Dementia is a broad term that refers to a range of symptoms linked to a progressive decline in brain function
Scientists have identified a potential link between higher BMI and a ‘devastating disease’, following new research. BMI – or Body Mass Index – is the most commonly used measure of a ‘healthy’ weight, generally calculated in relation to a person’s height.
As part of the new University of Bristol project, researchers analysed population data from the UK and around the world using an approach known as ‘Mendelian Randomisation’. This statistical technique specifically examines genetics and health outcomes to identify patterns across large groups of people.
While its results confirmed previously held beliefs that ‘high BMI does increase the risk of vascular-related dementia’, scientists also pinpointed a likely main driver behind this association. This factor is thought to be high blood pressure, suggesting that hypertension treatment could slash the risk of cognitive decline.
First author Dr Liv Tybjærg Nordestgaard, who initiated the project in Copenhagen and extended the work while at the University of Bristol, said: “Dementia is a devastating disease that currently affects 50 million individuals worldwide. Unfortunately, treatment and prevention options are scarce.
“Our study highlights the potential for reducing vascular-related dementia risk by addressing high BMI and/or high blood pressure in the population.”
Dementia is a broad term that refers to a range of symptoms linked to a progressive decline in brain function. Although Alzheimer’s disease is the most prevalent form, other types include Lewy body dementia and vascular dementia.
Vascular dementia, being the specific focus of the new study, is caused by reduced blood flow to the brain and is estimated to affect around 180,000 people in the UK, according to the NHS. Unfortunately, its symptoms generally worsen over time, though it’s sometimes possible to slow it down.
The recent study is part of a growing body of research showing that dementia cases may be preventable through changes in certain lifestyle behaviours. This includes notable findings from The Lancet Commission in 2024, which claimed that a staggering 45% of cases could be delayed or reduced, highlighting 14 key dementia risk factors.
High LDL cholesterol, diabetes, hypertension, smoking, excessive alcohol consumption and obesity were all encompassed in this, alongside hearing loss, depression and several others. Each factor was also said to have varying influence at different stages of life.
At the time, Alzheimer’s Disease International’s Director of Research and Publications, Wendy Weidner, said about its findings: “This study underscores the critical importance of a life-course approach to risk reduction, with targeted interventions across different stages of life.
“By identifying and addressing these risk factors early on, particularly in lower-resourced settings, we have a profound opportunity to reduce the global impact of dementia.
“While we have yet to find a cure for dementia, every proactive step in addressing dementia risk can make a world of difference at a personal and societal level, and policymakers have an essential role to play.” For more information, click here.
Is BMI a good measure of health?
Body mass index (BMI) is the most commonly used measure of a ‘healthy’ body weight. It generally provides a calculation based on your height and weight.
While it offers a good starting point for thinking about your health, it has some limitations. For instance, as NHS Inform points out, it often does not account for the following:
- High muscle mass (like athletes)
- Bone density
- Age
- Sex
- Ethnicity
- Fluid retention
- Loss of a limb
To calculate your BMI, you can use the calculator available on the NHS website here. It’s unsuitable for anyone under 18 years old, pregnant individuals, those diagnosed with an eating disorder, or others with a condition that affects height.
Official NHS guidance adds: “A higher BMI increases the chance of developing long-term conditions, such as type 2 diabetes and heart disease. The BMI calculation is just one measure of health. It cannot tell the difference between muscle and fat.
“For example, if you have a lot of muscle, you may be classed as overweight or obese despite having low body fat. This is why you may get a better idea of your overall health from measuring your waist.”
