Not only do narcissistic men have more problems in relationships, they may also have a greater risk for developing cardiovascular disease due to elevated levels of the stress hormone cortisol, according to a recent study.

Researchers from the University of Michigan and University of Virginia found that men who scored high on two different narcissistic traits, entitlement and exploitativeness, also had higher levels of a stress hormone that can lead to high blood pressure and heart problems, compared to others  who scored lower in those two personality traits. 

The study found while men and women are equally narcissistic, the elevated cortisol stress response was not observed in female participants. 

“Narcissistic men may be paying a high price in terms of their physical health, in addition to the psychological cost to their relationships,” said Sara Konrath, a study co-author.

Konrath said although people generally see narcissism as a bad personality trait, people with an inflated ego perceive their self-absorption to be a good characteristic.

Previous studies have shown that narcissism seemed to be growing in American culture, and that the destructive personality trait tended to be more prevalent among males.  Psychologists characterize narcissism by an inflated sense of self-importance, overestimations of uniqueness and a sense of grandiosity.

Researchers in the new study administered a 40-item survey to 106 college students that measured five components of narcissism: leadership, superiority, self-absorption, exploitativeness and entitlement. 

Cortisol levels were measured twice in the students’ saliva to assess baseline levels of the stress hormone that signals activity in the hypothalamic-pituitary-adrenal axis (HPA), the body's main stress response system.

Researchers noted that three of the five personality components of narcissism are considered useful or healthy: leadership/authority, superiority/arrogance and self-absorption/self-admiration.  Konrath aslo added that narcissists tend to be creative and have low levels of depression, however their views of themselves are easily breakable and can lead them to react defensively or aggressively when their sense of superiority is threatened.

Study authors noted to only observe significantly elevated levels of cortisol in men with unhealthy narcissism, and they predicted that these men may have a chronically activated HPA axis.

Researchers could not explain why only men seemed to suffer from a higher stress response to narcissism, but the speculated that societal definitions of masculinity such as arrogance and dominance, may overlap the egotistical trait and that may leave men to be particularly physiologically vulnerable. 

"They're at especially high risk because someone who admits they're stressed out is going to get help, but they're not likely to," Konrath said. "There may be a cost to this jerkiness. It's a little sad they're a group that wouldn't get help if they needed it."

Researchers hope to find a reason women don’t respond physiologically to narcissism as men seem to do.  They noted that narcissism levels in both genders have elevated in recent years, and suggested that the trend may be a byproduct of the so-called “self-esteem movement,” which emphasizes praise for children over criticism. 

The study is published Jan. 23 in the journal PLoS ONE.