A major new study has identified a direct causal link between obesity and a significantly increased risk of vascular dementia, with sustained high blood pressure acting as the primary mechanism. Published Thursday in the Journal of Clinical Endocrinology & Metabolism, the research found that a higher body mass index raises the risk of this common form of dementia by 50 to 60 percent. “We add a layer of evidence that suggests causality,” said lead author Dr. Ruth Frikke-Schmidt. “For public health, this is an important message.”
The research utilized Mendelian randomization, an analytical method that uses genetic variants to mimic a randomized clinical trial. By analyzing genes associated with body weight in over 500,000 individuals from Danish and U.K. biobanks, the team found these genetic drivers of obesity also elevated dementia risk. “It’s like nature’s own randomized clinical trial,” explained neuroradiologist Dr. Cyrus A. Raji, who was not involved in the study. He noted the genetic data shows obesity-linked variants raise dementia risk “by way of high blood pressure.”
The study quantified that high blood pressure explains 18 to 25 percent of the increased vascular dementia risk associated with obesity. This form of dementia, caused by impaired blood flow to the brain, leads to a decline in executive function and memory, often progressing in sudden steps. The findings offer a clear preventive target. “Controlling blood pressure in people with obesity may actually help prevent dementia,” said internist Dr. John N. Mafi of UCLA.
While experts hailed the study as a substantive advance, they noted limitations, including a participant pool that was exclusively White. The authors and independent researchers agree the evidence now strongly supports discussing dementia risk in weight management. “I’m probably going to start telling my patients, ‘There may, in fact, be a link between your weight and vascular dementia, so that’s another motivation for us to focus on weight loss,’” Dr. Mafi said.