As we age, our brains generally become slower and our memories less reliable – but there is a group of older people that appears to be unaffected by time. These superagers, as they are called, have been shown to have remarkable memories that are significantly better than people in the same age group.
For the first time, researchers have been able to understand why this might be the case. MRI images of the brains of superagers with an average age of 67 are remarkably similar to the brain of 25-year-olds. No matter the age difference, the older adults had somehow retained youthful activity patterns in their brains. The findings are published in the journal Cerebral Cortex.
"This is the first time we have images of the function of superagers' brains as they actively learn and remember new information," senior author Dr Alexandra Touroutoglou, from the Massachusetts General Hospital, said in a statement. "Using MRI, we found that the structure of superagers' brains and the connectivity of their neural networks more closely resemble the brains of young adults; superagers had avoided the brain atrophy typically seen in older adults."
The study involved 40 adults over the age of 65 and 41 young adults with a mean age of 25. Each one of them took the same memory test while functional magnetic resonance imaging (fMRI) recorded the activity in their brain. The test had the individuals going through 80 images featuring either a face or a scene. Each image was associated with an adjective. Examples of this were a cityscape with the word "industrial" or a picture of a guy’s face with the word "average".
During this part of the test, the subject determined if the words matched the image. After 10 minutes, each person was presented with the original 80 images and words, 40 new images and words, and 40 images they had previously seen but with different words. The task in this part of the test was to assess if they had seen the pair before, and if they hadn't, if they were looking at a new image or at an old image with a new word. The fMRI tracked how the brain in these people worked while the test was being carried out.
"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," added lead author Dr Yuta Katsumi, also at the Massachusetts General Hospital. "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."
During aging, this ability to select the categories declines – but this doesn’t seem the case for superagers. Their brain acts just like the people 40 years younger than them. The team is unsure if they always had this ability or if something is compensating for the natural decline of an aging brain.
Previous studies have shown that this part of the memory can be trained, so maybe superagers are not born – they are made. Researchers are planning to study these people in more detail to better understand how they keep their brains so young.