A new study offers fresh evidence that living a healthy lifestyle may help a person maintain their cognitive reserve, reducing their chances of developing dementia later in life.
The study involved 586 brain autopsies of people who had a mean age of 90.9 years at the time of death, and found that their lifestyle habits were more clearly linked to their chances of getting dementia than were amyloid plaques or abnormal blood flow in their brains.
For many years, the presence of beta-amyloid plaques, tau tangles, or other dementia-related brain pathologies in the brain post mortem have been associated with dementias — especially Alzheimer’s disease.
However, recent research, including this new study, has found that the presence of these features frequently occurs in people who do not have dementia.
Participants in this study had registered with RUSH University’s Memory and Aging Project. Individuals self-reported their lifestyle habits. They were asked whether they smoked, engaged in at least 150 minutes of physical activity each week, and limited their alcohol consumption.
The healthiest 40% of participants were considered low risk or “healthy.” This corresponded to a Mediterranean-MIND diet score of 7.5 or above and late-life cognitive health score higher than 3.2.
The researchers estimated that just 12% of cognition-related measurements were affected by amyloid plaques.
The study is published in
The study’s first author, Dr. Klodian Dhana, of the Department of Internal Medicine, Division of Geriatrics and Palliative Medicine at Rush University, summed up its main finding for Medical News Today:
“We may hypothesize that lifestyle factors, especially diet and physical activity, may have antioxidant and anti-inflammatory properties, cognitive activities may contribute directly to ‘cognitive reserve,’ and all together contribute to cognition.”
Physician, educator, and molecular biologist Dr. Allison Reiss, Assistant Professor at New York University’s Department of Medicine, who was not involved in the study, explained what “cognitive reserve means.“
“Cognitive reserve is the fuel in the tank of our brain that is built up by using the brain productively to think, absorb ideas and be active in life and with our social network,” she said. “It keeps us sharp and engaged, and gives us resilience and the ability to use our brains flexibly to face new challenges and to be lifelong learners.”
Dr. Reiss added that a healthy lifestyle keeps the brain nourished with nutrients and oxygen, and promotes an environment “where the brain can flourish and function at its best.”
Dr. Clifford Segil, neurologist at Providence Saint John’s Health Center in Santa Monica, CA, also not involved in the study, said that although much emphasis is placed upon Alzheimer’s dementia, there is another type of dementia called vascular — or multi-infarct — dementia, which is caused by small, even imperceptible, strokes.
“So if people have silent strokes,” said Dr. Segil, “they get vascular dementia or multi-infarct dementia. It’s clinically seen by people just getting slow.”
He said there is a direct correlation between the number of silent strokes a person has had and their cognitive ability.
“Many patients with diabetes, hypertension, and heart disease that come see me with memory loss from vascular dementia [end up in this situation] because their brain is unhealthy, since their heart is unhealthy,” said Dr. Segil.
There is some controversy regarding the value of autopsy investigations for dementia.
“I think our reliance on these post-mortem data has got us into trouble,” Dr. Segil said.
“I think it’s a problem because a lot of the current theory has been done with investigative data on post-mortem studies with amyloid [plaques].” Even with this concern, however, Dr. Segil still considered that autopsies generally remain worthwhile.
“Knowing the pathology in the human brain is absolutely critical to understanding the disease processes that affect cognitive function,” Dr. Reiss also said.
She expressed her gratitude to the now-deceased study participants, noting that “[t]he microscopic images from these participants give us a historical record back to the 1990s, and captured information from which generations going forward will benefit.“
“Their generosity and willingness to enroll cannot be appreciated enough,” said Dr. Reiss.
Dr. Dhana stressed that autopsy data is “very important” in Alzheimer’s research.
Although “[a] healthy lifestyle was associated with less amyloid load in the brain at autopsy,” said Dr. Dhana, “most of the association with cognition proximate to death was not thorough Alzheimer’s disease pathology, highlighting the multifactorial and complexity of the disease.”
Dr. Reiss said that looking for simple answers underestimates the complicated ways in which body systems interact.
She cited as an example X-rays of two people who have similar degenerative changes that might indicate arthritis in their joints, and yet one person is in terrible pain while the other is pain-free and living with full function.
“We also knew this years ago in relation to amyloid,” said Dr. Reiss. “Many older people have amyloid in the brain on imaging and they are cognitively sharp. There are so many factors that impact the human brain, and we are just beginning to understand.”
In terms of blood vessel damage in the brain, Dr. Reiss added that if deterioration occurs slowly, the brain’s plasticity may compensate for it. “We can counteract a lot of adverse conditions with the many backup systems we have built into our miraculous nervous system,” she said.
“The study sends a positive message that pathology is not destiny, and we can control more than we might think with respect to our mental functioning,” according to Dr. Reiss.
“Research has shown,” said Dr. Dhana, “that cognitive activities are important for brain health, particularly when accompanied by a high-quality diet and regular exercise. Individuals should consult their doctor about preventive measures, tailoring each lifestyle factor to their individual needs.”
Dr. Reiss added to that list social engagement with friends in person or even online, not smoking, not drinking to excess, controlling your blood sugar if you have diabetes, getting adequate sleep, as well as sufficient sunlight and vitamin D.
Dr. Segil suggested specifically that “people take classes at their junior college or online classes in a subject that they have not taken before. I think structure and new classes exercising your brain is cognitively protective.”
“As I say, if you don’t use it, you lose it,” noted Dr. Segil.
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