Scientists find the source of superagers' memory

Scientists from Massachusetts General Hospital (MGH) have viewed the brain activity of ‘superagers’ to uncover how they have been able to age without the usual loss of mental capacity.

In a research paper, published in Cerebral Cortex journal, the research team gave the 40 adults with a mean age of 67 a ‘very challenging’ memory test and compared them to a second group of adults with a mean age of 25.

While completing the test, subjects’ brain activity was monitored using functional magnetic resonance imaging (fMRI), which differs from standard MRI in that it specifically shows the activity of different brain areas while tasks are being completing.

The test involved participants viewing photos of faces or scenes that were each paired with an adjective such as a city skyline paired with the word ‘industrial’ or a face paired with the word ‘average’. Subjects were asked to confirm whether the word matched to the image was appropriate.

In a second task, subjects were presented with additional pairs of words and images containing some of the same images and words but in different pairs. They were then asked to identify whether they were looking at a new pair or an old one.

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“This is the first time we have images of the function of superagers’ brains as they actively learn and remember new information,” Alexandra Touroutoglou, PhD, director of imaging operations at MGH’s frontotemporal disorders unit told Science Daily.

The results indicated that the brain structure and neural pathways seen in superagers is similar to those seen in younger people. It appears the brains of superagers don’t deteriorate as normally happens in older adults.

“Using MRI, we found that the structure of superagers’ brains and the connectivity of their neural networks more closely resemble the brains of young adults; superagers had avoided the brain atrophy typically seen in older adults,” says Dr Touroutoglou.

While subjects were in the scanner, researchers focused on the visual cortex. This is the area that processes what you see and is prone to failure as we age.

“In the visual cortex, there are populations of neurons that are selectively involved in processing different categories of images, such as faces, houses or scenes,” says Yuta Katsumi, PhD, a postdoctoral fellow in psychiatry at MGH.

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“This selective function of each group of neurons makes them more efficient at processing what you see and creating a distinct memory of those images, which can then easily be retrieved.”

This selective function, known as neural differentiation, commonly diminishes as we age and a group of neurons that once specifically recognised faces, may now activate for other images, causing confusion.

The researchers found that unlike typical older brains, the brain patterns of superagers were virtually indistinguishable from those of the younger group.

“The superagers had maintained the same high level of neural differentiation, or selectivity, as a young adult,” Dr Katsumi says.

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“Their brains enabled them to create distinct representations of the different categories of visual information so that they could accurately remember the image-word pairs.”

The question the researchers face now is whether the superagers’ brains were always this efficient, or whether they have developed mechanisms to combat the ageing process.

The MGH research team has begun a clinical trial to ascertain whether non-invasive electromagnetic stimulus to targeted areas of the brain can improve memory in older adults.

How is your memory? Are you noticing any issues as you age or is it as reliable as ever? Let us know in the comments below.

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Written by Brad Lockyer



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