Study reveals strongest evidence yet on brain’s ability to compensate for age-related cognitive decline

Scientists have discovered the strongest evidence yet that our brains can compensate for age-related deterioration by recruiting other areas to contribute to brain function and maintain cognitive performance.

As we age, our brains gradually atrophy, losing nerve cells and connections, which can lead to a decline in brain function. We don’t really understand why some people seem to maintain better brain function than others and how we can protect ourselves from cognitive decline.

A widely accepted notion is that some people’s brains are able to compensate for deteriorating brain tissue by recruiting other areas of the brain to help them perform tasks. Although brain imaging studies have shown that the brain recruits other areas, it was not clear until now whether this made a difference in task performance or whether it provided additional information about way to accomplish this task.

In a study published in the journal eLifea team led by scientists from the University of Cambridge in collaboration with the University of Sussex has shown that when the brain recruits other areas, it improves its performance, particularly in the brains of older people.

Dr Kamen Tsvetanov, study leader and Alzheimer’s Society dementia researcher at the Department of Clinical Neuroscience at the University of Cambridge, said: “Our ability to solve abstract problems is a sign that we called “fluid intelligence,” but as we get older, this ability begins to show a significant decline. Some people are able to maintain this ability better than others.

“We wanted to ask why this was the case: Are they able to recruit other areas of the brain to overcome changes in the brain that would otherwise be detrimental?”

Brain imaging studies have shown that fluid intelligence tasks tap the “multiple demand network” (MDN), a brain network involving regions both in the front and back of the brain, but whose activity decreases with age. To see if the brain compensated for this decrease in activity, the Cambridge team examined imaging data from 223 adults aged 19 to 87 recruited by the Cambridge Center for Aging & Neuroscience (Cam-CAN).

Volunteers were asked to identify the intruder in a series of puzzles of varying difficulty while lying in a functional magnetic resonance imaging (fMRI) scanner so that researchers could examine brain activity patterns by measuring changes in blood flow.

As expected, in general, problem-solving ability declines with age. The MDN was particularly active, as were brain regions involved in processing visual information.

When the team analyzed the images in more detail using machine learning, they discovered two areas of the brain that showed greater activity in older adults and were also correlated with better performance in the task . These areas were the cuneus at the back of the brain and a region of the frontal cortex.

But of the two, only activity in the cuneus region was more strongly related to task performance in older than younger volunteers and contained additional information about the task beyond the MDN.

Although it’s unclear why the cuneus should be recruited for this task, researchers point out that this brain region is generally effective at helping us stay focused on what we’re seeing. Older adults often have more difficulty briefly recalling information they have just seen, such as the complex puzzle pieces used in the task. The increased activity in the cuneus could reflect a change in how often older adults look at these pieces as a strategy to compensate for their weaker visual memory.

Dr Ethan Knights from the Medical Research Council’s Cognition and Brain Sciences Unit in Cambridge said: “Now that we have seen this compensation happening, we can start to ask questions about why this happens. produced in some older adults, but not others, and in some tasks, but not others. Is there something special about these people – their upbringing or lifestyle, for example – and if so, is there a way we can intervene to help others see similar benefits? »

Dr Alexa Morcom from the Sussex School of Psychology and Neuroscience Research Center at the University of Sussex said: “This new finding also suggests that compensation in later life does not rely on the network of demands multiple as previously assumed, but recruits domains whose function is preserved in aging.”