Harold G. Koenig, MD completed his undergraduate education at Stanford University, his medical school training at the University of California at San Francisco, and his geriatric medicine, psychiatry, and biostatistics training at Duke University Medical Center. He is on the faculty at Duke as professor of psychiatry and behavioral sciences and associate professor of medicine. Dr. Koenig is also director of the Center for Spirituality, Theology, and Health at Duke University Medical Center, and is Distinguished Adjunct Professor at King Abdulaziz University in Jeddah, Saudi Arabia. Dr. Koenig has published extensively in the fields of mental health, geriatrics, and religion, with over 350 scientific peer-reviewed articles and book chapters and nearly 40 books in print or in preparation. He has given invited testimony to both the U.S. Senate and the U.S. House of Representatives on the role of religion in public health.

Overview of the Research

OUTLINE

I. Mental Health
1. Positive Emotions
a. Well-Being
b. Hope and Optimism
c. Meaning and Purpose
d. Self-Esteem
e. Sense of Personal Control
2. Negative Emotions
a. Depression
b. Suicide
c. Anxiety
d. Alcohol Use/Abuse
e. Drug Abuse

II. Social Health
1. Human Virtues
2. Social Support
3. Social Capital

III. Physical Health
1. Health Behaviors
a. Exercise
b. Diet
c. Weight
d. Risky Sexual Activity
e. Smoking
2. Physical Disorders
a. Heart Disease
b. Hypertension
c. Cerebrovascular Disease
d. Dementia
e. Immune Dysfunction
f. Endocrine Dysfunction
g. Cancer
h. Overall Mortality

IV. Relationships with Health

V Summary and Conclusions

FOR THOUSANDS OF years, as far back as historical records go, people around the world have held religious beliefs and engaged in religious practices. Why would humans spend their time and energy on such activities? Why would such beliefs and practices persist and even flourish in some of the most developed countries of the world and among well-educated and informed people? For example, recent national polls of the United States by the Gallup and Pew organizations have found that 55 to 65 percent of Americans indicate that religion is an important or very important part of their daily life.1 What function does religion serve that keeps people believing and practicing? One possibility is that it helps to preserve health.

In this first chapter I briefly review research on the relationships between religious involvement and mental, social, and physical health. That research has been rapidly increasing in volume, especially over the past twenty years. Figure 1.1 shows the number of peer-reviewed articles on religion/spirituality (R/S) and health appearing in Medline and PsychINFO from 1965 to 2009. Note that the figures are noncumulative, referring to the number of articles published during each five-year period. Although only about 5 to 10 percent of these articles are research related, the number of research studies is rapidly accumulating. Overall, there now exist about three thousand quantitative original databased studies on R/S and health. The review in this chapter sets the stage for the remainder of this book, which focuses on a critique of the research and, in particular, on a discussion of how to conduct, analyze, interpret, publish, and fund research on religion, spirituality and health.

Mental Health

The majority (70 to 75 percent) of research on R/S and health has focused on mental health (Figure 1.2). I summarize this research by dividing it into studies on positive emotions and studies on negative emotions. The summaries presented here (see Table 1.1 on page 19) are from systematic reviews of the literature contained in the appendices of two editions of the Handbook of Religion and Health; all studies referred to below are reviewed there in detail.

Positive Emotions

R/S has been linked to a number of positive psychological emotions that represent the opposite of the negative emotions and mental disorders that I discuss in the next section.

Well-Being

As of early 2010 at least 326 quantitative studies had examined relationships between R/S and well-being, with 256 (79 percent) finding greater happiness, satisfaction with life, or overall sense that life is good in those who were more R/S. All of these studies reported statistically significant findings, except for eight studies in which results were at a trend level (0.05 < p < 0.10). Of the 120 studies judged as the methodologically most rigorous, 98 (82 percent) found greater well-being among those who were more R/S (two at a trend level). Less than 1 percent reported lower well-being in the more R/S.

Hope and Optimism

At least 40 studies have examined relationships between R/S and hope, with 29 (73 percent) finding greater hope among the more R/S (two at a trend level). Likewise, at least 32 studies have examined relationships between R/S and optimism, and of those, 26 (81 percent) reported a significant positive relationship.

Meaning and Purpose

Having meaning and purpose in life is a positive aspect of mental health that is not only strongly correlated with well-being but also associated with resilience in the face of difficult circumstances. Of the 45 studies that have now examined relationships with R/S, 42 (93 percent) reported greater meaning or purpose among the more R/S. Of the 10 best studies in terms of methodological rigor, all 10 (100 percent) reported significant positive relationships.

Self-Esteem

Low self-esteem is often associated with an emotional disorder such as depression. In contrast, high self-esteem is strongly correlated with positive emotions and good mental health. Of 69 quantitative studies examining the relationship between R/S and self-esteem, 42 (61 percent) found significantly higher levels of self-esteem in those scoring higher on R/S; only 2 studies (3 percent) reported that R/S persons had lower self-esteem. Of the 25 methodologically most rigorous studies, 17 (68 percent) reported greater self-esteem in the more R/S.

Sense of Personal Control

Persons with a high internal locus of control (LOC) believe that events in life are a result of their own actions; in contrast, those with an external LOC believe that powerful others or external events control their lives. Of the 21 studies we identified in our systematic review that examined relationships between R/S and LOC, 13 (62 percent) reported that those who were more R/S scored significantly higher on having a sense of personal control.

Negative Emotions

In contrast to these positive indicators of mental health are negative emotional states, which when they interfere with an individual's functioning are called "mental disorders." These include depression, suicide, anxiety, alcohol abuse, and drug abuse.

Depression

Depression was the leading cause of disability in the world (measured by years of life lived with disability)...