Plasma melatonin and cortisol in patients with obsessive–compulsive disorder: relationship with axillary temperature, physical activity, and clinical symptoms

Background: Many studies have found biological abnormalities in obsessive–compulsive disorder (OCD), although most of them have not been replicated. The investigation of melatonin rhythm may thus provide an indirect clue to neurotransmitter alterations, and allow a biological comparison with depression. Methods: The circadian variations of plasma melatonin, plasma cortisol, axillary temperature, motor activity, and obsessive–compulsive symptoms have been documented on a circadian basis in 8 patients with OCD compared to 8 paired healthy volunteers. Results: The circadian pattern of axillary temperature was slightly different in OCD patients when compared to control subjects. No significant difference between the two groups could be observed for any other variable studied. Conclusions: The discrepancies with previous studies are discussed on the basis of the methods used (patients and control subjects samples, biological measurement procedures). An alteration of temperature circadian rhythm hypothesis is suggested.