What do Rudy Giuliani's messy personal life, John McCain's temper and Hillary Clinton's inability to seem authentic have in common? Maybe nothing. They may be just overblown issues in the otherwise normal lives of candidates under the political microscope.

Such symptoms, however, may mean a lot -- such as evidence of underlying brain dysfunction. Sometimes people with messy personal lives have low prefrontal cortex activity associated with poor judgment; sometimes people with temper problems have brain damage and impulse control problems; sometimes people who struggle with authenticity have trouble really seeing things from someone else's perspective.