When he walks into a room, he captures everyone’s attention immediately with his wide smile and witty jokes and charms strangers into becoming friends with him. You know the kind of person I’m talking about.

Maybe you’re friends with this person. Maybe you’re in love with this person. Or maybe…just maybe…you are this person. And if you are, you should pay especially close attention.

This type of person is likely a narcissist. Narcissists often make great first impressions, but a new study from University of Virginia in Charlottesville and University of Michigan in Ann Arbor shows that many male narcissists, in particular, have characteristics that can lead to serious health problems, such as a weakened immune system and cardiovascular problems.

MIRROR, MIRROR

The study of narcissism included 106 undergraduate men and women (average age 20). The subjects each provided two samples of saliva—one at the outset of the study and a second sample 25 minutes later after they had completed a series of questionnaires, including one that was intended to determine which, if any, types of narcissistic traits they had.

The questionnaire measures several key components of narcissism. Psychologists consider some of these traits—such as leadership/authority, superiority/arrogance and self-absorption/self-admiration—to be generally “healthy” because they contribute to positive aspects of narcissism, such as high self-esteem, said study coauthor David Reinhard, a graduate student in psychology at the University of Virginia. (Remember, we are talking about the health of the narcissist, not the health of those around him!) But other traits, such as exploitativeness (imagine Tom Sawyer tricking his friends into painting a fence by telling them how much fun it is) and entitlement (feeling that you deserve whatever it is that you want) are considered generally “unhealthy” because they have been associated with increased anxiety and depression.

Why the saliva samples? They were for measuring levels of the so-called stress hormone cortisol. And what the researchers found was that men (but not women) who scored high on questions that pertained to “unhealthy” narcissistic traits had significantly higher levels of cortisol than participants who scored high on questions about “healthy” narcissistic traits.

WHAT A HORMONE CAN DO TO YOU

This cortisol elevation, Reinhard told me, suggests that men who have unhealthy narcissistic traits may have stress response systems that are always “on.” And multiple studies in the past have linked long-term activation of this stress response system with a weaker immune system…cardiovascular problems such as high blood pressure and heart disease…chronic muscle pain…skin rashes…and more.

Researchers don’t know why certain narcissistic traits appear to crank up cortisol in men but not in women, but Reinhard speculated that it might be related to different societal expectations for men and women. For example, females generally are encouraged to value relationships and seek social support, which may offset some of the worst costs of unhealthy narcissism and cushion them from stress—whereas men, generally speaking, are less likely to call their buddies on the phone and talk about their feelings.

Even though narcissists have inflated self-opinions, their egos are often fragile, so constant perceived threats to their masculinity may cause narcissistic men to react defensively. They take things personally, and they tend to see minor annoyances—like someone cutting in front of them in line at the store or grabbing a parking space before them—as major affronts. Over time, the stress caused by defensive thinking and, in many cases, confrontational behavior takes its toll.

Narcissistic men are all around us—they are our husbands, fathers, brothers, sons and friends. They can be maddening but, ultimately, they are who they are. So here’s my proposal—when you can, help guide them away from stress. It’s for everyone’s good.