Perspective

Michael Robbins, left, and Merrill Elias Merrill Elias Title: University of Maine Professor of Psychology and Research Professor of Epidemiology in Mathematics and Statistics, Boston University Research focus: Behavioral correlates of hypertension, age and vascular diseases Years at UMaine: 30 Milestones: In 1975, initiated the Maine-Syracuse Longitudinal Study, one of the longest-running scientific investigations relating aging, arterial blood pressure and cardiovascular disease risk factors to comprehensive measures of neuropsychological test performance; in 2002, elected a Fellow in the Council of High Blood Pressure of the American Heart Association Michael Robbins Title: University of Maine Senior Research Associate and Cooperating Associate Professor of Psychology Research focus: Health behavior and personality in relation to cognitive aging Years at UMaine: 29, including nine as a Ph.D. student Milestones: Joined the Maine-Syracuse Studies in 1981, became an investigator on the Maine-Syracuse Studies in 2000   Links related to this story

Cognitive Function and Health

Question: You have been studying the relationship between high blood pressure and cognitive ability for more than 30 years. Why you were interested in blood pressure and what is the major thing you have learned?

Elias: I was a postdoctoral fellow at Duke University Medical Center when the first paper in this area was published in Science in 1971. By current research standards, the paper had a number of limitations, including an extremely small sample and no control for the possible confounding of blood pressure with blood pressure medication and hypertension-related medical complications. Nevertheless, it introduced the possibility that high arterial blood pressure (arterial hypertension) could contribute to accelerated age-related changes in cognitive performance over time in elderly persons. It seemed important to fix the problems in this study and to determine the relation between arterial blood pressure and cognition over many years for adults of all ages. Over three decades later we feel we made some progress with respect to this objective.

As always, some good luck made this possible. While at Syracuse University, I had the opportunity of teaming up with a word-class investigator in the area of hypertension: Dr. David H. P. Streeten, Professor of Medicine, SUNY Upstate Medical University. With support from the National Institute on Aging, we completed our baseline studies at Syracuse with 197 participants. Today we have enrolled 1072 men and 1351 women in our studies and have completed 30 years of longitudinal observations.

The study takes its name from its beginning in Syracuse and its continuation in Maine. In 1977 I moved to the University of Maine from Syracuse and Mike Robbins became an important member of our research team in 1981. Penelope Elias, previously a collaborating investigator, joined the research team full time in 2003. We now have international collaborators and study consultants at the University of Birmingham, England, University of Oxford, England, Cambridge, and Australian National University, Boston University, and the University of Southern California.

In 1977 we had baseline data from the first study in Syracuse, but still needed to follow individuals over many years to see if rise in blood pressure, the development of high blood pressure, and chronic (long-standing) hypertension were, in fact, related to accelerated decline in cognitive performance with advancing age. This required very loyal Syracuse study participants who were willing to come back every five years for a medical examination, blood draws, and approximately 2 to 3 hours of neuropsychological testing. These study participants live all over the country today. If they cannot come to us, we go to them thanks to the skill and hard work of Suzanne Brennan our chief medical technician and psychological examiner.

What have we found? When we started in 1975, comparatively little was known about the adverse effect of hypertension on brain structure and function. Today, hypertension is widely recognized as a risk factor for lowered cognitive performance and evidence for the role of brain lesions and blood flow disregulation is very strong. There were a number of benchmark findings in our 30-year longitudinal study (still ongoing) that led to the current state of the literature: (1) chronic hypertension is related to accelerated changes in cognitive performance at all ages, and although subtle these changes are progressive; (2) the higher the blood pressure, the greater the rate of change in cognition over time; (3) adverse affects of high blood pressure on cognition cannot be attributed to antihypertensive drug treatment; (4) well practiced verbal skills are spared by hypertension, but fluid, spatial, and working memory abilities are affected, as is speed of performance; (5) hypertensive individuals function very well in activities of daily life; hypertension-related changes in cognition are subtle and quite clearly can be offset by education.

For a variety of reasons it is important to detect and treat hypertension as early as possible in persons of all ages and prevent hypertension via good health habits including salt reduction, activity, weight reduction, etc. The goal is the prevention of stroke, hypertension-related complications and cognitive deficit, no matter how subtle.

Question: What is the relationship between cognitive ability and the risk factors for cardiovascular disease?

Elias: In recent years (2000 to 2006), with additional support from the National Heart Lung and Blood Institute (NIH) and collaboration with experts on cardiovascular disease in England and Australia, we have expanded the Maine-Syracuse study to include risk factors for cardiovascular disease and stroke (other than blood pressure). We do not at this time have longitudinal cognitive data for risk factors other than blood pressure and related cerebrovascular diseases. These studies are ongoing and we will have our first longitudinal data of these risk factors completed within 4 years.

Thus far our studies indicate that in persons free from dementia and stroke, modestly lower levels of cognitive performance are seen in the presence of risk factors such as diabetes, overweight, high blood levels of homocysteine, a product of 1-carbon metabolism, and APOE ε4, a gene allele possibly defective and involved in neuronal repair. Again, while deficits are mild initially, the concern is the progression of cognitive deficit over time if modifiable risk factors are not treated and adequately controlled. Not all risk factors are negative. In our studies we find that physical activity, vitamin B12, vitamin B6, and folic acid are positively related to cognition.

Question: How widespread is the problem of cardiovascular disease (CVD) in the U.S.?

Robbins: Despite public health initiatives CVD continues to be widespread in the U.S. For instance, approximately 30% of the adult population is classified as having high blood pressure (BP), termed arterial hypertension and traditionally defined as systolic blood pressure >140 mmHg and/or diastolic BP > 90 mmHg. Another 45 million persons have prehypertension (systolic BP between 120 and 139 mmHg and/or diastolic BP between 80 and 89 mmHg). The risk for stroke rises progressively above 115/75 mmHg.

High BP increases risk for lowered cognitive function as well as such leading causes of disability and death as heart attack and stroke. Young people might think that these are issues for their distant future, but we have shown in the Maine-Syracuse Study that higher BP is associated with relative cognitive decline even for people less than 50 years of age.

Question: What can people do to protect their cardiovascular health and cognitive functioning as they age?

Robbins: There are health-promoting behaviors that can prevent or at least delay the physical processes that lead to CVD. These include not smoking, being physically active, and eating a well balanced diet. Recent Maine-Syracuse data indicate that lower blood levels of vitamins B6, B12 and folate are associated with poorer cognitive functioning. For some people vitamin supplements may be appropriate to augment the amounts of these B vitamins they get in their diet.

Once CVD conditions are diagnosed, often medication along with lifestyle modification is prescribed for treatment. For instance, the majority of our participants are taking medications designed to lower BP. It is important to follow such treatment regimens closely. Salt intake reduction is important for hypertensive and pre-hypertensive individuals.

Being physically and mentally active continues to be important as we age in order to protect both cardiovascular health and cognitive functioning.