A recent controlled double-blind study of 28 patients treated with 12 gm daily of inositol or placebo revealed significant antidepressant effect for this second messenger precursor. Patients were followed-up by interview and Hamilton Depression Scale 10-12 months after the end of the study. Half of the patients who had responded well to inositol relapsed rapidly after inositol discontinuation whereas none of those who responded to placebo relapsed rapidly after placebo cessation. Klein suggested that true drug responders to tricyclic antidepressants respond slowly and gradually whereas placebo responders improve early in an abrupt fashion. However, in the recent study both inositol and placebo responders improved at similar rates. Hamilton Depression Scale Scores 10-12 months after completion of the study were not significantly different between those who had responded and those who had not responded to inositol or to placebo.
