Researchers reported today that women who perceive their lives to be stressful are less able to fight off the most common subtype of the HPV virus, which can cause cervical cancer. The idea that stress plays a role in how the immune system fights off infections and cancer has its roots in the broader study of the links between mental and physical health. Can our emotions and thoughts affect how our body responds to foreign invaders, or even to our own mutated cells growing unchecked? For the latest thinking, U.S. News talked with Anne Harrington, chair of the department of the History of Science at Harvard University and author of The Cure Within: A History of Mind-Body Medicine (W. W. Norton).
When did this idea arise that stress might make us more susceptible to cancer and affect the progress of the disease?
You don't really see that specific idea until the late 1970s or early 1980s, though there's a much older tradition of supposing that negative emotions—if you don't manage them properly—put you at risk of cancer. In the heyday of the psychoanalytic era, there was a view that repressing strong aggressive and sexual feelings might represent a "cancer-prone personality." When Norman Mailer stabbed his wife at a party [in 1960], his defense was going to be that he was afraid if he'd repressed the rage that made him do this, he would succumb to cancer. In the end, his wife didn't press charges.
What happened scientifically to make a stress-cancer link plausible?
There was the discovery that the nervous system might be able to communicate with the immune system. First these questions were around AIDS, not cancer. AIDS undermined immunity, and people wondered whether receiving a diagnosis might actually cause a worse outcome because of the stress of it. It was really then, on the back of that, that people began to ask about cancer.
What did early studies show?
Epidemiological studies suggested that women who had a "fighting spirit" when they received a diagnosis of cancer seemed to have a better outcome—they appeared to live longer and responded better than women who received the news with hopelessness and depression. [More recent studies don't show that.] The idea isn't completely dead, but it's controversial.
What about infections, which can directly or indirectly cause some cancers, like cervical cancer?
The question of whether stress affects how we fight off infection is open. One study looked at the caregivers of Alzheimer's patients, who are understood to really live under chronic stress. They looked at the response of these people to the flu vaccine, and found that the caregivers'' immune systems weren't able to mount as robust a response as the control group.
If there is a link between stress and infection, or stress and cancer, is it necessarily biological?
When people are under stress, there are behavioral consequences. Go back to the idea of a cancer patient. One who is extremely stressed by her diagnosis or by other things going on in her life may not be sleeping well, she may not be adhering to treatment as well; it may be in indirect ways that stress leads to poor outcomes.
What's the downside of believing that stress and emotions have an effect on cancer?
We went through an era where cancer patients were put under enormous pressure to stay positive, to harness the power of positive visualization to fight off their tumors, to avoid any stress. By that, many thought they weren't allowed to worry. But there's something enormously stressful about having to stay resolutely positive! I talked to some women with cancer who were involved in this research during the positive-thinking era. In support groups, they were encouraged to confront their deepest fears and talk about death, but some worried it would make them sicker. It can be harmful if it turns into this thing where you are afraid of your own emotions and think that if you let an anxious thought into your mind your immune system is going to poop out.
Any evidence that talking about the bad as well as the good is actually better for you?
Those who were encouraged to experience the full range of thinking certainly lived better. It's helpful if it empowers you to make the kind of changes that will enhance your quality of life regardless of your disease, or if it is likely to help you adhere better to your medications, or sleep better, or get exercise. Whether or not in the end your immune system will function better, we don't know.