People who have heart disease risk factors in middle age, including diabetes, high blood pressure and smoking, are at higher risk for dementia later in life, a large, long-term U.S. study suggested Monday.
The study, led by Rebecca Gottesman, professor of neurology at Johns Hopkins University, and published in the U.S. journal JAMA Neurology, analyzed the data of 15,744 people who participated in the Atherosclerosis Risk in Communities study, a project designed to investigate the causes and effects of the hardening of the arteries.
Participants, who were black or white, were aged 45 to 64 years whey they were recruited between 1987 and 1989.
Over an average follow-up of 23 years, they underwent a battery of medical examinations that included cognitive tests of their memory and thinking.
During that time, 1,516 participants were diagnosed with dementia.
Initially, when they analyzed the influence of factors recorded during the first exams about 25 years ago, 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.
Blacks were also found to have higher chance of dementia than whites and those who did not graduate from high school were also at higher risk.
What's more important, 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.
The researchers also found a link between dementia and prehypertension, a condition in which blood pressure levels are higher than normal but lower than hypertension.
And race did not influence the association between dementia and the vascular risk factors they identified, according to the study.
In addition, 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 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."