When most people think of dementia, specifically Alzheimer’s disease, they often think of memory loss first.
However, dementia changes a person’s behavior, whether it causes them to become agitated or anxious, sad, nervous or apathetic, or even changes their entire personality.
Over time, these behavioral changes can cause as much disruption to their lives as losing their ability to think and remember effectively.
Now, a team of researchers at the University of Michigan reports new clues as to what may be happening in the brains of people experiencing early symptoms of dementia-related behavioral changes.
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Using two types of advanced medical imaging to study the brains of 128 people in the early stages of dementia, they found a link between levels of a protein called tau, one of the brain’s most important communication networks, and a person’s behavioral symptoms. Show relationships.
This goes beyond the role of tau that scientists already know about in people with more advanced dementia: causing tangled nerve fibers in brain areas involved in thinking and memory.
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New study shows that tau disrupts the integrity of the brain’s salience network. This highway of connections between specific brain areas is vital to our ability to understand and decide how to react to things happening around us. It also helps us process our thoughts and emotions.
The researchers showed that the more a person’s salience network is disrupted in the presence of tau, the greater the changes in that person’s behavior. They report their findings in Alzheimer’s and Dementia: The Journal of the Alzheimer’s Association.
Although one-time imaging of these 128 research volunteers can’t show cause and effect, the team says the strong connection between tau, salience network disruption and behavioral changes is interesting.
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They call for further study of potential connections in other populations, and research to evaluate changes over time to find out what is happening within the pathways of connected brain cells that form key networks. make, and explore how it relates to tau buildup and changes in behavior over the years.
They also hope to test whether they could slow behavioral changes in people with early-stage dementia by targeting key networks with mild electric current or magnetic fields applied from outside the skull and guided by precise imaging. Are.
Researchers in the Research Program on Cognition and Neuromodulation Based Interventions (RP-CNBI) are led by Alexandru D. Iordan, Ph.D. Done through. and program leader Benjamin M. Hempstead, Ph.D. Both are faculty in the UM Medical School’s Department of Psychiatry.
Iordan, a neuroscientist who is lead author of the new study, says, “What we see is that the presence of tau pathology is not in direct relation to behavioral symptoms, but rather through dysfunction of a specific network in the brain. Is – the salience network. The more this network is affected, the more severe the behavioral symptoms will be.”
He adds, “This is the first study to link an individual’s biomarker status to dysfunction of this network and behavioral symptoms in people on the Alzheimer’s disease spectrum.”
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The team used functional magnetic resonance imaging, or fMRI, to study each volunteer’s brain and discover three distinct networks that connect far-flung areas of the brain. They used a measure called the network separation index to measure how functionally independent each network was relative to other brain networks.
They combined the fMRI findings with the results of neuropsychological tests and behavioral questionnaires taken by the volunteers. They also looked at the results of positron emission tomography, or PET, scans, which showed whether the person had excess tau protein as well as beta amyloid, another Alzheimer’s-related protein, in their brain.
The salience network was the only one of the three networks whose level of integrity was related to the presence of tau and the severity of dementia-related behavioral issues. It appears that the default-mode network is involved as a supporting player. The third network studied, called the frontoparietal network, was not related to behavioral symptoms.
The new study showed that unlike tau, just the presence of amyloid in the brains of some volunteers was not related to salience network issues or that person’s level of behavioral symptoms.
Iordan says the salience network is also thought to be involved in some mental disorders and in frontotemporal dementia, a type of early-onset, rapidly progressing dementia marked primarily by behavioral and personality changes.
Iordan says PET scans for tau and amyloid are now used in the diagnosis of dementia and in the management of treatment with new drugs aimed at reducing the buildup of amyloid with the goal of slowing cognitive decline. .
But blood tests that can also detect the presence of tau and amyloid, and use them as biomarkers of dementia risk, are also beginning to become available. Because they are much less expensive than PET scans, they may also be useful in future studies of tau’s role in behavioral change, he says.
Further research may help to explain and even predict variation in the speed of onset and decline of behavioral changes in people with dementia. It may also lead to ways to identify people whose changes in behavior are the earliest detectable sign of dementia risk, even before changes in cognitive ability.
But the most exciting thing for Iordan and his colleagues?
“Our findings provide us with a functional target for potential intervention,” he said. “Dr. We will soon be able to see whether brain stimulation changes these relationships, thanks to a large study led by Hempstead, which evaluated the effects of different doses of weak electrical currents applied to the brain. This large study is nearing completion, and we are very excited to see what the results show, so stay tuned!”
Disclaimer: This article is for informational purposes only and is not a substitute for professional medical advice. Always seek the advice of your doctor with any questions you may have about a medical condition.
