STOCKHOLM—A host of studies presented at the Alzheimer’s Association’s 8th International Conference on Alzheimer’s Disease and Related Disorders suggested a strong connection between lifestyle choices—especially those that contribute to cardiovascular disease—and Alzheimer’s disease. The broad collection of epidemiologic studies reflected a range of lifestyle elements, including diet and nutrition, cholesterol levels, body weight, exercise, and blood pressure and hypertension, as well as intellectual stimulation and social contact, all of which may have a role in preventing or delaying the onset of Alzheimer’s disease. Of particular note was the mounting evidence that the same risk factors for cardiovascular disease—high blood pressure, diabetes, and high cholesterol levels—may also play a role in Alzheimer’s disease.

HISTORY OF HYPERTENSION LINKED TO ALZHEIMER’S DISEASE

People may be able to reduce their risk of developing Alzheimer’s disease by taking early steps to treat high blood pressure. “A growing body of evidence suggests that a history of hypertension may be a risk factor for Alzheimer’s disease,” said William Thies, PhD, Vice President of Medical and Scientific Affairs for the Alzheimer’s Association. “This is an evolving story, but vascular disease and dementia appear to be related.”

A longitudinal study by Miia Kivipelto, MD, a research fellow in the Department of Neuroscience and Neurology at the University of Kuopio, Finland, found high blood pressure to be an independent risk factor for Alzheimer’s disease. Dr. Kivipelto examined 1,449 individuals (ages 65 to 79) after an average follow-up of 21 years. The risk of Alzheimer’s disease related to the treatable risk factors of elevated cholesterol and blood pressure appeared to be greater than the risk related to the apolipoprotein E e4 allele, one of the most important genetic risk factors for the disease.

Another study, conducted by Olivier Hanon, MD, and colleagues at Broca Hospital in Paris, also suggested hypertension as a risk factor for Alzheimer’s disease. This cross-sectional study of 1,560 elderly individuals with symptoms of memory impairment found a correlation between blood pressure and cognitive decline. Patients with hypertension were significantly more common in the group with Alzheimer’s disease (67%) and vascular or mixed dementia (78%) as compared to the group without dementia (56%).

Similarly, a study to test whether lowering blood pressure is associated with reduced risk of dementia was conducted by Ingmar Skoog, PhD, a Professor at the Institute of Clinical Neurosciences of Göteborg University, Sweden. The randomized double-blind study evaluated the effect of the antihypertensive medication candesartan versus a placebo in 4,964 mildly hypertensive patients (ages 70 to 89) recruited from 15 countries. The medication produced a nonsignificant risk reduction of 23% for cognitive decline.

However, a study published recently in Neurology by researchers at Columbia University College of Physicians and Surgeons in New York City found no correlation between hypertension and Alzheimer’s disease among patients older than 65. According to Richard Mayeux, MD, MSc, Director of the Taub Institute and lead researcher of this longitudinal study that followed 1,259 initially healthy Medicare patients from 1991 to 1998, hypertension late in life is not a risk factor for Alzheimer’s disease.

Additional research, including longer and larger prevention trials, is necessary to better understand the relationship between high blood pressure and Alzheimer’s disease, according to Dr. Thies. “Since high blood pressure can be controlled, we may have identified something people can do to lower their chance of developing Alzheimer’s disease,” he said. “While it seems likely that what is good for your heart is also good for your head, it looks like people need to start early to realize the full benefits.”

CORONARY SURGERY MAY BYPASS COGNITIVE HEALTH

Coronary artery bypass grafting (CABG) may be associated with an increased risk of stroke, short-term memory problems, and long-term cognitive changes. Guy M. McKhann, MD, and colleagues at Johns Hopkins University School of Medicine in Baltimore, Maryland, collected data on 3,300 patients who underwent CABG between 1997 and 2001. The researchers found that after CABG surgery, 2.6% of the patients suffered a stroke and 6.8% developed acute confusion or short-term memory problems. Both outcomes are associated with increased length of hospital stay and deaths.

The researchers then identified the following risk factors for stroke, acute confusion, and the combination of the two: hypertension, diabetes, carotid bruit, previous stroke, age, and length of time on the cardiopulmonary bypass pump. They found that there is a 50% increase in the probability of acute confusion for each hour on the bypass pump.

Dr. McKhann and colleagues evaluated changes in patients’ cognitive function at one month, one year, and five years after surgery. They found that cognitive changes involving memory and attention generally improved within one year after surgery. However, between one year and five years after surgery, the researchers identified cognitive declines. It was noted that individuals with more severe cerebrovascular disease at baseline were more likely to experience this delayed decline. “There appears to be a subpopulation of patients undergoing coronary bypass surgery, with risk factors for cerebrovascular disease, who are at greater risk for stroke, cognitive decline, and long-term cognitive changes,” said Dr. McKhann, who is a Professor of Neurology. “For this population of people, it may be beneficial to consider alternative cardiac interventional techniques in addition to carefully managing diabetes, hypertension, and other related risk factors.”

CARDIOVASCULAR CONCLUSIONS

“These studies are further evidence that knowing and managing your numbers—your blood pressure, cholesterol, and blood sugar levels, as well as your body weight—contribute to healthier aging and may decrease your risk for Alzheimer’s disease,” concluded Dr. Thies. “Even if they do not ultimately decrease your risk of Alzheimer’s disease, they will contribute to the best outcome of the later parts of your life.

“Furthermore,” he added, “the studies on exercise, which helps maintain blood pressure, cholesterol, and blood sugar levels as well as body weight, are impressive.” The increased interest in identifying risk factors for Alzheimer’s disease is in large part due to the fairly recent realization that environmental factors play a role in Alzheimer’s disease. However, the challenge for Alzheimer’s disease researchers is in collecting, tracking, and analyzing behavioral data going back 10, 20, or 30 years. “Alzheimer’s disease may start as many as 20 to 30 years before symptoms appear,” explained Dr. Thies. “It’s difficult to trace environmental influences back 30 years. Medical information such as blood pressure, for example, is more readily available, but otherwise it’s hard to assemble.

“While more research is necessary, especially in the form of prevention trials, we’re seeing the strongest evidence yet that there is a relationship between healthy aging and a reduced risk of Alzheimer’s disease,” he said. “Healthy aging is a process that should begin sooner rather than later in life in order to remain healthy of body and mind for as long as possible.”

Return to table of contents