New Delhi: Ageing memories may not be “worse,” just different, a new study suggests. While it may not always be the first sign of ageing, some faculties, including memory, do get worse as people age. But the process may not be as straightforward as it seems.
Zachariah Reagh, assistant professor of psychological and brain sciences at Washington University in St. Louis, looked at the brain activity of older people not by requiring them to recite a group of words or remember a string of numbers.
Instead, Reagh looked at a “naturalistic approach,” one that more closely resembled real-world activities. He found that brain activity in older adults isn’t necessarily quieter when it comes to memory. “It’s just different,” he says.
Common tests of memory involve a person’s ability to remember a string of words, count backward, or recognize repeated images. “How many times do you suspect a 75-year-old is going to have to remember, ‘tree, apple, cherry, truck?'” asked Reagh, first author on the paper with Angelique Delarazan, Alexander Garber, and Charan Ranganath, all of the University of California, Davis. Instead, he used a data set from the Cambridge Centre for Ageing and Neuroscience (Cam-CAN) that included functional MRI (fMRI) scans of people watching an 8-minute movie. “There were no specific instructions, or a ‘gotcha’ moment,” Reagh says. “They just got to kick back, relax, and enjoy the film.”
But while they may have been relaxing, the subjects’ brains were hard at work recognizing, interpreting, and categorizing events in the movies. One particular way people categorize events is by marking boundaries—where one event ends and another begins.
An “event” can be pretty much anything, Reagh says. “This conversation, or a component of it, for example. We take these meaningful pieces and extract them out of a continuous stream.”
And what constitutes a boundary is actually consistent among people. “If you and I watch the same movie, and we are given the instruction to press a button when we feel one meaningful unit has ended, you and I will be much more similar in our responses than we are different,” Reagh says.
When looking at the fMRI results—which use changes in blood flow and blood oxygen to highlight brain activity—older adults showed similarly increased activity as a control group at the boundaries of events. That’s not to say that brains of all ages are processing the information similarly. “It’s just different,” Reagh says. “In some areas, activity goes down and, in some, it actually goes up. Overall activity did decline pretty reliably across ages 18-88, Reagh says, and when grouped into “younger, middle aged, and older,” there was a statistically reliable drop in activity from one group to another.
