Particularly compelling evidence for the medical impact from distress has come from studies with infectious diseases such as colds, the flu, and herpes. We are continually exposed to such viruses, but ordinarily our immune system fights them off—except that under emotional stress those defenses more often fail. In experiments in which the robustness of the immune system has been assayed directly, stress and anxiety have been found to weaken it, but in most such results it is unclear whether the range of immune weakening is of clinical significance—that is, great enough to open the way to disease.22 For that reason stronger scientific links of stress and anxiety to medical vulnerability come from prospective studies: those that start with healthy people and monitor first a heightening of distress followed by a weakening of the immune system and the onset of illness.
In one of the most scientifically compelling studies, Sheldon Cohen, a psychologist at Carnegie-Mellon University, working with scientists at a specialized colds research unit in Sheffield, England, carefully assessed how much stress people were feeling in their lives, and then systematically exposed them to a cold virus. Not everyone so exposed actually comes down with a cold; a robust immune system can—and constantly does—resist the cold virus. Cohen found that the more stress in their lives, the more likely people were to catch cold. Among those with little stress, 27 percent came down with a cold after being exposed to the virus; among those with the most stressful lives, 47 percent got the cold—direct evidence that stress itself weakens the immune system.23 (While this may be one of those scientific results that confirms what everyone has observed or suspected all along, it is considered a landmark finding because of its scientific rigor.)
Likewise, married couples who for three months kept daily checklists of hassles and upsetting events such as marital fights showed a strong pattern: three or four days after an especially intense batch of upsets, they came down with a cold or upper-respiratory infection. That lag period is precisely the incubation time for many common cold viruses, suggesting that being exposed while they were most worried and upset made them especially vulnerable.24
The same stress-infection pattern holds for the herpes virus—both the type that causes cold sores on the lip and the type that causes genital lesions. Once people have been exposed to the herpes virus, it stays latent in the body, flaring up from time to time. The activity of the herpes virus can be tracked by levels of antibodies to it in the blood. Using this measure, reactivation of the herpes virus has been found in medical students undergoing year-end exams, in recently separated women, and among people under constant pressure from caring for a family member with Alzheimer's disease.25
The toll of anxiety is not just that it lowers the immune response; other research is showing adverse effects on the cardiovascular system. While chronic hostility and repeated episodes of anger seem to put men at greatest risk for heart disease, the more deadly emotion in women may be anxiety and fear. In research at Stanford University School of Medicine with more than a thousand men and women who had suffered a first heart attack, those women who went on to suffer a second heart attack were marked by high levels of fearfulness and anxiety. In many cases the fearfulness took the form of crippling phobias: after their first heart attack the patients stopped driving, quit their jobs, or avoided going out.26
The insidious physical effects of mental stress and anxiety—the kind produced by high-pressure jobs, or high-pressure lives such as that of a single mother juggling day care and a job—are being pinpointed at an anatomically fine-grained level. For example, Stephen Manuck, a University of Pittsburgh psychologist, put thirty volunteers through a rigorous, anxiety-riddled ordeal in a laboratory while he monitored the men's blood, assaying a substance secreted by blood platelets called adenosine triphosphate, or ATP, which can trigger blood-vessel changes that may lead to heart attacks and strokes. While the volunteers were under the intense stress, their ATP levels rose sharply, as did their heart rate and blood pressure.
Understandably, health risks seem greatest for those whose jobs are high in "strain": having high-pressure performance demands while having little or no control over how to get the job done (a predicament that gives bus drivers, for instance, a high rate of hypertension). For example, in a study of 569 patients with colorectal cancer and a matched comparison group, those who said that in the previous ten years they had experienced severe on-the-job aggravation were five and a half times more likely to have developed the cancer compared to those with no such stress in their lives.27
Because the medical toll of distress is so broad, relaxation techniques—which directly counter the physiological arousal of stress—are being used clinically to ease the symptoms of a wide variety of chronic illnesses. These include cardiovascular disease, some types of diabetes, arthritis, asthma, gastrointestinal disorders, and chronic pain, to name a few. To the degree any symptoms are worsened by stress and emotional distress, helping patients become more relaxed and able to handle their turbulent feelings can often offer some reprieve.28
The Medical Costs of Depression
She had been diagnosed with metastatic breast cancer, a return and spread of the malignancy several years after what she had thought was successful surgery for the disease. Her doctor could no longer talk of a cure, and the chemotherapy, at best, might offer just a few more months of life. Understandably, she was depressed—so much so that whenever she went to her oncologist, she found herself at some point bursting out into tears. Her oncologist's response each time: asking her to leave the office immediately.
Apart from the hurtfulness of the oncologist's coldness, did it matter medically that he would not deal with his patient's constant sadness? By the time a disease has become so virulent, it would be unlikely that any emotion would have an appreciable effect on its progress. While the woman's depression most certainly dimmed the quality of her final months, the medical evidence that melancholy might affect the course of cancer is as yet mixed.29 But cancer aside, a smattering of studies suggest a role for depression in many other medical conditions, especially in worsening a sickness once it has begun. The evidence is mounting that for patients with serious disease who are depressed, it would pay medically to treat their depression too.
One complication in treating depression in medical patients is that its symptoms, including loss of appetite and lethargy, are easily mistaken for signs of other diseases, particularly by physicians with little training in psychiatric diagnosis. That inability to diagnose depression may itself add to the problem, since it means that a patient's depression—like that of the weepy breast-cancer patient—goes unnoticed and untreated. And that failure to diagnose and treat may add to the risk of death in severe disease.
For instance, of 100 patients who received bone marrow transplants, 12 of the 13 who had been depressed died within the first year of the transplant, while 34 of the remaining 87 were still alive two years later.30 And in patients with chronic kidney failure who were receiving dialysis, those who were diagnosed with major depression were most likely to die within the following two years; depression was a stronger predictor of death than any medical sign.31 Here the route connecting emotion to medical status was not biological but attitudinaclass="underline" The depressed patients were much worse about complying with their medical regimens—cheating on their diets, for example, which put them at higher risk.