Why do some octogenarians have exceptional memories?
Research from the University of Chicago looked at 'superagers' - people over 80 years who have the memory of someone decades younger - to try to understand why.
When researchers looked at MRI scans of so called ‘superagers’, something surprising was revealed, Emily Rogalski, Professor of Neurology at the University of Chicago says.
“What we showed in those studies, by using MRI scans and really sophisticated technology, was that the youthfulness of the brain of the superagers more represented those 50- to 60-year-olds than 80 year olds, so their brains looked younger than expected.
“This was a big surprise, that despite being 80 plus years old, they could have very youthful looking brains.”
The thickness of the outer layer of the brain was also found to be a factor in better performing memory.
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Research in the area is starting to gain a better understanding of why this might be from a genetic and a lifestyle standpoint, she says.
“We see that superagers tend to have really strong social connections, and we first learned about that from self-report on questionnaires, and we're now following up through a multi-site study that we lead here.”
They are enrolling superagers across five sites in the US and Canada who are asked to wear sensors that track sleep and activity and social connection, she says.
“So that we can understand, do superagers talk to more people during the day than an average ager, or do they have a handful of close friends?
“So, we're looking both from a biologic standpoint, but also from a psychosocial standpoint.”
Unlocking the secrets of the "superagers"
The research also revealed physical differences between superagers and their more averagely aged peers, she said.
“We are measuring both the size of brain cells or neurons, and we see that for some superagers, it's not necessarily the number of neurons, but the size of neurons in memory-related areas that seems to be more robust or more well preserved in superagers,” she says.
There is also less build-up of plaques and tangles in the brain, she says - things that are associated with Alzheimer's disease diagnoses.
“What we see that in superagers is there tends to be fewer of those tangles in memory-related areas of the brain relative to average agers.
“So, that seems to be another cellular difference between the groups, but there is some variability, and it's still relatively early days.”
The thickness of the outer layer of the brain was also found to be a factor in better performing memory, she says.
“The outer layer of the brain, or what we call the cortex, where our neurons live, when we did that original MRI comparison, we found a region of the brain called the anterior cingulate, which is really important for attention, and attention supports memory.
"We found that that region was actually thicker in superagers than it was in their 50- to 60-year-old peers.”
A possible explanation is an abundance of a particular type of neuron, she says.
“A special type of neurons called Von Economo neurons. These are more newly described neurons, and they are thought to be important for social behaviours.”
The loss, or abnormal development, of Von Economo neurons has been shown in Alzheimer's disease, schizophrenia, bipolar disorder and ADHD, she says.
“It may be one factor that's contributing to superagers social interactions, because these Von Economo neurons are also only described in higher order species and tend to be very social, like elephants and whales.”
