The way the brain’s shape changes as it ages could help to paint the picture of its overall health and offer early warning signs for dementia—years before typical symptoms emerge.
Brain scan analysis led by researchers at University of California, Irvine and University of La Laguna in Spain revealed substantial alterations in shape that were closely linked to declines in memory, reasoning and other cognitive functions.
“Aging is typically associated with loss of brain tissue in specific parts of the brain” study author and La Laguna neuroscientist professor Niels Janssen told Newsweek.
“For example, we know from much previous work that memory problems in older age are associated with loss of tissue in a specific region of the brain called the hippocampus.
“However, our study takes a different approach and looks at how the global shape of the brain changes due to aging or clinical dementia.”
Analyzing more than 2,600 structural MRIs of adults aged 30 to 97, the team discovered that the inferior parts of the brain (essential for functions like breathing and heartbeat) and the anterior parts (essential for some cognitive functions) expanded outward.
Meanwhile the superior regions (crucial for language functions) and posterior regions (involved in visual processing and motor control) contracted inward.
“The shape of the brain changes with age in such a way that it appears to ‘slouch,’ i.e., the bottom parts of the brain seem to expand away from each while top parts seem to compress. The expansion and compression effects seem worse in dementia,” said Janssen.
Within this, expansion strongly occurred in regions like the entorhinal cortex. This is a small but particularly crucial memory hub and one of the first places where tau, a toxic protein linked to Alzheimer’s disease, accumulates.
More than seven million Americans are living with Alzheimer’s, the most common form of dementia.
“This could help explain why the entorhinal cortex is ground zero of Alzheimer’s pathology,” said study author Michael Yassa, director of the CNLM, and James L. McGaugh, endowed chair, in a statement.
“If the aging brain is gradually shifting in a way that squeezes this fragile region against a rigid boundary, it may create the perfect storm for damage to take root.
“Understanding that process gives us a whole new way to think about the mechanisms of Alzheimer’s disease and the possibility of early detection.”
The geometric approach could eventually provide new markers for identifying dementia risk, potentially years before symptoms present, according to the team.
“We’re just beginning to unlock how brain geometry shapes disease,” added Yassa. “But this research shows that the answers may be hiding in plain sight—in the shape of the brain itself.”
“One possibility is that one could imagine having a test in which the degree to which the shape of your brain is compared to a normal brain shape. If it deviates more than some threshold, it could be clinically important. However, such a test does not currently exist,” Janssen told us.
“The standard approach to studying Alzheimer’s disease is to look at changes in the brain at a very small, molecular level, which is certainly useful. However, our approach shows that looking at changes from a much more global perspective can also offer valuable clues. An approach where we combine both these approaches (molecular and global) is required to tackle a complex disease like Alzheimer’s.”
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