• Posted January 26, 2026

Obesity Directly Influences A Person's Risk Of Dementia, Study Concludes

Obesity and high blood pressure are directly linked to a person’s risk of dementia, a new study reports.

People’s odds of developing dementia can be as much as doubled if they have a high body mass index (BMI), researchers reported Jan. 22 in The Journal of Clinical Endocrinology & Metabolism.

Further, high blood pressure caused by excess weight appears to drive much of the link between high BMI and dementia. BMI is an estimate of body fat based on height and weight.

“This study shows that high body weight and high blood pressure are not just warning signs, but direct causes of dementia,” said senior researcher Dr. Ruth Frikke-Schmidt, chief physician at Copenhagen University Hospital-Rigshospitalet in Denmark.

“The treatment and prevention of elevated BMI and high blood pressure represent an unexploited opportunity for dementia prevention,” Frikke-Schmidt said in a news release.

For the study, researchers focused on vascular dementia, which occurs when the brain is damaged due to reduced or blocked blood flow.

Researchers analyzed data for more than 500,000 people taking part in long-term health studies in the U.K. and Denmark, using a genetics-based method that mimics a gold-standard randomized controlled trial.

The team looked for common genetic variants that cause high BMI, and tracked whether people with those genetics had a higher risk of dementia.

Since BMI-linked genetic variants are randomly passed down from parents to children, this study model provides the sort of randomization required in top clinical trials, researchers said.

Results showed that high BMI was indeed directly linked to vascular dementia, with risk running from 54% to 98% higher depending on the group being studied and the method of analysis.

About 18% of that relationship is explained by elevated systolic blood pressure caused by obesity, and 25% by higher diastolic blood pressure, researchers added.

Systolic represents the top number on a blood pressure reading, and is the pressure inside blood vessels during a heartbeat. Diastolic, the bottom number, is the pressure between heartbeats.

Heather Snyder, senior vice president of medical and scientific relations for the Alzheimer’s Association, told HealthDay that the new study adds to a growing pile of evidence linking weight and heart health to cognitive decline and dementia.

“Several studies have shown an association of BMI with later life dementia, and the authors of this paper suggest that this linkage is driven by systolic and diastolic blood pressure,” said Snyder, who was not involved in the study.

Though more research is needed to identify the underlying mechanisms, she said there are a number of potential reasons for the link between high BMI and cognitive decline in dementia.

“This can include a negative impact on the cardiovascular system, making it harder for the heart to pump blood throughout the body, including into the brain,” Snyder said. “In addition, research has demonstrated links between obesity/high BMI and increased inflammation. We are increasingly understanding that the immune system plays a central role in our overall health, including our brain health and diseases like Alzheimer’s.”

In addition, “obesity/high BMI also impacts the body's ability to metabolize food and energy, and this may impact overall brain health,” she said.

Based on this, heart-healthy lifestyle habits like a nutritious diet, exercise and good sleep might be able to protect a person’s long-term brain health, Snyder said.

“There is ample scientific evidence that what is good for your heart and metabolic health is also good for your brain,” she added. “Talk to your health care provider about taking action to improve your overall health.”

These findings also show there might be a role for weight-loss drugs like Ozempic and Zepbound when it comes to preventing dementia, researcher Frikke-Schmidt said.

“Weight-loss medication has recently been tested for halting cognitive decline in early phases of Alzheimer’s disease, but with no beneficial effect,” she said. “An open question that remains to be tested is if weight-loss medication initiated before the appearance of cognitive symptoms may be protective against dementia.”

The study points to a possible answer to that question.

“Our present data would suggest that early weight-loss interventions would prevent dementia, and especially vascular-related dementia,” Frikke-Schmidt concluded.

More information

The Alzheimer’s Society has more on obesity and dementia.

SOURCES: Endocrine Society, news release, Jan. 22, 2026; Heather Snyder, senior vice president of medical and scientific relations, Alzheimer’s Association; The Journal of Clinical Endocrinology & Metabolism, Jan. 22, 2026