Scientists at Cardiff University say they may have discovered how Lithium works to treat bipolar disorder (BPD). Lithium has been used for more than 50 years as an effective treatments for BPD, though scientists have never been entirely sure how it worked on the brain. Now, laboratory tests on cells have shown that Lithium affects a molecule that is important in controlling brain cell signaling. Scientists say this finding could open the door for even more effective treatments for BPD.