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by Candy Sagon
Updated September 28, 2022
My father is 95 and he’s mentally alert — enough so to give me some good tax advice, handle paying invoices for my brother’s advertising business, and remember the birthdays of all his kids, grandkids and great-grandson.
But not all older adults are like him. Why not? Why do some older adults have a better memory than others?
Understanding differences between individuals is crucial for understanding how memory functions or declines in older adults, say researchers with Stanford University’s Aging and Memory Study. It might eventually help identify when certain memory failures signal a greater risk for dementia.
In a May 2020 study of 100 healthy adults ages 60 to 82, published in the journal eLife, a team of Stanford researchers scanned the participants’ brains as they took memory tests. First the participants were shown words paired with pictures of famous people and places. Then brain scans were taken as they were given just the words and asked to recall the accompanying picture.
Due to advances in brain imaging technology, researchers are able to see and measure activity in the entire brain at high resolution. They could watch the activity in the brain’s hippocampus and cortex regions as they mentally recreated the event — the word-picture pair — that the person needed to remember.
“We could predict whether or not an individual would remember at a given moment in time” based on the patterns of brain activity seen in the scans, lead author Alexandra Trelle said in a statement.
What researchers found was that the heightened brain activity they observed in some of the older adults “looked remarkably similar to that of a 20-year-old. This was true regardless of one’s actual age, and was observed in individuals from age 60 to 75,” Trelle said.
“These results deepen our understanding of brain resilience and counter the idea that brain aging is inevitable.”
However, the scans also indicated that in the brains of those who had trouble remembering, activity in these regions was noticeably reduced.
What seems to be key is the relationship between the hippocampus, a complex structure deep in the brain that plays a major role in learning and memory, and part of the brain responsible for storing short-term information. When a person is trying to remember, these regions send and retrieve bits of information back and forth to help reconstruct a memory.
Regardless of age, a stronger, more active relationship between the hippocampus and the cortex was linked to better memory in the study. This was true not only for the memory test conducted during the scan, but also memory tests administered on a different day of the study.
Other parts of the brain are involved as well, which may explain why there was an age-related decline in certain tasks but not others, Trelle said.
“We found that areas of the brain that are involved in perceiving and remembering visual details of our experiences, such as places we’ve been and people we’ve encountered, did decline with age on average. This might explain why recalling specific details of past experiences can become more difficult as we get older,” she said.
What you need to know:
Knowing what is going on in the brain during memory recall is useful, but what advice does this research offer people who want to strengthen that memory process and reduce their risk of memory decline with age? Trelle, who leads the Stanford Aging and Memory Study, had these suggestions:
“Hippocampal and cortical mechanisms at retrieval explain variability in episodic remembering in older adults,” eLife, May 2020. In this study, researchers used functional MRI to measure brain activity in the hippocampus and cortex of 100 older adults (ages 60 to 82) while they completed a memory task. Results showed that a stronger relationship between the hippocampus and the cortex is associated with better memory. Read the full study.