- Tension: Some people in their 90s are sharper than people half their age — and the standard narrative that cognitive decline is inevitable can’t explain why.
- Noise: We’ve been told brain aging is either genetic luck or lifestyle discipline, but a protein called klotho suggests a third factor that complicates both sides of that equation — and the supplement industry is already racing to exploit it before the science is ready.
- Direct Message: The brain has built-in protective machinery that responds to how you live, not just what you inherited — and the real shift isn’t a pill, it’s abandoning the fatalism that cognitive decline is simply the price of getting old.
To learn more about our editorial approach, explore The Direct Message methodology.
Helen Kowalski was 91 when she beat her grandson at Scrabble for the third time in a row. Not by a little — by 83 points. She played “quixotic” on a triple word score without hesitation, then looked up and asked if anyone wanted tea. Her grandson, Derek, 34, a software engineer in Pittsburgh, told me he wasn’t even letting her win. “She’s faster than I am,” he said. “She reads two books a week. She remembers conversations from 1962 like they happened Tuesday.”
Helen isn’t an anomaly in the way we usually think of anomalies — some genetic lottery winner, some freak of biology. She’s part of a growing body of evidence that suggests the brain doesn’t have to decline the way we’ve been told it does. And a specific protein may explain why.
For decades, the dominant story about the aging brain went like this: after 30, you start losing neurons. After 60, the decline accelerates. By 80, if you’re still sharp, you’re lucky. This narrative was so deeply embedded in medicine and culture that it became something closer to a belief system than a scientific conclusion. Researchers at the University of California, San Francisco recently identified a protein called klotho — named after the Greek goddess who spins the thread of life — that appears to play a central role in whether the brain ages gracefully or falls apart. As we explored in an earlier piece on klotho and cognitive decline, this protein isn’t new to science. But what’s new is how dramatically its presence — or absence — seems to predict who stays cognitively intact and who doesn’t.
A 2023 study published in PNAS showed that when klotho levels were boosted in aging mice, their cognitive function improved measurably. Not just stopped declining — improved. The mice performed better on memory tasks, showed enhanced synaptic plasticity, and exhibited reduced neuroinflammation. The researchers described the results as “striking,” a word scientists use when they’re trying very hard not to say “we didn’t expect this.”
But the protein alone doesn’t tell the whole story. And this is where things get interesting — and uncomfortable for anyone hoping for a simple fix.
Marcus Chen, a 67-year-old retired high school principal in Sacramento, started noticing changes in his memory around 58. Nothing dramatic. He’d lose a name here, fumble for a word there. His doctor told him it was normal aging. His wife, Linda, 64, a former nurse, wasn’t so sure. “He was a man who could recite the names of every student in his graduating classes going back twenty years,” she said. “When he started forgetting the names of the teachers he’d worked with for a decade, I knew something was different.”
Marcus isn’t someone who ignored his health. He exercised. He ate well — avoiding the kinds of hyper-processed foods that hijack neural reward pathways. He did crossword puzzles, played chess, stayed socially engaged. And yet the decline came anyway. His klotho levels, measured as part of a clinical trial he joined at UC Davis in 2021, were notably low for his age.
Meanwhile, someone like Helen Kowalski — who by her own admission “never exercised a day in my life on purpose” — had klotho levels that looked like those of someone twenty years younger. This is the paradox that researchers are now grappling with. Lifestyle matters, but it’s not the whole equation. Genetics loads the gun in ways that lifestyle sometimes can’t fully override.
Dr. Dena Dubal, the neuroscientist at UCSF who has led much of the klotho research, has been careful to frame the findings with precision. In a 2023 paper in Cell Metabolism, her team demonstrated that a single injection of a klotho protein fragment enhanced cognitive function in aged primates — not just mice, but monkeys. The implications sent ripples through the neuroscience community. If klotho can cross the blood-brain barrier and improve cognition in non-human primates, the path to human therapeutics narrows considerably.
But Dubal herself has cautioned against what she calls “the supplement trap” — the tendency to take complex biological findings and reduce them to a pill marketed on Instagram. As neurologists have warned, the supplement industry often runs ahead of the science in ways that do real damage. There is currently no klotho supplement that works. Period. Anyone selling one is selling hope in a bottle — and hope, biochemically, does nothing for synaptic integrity.
What’s genuinely remarkable about the klotho research is what it reveals about the concept of “super agers” — people in their 80s and 90s whose brains look and function decades younger. Neuroscientists studying super agers have found that many of them share elevated klotho levels, thicker cortical regions, and — crucially — ongoing neurogenesis. They’re still producing new brain cells at rates that were once thought impossible past middle age.
Tomoko Ishida, 88, a retired mathematics professor in Kyoto who now participates in a longitudinal aging study at Osaka University, told researchers that she still solves differential equations “for pleasure” each morning before breakfast. Her MRI scans show cortical thickness comparable to a healthy 55-year-old. Her klotho levels are in the top percentile for her age group. She doesn’t take any supplements. She eats a traditional Japanese diet, sleeps seven hours a night, and walks to the market every day. When asked her secret, she said something that stuck with the research team: “I never stopped being curious. I think my brain knows that.”
It sounds like a greeting card, but the science underneath it is more profound than it appears. Curiosity, novelty-seeking, and sustained cognitive engagement are all associated with higher klotho expression. The protein isn’t just something you’re born with a fixed amount of — it responds, at least partially, to how you use your brain. Chronic stress suppresses it. Sustained learning may elevate it. Social isolation tanks it. The biology is listening to how you live, even if genetics set the baseline volume.
And this is where the conversation about brain aging needs to shift. For years, it’s been framed as a binary — either you decline, or you get lucky. But klotho research suggests a third possibility: that the brain has built-in protective machinery, and that some of us are running that machinery at full capacity while others have it dialed down to near silence. The question isn’t just whether you inherited high klotho expression. It’s whether anything you do in your daily life is keeping that expression alive — or killing it quietly.
Linda Chen watches her husband Marcus do his cognitive exercises every morning now, part of a trial exploring whether targeted interventions can boost klotho in people with below-average levels. She says the results have been modest but real. He remembered a neighbor’s name last week without prompting. He finished a novel for the first time in two years. “It’s not a miracle,” Linda said. “But it’s something. And something is more than what we had.”
The research on klotho isn’t going to produce a cure for Alzheimer’s next year, or even next decade. It’s not going to make 90-year-olds think like 30-year-olds. But it’s doing something arguably more important — it’s dismantling the fatalism that has surrounded brain aging for generations. The idea that cognitive decline is simply what happens, an unavoidable tax on being alive long enough, is starting to crack under the weight of evidence that says otherwise.
Helen Kowalski doesn’t know what klotho is. She’s never heard the word. But every morning she wakes up, reads the newspaper front to back, calls one of her four children, and works on the novel she started writing at 86. She’s on chapter eleven. “I don’t know if I’ll finish it,” she told me, smiling. “But I don’t think my brain knows that either. It just keeps going.”
Maybe that’s what the protein is really protecting — not just neurons and synapses, but the part of us that refuses to believe the story is over.
Feature image by www.kaboompics.com on Pexels
