The brain can compensate for age-related cognitive decline

Particularly in older adults

New research has revealed the strongest evidence that the human brain can compensate for age-related cognitive decline by recruiting alternative brain regions to maintain cognitive function. This breakthrough could explain why some older adults preserve cognitive abilities better than others.

As we age, our brains undergo a natural process of atrophy, losing nerve cells and connections. This can contribute to the decline of cognitive abilities. Despite this, some individuals maintain superior brain function as they age. Researchers have long suspected that the brain might counteract this decline by activating other areas to support cognitive tasks. However, the exact mechanism behind this compensation has remained unclear.

A new study published in eLife, led by scientists from the University of Cambridge in collaboration with the University of Sussex, has shown compelling evidence that when the brain compensates for age-related decline, it can improve performance on cognitive tasks, particularly in older adults.

Dr Kamen Tsvetanov, an Alzheimer’s Society Dementia Research Leader Fellow at Cambridge, noted that “our ability to solve abstract problems is a sign of so-called ‘fluid intelligence,’ but as we age, this ability shows a significant decline. Some people manage to maintain this ability better than others. We wanted to ask why that was the case—are they able to recruit other areas of the brain to overcome changes in the brain that would otherwise be detrimental?”

The study explored this question by focusing on fluid intelligence tasks requiring the brain to solve abstract problems. These tasks engage a network of brain regions known as the multiple demand network (MDN), located at both the front and rear of the brain. However, MDN activity naturally decreases with age. The Cambridge team aimed to determine whether the brain compensates for this decrease by activating other brain areas.

223 participants

To investigate this, the researchers examined brain activity in 223 participants aged between 19 and 87 using functional magnetic resonance imaging (fMRI). During the study, volunteers were asked to complete puzzles of varying difficulty, designed to assess their fluid intelligence, while lying in an fMRI scanner that measured changes in blood flow to identify active brain regions.

As expected, the study found that older participants showed a general decline in their ability to solve puzzles, with the MDN showing reduced activity compared to younger adults. However, the researchers also discovered something unexpected: two brain regions in older adults showed increased activity, which correlated with better performance on the task. These regions were the cuneus, located at the brain’s rear, and an area in the frontal cortex.

Interestingly, the cuneus, rather than the frontal cortex, demonstrated a powerful link to improved task performance in older adults. While it is not fully understood why this region is recruited for fluid intelligence tasks, the researchers believe that the cuneus plays a crucial role in helping individuals stay focused on visual information.

This is particularly important for older adults, who often struggle with retaining brief visual information, such as the complex puzzle pieces used in the study. The increased activity in the cuneus may reflect a compensatory strategy: Older adults pay closer attention to the pieces, improving their ability to remember and process them.

New questions

Dr Ethan Knights, a collaborator from the Medical Research Council Cognition and Brain Sciences Unit at Cambridge, highlighted the significance of this discovery, stating: “Now that we’ve seen this compensation happening, we can start to ask questions about why it happens for some older people, but not others, and in some tasks, but not others. Is there something special about these people—like their education or lifestyle—and if so, is there a way we can intervene to help others see similar benefits?”

The findings suggest that the brain’s ability to compensate for age-related decline might not be limited to the MDN, as previously thought. Instead, the brain appears to recruit other areas, such as the cuneus, which retain their function even in older age.

Dr Alexa Morcom from the University of Sussex’s School of Psychology also commented on the research, saying, “This new finding also hints that compensation in later life does not rely on the multiple demand network as previously assumed, but recruits areas whose function is preserved in ageing.”

This research opens up new avenues for understanding how the brain adapts to age-related decline and could inform strategies to help older individuals preserve cognitive function for longer. Future studies may focus on identifying specific lifestyle factors, such as education, physical activity, or mental stimulation, that could help boost the brain’s compensatory abilities.

The study was funded by the Medical Research Council, the Biotechnology and Biological Sciences Research Council, the European Union’s Horizon 2020 research and innovation programme, the Guarantors of Brain, and the Alzheimer’s Society.

Hero image: Researchers believe the cuneus is crucial in helping individuals focus on visual information. Credit: Murat Marangoz