Lithium was used during the 19th century to treat gout. Lithium salts such as lithium carbonate (Li2CO3), lithium citrate, and lithium orotate are mood stabilizers. They are used in the treatment of bipolar disorder, since unlike most other mood altering drugs, they counteract both mania and depression. Lithium can also be used to augment other antidepressant drugs. It is also sometimes prescribed as a preventive treatment for migraine disease and cluster headaches. The active principle in these salts is the lithium ion Li+, which having a smaller diameter, can easily displace K+ and Na+ and even Ca+2, in spite of its greater charge, occupying their sites in several critical neuronal enzymes and neurotransmitter receptors.