[Lithium: 55 years of history in the therapy of bipolar affective disorder].

The clinical history of lithium began in mid-19th century when it was used to treat gout. It was subsequently administered as a substitute for sodium chloride and towards the end of 1940 its effects for the control of mania were discovered. At present it is used effectively for treatment of mania and for the prophylaxis of bipolar disorder. Though its effect on affective illnesses is evident, the same cannot be said of its mechanism of action, since in spite of the numerous studies performed to date it is still not known exactly how this ion acts. Many theories have been proposed, the most important of which are: normalisation of possible ionic alterations; interactions with the adenylyl cyclase cAMP system; effects on the phosphatidylinositol cycle; stabilisation of the levels of neuroprotective proteins; normalisation of the values of some cytosolic endopeptidases; etc. In any case, it has yet to be determined which of these is the principal factor responsible for lithium's therapeutic action, while at the same time the possibility cannot be totally ruled out that its precise mechanism of action is still to be discovered.