Heart Health, Explained
Dementia: A Link with Atherosclerosis (Artery Stiffness)
A new study appears to reinforce a link between atherosclerosis (artery stiffness) and increased risk of developing dementia. The researchers found that atherosclerosis is associated with the buildup of a type of plaque (beta-amyloid) in the brain that is a hallmark of Alzheimer’s disease. The study was published in the online edition of JAMA Neurology and publicized by WebMD March 31, 2014.
Dementia Link with Atherosclerosis Q&A
- Q: What causes atherosclerosis?
A: Atherosclerosis is a disease that occurs in blood vessels, involving the buildup of plaque (fat, cholesterol, calcium and other substances). The lining of the artery becomes damaged by factors that include smoking, high blood pressure, high cholesterol, obesity and diabetes. This damage causes the plaque to accumulate in the wall of the blood vessel, and the artery becomes stiff. Aging and genetic factors also contribute to stiffness.
- Q: Are there ways to reduce the risks, and to slow or reduce the buildup of beta-amyloid plaque in the brain?
A: Given the results of this study, it makes sense to reduce or modify the risk factors listed above. This can be done by improving blood pressure control and blood sugar levels if diabetes is present, and by not using tobacco. A healthy diet, weight control and exercise are very important first steps toward heart health. In addition to lifestyle changes, many individuals may require medications to achieve the best levels for cholesterol and blood pressure, and to manage diabetes.
- Q: Do risks differ for women and men?
A: The incidence of Alzhiemer’s disease is higher and the disease progresses faster in women than men; this cannot be explained simply by how long women live compared to men. Researchers have found through brain imaging that carrying the gene variant ApoE4, a potent risk factor for dementia, disrupts brain function in normal older women but has little effect on men. A recent analysis of 5000 normal older people who carried this gene showed that women had twice the risk of men of developing mild brain impairment or Alzheimer’s disease. Fifteen percent of the population carries at least one copy of this gene.
- Q: Determining whether there is a connection between atherosclerosis and the accumulation of beta-amyloid plaque in the brain seems like a difficult task in research. How did the investigators go about their study and how many elderly persons participated in this observational study?
A: This study involved 81 participants over the age of 83 who had no signs of dementia. The researchers used PET scans, which produce three-dimensional images, and examined the brain images for deposits of a substance that is associated with dementia - called beta-amyloid (Aβ) plaques. Scans were performed twice, two years apart. At the time of the second PET scan, the researchers also examined blood vessels that carry oxygenated blood away from the heart (arteries) to determine their stiffness. The investigators found that 48% of the individuals studied had Aβ plaques at the start of the study, and this increased to 75% after two years. They also found the stiffness of certain arteries was significantly higher in those who were Aβ positive. Increased stiffness of certain larger arteries corresponded with increased Aβ deposits observed in the scans. The researchers did not find a link between the brain deposits and age, sex, body mass index or use of blood pressure medication. They did, however, find a relationship both with a history of cardiovascular disease and the presence of a type of gene named ApoE4.
- Q: Research on the link between cardiovascular disease and dementia is in the beginning stages. What types of investigations are needed to gain a better understanding of this emerging link?
A: This study is small and should be confirmed in a large trial in which patients are followed for a number of years to see if they develop clinical evidence of dementia. If the results are consistent, perhaps the focus should move to examining the cause and how best to prevent the arterial stiffness that may be related to the beta-amyloid deposits. For many years, the emphasis has been on battling the beta amyloid plaques themselves. Recent studies have shown disappointing results from two drugs that inhibit beta amyloid formation. These results have prompted researchers to consider whether the deposits are a marker rather than a cause of dementia. As there appears to be an association between a history of arterial stiffness and beta amyloid, an extremely important question is whether taking action to prevent cardiovascular disease would, in fact, prevent dementia.
- Q: What kinds of questions should individuals concerned about cardiovascular and dementia risks be asking?
A: As ongoing studies take shape, concerned individuals should be asking themselves whether they are doing everything possible to decrease their cardiovascular risks. As outlined above, a healthy lifestyle is well worth pursuing for the benefits of improved life expectancy, quality of life, and now possibly prevention of dementia. Regular visits to your primary care physician and measurements of your blood pressure, cholesterol, and blood glucose(sugar) levels will help you monitor, on a yearly basis, any changes that may require the addition of medications to reduce your risk factors.
Teresa Caulin-Glaser, MD, FACC, FAACVPR System Vice President, Heart & Vascular Services OhioHealth Healthcare System, Columbus, Ohio
Heart Health Explained is a collaboration of Women’s Health Research at Yale and the OhioHealth Healthcare System, a nationally recognized not-for-profit organization with providers across 46 counties, offering a holistic approach to prevention, treatment and rehabilitation of heart disease. OhioHealth is staffed by physicians, psychologists, nutritionists and nurses who answer the questions of the moment on heart and vascular health.
The information provided here may help you make more informed choices. However, it is not a substitute for an individualized medical opinion or diagnosis, and everyone should always consult with their personal physicians to make decisions about their condition or treatment.