Blog | Friday, August 26, 2011

Optimism, positive health and stroke risk

Way back in 1946, the chartering documents for a new agency of the U.N., the World Health Organization, defined health as "a state of complete physical, mental, and social well-being and not merely the absence of disease or infirmity."

We have made astounding progress in medicine and public health since the WHO charter was crafted, yet we have actualized only part of its comprehensive vision for health. What we call health care today is really just illness care. Even our disease prevention and health promotion programs focus on reducing risk factors for disease. It is the rare initiative indeed that encourages good health for its own sake.

New initiatives focused on the concept of positive health are changing that by helping us understand what it means to be healthy in a comprehensive sense, beyond the simple absence of symptoms and illnesses. The initiatives focus on health assets, which are biological, psychological, social and other characteristics that are associated with prolonged life, reduced morbidity and health care costs, and improved quality of life.

The initiatives have been triggered in large part by the seminal contributions of Martin Seligman. Many are funded by the Robert Wood Johnson Foundation's Pioneer Program. They have already produced provocative results, one of which I discussed last week.

In this post, the second in a continuing series, I review another initiative in the field of positive health. This one examines how optimism impacts the risk of stroke, the nation's third leading cause of mortality and disability after heart disease and cancer.

The study
The classic risk factors for cardiovascular disease (including stroke) include high blood pressure and cholesterol levels, cigarette smoking and diabetes. 'Negative' psychosocial factors like depression, anxiety, work stress, low socioeconomic status and poor social support also predict cardiovascular events. More recently, a few studies have filtered into the literature suggesting that health assets like life satisfaction are also predictive.

However, as the National Heart, Lung and Blood institute recently emphasized, essentially none of these factors are all that good at predicting near term (that is, 1-2 years) cardiovascular events, especially in asymptomatic adults. Furthermore, almost no studies have examined whether positive health assets can impact the risk of stroke, per se.

A study by Eric Kim of the University of Michigan and colleagues has addressed this opportunity. They concluded that optimism was in fact an independent predictor of short-term stroke risk.

To reach this conclusion, Kim's group looked at data from 6,044 adults with no prior history of cardiovascular or cerebrovascular disease. The subjects had participated in the Health and Retirement Study, a nationally representative, prospective study of Americans who were at least 50 years old.

The scientists assessed optimism using the Life Orientation Test, in which participants respond to 3 questions using a 6-point Likert scale. Kim's group created an 'optimism scale' based on participants' responses. The scale ranged from 3 (extremely pessimistic) to 18 (extremely optimistic).

It turned out across the entire survey population, each unit increase on the scale was associated with an age-adjusted 9% decrease in stroke-risk during the 2 year follow-up.

Negative psychological factors like anxiety, depression and neuroticism were also predictive of short-term risk for stroke, but optimism offset their impact.

Of note, the association between optimism and stroke risk persisted after controlling for cardiac disease and dozens of biological, behavioral and sociodemographic factors (including race/ethnicity, marital status, educational status, cigarette smoking history, exercise, alcohol use, diabetes, body-mass index, blood pressure).

What Can We Make of This?
Kim's study is the first to suggest that optimism may protect against stroke in older adults. It is consistent with other research which has shown that positive psychological factors like optimism are associated with a range of cardiovascular benefits, including a reduced risk of rehospitalization following bypass surgery, reduced risk of coronary heart disease and even reduced cardiovascular mortality.

One potential flaw in Kim's study is that stroke incidence was ascertained via self-reporting from participants, based on what they understood from their doctor or by proxy reports for participants that had died (many of the covariates were also self-reported in Kim's study). According to Kim's team however, self-reported stroke has been shown in several other studies to provide an accurate estimate of stoke incidence.

Why might optimism reduce stroke risk? Kim's group mentioned several studies showing that high optimism is associated with health knowledge and the pursuit of healthy behaviors. They hypothesized that optimists might be more proactive about their health in general, perhaps by adopting a healthier lifestyle that minimizes health risks and increases health and well-being.

These theories make sense but require further validation, especially before we can comfortably recommend interventions designed to promote optimism in the effort to reduce the incidence of stroke.

This post by Glenn Laffel, MD, PhD, appeared at Get Better Health, a network of popular health bloggers brought together by Val Jones, MD. Better Health's mission is to support and promote health care professional bloggers, provide insightful and trustworthy health commentary, and help to inform health policy makers about the provider point of view on health care reform, science, research and patient care.