News Release

Study suggests reducing 7 potential risk factors could prevent up to 3 million cases of Alzheimer's disease worldwide

Peer-Reviewed Publication

The Lancet_DELETED

The results of a Review to be presented at The Alzheimer's Association 2011 International Conference on Alzheimer's Disease (ICAD) in Paris and published simultaneously Online First in The Lancet Neurology suggest, but don't prove, that up to half of Alzheimer's disease (AD) cases worldwide are potentially attributable to seven preventable risk factors (quitting smoking, increasing physical activity, enhancing mental activity, controlling blood pressure and diabetes, and managing obesity and depression). Furthermore, a 25% reduction in all seven of these risk factors could prevent as many as 3 million cases of AD worldwide.

Dementia is a major cause of disability in older adults. Globally, an estimated 33.9 million people have AD and the number is expected to triple over the next 40 years. "Given the current absence of disease-modifying treatments, as well as increasing awareness that symptoms develop over many years or even decades, there has been growing interest in identification of effective strategies for prevention of AD…Observational studies have identified a wide range of potentially modifiable risk factors for AD and dementia", explain Deborah Barnes and Kristine Yaffe from the University of California, San Francisco, USA.

In this study, the authors reviewed the evidence related to predisposing factors for AD including cardiovascular risk factors, psychosocial factors, and health behaviours. They identified seven potentially modifiable risk factors—low educational attainment, smoking, physical inactivity, depression, midlife obesity, midlife high blood pressure, and diabetes.

Using data from recent systematic reviews and meta-analyses, they estimated the number of preventable AD cases that could be achieved by reducing the burden of each of these factors, with the aim of identifying interventions that might be able to delay the development of AD.

Overall, the findings suggest that these seven risk factors potentially contribute to as many as half of AD cases worldwide (17.2 million) and in the USA (2.9 million). Furthermore, a 10󈞅% reduction in all seven factors could reduce the number of AD cases by 1.1 - 3 million worldwide and by 184,000 - 492,000 in the USA.

The authors predict that low educational attainment contributes to the largest proportion (19%: 6.5 million) of AD cases worldwide and smoking to the second highest number (14%: 4.7 million); physical inactivity contributed to the third largest proportion (13%: 4.3 million) of AD cases worldwide and the largest number of cases in the USA (21%: 1.1 million).

Barnes remarks: "What really mattered was how common the risk factors were in the population. In the USA, about a third of the population is sedentary, so a large number of Alzheimer's cases are potentially attributable to physical inactivity. Worldwide, low education was more important because so many people throughout the world are illiterate or are not educated beyond elementary school. Smoking also contributed to a large percentage of cases because it is unfortunately still really common."*

The findings suggest that although treatments for Alzheimer's disease remain investigational, there are many options to reduce these preventable risk factors that could have a dramatic effect on AD including smoking cessation initiatives and public health initiatives to increase physical activity levels throughout life.

In a Comment, Laura Fratiglioni from Karolinska Institutet-Stockholm University and Chengxuan Qiu from Stockholm Gerontology Research Center, Stockholm, Sweden caution: "Accumulated evidence from epidemiological research strongly supports a role for lifestyle and cardiovascular risk factors in the pathogenesis and development of dementia. However, none of these factors has been proven to have a causal relation specifically with AD."

However, they add: "Interventions need to be implemented to verify findings from the many population-based observational studies, which suggest that preventive and therapeutic interventions have great potential…Large-scale multidomain intervention projects that could be undertaken in high-risk populations, as done with cardiovascular disease, should now be implemented."

###

Dr Deborah Barnes , University of California, San Francisco, USA. T) +1 415 298 5498 E) Deborah.barnes@ucsf.edu

Dr Laura Fratiglioni, Karolinska Institutet-Stockholm University, Stockholm, Sweden. T) +46 7077 35818 E) laura.fratiglioni@ki.se

Notes to Editors:

*Quote direct from author and cannot be found in text of Article


Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.