02

  And in 1978, cane toads from Central and South America were introduced to one of the islands, Ishigaki. The goal was pest control, to get rid of the bugs eating the cane sugar crops. But the toads are toxic, so predators who fed on them started dying, too.

• 5:52Speaker 03

  But the eagles are totally fine?

• 5:55Regina Barber?

  Yeah, so a new study documents the fact that they've been feeding on the toads for almost 50 years with no visible symptoms from the cane toad's toxins. The question is how. Like, I asked Alisa Tobe at Kyoto University about that. She's the lead author of a recent study in the journal BMC Ecology and Evolution. She got blood and tissue samples from these eagles on both islands and compared them to other raptors. And she found that the eagles have a special genetic adaptation to evade these toxins. An adaptation that Alisa says they've had for at least 10,000 years, long before the cane toad showed up on the island.

• 6:27Speaker 03

  So by chance, they can feed on them. That's so cool. Is there any idea why they even have this adaptation at all?

• 6:36Speaker 02

  It turns out it's a somewhat common adaptation. We talked with evolutionary biologist Shabnam Moamadi about this.

• 6:42Speaker 06

  This adaptation isn't unique to the eagles. It's actually very, very widespread. And what we found in rodents, in frogs, in snakes, many predators, sometimes they've gained this adaptation and they still have it today even though they don't need it.

• 7:02Speaker 03

  Okay, but what's the upshot? Like, is this good news for this endangered species?

• 7:08Speaker 02

  Yes and no. So some people have argued we should keep these cane toads for the eagles to feed on since they aren't harmed. But keep in mind, these toads are an invasive species, a human-induced ecological disaster, and haven't been good for the environment on Ishigaki. Many animals die of heart attacks if they eat them. So Alisa's still in favor of removing the invasive pest.

• 7:28Regina Barber?

  On the plus side, Shabnam says, understanding this adaptation can tell us much more about evolution, like when species so distantly related can have gene sequences that can do the same thing.

• 7:39Speaker 03

  That's so cool. Okay, last topic, life in the deep ocean. Rachel, what's going on down there?

• 7:46Speaker 02

  We're talking about the Hadal Zone, Elsa. It's the deepest part of the ocean, named for the Greek god of the underworld, Hades.

• 7:52Speaker 03

  Oh, I get it. Okay.

• 7:53Speaker 02

  Yeah, if you can imagine, based on that name. Life is pretty hard down there. No sunlight reaches down this far.

• 8:00Regina Barber?

  And for a long time, researchers thought that life in this zone mostly ate like organic matter falling from the ocean's surface, like bits of dead animals, like poop.

• 8:09Speaker 03

  Mmm, yum.

• 8:09Regina Barber?

  But now, a study in the journal Nature suggests that these deep-sea creatures may also get some energy from chemicals seeping out of the ocean floor.

• 8:16Speaker 03

  Ooh, how does that work?

• 8:18Regina Barber?

  So I talked to Mangren Du. She's a geochemist at the Chinese Academy of Sciences. And to study all this, she took this incredible journey down nearly six miles under the ocean's surface in a submersible. And she landed in two trenches in the Northwest Pacific Ocean, near Japan and Russia.

• 8:34Speaker 07

  So the submersible is like a time machine to me. So whenever I dive to a new ocean somewhere, it always opens a new world for me.

• 8:45Speaker 02

  During her aquatic time travel, she found tube worms, clams, and microbial mats living near cold seeps. Those are places where chemicals like hydrogen sulfide and methane seep out of the ocean floor.

• 8:56Speaker 03

  Ew, wait. How do these deep-sea creatures survive on that?

• 9:01Speaker 02

  The researchers think that microbes inside of the animals use those chemicals to make organic compounds. Then the animals feed off of those compounds.

• 9:09Regina Barber?

  Yeah, and the next step is exploring like more trenches at this depth. Now that we know that there's so much life down there, Mangren thinks that there are many more species to discover and more to learn about how life works there.

• 9:21Speaker 03

  Yeah, but she has to get in a submersible. Not for me, no way.

• 9:25Regina Barber?

  Yeah, she loved it. She said it was amazing.

• 9:27Speaker 03

  OK, good for her.

• 9:28Speaker 02

  But if you come back, we won't make you get in one.

• 9:31Speaker 03

  No, it'll never happen.

• 9:36Regina Barber?

  You can hear more of Elsa on Consider This, NPR's afternoon podcast about what the news means for you.

• 9:42Speaker 02

  This episode was produced by me, Rachel Carlson, and Michelle Aslam. It was edited by Rebecca Ramirez and Christopher Intagliata.

• 9:49Regina Barber?

  Tyler Jones checked the facts. Ted Meadbane and Gilli Moon were the audio engineers. I'm Regina Barber.

• 9:55Speaker 02

  And I'm Rachel Carlson. Thanks for listening to Short Wave, the science podcast from NPR.

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