Brain’s ‘wakeful rest’ network may be key to Alzheimer’s risk

Brain’s ‘wakeful rest’ network may be key to Alzheimer’s risk

Summary: In women, parts of the default-mode network responsible for memory retrieval and recall and spatial cognition were more likely to be connected to the overall DMN network. The patterns of connectivity, correlated with brain structures associated with short-term memory problems, resembled the alterations seen in preclinical Alzheimer’s disease.

Source: Yale

If you’ve ever let your mind wander, you’ve relied on the Brain’s Default Mode Network (DMN). Scientifically, the DMN is a connection of brain regions that interact when a person is in a state of wakeful rest.

This network is important for the use of our short-term memory, raising the question: do changes in the DMN play a key role in the loss of short-term memory observed in the progression of Alzheimer’s disease (AD)? ? And is DMN affected differently in women and men?

Yale Women’s Health Research Collaborator (WHRY), Carolyn Fredericks, MD, assistant professor of neurology, has worked to understand Alzheimer’s disease and why it disproportionately affects women.

Strong research shows that women clearly have an increased risk of Alzheimer’s disease compared to men. Although there has been a lot of research on AD, there are far fewer studies that take gender differences into account.

Fredericks’ latest study, published in Cerebral cortex, specifically examines gender differences in DMN connectivity in healthy aging adults. Fredericks and her team, including University of Washington sophomore medical student Bronte Ficek-Tani, set out to identify differences in these connections for women and men, which may provide clues on why the risk of Alzheimer’s disease is higher in women.

Previous studies have shown that brain connectivity within the DMN changes in association with symptomatic and preclinical AD, but investigation of gender differences in these changes has been limited. Fredericks’ study also looked at how connectivity changes in women and men as they age.

Using data from the Human Connectome Project-Aging, the team analyzed brain scans of patients who were in a state of awake rest. They found differences in how central communication points in the brain function for women and men.

For example, in females compared to males, the parts of the DMN responsible for remembering and retrieving memory and spatial cognition were more likely to be connected to the overall DMN brain network. These patterns of connectivity, correlated with brain structures responsible for short-term memory performance, resembled the changes seen in preclinical AD.

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Previous studies have shown that brain connectivity within the DMN changes in association with symptomatic and preclinical AD, but investigation of gender differences in these changes has been limited. Image is in public domain

In addition, greater gender differences were observed during aging. In their 30s and 40s, women relied more on connecting to the part of the brain responsible for spatial and verbal memory. During the decades surrounding menopause (40s and 50s), areas critical for memory retrieval showed higher connectivity to global DMN.

Males, on the other hand, showed a different pattern and their highest connectivity was observed only in their later years (60–80 years). For men, the highest connection to DMN was in a part of the brain responsible for habit formation and long-term memory.

The researchers believe their findings show that women depend more on DMN connections than men for memory and for a longer period of time. A high level of connectivity can result in a network that is under strain and more vulnerable to disorders like Alzheimer’s disease. This “wear and tear” on parts of the brain essential for memory could explain, in part, why women are at higher risk for Alzheimer’s disease.

Fredericks suggested that these findings may help doctors as well as scientists better understand memory performance and its connection to brain networks, even in people without Alzheimer’s disease, and in turn inform the type of loss. memory in Alzheimer’s disease.

By identifying patterns in the brains of healthy aging people, scientists may not only have a future target for intervention, but also have a greater window of time to treat before symptoms manifest.

About this Alzheimer’s disease research news

Author: Amanda Steffen
Source: Yale
Contact: Amanda Steffen-Yale
Picture: Image is in public domain

Original research: Access closed.
“Gender Differences in Default Mode Network Connectivity in Healthy Aging Adults” by Bronte Ficek-Tani et al. Cerebral cortex

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Summary

Gender Differences in Default Mode Network Connectivity in Healthy Aging Adults

Women have an increased risk of lifelong Alzheimer’s disease (AD) compared to men. Characteristic changes in brain connectivity, particularly within the Default Mode Network (DMN), have been associated with both symptomatic and preclinical AD, but the impact of gender on DMN function throughout aging is misunderstood.

We investigated gender differences in DMN connectivity over the lifetime of 595 cognitively healthy participants from the Human Connectome Project-Aging Cohort. We used the intrinsic connectivity distribution (a robust metric of functional voxel-based connectivity) and a seed connectivity approach to determine gender differences within the DMN and between the DMN and the whole brain.

Compared to men, women demonstrated higher connectivity with age in the posterior DMN nodes and lower connectivity in the medial prefrontal cortex.

The differences were greatest in the decades surrounding menopause. Seed-based analysis revealed higher connectivity in women from the posterior cingulate to the angular gyrus, which correlated with neuropsychological measures of declarative memory and the hippocampus.

Taken together, we show significant gender differences in DMN subarrays across the lifespan, including patterns in aging women that resemble changes previously observed in preclinical AD.

These results highlight the importance of considering gender in neuroimaging studies of aging and neurodegeneration.

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