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By studying centenarians, researchers hope to develop strategies to ward off Alzheimer’s disease and slow brain aging for all of us.
One of my greatest pleasures during the Covid-19 shutdowns was having the time to indulge in hourlong phone conversations with friends and family whom I could not see in person. Especially uplifting were my biweekly talks with Margaret Shryer, a twice-widowed 94-year-old Minneapolitan.
I met Margaret in Minneapolis in 1963, six months after her first husband was killed by a drunken driver. With four small children to support, this young widow wasted no time getting qualified to teach German to high school students. Margaret and I are kindred spirits who bonded instantly, and despite living half a country apart since 1965, we’ve remained devoted friends now for 58 years.
My conversations with Margaret are substantive and illuminating, covering topics that include politics, poetry, plays and philosophy as well as family pleasures and problems. I relish her wisdom and sage advice. I especially delight in the fact that she seems not to have lost an iota of her youthful brain power. She’s as sharp now as she was when we first met decades ago.
Recent findings about the trajectories of human cognition suggest that if no physical insult, like a stroke, intervenes in the next six years, Margaret is destined to be a cognitively sharp centenarian.
Fewer than 1 percent of Americans reach the age of 100, and new data from the Netherlands indicate that those who achieve that milestone with their mental faculties still intact are likely to remain so for their remaining years, even if their brains are riddled with the plaques and tangles that are the hallmarks of Alzheimer’s disease.
Findings from the Dutch study may eventually pave a path for many more of us to become “cognitive super-agers,” as researchers call people who approach the end of the human life span with brains that function as if they were 30 years younger.
One day everyone who is physically able to reach 100 may also be able to remain mentally healthy. By studying centenarians, researchers hope to identify reliable characteristics and develop treatments that would result in healthy cognitive aging for most of us. Meanwhile, there is much we can do now to keep our brains in tiptop condition, even if reaching 100 is neither a goal nor a possibility.
These hopeful prospects stem from the study of 340 Dutch centenarians living independently who were tested and shown to be cognitively healthy when they enrolled. The 79 participants who neither died nor dropped out of the study returned for repeated cognitive testing, over an average follow-up of 19 months.
The research team, directed by Henne Holstege at Vrije University in Amsterdam, reported in JAMA Network Open in January that these participants experienced no decline in major cognitive measures, except for a slight loss in memory function. Basically, the participants performed as if they were 30 years younger in overall cognition; ability to make decisions and plans and execute them; recreate by drawing a figure they had looked at; list animals or objects that began with a certain letter; and not becoming easily distracted when performing a task or getting lost when they left home.
Even those with genes linked to an elevated risk of developing Alzheimer’s disease were able to perform well on the tests.
Nearly a third of the participants agreed to donate their brains after death. Brain autopsies of 44 of the original centenarians revealed that many had substantial neuropathology common to people with Alzheimer’s disease although they had remained cognitively healthy for up to four years beyond 100.
Dr. Thomas T. Perls, a geriatrician at Boston University who directs the New England Centenarian Study who wrote an accompanying editorial, said in an interview that the Dutch participants represented “the crème de la crème” of centenarians who had averted the onset of Alzheimer’s disease by at least 20 to 30 years. They seemed to be either resistant to the disease or cognitively resilient, somehow able to ward off manifestations of its brain-damaging effects. Perhaps both.
Resistance, Dr. Perls explained, may reflect a relative absence of brain damage conferred by a person’s genes or lifestyle. Or they may have “protective biological mechanisms that slow brain aging and prevent clinical illness,” he said.
Resilience, on the other hand, characterizes people with normal cognitive abilities even though their brains may have damage typical of Alzheimer’s, the leading cause of dementia. In addition to plaques and tangles, such changes include loss of neurons, inflammation and clogged blood vessels.
People with cognitive resilience are able to accumulate “higher levels of brain damage before clinical symptoms appear,” the Dutch team reported.
Yaakov Stern, neuropsychologist and director of cognitive neuroscience at Columbia University College of Physicians and Surgeons, said that while resistant individuals may be spared much of the brain pathology typical of Alzheimer’s disease, resilient individuals have what researchers call a cognitive reserve that enables them to cope better with pathological brain changes.
Many studies have revealed that a variety of lifestyle factors may contribute to resilience, Dr. Stern said. Among them are obtaining a higher level and better quality education; choosing occupations that deal with complex facts and data; consuming a Mediterranean-style diet; engaging in leisure activities; socializing with other people; and exercising regularly.
“Controlled trials of exercise have shown that it improves cognition,” he said. “It’s not just a result of better blood flow to the brain. Exercise thickens the cerebral cortex and the volume of the brain, including the frontal lobes that are associated with cognition.”
Dr. Perls said, “Alzheimer’s disease is not an inevitable result of aging. Those genetically predisposed can markedly delay it or show no evidence of it before they die by doing the things we know are healthful: exercising regularly, maintaining a healthy weight, not smoking, minimizing red meat in the diet, and doing things that are cognitively new and challenging to the brain, like learning a new language or a musical instrument.”
Also important is to maintain good hearing, said Dr. Perls, a 60-year-old who wears a hearing aid. “I can’t emphasize enough how important it is for people to optimize their ability to hear,” he said. “There’s a direct connection between hearing and preserving cognitive function. Being stubborn about wearing hearing aids is just silly. Hearing loss results in cognitive loss because you miss so much. You lose touch with your environment.”
Vision, too, is important, especially for people who already are cognitively challenged. “Poor vision makes cognitive impairment worse,” Dr. Perls said. As his brain-challenging activity, he’s taken up birding, which requires both good hearing and good vision.
For her part, my friend Margaret reads, writes and recites poetry and occasionally acts in a relative’s films.