With predictions of a coming global avalanche of dementia cases, researchers are turning their attention to prevention strategies. Based on current data, at least four lifestyle factors robustly affect dementia risk, according to the World Alzheimer Report 2014, released September 16 by the umbrella group Alzheimer’s Disease International and Bupa, the largest private health insurance company in the United Kingdom. Researchers led by Martin Prince at King’s College London analyzed previous studies that examined the effects of developmental, psychological, lifestyle, and cardiovascular factors on dementia risk. They found that diabetes heightened risk by 50 percent, while smoking increased the odds of Alzheimer’s disease by the same amount. Hypertension in midlife pumped up the risk for vascular dementia by 60 percent, while education lowered dementia risk by about 40 percent. Factors such as depression and obesity also appeared to inflate risk, while physical activity and cognitive stimulation seemed to lower it, but existing data are not strong enough to draw firm conclusions about those factors, the report noted.
The findings belie the report from a 2010 National Institutes of Health State-of-the-Science panel, which concluded that insufficient evidence existed to endorse any health intervention for lowering Alzheimer’s risk (see May 2010 news story; May 2011 news story). The World Alzheimer Report argues that, “There is persuasive evidence that the dementia risk for populations can be modified through reduction in tobacco use and better control and detection for hypertension and diabetes, as well as cardiovascular risk factors.”
The findings add to a growing body of evidence suggesting that improving heart health and maintaining an active lifestyle and sensible diet wards off dementia (see, e.g., Jul 2014 news story; Apr 2014 news story). Researchers attribute recent drops in dementia incidence in developed countries to higher education levels and better cardiovascular care (see May 2013 news story; Jul 2013 news story; and Jul 2014 news story). In 2011, researchers at the University of California, San Francisco, estimated that reducing the prevalence of the risk factors listed above could significantly cut dementia cases worldwide (see Jul 2011 news story). Those researchers recently refined their analysis, concluding that a drop of 10 percent in each risk factor would reduce Alzheimer’s prevalence in 2050 by 8 percent worldwide (see Norton et al., 2014).
Despite all the research on this topic, the public remains largely unaware of the impact of lifestyle factors. In a survey conducted by Bupa, only a quarter of respondents knew that obesity and physical inactivity could increase their odds of developing dementia, and just one in six realized that social activity could protect them. Alzheimer's Disease International recommends greater public outreach. “Implementing effective public health campaigns may help to reduce the global risk,” director Marc Wortmann, said in a press release.
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- Norton S, Matthews FE, Barnes DE, Yaffe K, Brayne C. Potential for primary prevention of Alzheimer's disease: an analysis of population-based data. Lancet Neurol. 2014 Aug;13(8):788-94. PubMed.