That certainly isn't the case for a rare group of individuals in their 80s, whose memory, attention, problem-solving ability and other brain functions are equal to people 20, and even 30 years, their junior.
Researchers at Northwestern University in Chicago identified a group of 30 such SuperAgers, as they dubbed them, after testing about 300 octogenarians for a series of studies on cognitive function and integrity of brain tissue.
For the first of those studies, published Thursday in the Journal of the International Neuropsychological Society, researchers put 12 of the SuperAgers through their mental paces with a battery of standard tests that included how well they recalled a list of words and a story they had been told.
The researchers also performed MRI scans on the dozen SuperAgers to see how their brain structures compared to control subjects aged 50 to 65, with similar cognitive profiles, and to other octogenarians.
"And what we found was the SuperAgers' brains look more similar to the 50- to 60-year-olds than the 80-year-olds," said principal researcher Emily Rogalski of the university's Cognitive Neurology and Alzheimer's Disease Center.
Among the most intriguing findings was that the cortex — the outer layer of the brain important for memory, attention and other mental processing abilities — was much thicker in the SuperAgers than in the control subjects in their 80s, who were cognitively average for their age. Their cortexes showed significant thinning.
In fact, the size and thickness of the cortex in SuperAgers' brains more closely resembled what was seen in the 50- to 65-years-olds," Rogalski said from Chicago.
"So despite being 20 to 30 years younger, there was no significant difference in cortical thickness or atrophy with the SuperAgers versus the middle-aged controls."
Barb Shaeffer is one of the SuperAgers who took part in that study, which she heard about while enrolled in Northwestern's lifelong learning program three years ago. A friend suggested she might be a good candidate.
"I really didn't think about that," Shaeffer said Thursday from her Chicago home. "I have since learned I do have a fairly good memory for my age."
That would be a gross understatement by the 85-year-old, who was told the MRI scan showed she hadn't suffered the loss of brain cells that most people her age experience, and even many younger than her age.
"What struck me first is my mother had Alzheimer's for the last five years of her life. And I thought I really don't know that much about it. And I thought: 'What a way to learn, to be part of something where I can learn about this, just for myself,'" she said.
"And quite frankly, I like to test myself," added Shaeffer, who does two crossword puzzles every morning, and can't wait to get back to her university courses. She also travels to exotic destinations around the world, including El Salvador, China and Antarctica in the last three years.
"The thing that makes a SuperAger — that's their word, not mine — is the cells in the brain are not dying off at the same rate. That's one of the things that they want to find out, is why?"
Rogalski said the idea for the study came from the fact that during the normal process of aging, cognition — and especially memory — is vulnerable to decline. It's the same decline that occurs in Alzheimer's disease, but minimally by comparison, she added.
"So the question is: is it inevitable that everyone who ages is bound to go through this decline? Or is it possible that you can somehow resist that decline?"
Most research into Alzheimer's and other dementias focuses on what might be going wrong with the brain and how it might be fixed, she said.
"And we wanted to kind of flip that idea around and say ... well, what's going right with the brain and how can we use what's going right with the brain to avoid disease and disability?"
The 30 SuperAgers will take part in various studies, being tested cognitively and undergoing MRI brain scans every 18 months. Participants have also agreed to donate their brains upon their deaths, and pathological examination of those delicate organs may partly answer those questions.
But so far, their varied lifestyle habits aren't providing much of a clue as to how they've retained this cognitive fountain of youth, said Rogalski.
"Some are using a walker, others exercise five days a week and are lifting weights; some are retired, some are still working; some smoked a pack a day for 20 years, others never touched alcohol or cigarettes," she said.
"I think this is kind of good news because it means that there may not be just one path to becoming a SuperAger. It would be a little bit of a bummer to find out that there is only one way to be a successful ager or SuperAger."
Shaeffer can't point to any particular lifestyle factor that may have kept her brain intact and her intellect so sharp.
"Let's put it this way: I eat anything that won't eat me. I do believe in a drink everyday — I have a glass of wine at five o'clock. I exercise at least once a month," she says with a laugh.
She agrees with Rogalski that most likely, genetics plays a key role.
"I'm blessed that I have good genes. My mother was 95, my grandmother was 94 (when they died). They were all very active all the way up to the end of their lives, except for my mother who faded in the last few years," Shaeffer said.
"I feel like I can do anything that anybody else can do."
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