Improved brain mapping reveals subtle cognitive changes in older adults with preclinical Alzheimer’s disease

Neuroscientists at the Medical University of South Carolina (MUSC) brain connectivity They found subtle differences in how the brains of older people in the preclinical stages of Alzheimer’s disease (AD) function.

Adults with preclinical AD show the earliest signs of the disease, including accumulation of amyloid-beta protein in the brain. However, there are no notable symptoms of cognitive decline.

A research team led by Dr. Andreana Benitez and Dr. Stephanie Fountain-Zaragoza used a novel brain-imaging technique to create personalized maps of brain function. Next, we investigated whether there was an association between subtle changes in brain function and cognitive decline and assessed using behavior-based tests. This approach may improve our ability to study the preclinical stages of AD.

Previous studies have not found an association between brain function and behavior in preclinical AD. Using these individualized maps of brain function, we have discovered potential brain-based reasons for highly subtle cognitive changes in the early stages of this disease.”

Dr. Andreana Benitez

Detect subtle changes in brain function with improved brain mapping

Studies of the preclinical stages of Alzheimer’s disease may help us understand how the disease begins and progresses. However, early changes in brain function are very subtle and difficult to study. Funded by the South Carolina Clinical and Translational Institute for a pilot project, MUSC researchers used a new form of brain mapping to detect these subtle effects.

They used the functional connectome to examine brain activity. This is a type of brain map that measures how different brain regions communicate with each other. Think of your brain like a big city, according to Fountain-Zaragoza. There, areas of the brain are clustered in regions connected by highways. A functional connectome is like observing the activity of the whole city. That is, how much is happening within each region and how well traffic flows between them.

Researchers have relied on newer and more sensitive forms of image analysis to assess how these neighborhoods perform within individuals. This technique – an individualized functional connectome – was developed by his collaborator Dr. Hesheng Liu.

The traditional functional connectome uses the brain average of many people as a map of functional brain regions. In contrast, Liu’s method can show unique patterns of brain function in each individual.

“We all have the same functional parts of the brain, but they are like fingerprints, in slightly different locations,” said Fountain-Zaragoza. It creates an individualized brain fingerprint that more accurately reflects where functional areas are located.”

Linking subtle changes in brain function to behavior

Researchers used this novel brain fingerprinting technology to look for subtle changes in brain function in 149 participants between the ages of 45 and 85, without signs of cognitive decline. All participants underwent her PET scan of the brain and were divided into two groups. Groups with and without evidence of early amyloid-beta protein accumulation by PET scan. Participants also underwent MRI scans used to generate brain fingerprints.

The researchers then tested how well participants in each group performed on behavior-based tests of information processing. They found that specific changes in brain fingerprints were associated with amyloid-beta accumulation, or worsening of information processing in participants with preclinical AD.

In participants with preclinical AD, information processing was worse in those with greater than normal connections between networks or with too much activity on brain highways. People with higher S, or more brain activity within key regions of the brain, were better at processing information.

“A healthy brain typically balances connections within and between networks,” says Fountain-Zaragoza. “We found that in preclinical AD, where there is amyloid accumulation in the brain, this balance may be disrupted and information may not be processed efficiently.”

What Research Tells Us

This study demonstrates that individualized functional connectomes can detect subtle changes in brain function that may be missed by other conventional brain imaging techniques.

It also suggests that early stages of amyloid-β accumulation may affect the function of brain networks, even before symptoms of cognitive decline become prominent.

Finally, we reveal that changes in connectivity within and between specific brain networks may indicate early problems in information processing. This connectivity imbalance may therefore be a good target for therapy to improve outcomes in patients with AD.

next step

A new grant from the National Institute on Aging will allow Benitez and Fountain-Zaragoza to continue their work in preclinical AD. They want to focus more on how changes in the brain affect the progression of the disease, and on exploring new treatments, such as brain stimulation, that could help slow the progression. I’m here.

“There is a lot of great research aimed at helping us understand the early signs and symptoms of Alzheimer’s disease,” said Fountain-Zaragoza. It’s important to identify if you’re at risk of developing it.”