Memory disorder diagnoses may benefit from seeing brain as networks

Looking at the brain as a highly interactive network of nodes, rather than a collection of individual areas of activity, could offer a new way to diagnose the memory disorders that tend to affect older people.

"By studying the brain as a network, we are, in a sense, adjusting our perspective - akin to examining the patterns that make up constellations of stars instead of focusing on each of the individual stars," says Prof. Wig.

This was the conclusion that researchers from the Center for Vital Longevity (CVL) at the University of Texas (UT) at Dallas came to in a study they reported in the Proceedings of the National Academy of Sciences (PNAS).

The researchers at UT Dallas School of Behavioral and Brain Sciences examined how brain areas talk to each other to form brain networks and how these change with age.

The research team says brain networks are not unlike social and technological networks; they comprise groups of highly interactive nodes, and:

"These nodes all communicate with one another in a large-scale brain network. A considerable amount of research has highlighted how older adults use different brain areas than younger adults when performing the same tasks."

The research team explains that their approach offers an alternative way to evaluate the differences between the younger and the older brain that focuses on the brain as a network.

By studying the brain as a network, we are, in a sense, adjusting our perspective - akin to examining the patterns that make up constellations of stars instead of focusing on each of the individual stars.

The older the brain, the less segregated the sub-networks

For their study, the researchers looked at how separate sub-networks of the brain come together to operate specialized functions.

They found that the older the brain, the less segregated the sub-networks. They also found that less segregation was more strongly tied to poorer long-term memory, independent of age.

The research team suggests perhaps measuring the extent of segregation among the brain's sub-networks could be a way to predict memory decline.

The team examined data from the Dallas Lifespan Brain Study. The data they analyzed came from 210 healthy adults aged between 20 and 89 who completed assessments of thinking and memory.

The participants also underwent brain scans while they were thinking of nothing in particular. The brain scans were used as a measure of brain connectivity.

To analyze the results, the researchers looked at the brain connections from a network point of view. To do this, they used graph theory - an area of mathematics that is used for studying traffic flows, disease spread and social networks, such as Facebook.

They found the brain networks in the younger brains tended to show lots of connections within the networks that are associated with processing of specific tasks, and fewer connections that aid communication between networks.

But this distinction was less noticeable in the older brain. Prof. Wig says they found that segregation between brain networks reduced as age increased.

Funding for the study came from the National Institute on Aging, a part of the National Institutes of Health.

In another recently published study, another team of researchers explained how they found that injury to brain hubs does more damage. They showed how damage to brain hubs disrupts people's capacity to think and adapt to everyday challenges more severely than damage to locations that are distant from hubs.