A clearer picture of dementia risk could improve care and treatments—and a new study links sudden shifts in brain shape to declines in memory and reasoning.
The University of California, Irvine and La Laguna conducted the study, which adds to our knowledge of brain aging—that the brain shrinks naturally. According to neuroscientist Niels Janssen, “Most studies of brain aging focus on how much tissue is lost in different regions.” Here, the attention changes. “What we found is that the overall shape of the brain shifts in systematic ways, and those shifts are closely tied to whether someone shows cognitive impairment.”
The team compared thinking skills with structure and shape using magnetic resonance imaging (MRI) from adults ages 30 to 97. According to their findings, which have been released in Nature Communications, cognitive decline is associated with more noticeable changes in shape, which may have consequences for neurodegeneration, including Alzheimer‘s disease.
Understanding the shape of the brain
The researchers compared brain shape patterns to reasoning and memory tests after analyzing 2,603 MRI scans. Age-related brain contractions and expansions were not uniform across regions, and differences appeared to be stronger in those who were impaired. For example, regions near the back of the head tended to get smaller as people aged, particularly those with lower reasoning ability scores.
This is significant because shape provides information that goes beyond simple volume loss and may be used in the early stages of dementia risk assessment. The concept is useful: shape is visible, identifiable, and instructive about neurodegeneration; however, more scans and accurate measurements are required.
The relevance of the Entorhinal cortex
One important memory center that may be impacted by age-related shape changes is the Entorhinal cortex. The researchers believe that biological geometric changes that push this area against an established limit may make it especially vulnerable.
Toxic proteins associated with Alzheimer’s disease also tend to build up in that area. According to Michael Yassa from the University of California, Irvine, “This could help explain why the entorhinal cortex is ground zero of Alzheimer’s pathology… 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.”
It basically illustrates how shape—a feature that is often overlooked—may help explain why some regions are more vulnerable than others. “Understanding that process gives us a whole new way to think about the mechanisms of Alzheimer’s disease and the possibility of early detection.” As Yassa also notes, “We’re just beginning to unlock how brain geometry shapes disease,” and “the answers may be hiding in plain sight – in the shape of the brain itself.”
From awareness to early detection
Our brain’s shape is just as important as its size. This study puts the findings within the context of neurodegeneration and Alzheimer’s disease, relates them to the entorhinal cortex, and links inconsistent, age-related shape changes to cognitive decline. The work of the University of La Laguna and the University of California, Irvine encourages deeper, larger-scale MRI studies to identify the shape patterns most important for memory and reasoning.
The concept is simple for the general public: monitoring brain geometry may provide an early window into dementia risk. It gives a hopeful, testable clue for earlier detection and better care, but it will not take the place of clinical evaluations.
In the meantime, this study gives researchers and clinicians a helpful goal: shape features that may indicate risk before symptoms appear. The maps will be improved with more data. So in this case, shape represents more than just a shape; it is a tool that guides us to earlier detection and better care.