Autopsy of long-lived brains reveals how lifestyle helped avoid dementia
A healthy lifestyle helps people build up a kind of reserve that allows them to preserve their cognitive functions in old age. This has been shown by a new study based on the analysis of brain autopsies of almost 600 people who have passed the ninth decade at the time of death.
The work, which was published in the journal JAMA Neurology, was based on data from the Rush Memory and Aging Project. This is a long-term clinical and pathological study of Rush University Medical Center (Chicago, USA), in which physicians observed the lifestyle and cognitive functions of people from 1997 to 2022, and after their death took the brain for research.
Scientists have long known that proper diet, exercise, avoiding smoking and alcohol abuse correlate with lower rates of dementia. To understand what happens in the brain, a team of neurologists, pathologists and other specialists from the Chicago Medical Center studied autopsy data from 586 deceased long-livers (415 women and 171 men). The average age of death was nearly 91 years.
In addition, the scientists considered the results of a battery of cognitive tests performed by the subjects during their lifetime, and information from questionnaires about their lifestyle. To assess lifestyle, the researchers used a zero to five-point scale, with high scores corresponding to healthier habits.
A comparison of these data showed, expectantly: the healthier the lifestyle people led, the more likely they were to retain mental function near the end of life. Each additional healthy lifestyle score was associated with higher scores on cognitive tests.
However, this relationship had little correlation with brain changes detected at autopsy. In analyzing the autopsies, the researchers focused on typical neurological signs of dementia. These included the presence of clusters of amyloid plaques and neurofibrillary tubules in brain tissue, as well as blood flow impairing changes in the vascular system that can occur as a result of microstroke or stroke.
It turned out that even if the above signs were found in the brain of a deceased person who followed a healthy lifestyle, their mental performance was still high. The only thing, the researchers found that a healthier lifestyle was still associated with a slightly less pronounced accumulation of amyloid plaques in the brain.
The findings reinforce the suggestion that a healthy lifestyle provides the aging brain with a cognitive reserve that allows it to continue to function normally despite the changes that typically signal the development of dementia.
Liron Sinvani, a professor of medicine who was not involved in the study but commented on it, likened the effect to a trick that allows you to cheat a little biology. If you take two people with the same cluster of abnormal proteins in their brains, she said, the person with the healthier life style will retain better cognitively.
"You'll be able to function normally, without impairment, and for longer," the medical professional explained.