Being overweight could significantly increase the risk of dementia in later life, world-leading experts said today.
The research, led by the University of Bristol, found that millions of dementia cases could be prevented through losing weight and managing blood pressure.
Previous studies have shown that being obese in midlife – defined by a Body Mass Index (BMI) of 30 or over – can increase the risk of developing the memory robbing condition.
But until now, it’s been unclear whether there is a direct correlation between obesity and dementia, or whether the risk is driven by other lifestyle factors like smoking and uncontrolled blood pressure, both major risk factors for dementia.
In the new study, published in The Journal of Clinical Endocrinology and Metabolism, researchers found a direct, causal link between BMI and vascular-related dementia.
This form of dementia is caused by reduced blood flow to the brain, which damages and eventually kills brain cells. This can happen as a result of narrowing and blockage of the small blood vessels in the brain, often linked to lifestyle factors, or a stroke.
Dr Ruth Frikke-Schmidt, chief physician and expert in age-related disease, said: ‘In this study we found high BMI and high blood pressure are direct causes of dementia.
‘The treatment and prevention of elevated BMI and high blood pressure represent an unexploited opportunity for dementia prevention.’
Having a high BMI could increase your risk of developing vascular dementia
The researchers analysed data from over 500,000 participants across Copenhagen and the UK, representative of the general population.
They used a Mendelian Randomisation approach – to examine genetic variants linked with BMI that are not affected by lifestyle factors such as smoking – and found that people genetically predisposed to higher BMI were more likely to develop vascular dementia.
Around a quarter of this increased risk appeared to be driven by high blood pressure, also known as hypertension, highlighting the potential of treating the condition to reduce dementia risk.
‘This study shows that being overweight and high blood pressure are not just wanting signs, but direct causes of dementia.
‘That makes them highly actionable targets for prevention,’ Dr Frikke-Schmidt said.
Dr Liv Tybjærg Nordestgaard, an expert in clinical biochemistry who initiated the project in Copenhagen and study first author, added: ‘Dementia is a devastating disease that currently affects 50million 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.’
Two in three Britons are now classed as overweight or obese, a trend which has already been linked to significant brain changes in areas linked to dementia and an increased risk of Alzheimer’s.
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It has also fuelled a explosion in cases of type 2 diabetes and high blood pressure in among under 40s.
But the arrival of miracle weight loss jabs, including now household names such as Mounjaro and Wegovy, has transformed obesity treatment, offering dramatic weight loss and cardiometabolic benefits.
But, Dr Frikke-Schmidt cautioned: ‘It remains to be tested whether weight-loss medication initiated before the appearance of cognitive symptoms may be protective against dementia.
‘Weight-loss medication has recently been tested for halting cognitive decline in early phases of Alzheimer’s disease, but with no beneficial benefit.
‘Our study supports that early weight-loss interventions could prevent dementia, and especially vascular-related dementia.’
A groundbreaking study published this year also found that the benefits of the fat-busting jabs may be short-lived once treatment ends with improvements in blood pressure fading in just 18 months.
It comes as world-leading experts this week set out 56 evidence-based recommendations aimed at slashing dementia risk, including taking high blood pressure and improving public health messaging.
The panel said prevention efforts work best when public health messages focus on risk factors people can act on, and for which there is strong evidence that change can reduce dementia risk.
They argued that clear, direct messaging – such as ‘Losing weight could reduce the risk of dementia’ – is more effective than vague warnings or technical language, and avoids people feeling blamed or overwhelmed.
Around 900,000 people are currently living with dementia in the UK, a figure expected to rise to more than 1.6 million by 2040.
Vascular dementia is the second most common form of the devastating condition, after Alzheimer’s. Dementia is the leading cause of death, accounting for more than 74,000 deaths a year.
An estimated 6.7 million Americans aged 65 and over are living with dementia, including Alzheimer’s disease.
This is projected to reach nearly 14 million by 2060, with around 120,000 deaths a year attributed to Alzheimer’s alone.
