Try as we might to prevent it, we all age. Over time, we develop laugh lines and crow’s feet, stiffer joints, and it becomes harder to remember names and dates like we used to.
While physical changes may be written off as normal wear and tear, scientists aren’t sure why only some people decline mentally over time. Now, though, research from a team at Massachusetts General Hospital (MGH) published (paywall) Sept. 13 in the Journal of Neuroscience shows that there’s actually a physical difference in the brains of older adults who have as good memories as young adults. By observing these differences, researchers hope to understand more about preventative measures individuals can take to preserve their cognitive abilities.
It’s common for people to experience some kind of memory decrease with age. While some indicators of mental sharpness, like vocabulary, tend to stay intact, others, like rote memorization, tend to become inferior to those seen in younger adults. Healthy young adults around 25 years old can usually remember 14 out of 16 random words off the tops of their heads in a basic memory test, whereas the average 75-year-old remembers only nine.
But some people’s memories stay youthful. It’s hard to say how many; in past experiments researchers found that 10% of subjects could be counted as so-called “super agers,” but in the MGH study, the number was closer to 50%.
The research team at MGH studied 81 healthy patients from Boston with similar levels of education, 41 of whom were between 18 and 35 years old and 40 of whom were between 60 and 80 years old. Researchers gave each individual several tests to study their general cognitive abilities, like word memorization and focus, and identified 17 super agers from the older group. These individuals performed just as well—and even slightly better, in some cases—as the younger group.
The next day, researchers took images of the participants’ brains. They found that super agers’ brains had a thicker cortex than in their peers’ brains. The cortex—which normally shrinks with age—houses two different networks made of eight smaller areas. These networks are called the “default mode network” and the “salient network,” and are involved in learning and recalling information and the focus needed to do so, respectively. Super agers’ tended to have cortices that were as big or nearly as big as younger participants’.
Based on this research, the team thinks that the differences in memory recall in super agers and other older adults has something to do with these variations in brain anatomy. The next step for them will be to examine the different factors that may slow or speed up the shrinking of the cortex over time, like diet, exercise, social habits, and genetics.
“We desperately need to understand how some older adults are able to function very well into their seventh, eighth, and ninth decades,” said Bradford Dickerson, a physician at MGH and co-author of the paper, in a statement. “This could provide important clues about how to prevent the decline in memory and thinking that accompanies aging in most of us.”