RENEE MONTAGNE, Host:
This is MORNING EDITION, from NPR News. Good morning. I'm Renee Montagne.
STEVE INSKEEP, Host:
And I'm Steve Inskeep.
MONTAGNE: Here's NPR's Richard Knox.
RICHARD KNOX: Phyllis Hersch is very precise about her age.
MONTAGNE: I just turned 70 years old - just turned 70 years old.
KNOX: Well, happy birthday.
MONTAGNE: Thank you very much.
KNOX: Seems like she doesn't want me to think she's a day older than she is, but she talks freely about some problems she's been having with her memory.
MONTAGNE: I do five errands and miss the most important one because I've gotten distracted about something else.
KNOX: Twice, she's left her car in the garage with the motor running.
MONTAGNE: I was really scared - not just that I'd left the car going, but that it was an indication that there was something more significant going on with my mind.
KNOX: She's especially anxious because her husband, Charlie, has early Alzheimer's. So she consulted Dr. Kirk Daffner. He directs the Mind-Brain Center at Brigham and Women's Hospital in Boston. Dr. Daffner put Phyllis Hersch through a series of memory tests. I was curious about them, so I asked him to run through the tests with me.
KNOX: You ready?
KNOX: OK. Four, two, seven, three, one.
KNOX: Four, two, seven, three, one.
KNOX: And it got harder.
KNOX: Now I'm going to ask you to start with the number 100, subtract seven in your head, and give me the answer. Then take that number, subtract seven. And continue the pattern of subtracting seven and giving me the answer as you go.
KNOX: On top of that, there's a slowing of the way the brain works.
KNOX: What's common, as people age, is that the speed at which information can be retrieved on demand is slowed. And through much of our lives, it was this wonderful gift. We wanted some information and bang, it came to us.
KNOX: Dr. David Bennett directs the Alzheimer's Disease Center at Rush University Medical Center in Chicago.
KNOX: If you look in the brains of older people, it's hard not to have at least a little bit of Alzheimer's pathology.
KNOX: Bennett's findings come from 16 years of studying thousands of older people who agreed to donate their brains after death. But those same studies contain some really good news. Bennett says many people are able to tolerate a little bit of Alzheimer's in their brain, or even more than a little bit. Their secret is something called cognitive reserve - extra brain capacity. It compensates for whatever damage is accumulating.
KNOX: I think of reserve like the side streets when there's an accident on the expressway. Everything comes to a dead stop, and you get off and you meander through the side streets, and you can actually get to your destination.
KNOX: Now, some people are just lucky when it comes to cognitive reserve. They inherit more of it. Others have bad luck. Their reserve gets depleted by loneliness, anxiety, depression. But Bennett says people who tolerate Alzheimer's-like brain damage have certain things in common.
KNOX: Purpose in life, conscientiousness, social networks - all of these things seem to be protective in terms of how your brain expresses whatever pathology it's accumulating.
KNOX: So rather than worrying about whether your memory is slipping, maybe you'd do better to invest your energy in stimulating activities, and maintaining your social life.
MONTAGNE: Richard Knox, NPR News.
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