Observers may have noticed recently that mainstream medicine is taking a harder line against positive thinking. Surveys of the leading research in the field conclude that recovery rates from cancer, for example, are not higher among patients who take a positive attitude about fighting their disease. Studies that show the reverse have been small and, according to their critics, flawed in serious ways. Anyone would be forgiven for throwing up their hands. This seems like another example of dueling data, where one study's findings are contradicted by the next study, leaving the public in a state of confusion. Doctors are confused, too. It has always been part of a doctor's kit bag to tell patients to keep their spirits up. Until a few decades ago, it was standard not to acquaint a dying patient with the gravity of his condition, which implies an unspoken agreement that hearing bad news isn't good for patients. At the same time, doctors want to protect their profession, so few want to cross the line and support the notion that how you think can work as powerfully as "real" medicine. Let's see if some of this confusion can be cleared up. First of all, thinking is "real" medicine, as proven by the placebo effect. When given a sugar pill in place of a prescription drug, an average of 30% of subjects will show a positive response. What causes this response isn't a physical substance but the activity of the mind-body connection. Expectations are powerful. If you think you've been given a drug that will make you better, often that is enough to make you better. This implies that a person should be able to trigger the placebo effect on himself. However, there is a psychological illusion involved. Take away the authority figure in a white coat to tell you that you are taking an effective drug, and suddenly the sugar pill is just a sugar pill. You can't fool yourself when you know what the placebo is. This can't be the whole story, however. We can't deny that the mind-body connection is powerful. So is there a placebo effect that doesn't involve fooling the patient? Can you trigger your own inner defenses by the way you think? Those who believe in positive thinking say yes. I believe the situation is more nuanced. On the plus side, the studies that debunk positive thinking deal with very sick patients struggling to recover from major diseases. They do not comment on how positive thinking might prevent disease or how it might affect someone in the very early stages of illness. The real point isn't to rescue a dying patient but to maintain wellness. Does positive thinking keep you well? Right now the camps are divided, because with the rise of genetics, many disorders clearly have triggers that originate in our genes. In the public's mind, being told that cancer or diabetes is genetic acts as final authority. Luckily for the positive-thinking camp, this fatalistic attitude is mistaken. Genes are dynamic, not fixed; they respond to a person's environment, behavior and attitudes. Indeed, a now-famous study in Sweden showed that a tendency to diabetes may be strongly affected by the diet your great-grandfather ate. A whole new field is studying how much choice we have at the genetic level. The findings are not complete by any means, yet there is no harm in assuming that your mind affects your genes, because there is abundant evidence to support this attitude. Medicine hasn't proven that positivity is good prevention, but let's go a step further. To me, the problem with positive thinking is the thinking part. It takes effort to be positive all the time. The mind has to defend itself from negativity, and that is exhausting as well as unrealistic. You may succeed in calming the appearance you present to the world, but there's almost always a struggle hidden just below the surface; at the very least there is a good deal of denial. Being fanatically positive is still fanaticism. The alternative to thinking is a calm mind that is at peace with itself. I believe that such a mind delivers the benefits that positive thinking cannot, and my view is supported by studies showing a decline in high blood pressure, stress levels and other disease states among long-term meditators. Meditation is a spiritual practice, but it's also a mind-body practice. Here the results are not final, either, in part because almost the only research subjects tend to be Buddhist monks. We need expanded studies based on Western subjects; that much is clear. The upshot is that medicine cannot be definitive on how mood affects wellness. But if I wanted to enhance a state of wellness before symptoms of illness appeared, there is much to be gained and no risks involved in trying to reach the best state of mind possible.