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Memory Lapses: What's Normal, What's Not

This Is Your Brain. This Is Your Brain at 70.
Woman lost
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Ann E. Cutting

Reassuring insights, for sure. But a short stroll down the hall to the office of Mony J. de Leon, Ed.D., quickly reveals that things aren't quite so straightforward. Surrounded by models of the brain and colorful pictures of the same, de Leon is a sort of counterpart to De Santi: While De Santi analyzes performance, de Leon uses high-tech imaging tools like PET scans and MRIs to study the actual structure of the brain. And what he tells me is disconcerting: Although tests like De Santi's are very good at detecting disease, they aren't necessarily designed to track how the healthy brain subtly—but definitely—changes as we age.

"You see these structures here," says de Leon, pointing to a pair of kidney-shaped red blobs on the scan of a 20-something adult. "And you see how much smaller they are in a scan of an adult in his 70s?" Those two red blobs, explains de Leon, make up the hippocampus, which acts as a sort of gateway for new memories. As that "gateway" shrinks with age, de Leon explains, it becomes less efficient at dispatching names, faces, smells, and more to other regions of the brain where they are stored as actual memories.

That's not all that slowly begins to shrivel when we hit the age of about 40 (mind you, we're still talking brain here). So, too, does the frontal lobe, says de Leon, as he waves his hand over a large region at the front of a rubbery model brain. "The frontal lobe acts like an index system. It's responsible for retrieving all the memories that are stored elsewhere in the brain," he says. When we find ourselves with a name or a word at the tip of our tongue, it's not because the memory isn't there, explains de Leon. "It's because the machinery that is supposed to find that word is becoming less efficient," he says.

De Leon goes on to explain that the frontal lobe is also responsible for something else: our ability to pay attention, that all-important piece of the memory puzzle that helps us actually notice where we put our coffee cup or truly hear what someone said her name was. At this point I'm imagining my frontal lobe being the size of a pine nut. "Tasks that demand attention are very vulnerable to age because as the frontal lobe shrinks it has less bandwidth, or capacity to manage information," says de Leon. This doesn't mean, however, that we're doomed to a lifetime of being locked out of our cars. It simply means that as we get older, we have to take an extra second or two to look at where we are putting those keys, so our brains have a chance to grasp the information. One more fascinating fact to consider: Men's brains begin to age earlier than women's, but we do, unfortunately, catch right up. "During and around the time of menopause, chemical and hormonal changes cause the brain to reduce in size. So by the time they are 60 to about 80, men and women are basically going downhill at the same rate," says de Leon.

With all this shrinking and shriveling, how is it, then, that De Santi's performance tests don't reflect such changes? "Because they don't ask the right questions," says de Leon, almost smiling. Sure, portions of standard evaluations touch on age-sensitive issues like attention. "But if you really want to see how a 45-year-old brain compares to a 20-year-old brain, ask your subjects to perform tests that are speed dependent or that require them to switch back and forth between two tasks. That's where the younger brain will dominate."

But de Leon is quick to emphasize the flip side of this story. Apparently, while we may become less efficient at things like rattling off phone numbers backward, a lifetime of experience gives us tools that our children may lack to cope with and compensate for memory weaknesses. Aware that we may not remember to call a friend after her doctor's appointment, we get to a place where we write ourselves a note on the calendar to do so. We're not surfing the Internet or watching TV while talking to her on the phone. And, if her news is bad, we know all the right things to say. "That's called wisdom. And in life," says de Leon, "wisdom can take you pretty far."

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