Portions of the Brain Involved in Daydreaming May Be Linked with Alzheimer's Disease Risk
Michelle Milliken
The default mode network (DMN) consists of connected brain regions that are active when a person isn't focused on what's happening around them, or when we're in wakeful rest. Researchers at Yale School of Medicine say this network is important to our short-term memory, and they recently set out to see if changes to it may impact the short-term memory loss stemming from Alzheimer's. They also investigated DMN in men and women, as women are at a higher risk of developing the disease. The team found that there were some differences that could play a role in this increased Alzheimer's risk.
Dr. Carolyn Fredericks, Women's Health Research at Yale collaborator, has been studying the outsized impact Alzheimer's has on women, and this study, published the journal Cerebral Cortex, builds on that. The paper notes that DMN changes have been linked with symptomatic and preclinical Alzheimer's, but the team wanted to look specifically at how DMN changes differ between men and women, especially as they age.
They investigated this with data from the Human Connectome Project in Aging, which gathers data on how individual experiences impact brain connectivity. The data the team pulled for this study included brain scans from patients who were in a state of wakeful rest.
In looking at these scans, they pinpointed differences between men and women, including that women were more apt to have the portions of the DMN responsible for memory recollection and retrieval and spacial cognition connected to the overall DMN network. These patterns of connectivity, along with portions of the brain responsible for short-term memory, mirrored changes seen in preclinical Alzheimer's.
The team also found that in their 30s and 40s, women were more apt to rely on connection to portions of the brain responsible for spatial and verbal memory. Once menopause hit, though, areas key for memory retrieval were more highly connected to the overall DMN. For men, the highest connectivity wasn't seen until they reached their 60s through their 80s, and the portions of the brain linked to the DMN for them were those related to habit forming and long-term memory.
The team says they believe this shows that women rely more on DMN connections for memory than men and do so for a longer period of time. With so much usage, there could be more stress to the network, putting it at higher risk for conditions like Alzheimer's. This stress on the portion of the brain linked with memory could also help further unlock the mystery of Alzheimer's being more common in women.
The researchers say their findings highlight the importance of considering sex in neuroimaging studies on aging and neurodegeneration. They also say identifying brain patterns in healthy aging people may pinpoint an area for treatment, and allow more time for treatment before symptoms develop.
