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A Case for Double-Edged Optimism

Personality and outlook are critical for staying healthy but a sunny disposition only goes so far. For some, a shot of pessimism packs more medicinal punch. From good stress to lethal optimism, the new rules of the immunity game.

Yet Brian was in fact gifted: A top New York publisher finally bought his novel, fulfilling his lifelong dream. But for Brian, it proved too much. "At first he just seemed depressed," says his former wife, Meg, who witnessed the tailspin. But depression turned into alcoholism, then obesity and finally heart disease. When the book came out, Brian was too ill to go on tour.

Brian's downfall seems counterintuitive: Shouldn't success bring happiness, boosting the immune system and improving our overall health? Not according to research from psychologists at Duke. Enormous success is healthy only for people with self-esteem to match, it turns out. For someone struggling with a poor self-image, like Brian, hitting a ball out of the park may tax the immune system, helping the body to spiral into disease. Instead, say the Duke scientists, the Brians among us stay healthier when success is more modest and slower to arrive.

The Duke research is just one example of a new paradigm in psychoneuroimmunology (PNI), the study of the link between emotion, immunity and the brain. While we've long equated positive emotion with health and negative emotion with illness, studies have added nuance and subtlety to these broad ideas, proving them just partially correct and in many cases wrong. Among the surprising findings: Stress can prime the immune system, making us stronger. Too much optimism may be an immunological drain. And health improves when self-esteem and success stay in sync. With thousands of new studies and a better understanding of immunity, today's experts agree that the link between emotion and immunity is robust. But it is also intricate and filled with surprises that open a dramatic new window on the nature of emotional health.

Healthy Stress Raises Immunity

Conventional wisdom holds that stress is ruinous, and who can argue? Too much stress increases blood pressure and the risk of heart disease. Studies tie stress to immune suppression, including a surplus of flu and colds.

Yet the "rule" didn't apply to Rachel, a special education teacher with the autoimmune disease lupus. She suffered a relapse a few years back, over the summer, and was still so tired by Labor Day, she didn't see how she could return to work. "I was better, but drained, and I thought the strain of the commute alone would do me in," she recalls. Encouraged by her doctor, she went back anyway. And instead of crashing under the burden, Rachel thrived. "Each day was a shot of energy," she says, explaining how good she felt when one of the children made a breakthrough or gave her a hug. "I went home to chill."

In Rachel's case, the ebb and flow of daily stress, much of it ultimately rewarding, provided a health boost. The harmful effects of stress occur "when the stress is chronic," explains Monika Fleshner, a neuroimmunophysiologist at the University of Colorado in Boulder. It's extreme, constant stress over a long period of time that impairs the immune system. But "short-term stress, under most circumstances, actually boosts immunity. It all makes sense in light of our evolutionary past. When we're threatened or frightened, we become hyperalert, primed to get out of what could be a life-or-death situation," she explains.

To prove the point, Fleshner replicated her scenario with rats in the lab. All the rats were exposed to bacterial infection, but some were also stressed by receiving electric shocks to the tail. The rats that were infected and shocked at the same time resisted disease and stayed far healthier than rats not given the shock. This finding may warrant notice in emergency rooms, where overwhelmed patients are frequently treated with antianxiety drugs. Yet if a patient has an infection, reducing anxiety may depress the very immune response the patient needs to get well.

Find Your Crowd

People cultivating a few close friendships can be just as rich in emotional nourishment as those belonging to larger social networks, right? Not necessarily, according to research showing that those with wider social circles may literally be more immune.

Working with college students, Carnegie Mellon researchers Sarah Pressman and Sheldon Cohen found that freshmen with larger social networks had a more robust immune response than those in smaller groups when given a flu vaccine. The researchers found freshmen who reported feeling lonely produced fewer antibodies than those who didn't. Lonely freshmen with few friends had the lowest immunity of all.

The most interesting finding was the distinction between loneliness and size of the social network. Lonely students had a lowered immune response to one vaccine component while those who had few friends had a depressed immune response to another. According to the researchers, the fact that social-network size and loneliness are separate factors in immunity is supported by the observation that you can have many friends yet feel lonely. For optimal immunity, the findings seem to suggest, a few close friends simply may not be enough. The findings may also explain why freshmen visit the infirmary more often than better-connected students in sophomore, junior and senior years.

Keeping Self-Esteem And Success In Sync

In another surprising reversal of long-held beliefs, the holy grails of self-esteem and stratospheric success may each threaten immunity in certain people. Specifically, great success may be a health risk when self-esteem is low. That's why someone like Brian, who lacks confidence, may suffer if success is especially heightened or comes on too fast. Self-esteem, for its part, can be risky when achievement doesn't measure up to personal expectations. The phenomenon, called "self-discrepancy," occurs when self-image differs markedly from your actual self, your wished-for self or the unfolding of life events.

To make the point, Timothy Strauman, head of psychology at Duke, asked healthy college students three basic questions: What kind of person do you think you are? What kind of person would you like to be? And, what kind of person do you think you ought to be? "If somebody says, 'I'm lazy, but I think I should be hard-working,' that's a discrepancy," Strauman explains.

Blood tests showed that students with fewer discrepancies had a greater killer T cell count. When members of this group made progress commensurate with their own self-evaluation, they had stronger immunity than those who weren't making progress or were making progress too fast. Immunity was optimized for those rich in both self-esteem and success.

The hit to immunity, Strauman suggests, may come from continually evaluating and then modifying behavior to reach a goal—a disruption in the phenomenon known as "self-regulation." When initial efforts to reach the goal fail, mood typically drops, but motivation may soar. When failure continues, however, motivation also falters. The higher one's self-esteem is at the outset, the bigger the potential for both mood and motivation to fall hard.

The Curiosity Cure

The connection between good health and optimism is widely accepted, but studies show that optimism seasoned by reality works best. Researchers at Harvard studied 1,041 patients and found those identified as hopeful (optimistic but ultimately realistic) were less likely to develop diabetes, high blood pressure, colds and flu than out-and-out optimists, who were convinced they would thrive no matter what. Curious, skeptical patients, those who peppered doctors with questions or scoured the Internet for information, received an immune boost as well.

University of Kentucky psychologist Suzanne Segerstrom suggests that some optimists could be pushing so hard they end up taxing their immune system and making themselves sick. In a study that was published last year, Segerstrom gave optimists a stressful arithmetic test and found that they showed a drop in immunity. "It can be more difficult to keep working on a problem than to give up," she notes. "When pessimists encounter difficult situations, they're likely to disengage. Optimists are likely to keep working at them." As a consequence of the struggle, their immune systems weaken.

Type D: A Killer Personality

Impatient, anxious and hostile, the Type A individual has for years been considered a walking time bomb, a heart attack waiting to happen and sure to keel over years before the calmer, happier Type B. But now psychologists have identified an even deadlier personality: Type D, a cynical, hostile individual who is also unexpressive, keeping those bad feelings inside.

Investigating a possible connection between Type D traits and cardiac risk, psychologists, cardiologists and immunologists followed male heart disease patients from Belgium over a period of years. Those with Type D personalities were far more likely to have heart attacks. And Type D was predictive of the worst case scenario: coronary heart failure. Type D patients were four times more likely than others to die of the disease.

Looking for an explanation, the researchers discovered that Type D heart patients all had one thing in common: an alarming overabundance of tumor necrosis factor (TNF-alpha), an inflammatory molecule produced by immune cells. Among other destructive actions, TNF-alpha can rupture arterial plaque. Ruptured plaque can obstruct the artery or vein, a condition called thrombosis, and heart attack can result.

Other research has found that Type D individuals also have killer T cells that are less active and have a diminished ability to fight infection compared with those found in more emotionally expressive peers. The finding is in line with a body of research linking social inhibition to less active immunity in the face of infectious disease.

The connection between emotion and health is still unraveling. From the subtle role of stress to the double-edged sword of optimism, emotional states influence the strength of our hearts, the pace at which we age and the way we fight disease. As with nutritional science—where a nutrient is considered protective one day and harmful the next—psychoneuroimmunology is still in its adolescence. When the code is deciphered in full, PNI will be not just a fascination, but a precision tool for a longer, healthier life.