The brains of older adults with obesity show patterns of gray matter loss that are strikingly similar to those seen in people with early Alzheimer’s disease, a new study suggests. These patterns overlap in the location of the tissue loss but not in the severity; in other words, Alzheimer’s patients exhibit a far greater degree of brain atrophy than cognitively healthy, obese adults of the same age do.
“The degree of the changes is much lower in obesity,” confirmed Filip Morys (opens in new tab), first author of the new study and a postdoctoral fellow at McGill University’s Montreal Neurological Institute. However, the spatial distribution of the tissue loss may help to explain why obesity is a major risk factor for Alzheimer’s, Morys told Live Science; past studies have specifically linked midlife obesity to an increased risk of Alzheimer’s and other types of dementia down the line.
“It’s further evidence that this major cardiovascular risk factor of obesity is linked with evidence of neurodegeneration,” or the progressive loss of brain cells, said Dr. Jeffrey Burns (opens in new tab), co-director of the Alzheimer’s Disease Research Center at the University of Kansas Medical Center, who was not involved in the study.
However, the new research, published Tuesday (Jan. 31) in the Journal of Alzheimer’s Disease (opens in new tab), cannot reveal the exact cause of this tissue loss, nor can it pinpoint which of the cognitively healthy, obese participants might go on to develop dementia, Burns told Live Science. That’s partly because the analyses captured only one point in time, in each participant’s early to mid-70s.
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“We need long-term, longitudinal studies where we’re measuring these things over time,” Burns said. “For these individuals without cognitive issues, how strongly is this linked to poor outcomes in the future?” We don’t know yet.
Prior to their new study, Morys and his colleagues found evidence that, in people in their 60s, obesity seems linked to distinct patterns of thinning in the brain’s gray matter. Named for its color, gray matter is made up of the bodies of brain cells, or neurons, and the uninsulated wiring that extends from those cells; gray matter is found primarily in the cerebral cortex, the brain’s wrinkled outer surface.
“We saw that the patterns there are very similar to the ones we see in Alzheimer’s disease,” Morys said of that…
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