Summary: In women, parts of the default mode network associated with memory retrieval and memory and spatial awareness are more likely to connect to the entire DMN network. Connectivity patterns associated with brain structures associated with short-term memory impairment are similar to changes observed in preclinical Alzheimer’s disease.
If you let your mind wander, you are guided by the brain’s default mode network (DMN). Scientifically, the DMN is a network of brain regions that interact when a person is awake and at rest.
This network is essential for the use of our short-term memory, raising the question: Do changes in the DMN play a key role in the short-term memory loss seen in the development of Alzheimer’s disease (AD)? And does the DMN affect women and men differently?
Carolyn Fredericks, MD, assistant professor of neurology at the Women’s Health Research Center at Yale (WHRY), is working to understand why AD and women are disproportionately affected.
Strong research shows that women are more likely to develop AD than men. In AD Although much research has been done, there are very few studies that take gender differences into account.
Fredericks’ new study, published in The front part of the brain, specifically examining gender differences in DMN connectivity in healthy aging adults. Fredericks and her team, including second-year medical student Bronte Fike-Tani of Washington University, characterized these relationships differently for women and men, which may provide clues as to why the risk of AD increases in women.
Previous studies have shown that brain connectivity in the DMN is altered with symptomatic and preclinical AD, but the investigation of gender differences in such changes is limited. Fredericks’ study also examined how aging affects women and men.
Using data from the Human Connectome Project-Aging, the team analyzed brain scans from patients who were actively resting. They found differences in how the central communication points in the brain work for women and men.
For example, in women compared to men, the parts of the DMN responsible for memory and retrieval and spatial awareness are connected to the entire DMN brain network. These connectivity patterns, associated with brain structures responsible for short-term memory performance, are similar to changes observed in preclinical AD.
In addition, significant gender differences were observed in old age. In the 30s and 40s, women rely more on the part of the brain responsible for spatial and verbal memory. In the decades following menopause (40s and 50s), areas critical for memory retrieval showed greater connectivity with the overall DMN.
Men, on the other hand, showed a different pattern and their highest correlation did not appear until their late years (60s-80s). For men, the higher connectivity with the DMN is the part of the brain responsible for habit formation and long-term memory.
The researchers believe that their results show that women rely on DMN connections to remember more and for longer than men. A high level of connectivity may result in a stressed network and greater susceptibility to diseases such as AD. This “wear and tear” on parts of the brain critical to memory is why women are more prone to AD. It may partly explain their higher vulnerability.
Fredericks said these findings will help doctors and scientists better understand memory and how it relates to brain networks, even in people without AD, and in turn inform the type of memory loss in AD.
By identifying patterns in the brains of healthy, older adults, scientists may not only be targets for future interventions, but they may have a larger window of time to treat them before symptoms appear.
So Alzheimer’s disease research news
Author: Amanda Stephen
Contact: Amanda Stephen – Yale
Image: The image is in the public domain.
Preliminary study: Closed access.
“Gender differences in default mode network connectivity in healthy aging adults” by Bronte Ficek-Tani et al. The front part of the brain
Gender differences in default mode network connectivity in healthy aging adults
Women have a higher lifetime risk of Alzheimer’s disease (AD) than men. Changes in behavioral brain connectivity, particularly in the default mode network (DMN), have been associated with both symptomatic and preclinical AD, but the effect of sex on DMN function in aging is poorly understood.
We examined gender differences in DMN connectivity across the lifespan in 595 cognitively healthy participants from the Human Connectome Project-Aging cohort. We used intrinsic connectivity distribution (a robust voxel-based measure of functional connectivity) and a genetic connectivity approach to determine sex differences within the DMN and between the DMN and the whole brain.
Compared to men, women showed higher connectivity with age in posterior DMN nodes and lower connectivity in medial prefrontal cortex.
Differences in menopause have become more pronounced over the decades. Race-based analysis revealed higher connectivity in females from the posterior cingulate to the angular gyrus, which is associated with neuropsychological declarative memory and the hippocampus.
Taken together, we demonstrate significant gender differences across the lifespan in DMN subnetworks, including patterns in older women that resemble changes previously observed in preclinical AD.
These findings highlight the importance of considering gender in neuroimaging studies of aging and neurodegeneration.