January 9, 2007

Now, it seems, pessimists may really have something to worry about: their health.

A study by researchers in the Netherlands has found that people who are temperamentally pessimistic are more likely to die of heart disease and other causes than those who are by nature optimistic.

The study, led by Dr. Erik J. Giltay of the Psychiatric Center GGZ Delfland and published in The Archives of General Psychiatry, followed 941 Dutch subjects, ages 65 to 85, from 1991 to 2001. Subjects were ranked in quartiles as pessimistic or optimistic on the basis of their reactions to statements like, “I still have positive expectations concerning my future” and, “I often feel that life is full of promises.”

Dr. Giltay and his colleagues found that subjects with the highest level of optimism were 45 percent less likely than those with the highest level of pessimism to die of all causes during the study. For those in the quartile with the highest optimism score, the death rate was 30.4 percent; those in the most pessimistic quartile had a death rate of 56.5 percent. There were 397 deaths in the study, and prevention of cardiovascular mortality accounted for nearly half of the protective effects of optimism.

This is the kind of study that worries me. Not personally, though — I’m as optimistic as they come. No, I’m worried about my pessimistic friends and patients who will get hold of this article. After all, if the findings are valid, how much can anyone really do about a gloomy disposition? 

Up to this point there has been solid evidence that certain pathological mental states, like depression, are linked with a significantly higher risk of cardiovascular death, but the relationship between normal personality traits like optimism and health have not been as thoroughly studied.

For example, there have been several well-controlled studies showing that depression can as much as double the relative risk of having a first heart attack or dying of heart disease, independent of other factors. And for people who already have well-documented heart disease, depression increases the risk of death about threefold.

But finding a correlation between certain attitudes and health outcomes doesn’t, of course, prove causality. Maybe pessimists have shorter lives because they are sicker to start with than optimists; that may be why they feel bleaker about their future in the first place. 

Dr. Giltay carefully controlled for baseline risk factors like blood pressure, cholesterol, smoking and alcohol consumption in his study. Even after controlling for these confounding variables, there was still a significant excess of mortality in the pessimists compared with the optimists. And when he factored in the subjects’ own perception of their health — optimists, not surprisingly, report feeling better — pessimists still had higher morbidity and mortality.

What about the possibility that some of the pessimistic subjects were simply suffering from undiagnosed depression? After all, depression is a strong risk factor for cardiovascular mortality.

Dr. Giltay conceded that the subjects were not psychiatrically screened for depression or any other mental disorder, so this is a possibility. But he said depression was unlikely to explain the correlation between pessimism and mortality. 

Perhaps, but we know that depression exists, too, on a spectrum. Mild chronic depressive states like dysthymia could easily masquerade as everyday pessimism, so this study cannot rule out mild depression as a contributor to excess mortality in the pessimistic subjects. 

Still, assuming that these findings are replicated and optimism does indeed confer a survival advantage, what mechanism could explain it?

One possibility is that optimists may simply cope better with adversity than pessimists do and engage in behaviors that are more likely to promote health. It is well known, for example, that optimism is strongly associated with seeking social support and coping better with stress. There might even be biological differences between optimistic and pessimistic people that give optimists an edge. This is not so far-fetched if you consider that depression is associated with alterations in many neurotransmitters and hormones like cortisol, which can adversely affect physical health.

At this point, pessimism in the absence of clinical depression is not considered a disease or a risk factor for developing one. But if these data are replicated, perhaps it should be. If that’s the case, then trials of optimism-enhancing treatments, including psychotherapies and probably antidepressants, won’t be far behind. After all, there is already preliminary evidence that serotonin-enhancing antidepressants can alter normal personality traits like sociability, even in people without depression. 

But even if pessimism could be “treated,” would that guarantee a longer life? Judging from recent research in depression, it may be no slam dunk. Efforts to decrease heart disease and mortality by treating depression have been disappointing. Two large randomized trials involving depressed heart-attack patients found no survival benefit in treating them with either cognitive behavior therapy or serotonin-enhancing antidepressants, though their depression did improve. (There is some debate about the findings.) 

In the end, pessimists have enough to fret about without worrying that their own temperament will doom them to a short life. If pessimists should worry about anything, though, it’s that they may have an undiagnosed — and treatable — depression. Treating depression may not guarantee a longer life. But it will certainly make it a happier one.

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