One-third of Alzheimer’s diseases cases worldwide might be attributable to potentially modifiable risk factors such as physical inactivity, smoking, midlife hypertension, midlife obesity, diabetes, and depression, a study found
Researchers used relative risks from existing meta-analyses done from 2004 to this year to estimate the population-attributable risk of Alzheimer’s disease worldwide by accounting for the association between 7 risk factors: diabetes, midlife hypertension, midlife obesity, physical inactivity, depression, smoking, and low educational attainment. They then examined the combined effect of relative reductions of 10% and 20% per decade for each of the 7 risk factors on projections for Alzheimer’s disease cases to 2050 in order to determine the potential of risk factor reduction.
Results appeared in the August issue of The Lancet.
Worldwide, the highest estimated risk factor was low educational attainment (19.1%, 95% CI, 12.3% to 25.6%). Among Western nations, the highest estimated risk factors was physical inactivity, in the U.S. (21.0%, 95% CI, 5.8% to 36.6%), Europe (20.3%, 95% CI, 5.6% to 35.6%), and the UK (21.8%, 95% CI, 6.1% to 37.7%).
The combined worldwide population-attributable risk for the 7 risk factors was 49.4% (95% CI, 25.7% to 68.4%), or 16.8 million attributable cases (95% CI, 8.7 million to 23.2 million) of 33.9 million cases. When researchers adjusted for the association between risk factors, the estimate fell to 28.2% (95% CI, 14.2% to 41.5%), or 9.6 million attributable cases (95% CI, 4.8 million to 14.1 million) of 33.9 million cases.
Combined population-attributable risk estimates were about 30% for the U.S., Europe, and the UK, researchers noted. Reducing the prevalence of each of the 7 risk factors by 10% per decade could reduce Alzheimer’s disease in 2050 by 8.3% worldwide.
Researchers wrote, “Although the analysis herein is necessarily simplistic, and other approaches to reduce disease burden for the tens of millions of people who will develop Alzheimer’s disease or other forms of dementia will be important, public health interventions targeted at vascular risk factors (e.g., physical inactivity, smoking, midlife hypertension, midlife obesity, and diabetes), depression, and low educational attainment will probably achieve the greatest reduction in the prevalence of the modifiable risk factors and will provide other major benefits to society and health-care systems.”