
Sorry to say that if he keeps this expression, his mouth will turn down permanently - the trait of pessimism.


Perhaps he is ill or has been emotionally stretched for a long time.
Watching Barack Obama during the recent Ohio debates was an exercise in observing low emotionality at work. He was outwardly calm, cool, and collected. Thoughtful in his responses, and seemingly unflappable. We will have to watch for Signs of Strain as an indication of his interior life.