A large, long-term study suggests that middle aged Americans who have vascular health risk factors, including diabetes, high blood pressure and smoking, have a greater chance of suffering from dementia later in life. The study, published in JAMA Neurology, was funded by the National Institutes of Health (NIH).
“With an aging population, dementia is becoming a greater health concern. This study supports the importance of controlling vascular risk factors like high blood pressure early in life in an effort to prevent dementia as we age,” said Walter J. Koroshetz, M.D., director of NIH’s National Institute of Neurological Disorders and Stroke (NINDS), which partially funded the study and created the Mind Your Risks® public health campaign to make people more aware of the link between cardiovascular and brain health. “What’s good for the heart is good for the brain,” he added.
The study was led by Rebecca Gottesman, M.D., Ph.D., professor of neurology at Johns Hopkins University in Baltimore. Her team analyzed the data of 15,744 people who participated in the Atherosclerosis Risk in Communities (ARIC) study, funded by the NIH’s National Heart, Lung, and Blood Institute (NHLBI). From 1987-1989, the participants, who were black or white and 45-64 years of age, underwent a battery of medical tests during their initial examinations at one of four centers in four different states. Over the next 25 years they were examined four more times. Cognitive tests of memory and thinking were administered during all but the first and third exams.
Her team found that 1,516 participants were diagnosed with dementia during an average of 23 follow-up years. Initially, when they analyzed the influence of factors recorded during the first exams, the researchers found that the chances of dementia increased most strongly with age followed by the presence of APOE4, a gene associated with Alzheimer’s disease. Whites with one copy of the APOE4 gene had a greater chance of dementia than blacks. Other factors included race and education: blacks had higher chance of dementia than whites; those who did not graduate from high school were also at higher risk.
In agreement with previous studies, an analysis of vascular risk factors showed that participants who had diabetes or high blood pressure, also called hypertension, had a higher chance of developing dementia. In fact, diabetes was almost as strong a predictor of dementia as the presence of the APOE4 gene.
Unlike other studies, the researchers discovered a link between dementia and prehypertension, a condition in which blood pressure levels are higher than normal but lower than hypertension. Also, race did not influence the association between dementia and the vascular risk factors they identified. Diabetes, hypertension and prehypertension increased the chances of dementia for white and black participants. Finally, smoking cigarettes exclusively increased the chances of dementia for whites but not blacks.
“Our results contribute to a growing body of evidence linking midlife vascular health to dementia,” said Dr. Gottesman. “These are modifiable risk factors. Our hope is that by addressing these types of factors early, people can reduce the chances that they will suffer from dementia later in life.”