A Double-Blind Trial of Long-Term Lithium Therapy in Mental Defectives

A two-year double-blind trial of the prophylactic effect of lithium therapy was carried out on an in-patient group of mentally defective patients who were suffering from frequently recurring affective or behavioural changes. Fourteen patients completed the trial. The number of weeks ill during the year on lithium was significantly less than the number of weeks ill during the year on placebo. There appeared to be less effect on the actual number of episodes of illness. The number of episodes during the year on lithium was less than that during the year on placebo, but the difference was not statistically significant.