Can you think of a narcissist? Some people might picture Donald Trump, perhaps, or Elon Musk, both of whom are often labeled as such on social media. Or maybe India's prime minister, Narendra Modi, who once wore a pinstripe suit with his own name woven in minute gold letters on each stripe over and over again.

But chances are you've encountered a narcissist, and they looked nothing like Trump, Musk or Modi. Up to 6 percent of the U.S. population, mostly men, is estimated to have had narcissistic personality disorder during some period of their lives. And the condition manifests in confoundingly different ways. People with narcissism “may be grandiose or self-loathing, extraverted or socially isolated, captains of industry or unable to maintain steady employment, model citizens or prone to antisocial activities,” according to a review paper on diagnosing the disorder.

Clinicians note several dimensions on which narcissists vary. They may function extremely well, with successful careers and vibrant social lives, or very poorly. They may (or may not) have other disorders, ranging from depression to sociopathy. And although most people are familiar with the “grandiose” version of narcissism—as displayed by an arrogant and pompous person who craves attention—the disorder also comes in a “vulnerable” or “covert” form, where individuals suffer from internal distress and fluctuations in self-esteem. What these seeming opposites have in common is an extreme preoccupation with themselves.

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What makes narcissism particularly complex is that it may not always be dysfunctional. “Being socially dominant, being achievement-striving and focused on improving one's own lot in life by themselves are not all that problematic and tend to be valued by Western cultures,” notes Aidan Wright, a psychologist at the University of Michigan.

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Clinicians' evaluations, as well as studies in the wider population, support the idea that narcissists oscillate between these two states. In recent surveys, Wright and his graduate student Elizabeth Edershile asked hundreds of undergraduate students and community members to complete assessments that measured their levels of grandiosity and vulnerability multiple times a day over several days. They found that whereas vulnerability and grandiosity do not generally coexist in the same moment, people who are overall more grandiose also undergo periods of vulnerability—whereas those who are generally more vulnerable don't experience much grandiosity. Some studies suggest that the overlap may depend on the severity of the narcissism: clinical psychologist Emanuel Jauk of the Medical University of Graz in Austria and his colleagues found in surveys that vulnerability may be more likely to appear in highly grandiose individuals.

Read the complete article in Scientific American