New study reveals incidence of dementia may be declining

Another factor might be declining levels of lead, due to government regulation. There is evidence that exposure to lead early in life can increase your chances of getting dementia later.

http://www.eurekalert.org/pub_releases/2016-02/bumc-nsr020916.php

Public Release: 10-Feb-2016
New study reveals incidence of dementia may be declining
Boston University Medical Center

Despite the concern of an explosion of dementia cases in an aging population over the next few decades, a new study, based on data from the Framingham Heart Study (FHS), suggests that the rate of new cases of dementia actually may be decreasing.

These findings, which appear in the New England Journal of Medicine, provide hope that some cases of dementia might be preventable or delayed and encourages funding agencies and the scientific community to further explore demographic, lifestyle and environmental factors underlying this positive trend.

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Looking at four distinct periods in the late 1970s, late 1980s, 1990s and 2000s, the researchers found that there was a progressive decline in incidence of dementia at a given age, with an average reduction of 20 percent per decade since the 1970s, when data was first collected. The decline was more pronounced with a subtype of dementia caused by vascular diseases, such as stroke. There also was a decreasing impact of heart diseases, which suggests the importance of effective stroke treatment and prevention of heart disease. Interestingly, the decline in dementia incidence was observed only in persons with high school education and above.

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