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November 29, 2004
The pith of depression
Charles raison is assistant professor of psychiatry and behavioral sciences
Recently I had the honor of helping to organize the symposium, “Mind-Body Medicine at the Interface of Mood and Health: Tibetan Buddhist and Western Perspect-ives on Depression in the Medically Ill.” I was additionally charged by the Emory-Tibet Partnership with presenting the “Western” view of how mind and body interact in ways relevant to mood disorders—a daunting task under any circumstance, but one made even more so by the fact that my “Eastern” counterpart was the world’s foremost Tibetan physician (that I had only 45 minutes to present the “pith” of the issue, as the Buddhists would say, didn’t help either).
One of the great pleasures of taking part in events like this is they are great excuses for talking extensively with people like Dr. Pema Dorjee, whose six-week stay at Emory was the impetus for organizing the symposium in the first place. Dr. Dorjee is widely regarded as the most eminent living practitioner of Tibetan medicine—a system of diagnosis and treatment based on Buddhist philosophy that extends backwards into antiquity. Befitting his great expertise, he serves as physician for His Holiness the Dalai Lama.
Several hours of lively exchange with Dr. Dorjee left me marveling at a paradox. Despite radically different assumptions about how the body works, developments in Western science give increasing credence to a central tenant of the Tibetan system: that conscious states play a key role in maintaining health and in developing illness. Moreover, my stereotyped notion—that traditional Eastern medical systems ascribe all major causes of illness to either mental or spiritual factors—was overthrown as I listened to Dr. Dorjee talk about ways in which changes in the physical body can profoundly affect a person’s mood state. When he told me that he counsels many patients with mood disorder symptoms, “It is not you; it’s the depression,” I felt a sudden urge to offer him a faculty position in the Department of Psychiatry here at Emory.
However, I also was struck by a difference between our traditions that previously had escaped my notice. In the West, medical education involves learning the answers to all sorts of “how” questions, which is why doctors are often so good with facts and figures but (frequently) so sadly lacking when patients ask “why” questions.
Tibetan medicine, on the other hand, is an elaborate system (also requiring the memorization of a burdensome number of facts and figures) that derives from—and is organized by—a central question: “Why do people get sick?” Although there are many intermediate answers, the final answer from a Buddhist perspective is that human beings are captive to the three mental poisons of ignorance, craving and aversion. Even the type of physical body we possess (as well as the character of the world we inhabit) is created by these three primordial stains on consciousness. This is the “pith” of Tibetan Buddhist medicine.
What is the pith of Western medicine? How does it answer “why” questions? Specifically, what is behind the tragic phenomenon of major depression in patients who are medically ill? Is there a Western equivalent to the three Buddhist poisons? Amidst great foreboding, given my 45-minute time limit, I made this the quest of my lecture for the mind-body symposium.
Western science is based on the premise of physical reductionism: All phenomena have a physical base, and higher-level entities are dependent upon, and emerge from, the activity of simpler elements. Hence, for example, science does not believe that life is the result of any type of special living substance or force (such as Bergson’s élan vital). Rather, life is a process that arises from certain very complicated ways that matter can self-organize.
A central attribute of this process is the ability to replicate itself, to incorporate nonliving matter from the environment into the same complex patterns that allow the living process to continue into a new generation. A striking (and underappreciated) conclusion that emerges from this worldview is that we are here because this copying process isn’t perfect. Every once in a while, a copying error improves the survival chances of the affected offspring and gets passed along to future generations. Were it not for the slow accumulation of these adaptive copying errors over millions of years, the world would hold no denizens as complicated as even the simplest bacterium. Perfection, in other words, would have produced a sterile world.
However, evolutionary theory does imply a more ragtag type of perfection that goes under the rubric of adaptationism. This idea assumes the following:
• Differences exist between organisms in the same species.
• These differences are at least partly encoded in genes and are thus heritable.
• Certain differences better promote survival and reproduction in a given environment.
• Organisms that better survive and reproduce will produce more offspring in the next generation.
• These offspring will be enriched for the genes that fit more optimally with the environment.
• Over time, therefore (and if the environment is stable), natural selection should cause surviving species/individuals to be optimally adapted to their place in that environment.
A surprising upshot of these assumptions is that purely maladaptive traits should be removed from the population by natural selection. When this doesn’t happen, either the maladaptive trait confers an unrecognized benefit or not enough time has passed to remove it.
Many people working in the field of mental health, either as clinicians or researchers, spend their lifetimes trying to treat and/or understand the physiology of conditions such as depression without ever pondering a more immediate question: Why hasn’t the genetic vulnerability to depression been eliminated by evolution operating through natural selection? After all, by any system of reckoning, depression would seem inimical to the survival of any genes that promoted it.
Depression typically strikes—and frequently disables—people in their peak reproductive years. Depression during pregnancy increases the risk of premature birth. Children raised by depressed mothers tend to thrive less well. Finally, in addition to the tragedy of suicide, data increasingly demonstrate that depression increases all-cause mortality and significantly increases morbidity and mortality across a range of medical illnesses.
Given all this, why aren’t genes for depression “dying out?” Why are rates of depression increasing in the modern world? And why is depression such a common reaction to both psychological stress and physical illness? Would it not be more adaptive to respond to these challenges with a behavioral syndrome characterized by optimism, fortitude and hope?
Potential answers for these questions formed the core of my symposium lecture, but the larger point is that evolutionary theory—so often ignored in the practice of medicine—provides a framework for understanding many aspects of mental and physical functioning that otherwise appear meaningless. More than this, an evolutionarily based understanding of mind-body relationships also suggests novel therapeutic strategies for the treatment of major depression.
Fore more information, visit the Mind-Body Program website at www.psychiatry.emory.edu/PROGRAMS/mindbody/. Information related to the Mind-Body Symposium is located under the “recent events” link.