The Remarkable Brains of ‘Superagers’: Study Reveals the Cognitive Differences in Older Adults Who Defy Memory Loss
We all know someone who seems to resist the memory loss typically seen in older adults, remaining sharp as a tack no matter their age. Instead of succumbing to age-related cognitive decline, this lucky group of people experiences mental sharpness well into their 70s, 80s, and beyond. Coined as ‘superagers,’ these rare individuals may be growing older each year — but their brains are not.
Unsurprisingly, researchers are highly interested in what makes superagers’ brains stay strong through the decades. Now, a research team out of Harvard Medical School and Massachusetts General Hospital finds that superagers show distinct structural and functional changes in their brains, keeping their memory and recall abilities similar to that of 25-year-olds. Published in the journal Cerebral Cortex, this study provides groundbreaking data about how the brains of superagers differ from typical older adults. As stated by senior author Alexandra Touroutoglou, Ph.D., “This is the first time we have images of the function of superagers’ brains as they actively learn and remember new information.”
How the Mind Makes Memories
Many aspects of cognition tend to decline with age, including episodic memory (recalling specific episodes from past experiences), executive control (higher-level cognitive skills, like thinking before acting), and processing speed (how quickly and efficiently someone understands and reacts to the information they receive.)
When it comes to making (and keeping) memories, there are three essential stages that the brain goes through — encoding, storage, and retrieval. When information comes into our brain from sensory input (like reading a book or meeting someone new), it is first changed or encoded into a form our brains can use. This stage uses the visual cortex — the brain area that receives and processes what we see and turns it into storable information. The visual cortex is sensitive to functional deterioration with age, as older adults exhibit inhibition and reduced plasticity, or adaptability, of this region.
As lead author Yuta Katsumi, Ph.D., explains, “In the visual cortex, there are populations of neurons that are selectively involved in processing different categories of images, such as faces, houses, or scenes. This selective function of each group of neurons makes them more efficient at processing what you see and creating a distinct memory of those images, which can then easily be retrieved.”
The ability of neurons to efficiently select and process images is known as neural differentiation. This process diminishes with age, as the neurons that once precisely responded to an image of someone’s face, for example, may now activate for someone or something else. Older adults are less likely to encode new information with all of the same details and precision as they did when they were younger, making it more difficult to retrieve the correct information later — also known as neural dedifferentiation or reduced selective activation.
Similarly, older adults can also experience a loss of memory retrieval — meaning, they can store a memory but may have trouble accessing it when needed (this could look like forgetting someone’s name or having a word “on the tip of your tongue.”) While this forgetfulness can certainly happen at any age, it’s increasingly more common for declining memory retrieval to occur with advancing age.
Superagers Show Superior Brain Power
So, what do superagers’ brains do differently? Katsumi and colleagues aimed to find out by comparing neuroimaging scans — functional magnetic resonance imaging (fMRI) — between three groups of adults: young adults aged 18 to 35, “typically aged” older adults, and older adults aged 60 to 80 who were classified as superagers.
While their brains were being fMRI scanned, the participants viewed 80 image-word pairs and were asked to judge within 6 seconds whether the word matched the image, which measured memory encoding. (For example, they would decide the accuracy of an image of the woods paired with the word “friendly,” or if a cityscape paired with the word “industrial.”) After ten minutes, they saw 40 of the same image-word pairs with 40 new ones and had to quickly judge whether they had previously seen the pair or not, assessing memory retrieval.
Katsumi and colleagues described the results as remarkable — the older adult superagers scored the same as the young adults on this challenging memory test, while the typically-aged older adults performed significantly worse. Plus, the superagers’ brains exhibited youthful patterns on the brain scans, showing similar activity in their visual cortex regions and selective activation abilities as the young adults. The greater, more youthful neural differentiation patterns then predicted better recognition memory performance in the superagers.
“The superagers had maintained the same high level of neural differentiation, or selectivity, as a young adult,” says Katsumi. “Their brains enabled them to create distinct representations of the different categories of visual information so that they could accurately remember the image-word pairs.”
Can We All Be Superagers?
This study advances our understanding of how neural activity differs between young, old, and superager adults and how these variations alter memory encoding, storage, and retrieval. As maintaining memory is a significant component of supporting cognitive vitality with age, this research could set the stage for novel therapies that stimulate the brain to become more “superager-like.”
Currently, the research team is undergoing a clinical trial to test the efficacy of non-invasive electromagnetic brain stimulation, which can target electrical currents to specific brain regions. Additionally, the Harvard-based researchers are studying how other brain regions are involved in maintaining memory with age and how diet, exercise, and other lifestyle factors play a role in supporting superagers’ brains. (Previous research has found that maintaining friendships and social engagements, mentally stimulating hobbies like puzzles or chess, moderate exercise, and light alcohol consumption contribute to superager-like brains.)
As the authors conclude, ”These findings have implications not only for our understanding of the possible mechanisms of successful cognitive aging but also for possible interventions to promote brain health. Given that the fidelity of sensory processing is dependent on neural plasticity and is possible to improve with training, neural differentiation may be one potential biomarker to be targeted by future interventions to promote superaging.”
Katsumi Y, Andreano JM, Barrett LF, Dickerson BC, Touroutoglou A. Greater Neural Differentiation in the Ventral Visual Cortex Is Associated with Youthful Memory in Superaging [published online ahead of print, 2021 Jun 30]. Cereb Cortex. 2021;bhab157. doi:10.1093/cercor/bhab157
Maccora J, Peters R, Anstey KJ. Gender Differences in Superior-memory SuperAgers and Associated Factors in an Australian Cohort. J Appl Gerontol. 2021;40(4):433-442. doi:10.1177/0733464820902943