Scientists have recently discovered that a gene called NCAN plays an essential part in facilitating the wild mood swings that occur in people suffering from bipolar disorder.  NCAN seems to be correlated with the cyclic manic symptoms, but not the depressive symptoms, associated with the disorder.  In an experiment with mice, those who contained an extra NCAN gene displayed more risk taking behavior than those mice who did not.  Read more here.

Image from health.com