People who have obesity and high blood pressure may be more likely to develop dementia, according to new research published in Journal of Clinical Endocrinology & Metabolism.
Dementia is a growing global public health problem and there is currently no cure. People affected by this condition experience a severe decline in mental abilities, including memory, thinking and reasoning, which can significantly interfere with daily life.
What is dementia and how does it develop?
Dementia refers to a group of brain disorders rather than a single disease. The most common forms are Alzheimer’s disease, vascular dementia and mixed dementia. These conditions gradually damage nerve cells in the brain, and symptoms worsen over time. As the disease progresses, people may struggle with memory, language, problem solving and behavioral changes.
Study finds direct causes of dementia
“In this study, we found that high body mass index (BMI) and high blood pressure are direct causes of dementia,” said study author Ruth Frikke-Schmidt, MD, Ph.D., professor and chief physician at Copenhagen University Hospital – Rigshospitalet and Copenhagen University in Copenhagen, Denmark. “Treatment and prevention of elevated BMI and high blood pressure represent an untapped opportunity for dementia prevention.”
To reach these conclusions, the researchers analyzed data from participants in Copenhagen and the United Kingdom. Their findings showed that higher body weight is not only associated with dementia, but plays a causal role in its development.
How genetic data helped to discover cause and effect
Researchers were able to demonstrate a direct link between high BMI and dementia using a Mendelian randomized trial design that closely resembles a randomized controlled trial. In this approach, common genetic variants that lead to higher BMI are used as surrogates for BMI-modifying drugs.
In drug trials, participants are randomly assigned to receive either an active treatment or a placebo. Similarly, genetic variants that increase BMI and those that do not are randomly passed from parents to children. Because this process is randomized, it allows researchers to see how BMI affects disease outcomes without affecting other factors that may cloud the results.
This method allowed the research team to clearly identify high BMI as a direct cause of the increased risk of dementia.
Blood pressure plays a key role
The analysis also revealed that much of the increased risk of dementia associated with obesity appears to be due to high blood pressure. This finding suggests that preventing or treating both obesity and hypertension could reduce the risk of developing dementia later in life.
“This study shows that high body weight and high blood pressure are not just warning signs, but direct causes of dementia,” said Frikke-Schmidt. “That makes them highly actionable prevention targets.”
Implications for early prevention
The researchers noted that weight-loss drugs had already been tested in people with early-stage Alzheimer’s disease, but those treatments did not slow cognitive decline once symptoms began. However, the timing of the intervention can be critical.
“Weight loss drugs have recently been tested to halt cognitive decline in the early stages of Alzheimer’s disease, but with no beneficial effect. An open question that remains to be tested is whether weight loss treatment started before the onset of cognitive symptoms can be protective against dementia. Our current data suggest that early weight loss interventions would prevent dementia, and vascular dementia in particular,” she continued.
Study authors and funding sources
Other study authors include Liv Tybjærg Nordestgaard of Copenhagen University Hospital — Rigshospitalet and the University of Bristol in Bristol, England; Jiao Luo, Frida Emanuelsson and Mette Christoffersen from Copenhagen University Hospital – Rigshospitalet; Genevieve Leyden, Eleanor Sanderson and George Davey Smith from the University of Bristol; Børge Nordestgaard and Shoaib Afzal from Copenhagen University Hospital – Herlev Gentofte and University of Copenhagen; and Marianne Benn and Anne Tybjærg-Hansen from Copenhagen University Hospital – Rigshospitalet and the University of Copenhagen.
The study was funded by the Danish Independent Research Fund, the Capital Region of Denmark, the Lundbeck Foundation, Hjerteforeningen and Sygeforsikringen Danmark.
The article, titled “High Body Mass Index as a Causal Risk Factor for Vascular-related dementia and a Mendelian Randomization Study,” was published online ahead of print.
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