Spirituality occupies an unprecedented place in contemporary biomedical research. The increased inquiry into spiritual variables and resources, by both investigators and funding agencies, reflects a growing interest in systematically evaluating and rigorously studying the interaction of mind, body, and spirit. Despite this embrace, some vital elements remain in their infancy, including operational and clinically useful definitions, a classification schema, and methods to assess spirituality in medical and health care contexts.

Past
Historically, biomedical research into spirituality has been closely linked with research into its fraternal sibling, religion. In a seminal, exhaustive review of epidemiological data released in 1987, Jeffrey Levin and Preston Schiller found that studies examining religious variables were largely based upon research subjects' reported religious denomination and frequency of religious service attendance. Most medical or epidemiological studies had incorporated religious or spiritual variables in an uncritical fashion, severely compromising the quality and integrity of work in this area. In addition, they observed that the lack of a conceptual framework and methodology and the use of nonstandardized research techniques contributed to a predominant skepticism regarding any association between religion, spirituality, and health and medical variables.

In the last 15 years, the body of research documenting spiritual and religious influences on health, illness, and well-being has grown. The majority of these studies reflect an orientation toward geriatrics, psychiatry, and oncology and their specific populations. The independent work of Jeffrey Levin, David Larson, and Harold Koenig confirmed an association between spirituality, religion, and health and medical factors. These investigators also implemented specific research methods and created theoretical models that could be used in health care settings. One such model tested and validated a construct of religiosity in large, population-based studies, incorporating three dimensions: organized religious activity, such as worship attendance; nonorganized religious activity, such as private prayer or devotion; and subjective religiosity.

Although religiously derived variables and constructs were predominant in past studies, gradually researchers began to differentiate and explore spirituality as a separate variable, independent of religion. Due to a limited understanding of spirituality as a variable, many investigators turned to psychology, sociology, and to a lesser extent theology, for guidance.

Present
While researchers continue to empirically test and validate the association of spiritual variables in medical research, two parallel movements in American medicine have independently legitimized exploration within this field: end-of-life care and alternative medicine.

The influential, eight-year SUPPORT study examined various aspects of end-of-life treatment for nearly 10,000 critically ill patients. While not specifically addressing spiritual concerns, the 1995 study indirectly promoted a rapprochement among the realms of spirituality, health care, and medicine. As a result, there has been a greater interest in evaluating and assessing psychospiritual or spiritual influences and processes in end-of-life situations.

The popularity of alternative or integrative medicine has also accelerated interest in spirituality. A 1993 study of the prevalence and practices of alternative medicine in the United States found that spiritual interventions such as prayer and certain types of relaxation techniques are an accepted part of medical therapy in the general population. The philosophical promotion of a "new spirituality" can be found in much alternative medicine.

It is important to consider end-of-life care and alternative medicine when viewing the development of spirituality in medical research, since both movements are patient- centered and oriented primarily toward interventions or outcomes. Some of the "spiritual" variables that researchers have applied in these movements are social support and the frequency of prayer or meditation. Both of these movements, however, continue to struggle with operationally defining spirituality in a critical and systematic fashion.

A consensus report published last year by the National Institute for Healthcare Research may help standardize spirituality in medical research settings. The criteria included:

The feelings, thoughts, experiences, and behaviors that arise from a search for the sacred. The term "search" refers to attempts to identify, articulate, maintain, or transform. The term "sacred" refers to a divine being or Ultimate Reality or Ultimate Truth as perceived by the individual.

Although broadly based, this definition acknowledges the importance of an "intra-individual" or "patient-centered" focus.

An additional contribution grew out of the National Institute on Aging/Fetzer Institute Working Group on Measurement in Religion, Spirituality, Health, and Aging. The report reflects the complexity of the spiritual variable, the importance of clearly defining the measure to be studied, and the need to avoid reification by identifying and clarifying 10 key domains of research, including religious/spiritual preference, history, social participation, and commitment.

Future
While inquiry involving end-of-life care and alternative medicine will continue to engage medical research involving spiritual variables, the scope and focus of future work will expand beyond these two movements. Diseases that are primarily lifestyle-related, such as heart disease and diabetes continue to be the major causes of morbidity and mortality in the United States. The prevalence of these diseases reflects the importance of social and behavioral determinants of health and illness. The traditional biomedical model, which emphasized molecular and cellular causes of disease and illness, has been expanded to the biopsychosocial model of illness proposed by George Engel in 1977.

Future medical models will expand Engel's paradigm to include spiritual variables as well. The Robert Wood Johnson Foundation recently commissioned the Institute for the Future to examine the future of health and health care in America in the next decade. The Institute has forecast the gradual adoption of an expanded view of health by the medical establishment, one that incorporates social, mental, and spiritual factors. This forecast predicts that priority areas of medical researchers will shift from validation of spiritual factors in health promotion, recovery from illness, and well-being, to questions of process and efficacy specific to spiritual variables.

Process and efficacy will frame successful biomedical research of spirituality and spiritual resources around three overlapping domains. The first will examine religious and spiritual influences as a behavioral determinant of health. With contributions from epidemiology and health theory, the convergence of public health and medicine will further promote a greater understanding of spirituality as a behavioral and social health construct.

A second domain of future research will evaluate spirituality in a more global social context. The impact of community and social support on coping and stress mechanisms, end-of-life care, and health care delivery systems is an area enlivened by spiritual resources.

The final domain will build on existing basic science research to further explore the effect of spirituality and spiritual practices on physiology, neuroendocrinology, and psychology. Technological advances in medical imaging, such as PET scan and MRI, and chemical assay techniques will further advance work such as that of Herbert Benson, author of Timeless Healing: The Power and Biology of Belief, in documenting the physiologic effects of spiritual and religious practices. Future exploration of spiritual variables will provide profound new insights into our understanding of the interactions of mind, body, and spirit.

Timothy P. Daaleman, D.O., Robert Wood Johnson Generalist Faculty Scholar, is an Assistant Professor of Family Medicine at the University of Kansas Medical Center.