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Dementia cases in the UK have gone down in the last 20 years

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The number of people in the UK who get dementia each year may be decreasing, a trend that breaks with many researchers' predictions. In the country, the incidence rate of dementia — the number of new cases reported during a given time period — has gone down by 20 percent since the 1990s, according to a new paper in Nature CommunicationsIt suggests that today's aging population may not be as prone to cognitive problems as those of the past.

A trend that breaks with many researchers' predictions

Some researchers have expected rates of new dementia cases to go up over the years — a result of an increasingly aging population. The idea is that as people worldwide continue to live longer, more and more of them will be at risk for contracting dementia. Some studies have supported this, but others have suggested that dementia incidence may be on the decline as well. Unlike many other studies, today’s study looked at two completely separate generations to see how they differed, according to the study authors.

To determine the rates of dementia in the UK, researchers from the University of Cambridge followed two different aging populations: a group of 7,635 people over the age of 65 were interviewed between 1989 and 1994 and another group of 5,288 people over the age of 65 were interviewed between 2008 and 2011. The study participants all lived in the same three areas of England: Cambridgeshire, Newcastle and Nottingham. That way, the researchers could see how dementia rates changed among people within the same communities. After figuring out which participants contracted cognitive problems, the study authors saw a 20 percent decrease in dementia rates over the research time period. The reduction was mostly driven by a large decrease in incidence rates among men. (Women also had a lower incidence in dementia, but it wasn’t as strong a drop.)

People today have very different lifestyles compared to those in the past

The researchers suspect that number of new dementia cases is decreasing because people today have very different lifestyles compared to those in the past. "The cohorts had very different life experiences," study author Carol Brayne, a professor of public health medicine at Cambridge, told The Verge. Smoking rates have gone down over the years, and the two populations were exposed to very different types of education and nutrition, she said. Today's population has also benefited from advances in medical treatment in regards to heart disease, a major risk factor for dementia.

The study authors suggest that the positive changes may be limited to the most advantaged countries, like the UK. Wealthy European nations and the US have made investments in public health campaigns and education, the authors argue, which may play a role in reducing the incidence of dementia. Brayne says it's important to know what may be responsible for the decrease in new cases, so that people and policy makers can make steps toward protecting individuals' brain health. "If we know that health can be improved by a variety of activities," she said, "it's important to have a look and say: are we going to do the things to potentially enhance brain health across life?"