A CARDIOVASCULAR condition affecting millions of Brits could be the biggest risk factor for developing dementia, scientists have revealed.
Persistent high blood pressure - also known as hypertension - puts extra strain on your arteries and your heart, which can lead to strokes and heart attacks.
According to UCL researchers, the condition could make you more likely to develop memory-robbing dementia.
Up to one in three adults in the UK have high blood pressure, according to .
Dementia risk factors associated with heart health may have increased over time, according to the study, compared with factors such as smoking and having less education.
The findings suggest that boosting cardiovascular health may help to prevent future cases of dementia.
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An estimated 944,000 people in the UK live with dementia and data suggests more than half of the adult population knows someone who has been diagnosed with a form of the disease.
In the new study, UCL researchers analysed 27 papers, involving people with dementia across the world with data collected between 1947 and 2015.
Using the data, they calculated the biggest risk factors associated with developing dementia over time.
The condition usually develops because of a combination of genetic and environmental factors, including high blood pressure, obesity, diabetes, education and smoking.
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The team found that obesity and diabetes rates have increased over time, as has their contribution to dementia risk.
But having less education and smoking have become less common throughout the years, and was associated with a decline in rates of dementia.
Most studies reviewed showed hypertension to be the greatest risk factor of dementia.
But researchers also noted proactive management of high blood pressure has also gotten better over time.
Lead author Dr Naaheed Mukadam, of the UCL Division of Psychiatry, said: "Cardiovascular risk factors may have contributed more to dementia risk over time, so these deserve more targeted action for future dementia prevention efforts.
"Our results show that levels of education have increased over time in many higher income countries, meaning that this has become a less important dementia risk factor.
"Meanwhile, smoking levels have also declined in Europe and the US as it has become less socially acceptable and more expensive."
Dr Mukadam added that the findings - published in The Lancet Public Health - suggest interventions in the population could "significantly" affect the occurrence of risk factors.
Governments should consider implementing schemes such as worldwide policies of education, and restrictions on smoking, she said.
It's estimated that 50 million people across the world now living with dementia, and by 2050 this is set to triple to 152 million, according to Alzheimer's Research UK.
Dr Isolde Radford, senior policy manager at the charity, said: "This new analysis says it loud and clear - that managing high blood pressure and keeping our hearts healthy is playing an important role in reducing our risk of developing dementia.
"With no treatments currently available in the UK that can stop or slow the diseases that cause dementia, there has never been a more pressing need for looking after our brain health to help reduce the future risk of developing dementia.
"Evidence tells us that what's good for our hearts is good for our brains, and this new research underlines the importance of this message.
"So, things like eating a healthy balanced diet and staying physically active can all help people to reduce their risk of dementia.
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"But just one in three people know they can reduce their risk of developing dementia and there are many factors such as income and ethnicity that affect our ability to do so.
"That's why it's vital the next UK government takes steps to help make healthy lifestyles as achievable as possible for everyone."
How to lower blood pressure
Persistent high blood pressure (hypertension) puts extra strain on your blood vessels, heart and other organs and it can raise your risk of serious conditions like heart disease, heart attacks and stroke. Here's how to reduce it.
Reduce salt
Adults are recommended to limit their salt to 6g per day (around one level teaspoon) to avoid health consequences including high blood pressure.
The top tip is to swap out table salt, according to the Salt Substitute and Stroke Study, replacing it with a reduced sodium and added potassium alternative.
Cut down on alcohol
Excessive boozing can narrow the blood vessels, which raises the risk of hypertension.
Official drinking guidelines advise that people should not regularly drink more than 14 units a week to keep health risks from alcohol low.
Get moving
Exercise is good for the heart and the blood vessels.
Although the guidelines recommend 150 minutes of activity per week, if you're currently very inactive, just a walk to the shop every day is better than nothing, and you can work up from there.
Studies suggest that isometric exercises - when you hold the body in one position without moving, such as a wall squat or plank - are best for lowering blood pressure.
Stop smoking
Smoking cigarettes is a killer. It makes the arteries sticky and narrow, which can cause blockages.
While smoking is not a direct cause of high blood pressure, it can cause an instant rise to pressure, heart rate and reduce the amount of oxygen that gets to the body’s cells.
Skip coffee
Sadly, caffeine can cause a short, but dramatic increase in your blood pressure - even if you don't have high blood pressure.
Therefore cutting back on coffee is recommended as a lifestyle tip for those with hypertension.
Lose weight
The above tips can help you to lose weight, which is beneficial because being overweight in itself is a risk factor for hypertension.
Being overweight forces your heart to work harder to pump blood around your body, which can raise your blood pressure.
The only way of knowing whether you have high blood pressure is to have a blood pressure test. All adults over 40 years old are advised to have their blood pressure checked at least every five years.