Cardiovascular Risk Factors May Result in Dementia

Diabetes, hypertension, and prehypertension could increase the risk of dementia regardless of race.

The results of a long-term study suggest that cardiovascular risk factors during midlife may affect cognitive health. The authors discovered that diabetes, high blood pressure, and smoking may increase the risk of developing dementia later in life, according to the study published by JAMA Neurology.

“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, MD, director of the National Institute of Neurological Disorders and Stroke. “What’s good for the heart is good for the brain.”

Included in the study were data for 15,744 patients who were enrolled in the Atherosclerosis Risk in Communities study (ARIC). From 1987-1989, a number of medical tests were administered to the patients, who were black or white and aged 45 to 64 years. Over the next 25 years, they received 4 examinations, including cognitive tests of memory and thinking, according to the authors.

The investigators found that 1516 patients were diagnosed with dementia during follow-up. Upon first examination, the authors found that the presence of the APOE4 gene increased the risk of dementia.

Overall, black patients and those who did not graduate high school had a higher risk of developing dementia. Significantly, the authors found that white patients with 1 copy of the gene were observed to have a higher risk of dementia compared with blacks, according to the study.

A further analysis of vascular risk factors revealed that patients with diabetes or high blood pressure had a higher risk of dementia. The investigators noted that diabetes was nearly as strong of a predictor of dementia as APOE4, according to the study.

For the first time, the researchers also found a link between dementia and prehypertension.

Race was not observed to influence the link between dementia and the risk factors. Diabetes, hypertension, and prehypertension were found to increase the chances of dementia for participants regardless of race; however, the authors found that smoking cigarettes only increased the chances of dementia for white patients.

“Our results contribute to a growing body of evidence linking midlife vascular health to dementia,” said lead researcher Rebecca Gottesman, MD, PhD. “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.”

Additional analyses reinforced the hypothesis that the risk factors were linked to dementia. For example, the team reanalyzed data from participants who did not experience a stroke to determine if the stroke influenced dementia. The authors found that diabetes, hypertension, prehypertension, and smoking increased the risk of dementia for both stroke-free participants and those who had a stroke, according to the study.

In a separate study, the team of researchers analyzed brain scans from a group of patients without dementia at baseline. They discovered that at least 1 cardiovascular risk factor during midlife was linked to higher levels of amyloid beta, which is known to play a role in Alzheimer’s disease.

The authors reported that the relationship was not observed to be affected by the APOE4 gene and was not observed in risk factors developed later in life, according to the study.

The investigators plan to conduct future research into how vascular conditions may affect the brain and why dementia is affected by race.

“With many years of data from a large and diverse population, the ARIC study is a powerful source of information for medical research,” said Jacqueline D. Wright, DrPH, program director at the National Heart, Lung, and Blood Institute. “This epidemiologic study aimed to improve our understanding of atherosclerosis and heart disease and, through the investigators’ efforts; it has become a great resource for research on dementia and other diseases of aging. The investments in longitudinal cohort studies like ARIC will benefit all of us for many years to come.”