The authors found elevated levels of cortisol only in the men with unhealthy narcissism, and they speculated that in these men the HPA axis is chronically activated.
While study data didn't explain why only men seem to suffer from a higher stress response to narcissism, Konrath speculated that societal definitions of masculinity that overlap with the trait -- such as arrogance or dominance -- may leave men particularly vulnerable physiologically.
"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," she 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."
While the study "invites people to look at this issue in a more comprehensive way," it did not prove a cause-and-effect relationship between narcissism and the body's stress response, said Dr. Mark Russ, director of psychiatric services at Zucker Hillside Hospital in Glen Oaks, N.Y.
"People with narcissism may be type-A, very driven, perfectionistic and seek high-stress situations, and the cortisol levels may be measuring that," Russ said. "There may be an overlap."
Konrath said future research will focus on the reason women don't respond physiologically to narcissism as men apparently do. Narcissism levels have increased in both genders in recent years, she said, perhaps as a byproduct of the so-called "self-esteem movement," which emphasizes praise for children over criticism.
"It could be a change in the educational environment," she said. "I think it's nice we're trying to be thoughtful and careful of people's feelings, but we may err on the side of not being [constructive]."
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