In a recent study of U.S. presidents' personality traits, Lyndon Johnson ranked highest in grandiose narcissism.

While it frequently gets a bad rap, grandiose narcissism may predict both positive and negative leadership behaviors, according to a group of researchers who published a paper in October in Psychological Science.

Grandiose narcissism, which is characterized by an extroverted, flamboyant style, is distinct from vulnerable narcissism, which is more associated with emotional sensitivity and vulnerability.

The paper, titled "The Double-Edged Sword of Grandiose Narcissism: Implications for Successful and Unsuccessful Leadership Among U.S. Presidents," looks at data on the 42 U.S. presidents from George Washington through George W. Bush....