I’ve always been annoyed — and, yes, often even sometimes angered — by people who claim that positive thinking is the key to good health.

Particularly when they say this to others with serious chronic or life-threatening illnesses.

As if individuals with such illnesses would just miraculously get better if they had a more "positive attitude.”

Scott Lilienfeld

The flip side of this kind of thinking is even crueler — the message that people bring on illnesses by their own negative thoughts.

The truth is, there’s no good scientific evidence that “accentuating the positive” (as the 1944 Johnny Mercer–Harold Arlen song famously urged us to do) has any effect on our health. In fact, as psychologists Scott Lilienfeld (Emory University in Atlanta, Ga.) and Hal Arkowitz (University of Arizona) explain in a recent article in Scientific American Mind, “research suggests that optimism can be detrimental under certain circumstances.”

Here’s an excerpt from the article:

Much of the data supporting solid benefits from positive thinking is weak. According to a 2010 review by Cornell University psychologist Anthony Ong, although most studies show that optimistic people tend to be physically healthier than others and they may also live longer, these findings come from correlational studies, which examine statistical associations between positive thinking and life outcomes but cannot tell us about cause and effect. Thus, thinking positively might make us healthier, but being healthier may instead lead us to think positively. …

Julie Norem

Even if more optimistic results about optimism eventually surface, a rosy outlook is unlikely to benefit everyone. Defensive pessimists, for example, tend to fret a great deal about upcoming stressors such as job interviews or major exams, and they overestimate their likelihood of failure. Yet this worrying works for these individuals, because it allows them to be better prepared. Work by Wellesley College psychologist Julie Norem and her colleagues shows that depriving defensive pessimists of their preferred coping style — for example, by forcing them to “cheer up” — leads them to perform worse on tasks. Moreover, in a 2001 study of elderly community participants, Seligman and Brandeis University psychologist Derek Isaacowitz found that pessimists were less prone to depression than were optimists after experiencing negative life events, such as the death of a friend. The pessimists had likely spent more time bracing themselves mentally for unpleasant possibilities.

Another study calls into question the healing power of positive affirmations — those ubiquitous fixtures of pop psychology parodied by former comedian Al Franken as counselor Stuart Smalley (“I’m good enough, I’m smart enough, and doggonit, people like me”). In a study published in 2009 University of Waterloo psychologist Joanne Wood and her colleagues found that for participants with high self-esteem, repeating a positive affirmation (“I am a lovable person”) multiple times indeed resulted in slightly better moods right afterward. But among those with low self-esteem, the positive affirmations backfired, resulting in worse moods. Wood and her colleagues conjectured that statements like Smalley’s ring hollow in the minds of individuals with low self-esteem, serving only to remind them of how often they have fallen short of their life goals.

You can access the full article through Scientific Mind’s website. You may also want to read Barbara Ehrenreich’s “Bright-sided: How the Relentless Promotion of Positive Thinking Has Undermined America.”