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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Trump's Tucker mind-meld

Photo illustration: Sarah Grillo/Axios. Photo: Roy Rochlin/Getty Images and BRENDAN SMIALOWSKI/AFP via Getty Images

If you want to understand the rhetorical roots of Trump's Independence Day speech at Mount Rushmore, go back and watch Tucker Carlson's monologues for the past six weeks.

Between the lines: Trump — or rather his speechwriter Stephen Miller — framed the president's opposition to the Black Lives Matter protest movement using the same imagery Carlson has been laying out night after night on Fox.

Updated 2 hours ago - Politics & Policy

Coronavirus dashboard

Illustration: Aïda Amer/Axios

  1. Global: Total confirmed cases as of 6 p.m. ET: 11,366,145 — Total deaths: 532,644 — Total recoveries — 6,154,138Map.
  2. U.S.: Total confirmed cases as of 6 p.m. ET: 2,874,396 — Total deaths: 129,870 — Total recoveries: 906,763 — Total tested: 35,512,916Map.
  3. States: Photos of America's pandemic July 4 ICU beds in Arizona hot spot near capacity — Houston mayor warns about hospitals
  4. Public health: U.S. coronavirus infections hit record highs for 3 straight days.
  5. Politics: Former Trump official Tom Bossert says face masks “are not enough”
  6. World: Mexican leaders call for tighter border control as infections rise in U.S.
  7. Sports: Sports return stalked by coronavirus
  8. 1 📽 thing: Drive-in movie theaters are making a comeback.

Bolton's hidden aftershocks

Photo illustration: Sarah Grillo/Axios. Photo: Justin Sullivan/Getty Images

The news media has largely moved on, but foreign government officials remain fixated on John Bolton's memoir, "The Room Where It Happened."

Why it matters: Bolton's detailed inside-the-Oval revelations have raised the blood pressure of allies who were already stressed about President Trump's unreliability.