In the fall of 2005, psychiatrist J. Anderson Thomson Jr. was treating an 18-year-old college freshman whom he describes as "intensely depressed, feeling suicidal and doing self-cutting."
A few years before, Thomson says, he would have interpreted her depression as anger turned inward. But instead he decided that her symptoms might be a way of signaling her unhappiness to people close to her.
He discovered that his client's parents had pressured her to attend the university and major in science, even though her real interest lay in the arts. In the course of therapy, he helped her become more assertive about her goals. When she transferred to another school and changed majors, he says, her depression lifted.
Thomson based his approach on the idea that depression is not simply a disease to be eliminated, but a way of eliciting support from family and friends. It's a concept derived from evolutionary psychology, a burgeoning field that is starting to influence psychotherapy.
Evolutionary psychology sees the mind as a set of evolved mechanisms, or adaptations, that have promoted survival and reproduction. Evolutionary psychopathology -- abnormal psychology through an evolutionary lens -- looks at what has gone wrong.
The discipline is so new that "some people would say it hasn't started yet," jokes Randolph M. Nesse, a professor of psychiatry at the University of Michigan, and one of its pioneers. No one paradigm has won universal acceptance. Evolution-based therapies rely on an eclectic mix of techniques, and their effectiveness is still being tested.
Some evolutionary psychologists emphasize the benefits of what we label as disorders. For example, Edward H. Hagen, a research scientist at Humboldt University in Berlin, with whom Thomson has collaborated, has argued that depression, suicide attempts and deliberate self-harm are rational bargaining tactics to manipulate others into providing support they might otherwise withhold.
Stephen S. Ilardi, an associate professor of psychology at the University of Kansas, suggests that depression results from a "mismatch" between human beings adapted for hunter-gatherer societies and the contemporary world. His therapy -- which he calls "therapeutic lifestyle change" -- emphasizes behavioral remedies, including getting more sleep, consuming more omega-3 fatty acids and increasing social interaction.
A third school of evolutionary thought sees mental disorders as the result of an accumulation of harmful genetic mutations -- flaws in the system.
Many clinical psychologists remain skeptical of all these divergent evolutionary approaches, as well as efforts to devise treatments based on them.
"The idea that evolution is an important determinant of who we are as human beings is unquestionable," says Laurence J. Kirmayer, director of the division of social and transcultural psychiatry at McGill University in Montreal. "The question is, what does our evolutionary history or our theories of evolution tell us specifically about the nature of human problems or about their potential solutions?"
Robert A. Neimeyer, a professor of psychology at the University of Memphis, suggests that evolutionary psychology is better at dealing with typical human behavior than with individual variations. He points out, for example, that while we are "evolutionarily wired for attachment," people grieve losses in ways that vary across cultures and individuals. And treatments must take account of those differences, he says.
The recurrence of mental disorders despite the pressures of natural selection is "really a technical question that none of us have a good answer to," says psychiatry professor Nesse, who has written widely on mood disorders. "We're not at a point where every discovery leads to another discovery. We're at a point where a bunch of people are trying to think hard about it."
In an article in the November issue of the journal Behavioral and Brain Sciences, Matthew C. Keller, a postdoctoral fellow at the Virginia Institute for Psychiatric and Behavioral Genetics, and Geoffrey Miller, assistant professor of psychology at the University of New Mexico, address why diseases such as depression and schizophrenia persist. The answer, they say, is that they reflect the accumulation of harmful mutations.
"There are so many genes that are involved in growing a brain, and each of the genes is vulnerable to mutation in every generation," says Miller, author of "The Mating Mind: How Sexual Choice Shaped the Evolution of Human Nature." When too many coincide, illnesses result.
One critic, Joseph Polimeni of the University of Manitoba, in Canada, points out that because so many psychiatric disorders have strong environmental triggers, no single explanation can account for all of them.
Daniel Nettle, a psychology professor at the University of Newcastle, in England, says he finds the mutation theory persuasive for major disorders such as schizophrenia. But he suggests that other problems, such as addictions, may be outgrowths of the changing social environment -- including modern distractions such as bars and casinos. "For our ancestors, it was quite useful to follow impulses strongly and spontaneously," he says, while today, with temptations to indulge at every turn, "suddenly, [these people] have a disorder."
Depression, the most common mental illness, has inspired several theories on its own.
"Rank theory," proposed by psychiatrist John Price, sees depression as an adaptation that originally caused losers to withdraw from conflict, avoid further aggression and accept their subordinate status. Hagen has concentrated on the link between depression and social support, while Paul Andrews, a postdoctoral fellow at the Virginia Institute for Psychiatric and Behavioral Genetics, proposes that depression evolved to help people analyze their problems after a failure.
In the August issue of the Journal of Personality and Social Psychology, Keller and Nesse present studies backing both the Hagen and Andrews hypotheses. They show that depressions triggered by different stresses result in different symptom patterns, suggesting that each developed as a separate adaptation For instance, Keller says, "failures of effort" lead to what he calls a "despondent type of depression," with symptoms such as fatigue, pessimism, guilt, rumination and excessive sleep. "The point is really to quit wasting effort and to conserve energy when the situation has proven itself unpropitious," he says.
By contrast, social losses, including bereavement and failed romances, lead to emotional pain, crying and the desire to be with loved ones. Crying may serve as a way of attracting social support, Keller says, and the desire to avoid emotional pain may provide an incentive to care for family members.
If we're blocking the depressive symptoms -- through medication for example -- we could be hamstringing the body's defenses, Keller says.
As the theoretical debate continues, some researchers are developing evolution-based therapies.
The backdrop to therapeutic lifestyle change, or TLC, is an increase in depressive illness since World War II, Ilardi says. "There's increasing evidence that we were never designed for our sedentary, socially isolated, indoor, sleep-deprived, frenzied, poorly nourished lifestyle," he says.
Ilardi combines group therapy sessions with a set of lifestyle changes, each of which has proven effective against depression: aerobic exercise; ingestion of omega-3 fatty acids; light; positive social interaction; substituting activity for rumination; and increased sleep. The goal is for patients to live more like their Paleolithic ancestors.
The results of the 14-week regimen so far have been encouraging. In an ongoing study of 79 patients, with two-thirds assigned to his therapy and the rest to a control group treated mainly with antidepressant medication or traditional psychotherapy, Ilardi reports a 74% favorable response, compared with 16% for the controls.
Rebecca Ann Foerschler, a 49-year-old homemaker in Lawrence, Kan., with three teenage children, entered the study after friends noticed that she was withdrawing from social and volunteer activities. She says she also experienced chronic fatigue.
During the therapy, she says, she "relearned how to walk my dog ... in a more aerobic manner," and now on mild winter days she can "get my sunlight, get my aerobic exercise, and get my dog walked." At the end of the treatment, Foerschler reported an increase in energy and "a feeling of my brain being more clear." She describes herself now as virtually depression-free.
Two other new therapies rely on the common-sense notion that normal, adaptive functioning can go awry because of unfavorable life circumstances, including abuse and trauma.
Paul Gilbert, professor of clinical psychology at the University of Derby and former president of the British Assn. for Behavioral and Cognitive Psychotherapies, is developing a regimen he calls "compassionate mind training." Its aim is to help patients who are highly self-critical learn techniques for soothing themselves.
The therapy draws on both evolutionary psychology and attachment theory. Certain systems in the mind trigger anxiety and depression, while others soothe and provide feelings of safety -- a capacity that may not develop in people from abusive or neglectful families, Gilbert says.
For a pilot study published in December in the journal Clinical Psychology and Psychotherapy, Gilbert recruited nine volunteers already undergoing cognitive behavioral therapy for personality disorders or chronic mood disorders.
Therapists explained the evolutionary significance of attachments to the participants and helped them analyze the origins of their self-critical feelings. Participants were taught to feel empathy for their own distress, and then practiced imagining an "ideal of caring and compassion."
They kept weekly diaries of their progress. The paper reports "a significant impact on depression, anxiety, self-attacking, feelings of inferiority, submissive behavior and shame" among the six who completed the regimen.
In Toronto, Leslie Greenberg, professor of psychology at York University, is testing "emotion-focused therapy," which seeks to replace unhealthy, or maladaptive, emotions with healthy ones.
In an article in the summer issue of the Journal of Contemporary Psychotherapy, Greenberg offers a case study of a woman suffering from major depression, anxiety disorder and interpersonal problems after having been raised by emotionally and physically abusive parents.
Greenberg encouraged the woman to engage in imaginary conversations with her parents in which she expressed her feelings about their sadistic behavior.
In therapy, the anger she felt, an adaptive emotion, eventually replaced her fear and feelings of worthlessness. "She began to create a new identity narrative," writes Greenberg, "one in which she was worthy and had unfairly suffered abuse at the hands of cruel parents." That emotional rewiring left her "open to learn to love" again, he writes.
Shani Robins, president of the Institute for Wisdom Therapy in San Diego, also draws on evolutionary psychology in his therapy -- a combination of cognitive behavioral therapy, mindfulness meditation, training in humility, and psycho-education.
Understanding the evolutionary origin of problems can help patients put them in perspective, he says. Fear of heights, snakes and open spaces may have been useful to our ancestors, for example, even if such phobias seem excessive today.
Explaining these mechanisms "normalizes the reaction itself, and that's huge," Robins says. "When patients come in, they not only have symptoms -- they're feeling pretty bad about it." In time, they learn to "self-judge a lot less."
Despite some progress in research, Leif Edward Ottesen Kennair, associate professor of psychology at the Norwegian University of Science and Technology, says that not enough evolutionary psychologists are investigating mental illness, and not enough clinical psychologists "are working on developing procedures based on evolutionary understandings ... and testing these out in clinical trials." Much more such testing needs to be done, he says.
Thomson, of the University of Virginia, agrees that psychiatry has been slow to adopt evolutionary models. But the situation is changing, he says, as young clinicians are trained in evolutionary psychology.
"This is a marvelous paradigm shift," he says. "I think it's affecting very few now, but in time it will affect everybody."