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40-year study suggests the incidence of dementia in the US is actually falling

Finally some good news!

PETER DOCKRILL
12 FEB 2016
 

While health experts the world over are warning that dementia will boom in the years ahead as the global population ages, a new study provides a silver lining to this stark situation.

According to research led by Boston University, the proportional incidence of dementia cases in the US appears to actually be in decline, thanks to a range of general measures boosting things such as cardiovascular health.

 

While there's no specific remedy for dementia itself – and the prevalence of the illness is still expected to grow with time as more people reach old age than ever before – health advancements in higher-income countries appear to be helping us indirectly push back against the disease.

"Currently, there are no effective treatments to prevent or cure dementia," said neurologist Sudha Seshadri from the Boston University School of Medicine. "However, our study offers hope that some of the dementia cases might be preventable – or at least delayed – through primary (keep the disease process from starting) or secondary (keep it from progressing to clinically obvious dementia) prevention."

These measures won't be able to stop the huge number of dementia cases expected to be diagnosed in the first half of this century, but they will have a positive impact.

"Effective prevention could diminish in some measure the projected explosion in the number of persons affected with the disease in the next few decades," said Seshadri.

The researchers based their findings on data from the Framingham Heart Study, a long-running cardiovascular study that originally began in the 1940s and is now onto its third generation of participants. The authors of the present study looked at data from more than 5,000 individuals aged 60 or older who took part in the Framingham research during the 1970s, 1980s, 1990s, and 2000s.

Over a timeframe measuring nearly 40 years, the researchers found the cohort demonstrated a progressive decline in incidence of dementia at a given age, with an average reduction of 20 percent per decade since the 1970s.

The declines correspond to parallel decreases in vascular and heart diseases in the group, although the researchers acknowledge that the trends themselves don't explain the decrease in the incidence of dementia.

Interestingly, the participants who demonstrated the decline in dementia were those who had a high school education or above – a result that puzzles the study's authors.

"Whether education is beneficial in itself or whether education is a marker for other things like poverty and unhealthy lifestyle, we didn't parse that out," Seshadri told Pam Belluck at The New York Times.

The scientists also concede that the findings pertain to a sample population of largely European ancestry, and that broader studies in other environments would be needed to replicate the results. Nonetheless, it's a useful starting point to help scientists refocus on ways of fighting dementia through side avenues.

"[It] is very likely that primary and secondary prevention and better management of cardiovascular diseases and stroke, and their risk factors, might offer new opportunities to slow down the currently projected burden of dementia for the coming years," said one of the team, Carole Dufouil.

With figures indicating the amount of people in the US with Alzheimer's and worldwide with dementia are both expected to roughly triple by 2050, any inroads we can make in preventative measures have to be welcomed with open arms.

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