Plasma melatonin and cortisol circadian patterns in patients with obsessive-compulsive disorder before and after fluoxetine treatment.

The circadian rhythms of melatonin and cortisol were evaluated in seven outpatients with obsessive-compulsive disorder (OCD) before and after 8 weeks of fluoxetine treatment (20 mg/day in the first 2 weeks, and 40 mg/day afterwards), and in seven healthy subjects matched to patients on age, sex and season of testing. The results confirm our previous findings of a decreased 24-h production of melatonin (p < .05; two-way ANOVA with repeated measures) and of an increased circadian secretion of cortisol (p < .01) in OCD patients with respect to matched controls, and show, for the first time, that these hormonal alterations do not significantly change after 2 months of fluoxetine administration, in spite of a good clinical improvement. These data suggest that the normalization of the biochemical changes underlying the altered endocrine parameters in obsessive-compulsive patients is not necessary for effective therapy or clinical remission.