Why brain aging varies greatly from person to person

Some aspects of cognitive ability in older age may be related to test results around age 11.
Researchers are uncovering deeper insights into how the human brain ages and which factors may be associated with healthier cognitive aging, including exercise, avoiding smoking, speaking a second language, or even playing a musical instrument.
Some aspects of cognitive ability in older age may be linked to test scores around age 11, according to a review article published in the journal Genomic Psychiatry.
The article, based on data from studies in Scotland, suggests that about half of the variable characteristics of people's cognitive abilities in older age were present in childhood, which may be why some people have greater cognitive decline than others.
Yet some adult lifestyle factors appear to be associated with better cognitive outcomes and slower brain aging.
"We have found that there are detectable but small links between things like keeping physically and mentally active and engaged, having few 'vascular' risk factors (such as high blood pressure, cholesterol, smoking, body mass index), speaking a second language, playing musical instruments and many others," says Simon Cox of the University of Edinburgh.
"We concluded that 'small steps rather than a magic leap' is the recipe . Many (often partially overlapping) factors contribute little to the risk of cognitive ageing," Cox said.
These lifestyle factors, when considered together, can explain "about 20%" of the differences seen in cognitive decline from age 70 to 82.
The paper includes data from two studies of older adults: a group of Scottish adults born in 1921 and another group born in 1936. They all took a cognitive test at age 11 and were then tested in their 70s, 80s and 90s for cognitive function and physical fitness, among other factors.
"We first did MRI scans on the participants when they were 73 years old. One of the most striking things about the study to me was how big the differences were between different people," Cox explained.
"Even though everyone was the same age, some brains appeared to be perfectly healthy, while others showed a great deal of shrinkage and damage to white matter connections, as well as other features that are associated with cognitive aging and dementia," he added.
White matter is tissue that forms connections between brain cells and the rest of the nervous system, helping them communicate with each other via nerve signals. Having reduced or damaged white matter can slow down the brain's ability to process information.
Overall, "this shows us that brain aging at age 73 is not inevitable. This motivates us to explore what we can do to emulate those lucky few who reach this age with such pristine brains," Cox says.
Meeting older people whose memory seems as sharp as that of people who are 20-30 years younger.
"Not all aspects of brain aging occur simultaneously in the same individuals," Cox says. "We are now investigating whether different constellations of brain aging characteristics are determined by particular subsets of risk factors."
There is a substantial body of research on the underlying lifestyle differences that may contribute to differences in brain aging. For example, poor sleep is a key risk factor for cognitive decline, and mental health problems, such as depression, are known risk factors for developing dementia.
According to a 2018 study, regular exercise such as walking or cycling just three times a week can improve thinking skills. Adding a heart-healthy diet to your daily routine can also help slow brain aging and reduce the risk of dementia. And a 2020 study shows that daily meditation also helps.
Experts have developed a tool called the Brain Care Score, and a study published last year shows it can help assess a person's risk of developing dementia or stroke as they age.
According to the study, published in the journal Frontiers in Neurology, the 21-point score refers to how a person copes with 12 health-related factors pertaining to the physical, life and social-emotional components of health. Researchers found that participants with higher scores had a lower risk of dementia or stroke later in life.
These 12 factors were: blood pressure, blood sugar, cholesterol, body mass index, diet, alcohol consumption, smoking, aerobic activities, sleep, stress, social relationships, and finding meaning or purpose in life.
For anyone hoping to improve the health of their aging brain, it's important to "see your doctor at least every year or two" to talk about your overall physical health, blood vessel health, and chronic diseases. | BGNES