May 18, 2019

How memory changes as we age

Illustration: Aïda Amer/Axios

About 11% of Americans over the age of 65 are diagnosed with Alzheimer's disease and related dementia. For others, the changes in memory we experience as we age are normal.

The big picture: Rather than passively declining, the brain adapts and changes as humans age. Researchers want to understand how our ability to remember changes with age in hopes of improving it, and of treating and preventing Alzheimer's disease and dementia. Those diseases are "superimposed on an aging brain," says Carol Barnes, who studies healthy brain aging at the University of Arizona.

"The older ideas that brain ages passively is the wrong way to understand the changes that occur with age."
— Carol Barnes, neuroscientist, University of Arizona

How it works: Different kinds of memories are formed, stored and maintained in and between different regions of the brain, but the hippocampus is a central player.

  • As people pass 60 years of age, they often experience a decline in episodic memory, or autobiographical experiences, which some research ties to changes in the hippocampus.
  • The upside is that semantic memory — our knowledge about the world — declines later in life, says Michael Rugg, a memory researcher at the University of Texas at Dallas.

"Aging isn’t passive. The brain is always plastic and always changing," he says of shifts at the level of individual neurons but also the different cognitive strategies individuals adopt. "As we grow older, you get adaptive changes in the brain."

What's next: There are individual differences in when and how fast our cognitive abilities change as we age. Researchers want to understand them in hopes of identifying risks for cognitive decline and tailoring treatments to maximize brain function.

  • Barnes tells Axios she envisions a field of "precision aging" — applying the approaches of precision medicine to cognitive health by studying factors like genetics, environmental exposure and social interactions in a large, diverse group of people over time.

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