One of the most serious mental disorders is, perhaps, a bipolar syndrome. This disorder is also known as the manic-depressive one. 2.6% of the US citizens appear to suffer from this problem. They stop understanding who they are. They are unable to differentiate real things and their imaginary world. These people demonstrate rapid mood fluctuations and other changing patterns of behavior. They become less productive. Such people report of regular depressions. They feel like more than one person is inside their heads, so they may behave like two different personalities. They also can talk a mile a minute; it is difficult for them to listen to others attentively. They also may have troubles with memory.