Aging memories may not be worse, just "different"

As many of you might already know, Fortinberry Murray is very proud to be part of the Queensland University-led Cooperative Research Center for Longevity. We will be working to extend the active life of older people.

It’s a subject I have written much on over the years. I am particularly interested in dispelling the many myths about aging. Many of these have contributed to the present frightening death toll on the over 55s that the pandemic has wrought. They have also led to the shocking and inhuman way we tend to treat—and abuse—older people.

One of the many myths is that cognitive ability necessarily declines with age. Many studies have shown the fallacy of this assumption. It changes—older people forget words and where they put the keys more often than teens, but they gain wisdom and often (believe it or not) mental flexibility and adaptability.

When decline does set in, it’s more often than not because they have come to believe the prevailing myths and their minds, and bodies, act accordingly.

A brilliant new study looks at the question of memory and calls into question all the tests we use to test it—and cognition generally—in older people.

“Memory is the first thing to go.” Everyone has heard it, and decades of research studies seem to confirm it: While it may not always be the first sign of aging, some faculties, including certain kinds of memory, do get worse as people age. But it’s not straightforward.

The team behind the study looked at the brain activity of older people not by requiring them to recite a group of words or remember a string of numbers. Instead, they looked at a “naturalistic approach,” one that more closely resembled real-world activities.

They found that brain activity in older adults isn’t necessarily quieter when it comes to memory.

What the researchers say: “It’s just different,” the lead author said.

The study results were published in the journal Nature Communications.

Common tests of memory involve a person’s ability to remember a string of words, count backward, or recognize repeated images. “How many times do you suspect a 75-year-old is going to have to remember, ‘tree, apple, cherry, truck?’” he asked.

Instead, the researchers used a data set from the Cambridge Centre for Ageing and Neuroscience (Cam-CAN) that included functional MRI (fMRI) scans of people watching an 8-minute movie. “There were no specific instructions, or a ‘gotcha’ moment,” the lead author said. “They just got to kick back, relax and enjoy the film.”

But while they may have been relaxing, the subjects’ brains were hard at work recognizing, interpreting, and categorizing events in the movies. One particular way people categorize events is by marking boundaries—where one event ends, and another begins.

An “event” can be pretty much anything, he said. “This conversation, or a component of it, for example. We take these meaningful pieces and extract them out of a continuous stream.” And what constitutes a boundary is actually consistent among people.

“If you and I watch the same movie, and we are given the instruction to press a button when we feel one meaningful unit has ended, you and I will be much more similar in our responses than we are different,” he added.

When looking at the fMRI results—which use changes in blood flow and blood oxygen to highlight brain activity—older adults showed similarly increased activity as a control group at the boundaries of events. That’s not to say that brains of all ages are processing the information similarly.

“It’s just different,” the researchers said. “In some areas, activity goes down and, in some, it actually goes up.”

Some activity did decline pretty reliably across ages 18-88, they noted, and when grouped into “younger, middle aged, and older,” there was a statistically reliable drop in activity from one group to another.

“But we did find regions where activity was ramped up across age ranges,” they said. “That was unexpected.”

Much of the activity he was interested in is in an area of the brain referred to as the posterior medial network—which includes regions in the midline and toward the backside of the brain. In addition to memory, these areas are heavily involved in representing context and situational awareness. Some of those areas showed decreased activity in the older adults.

“We do think the differences are memory-related,” they said. At the boundaries, they saw differences in the levels of activity in the hippocampus that was related to memory in a different measurement—'story  memory,’” they called it.

“There might be a broad sense in which the hippocampus’s response to event boundaries predicts how well you are able to parse and remember stories and complex narratives,” no matter one’s age, the lead author said.

But for older adults, closer to the front of the brain, particularly the medial prefrontal cortex, things were looking up.

Activity in that area of the brain was ramped up in older adults. This area is implicated in broad, schematic knowledge—what it’s like to go to a grocery store as opposed to a particular grocery store.

“What might be happening is as older adults lose some responsiveness in posterior parts of the brain, they may be shifting away from the more detailed contextual information,” he told me. But as activity levels heighten in the anterior portions, “things might become more schematic. More ‘gist-like.’”

In practice, this might mean that a 20-year-old noting an event boundary in a movie might be more focused on the specifics—what specific room are the characters in? What is the exact content of the conversation? An older viewer might be paying more attention to the broader picture: What kind of room are the characters in? Have the characters transitioned from a formal dinner setting to a more relaxed, after-dinner location? Did a loud, tense conversation resolve into a friendly one?

“Older adults might be representing events in different ways, and transitions might be picked up differently than, say, a 20-year-old,” he continued.

“An interesting conclusion one could draw is maybe healthy older adults aren’t ‘missing the picture.’ It’s not that the info isn’t getting in, it’s just it’s getting in differently.”

So, what? This broader perspective, this ability to find deeper meaning in situations is called wisdom. By shutting older people away in retirement villages and the like—away from the community—we not only condemn them to an early demise (as a ton of research has shown) but we deprive the rest of the community of their wisdom.

More fools us!