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Why Memories of Some 80-Year-Olds Are as Sharp as 20-Year-Olds

What researchers hope to learn by studying "superagers"


(This article appeared previously on PBS’s Nova Next.) 

It’s as inevitable as gray hair and wrinkles — when we get old, our memories decline, even if Alzheimer’s or dementia doesn’t accelerate that process.

But there are a select few whose memories seem to remain as hale as those decades younger. Scientists call them superagers. And now, there is some clarity as to how these superagers hold on to their robust memory.

One interpretation is that older adults who stay engaged with work, life and family end up keeping these memory networks active, keeping them healthy later on.

In superagers, the brain networks used for memory, learning and resilience are nearly untouched by age. While other areas of their brains atrophied, the memory networks of superagers aged 60 to 80 were as healthy as those of the average 18-to-32-year-old’s brain, researchers at Massachusetts General Hospital reported recently in the Journal of Neuroscience.

“We were surprised by that,” said Alexandra Touroutoglou, a researcher in neurology at Massachusetts General Hospital and a co-author of the study.

While some earlier evidence of “superaging” had been found in the brains of patients older than 80, the new results show how the trait can appear in brains up to two decades younger.

Superagers Offer A Window into Healthy Aging

By watching how superagers avoid some of the consequences of normal aging, the researchers hope to understand and alleviate the slow decline of healthy aging and the diseases that accelerate it.

To measure brain health, Touroutoglou and her collaborators examined the cortex — the layer on the surface of our brains rich in grey matter. Only a few millimeters thick, the cortex coats the brain’s distinctive folds and is involved in many of the advanced thought patterns that are hallmarks of our humanity, like language, memory and consciousness.

But as we age, that cortex grows thinner, reducing the brain’s cognitive resources. By measuring the thickness of this cortex, then, scientists can see how much aging has degraded that part of the brain.

When the team looked at the cortex of superagers, they found that in many areas, it had thinned out as expected. But in areas used to recall memories and to make new ones, it remained about as thick as those in the 18-to-32-year-old brains.

More Than Just Memory

The researchers also found thick, healthy cortex in regions where it would bolster what Touroutoglou called “tenacity and the will to persevere in the face of challenges.” If this correlation is replicated in other studies, it could mean that the memory networks alone aren’t responsible for superaging.

One interpretation is that older adults who stay engaged with work, life and family end up keeping these memory networks active, keeping them healthy later on.

The study reinforces similar results previously seen in the brains of superagers older than 80, said Emily Rogalski, a research associate professor of cognitive neurology at Northwestern University’s School of Medicine who also studies the brains of superagers. She said she hoped more research on superaging could give a more optimistic view of aging: “There’s a need for looking at more than what’s going wrong with the brain,” said Rogalski.

Joseph Adreano, a psychiatry researcher at Massachusetts General Hospital and co-author on the study, said the next step is to understand how superager brains stay healthy.

Even when brains age normally, without any visible sign of disease, they accumulate molecules called amyloids — the suspected culprits behind Alzheimer’s and some dementias. Adreano is studying superagers to see if their brains contain fewer of these molecules, especially in the areas that have remained unusually healthy. “There’s a possibility that these superaging people might be more resilient to disease,” he said.

Despite their hopes to better understand Alzheimer’s and dementia, the team is unsure how quickly, if at all, superaging research will help treat or prevent those diseases. The study used only healthy volunteers, so more research comparing the brains of superagers to those of diseased patients is needed to make progress on those diseases.

“We are at the very early stages, but it’s exciting,” Touroutoglou said.

By Bennett McIntosh
Bennett McIntosh is an occasional writer for NOVA Next, NOVA’s award-winning digital publication that provides answers from the cutting edge of science and technology.

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