If you're beginning to forget words or find yourself becoming absent-minded and losing track of what you were doing, you may be starting to worry about dementia.

One in 10 older Americans has dementia, a general term for the impaired ability to remember, think or make decisions that interferes with doing everyday activities. Occurences of this condition, which includes Alzheimer's Disease, are on the rise.

The medical community is focusing not only on its treatment and cure, but also on its risk factors. Both genetics and lifestyle choices contribute to the development of dementia. It's estimated that by eliminating these risk factors, the incidence of dementia can be reduced by as much as 40 percent.

Cardiovascular problems, particularly hypertension, are now seen as the most significant risk factors for dementia.

A new study led by a group of researchers at University College London (UCL) shows that cardiovascular health is now the most significant risk factor of dementia. In the past, smoking and level of education were considered to be more important factors.

The researchers reviewed 27 papers that involved people with dementia worldwide using data that were collected over more than 70 years. The data analysis examined dementia's risk factors and calculated what portion of these risk factors were responsible for the development of dementia disease cases.

What causes dementia isn't entirely clear, but it's generally agreed that it is usually the result of a combination of factors that includes hypertension, obesity, diabetes, education, smoking — and genetics.

The researchers found that the relative importance of the factors contributing to dementia had shifted. Overall levels of education have increased and smoking has declined. As a result, their association with rates of dementia have also declined. During the same period of time, rates of obesity and type 2 diabetes have increased, along with their rising contribution to the risk of developing dementia.

But far and away, the greatest risk factor is high blood pressure, hypertension, the study's lead author Naaheed Makadam, a professor in psychiatry at UCL, said. Her team reported that among the cardiovascular disease conditions affecting the heart and blood vessels, high blood pressure was the single biggest contributor to dementia. That doesn't mean hypertension is solely responsible, Makadam explained. “Cardiovascular risk factors may have contributed more to dementia risk over time, so these deserve more targeted action for future dementia prevention efforts.”

According to the American Heart Association (AHA), hypertension or high blood pressure usually doesn't always have signs or symptoms — one of the reasons why it's so dangerous and so often overlooked.

Nearly half of the American population over the age of 20, has hypertension — and many people aren't aware of it. That's why it's a good idea to check your blood pressure regularly at home, at your doctor's or at a local drug store.

There are no guarantees that certain lifestyle choices can prevent dementia, but they can reduce the risk of developing cardiovascular disease. The AHA recommends approaches that can help control your blood pressure:

The study is published in The Lancet Public Health.