April 17, 2017
In one of the largest studies of its type, researchers confirm a link between midlife vascular disease and late-life dementia. As reported in the April 11 Journal of the American Medical Association, 50-year-olds with two or more vascular risk factors were almost three times more likely to have amyloid in the brain in their 70s as were those with no signs of cardiovascular disease in middle age. Researchers said that the study, led by Rebecca Gottesman at Johns Hopkins University School of Medicine, Baltimore, was impressive for the number of subjects and its prospective design. However, scientists are still unsure how vascular disease begets amyloid.
Gottesman and colleagues analyzed data collected from the Atherosclerosis Risk in Communities (ARIC) study, which has been following almost 16,000 volunteers recruited from four communities since 1987 (see ARIC Investigators, 1989). A subset of 346 people from three of those communities (in Maryland, North Carolina, and Mississippi) underwent 3T MRI and amyloid PET scanning with florbetapir between 2011 and 2013, when they were about 76 years old on average. Using a standard uptake value ratio (SUVR) of 1.2 as a cutoff for tracer uptake, Gottesman correlated amyloid positivity with earlier cardiovascular factors, including body mass index, high blood pressure, diabetes, plasma cholesterol, and smoking history.
When comparing individual risk factors, only people with a body mass index of 3.0 or higher at midlife were more likely to have amyloid in their 70s, with an odds ratio of 2.06. This included 38 percent of whites and 32 percent of blacks. A stronger correlation emerged when the researchers accounted for multiple cardiovascular risk factors. Those with two or more were 2.8 times as likely to have amyloid in late life as those with fewer than two. Almost 42 percent of people in the study had more than two risk factors.