A small percentage of people retain their razor-sharp memory well into their 80s and beyond, and now researchers have the first clue to explain why.
With “normal” aging, most people see a decline in their memory, starting in their 40s or 50s. These so- called “SuperAgers” show no such decline. When tested for memory, SuperAgers in their 80s score as well as and sometimes better than those 20 to 30 years younger.
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Researcher Emily Rogalski, assistant research professor at the Cognitive Neurology and Alzheimer's Disease Center at Northwestern University Feinberg School of Medicine in Chicago, wondered what was going on in the brains of the elderly who seemed so resistant to memory loss.
“Instead of trying to understand what is going wrong with the brain, we are attempting to identify factors that contribute to optimal cognitive aging,” Rogalski said.
To that end, she and her co-authors conducted MRI scans on the brains of 12 SuperAgers and compared them to two control groups—10 normally aging (for example, forgetful) 80 year olds and 12 middle-aged adults (between 50 and 65) who were also aging normally.
To be defined as a SuperAger, the elder participants needed to score at or above the norm of the 50 to 65 year olds on memory screenings, specifically the recall of facts. Incidentally, only 10 percent of those who believed they still had great memories met the criteria, suggesting that a very small percent of the population are SuperAgers.
The MRI scans assessed a region of the brain called the cortex, familiarly known as grey matter, the layer of the brain that’s important for memory, attention and other cognitive skills. The thickness of the cortex is related to the number of neurons in the brain. The study, published in the Journal of the International Neuropsychological Society, found that the cortex of the SuperAgers was much thicker than that of the normal elderly and about equal to the cortex of the adults 20 to 30 years younger than them. The normally aging elderly showed significant thinning of the cortex.
“These findings are remarkable given the fact that grey matter or brain cell loss is a common part of normal aging,” Rogalski said.
At this point it is unclear whether SuperAgers were born with a particularly thick cortex or whether their brains simply didn’t thin over time. But the study did not find that SuperAgers were any more educated or had a greater memory when younger than the controls.
The study also found that a particular region of the cortex associated with attention, called the cingulate cortex, was significantly thicker in SuperAgers than even in the middle-aged subjects.
“This is pretty incredible,” Rogalski said. “Attention supports memory. It’s possible that SuperAgers have particularly keen attentional abilities that may help them maintain superior memory performance in old age."
These findings provide evidence that maintaining a superior memory into old age is biologically possible, said Rogalski.
This study is part of a larger study on SuperAgers. The Northwestern researchers are following these individuals, while collecting information about their genetic background, lifestyle and medical history. The SuperAgers have also agreed to donate their brains at the time of death.
By looking at SuperAgers who seem to be protected from memory loss, the researchers hope to find what factors contribute to that longevity, ultimately leading to the development of treatments that can forestall memory loss or even Alzheimer’s disease.