RT Journal A1 Brewerton TD, Flament MF, Rapoport JL, Murphy DL T1 SEasonal effects on platelet 5-ht content in patients with ocd and controls JF Archives of General Psychiatry JO Archives of General Psychiatry YR 1993 FD May 1 VO 50 IS 5 SP 409 OP 409 DO 10.1001/archpsyc.1993.01820170095015 UL http://dx.doi.org/10.1001/archpsyc.1993.01820170095015 AB Flament et al1 reported no significant differences in platelet serotonin (5-HT) content between 25 children with obsessive-compulsive disorder (OCD) and 22 age- and sex-matched controls. Independent of this work, significant seasonal variations have been reported for several parameters of 5-HT function in humans,2-5 including platelet 5-HT content.6-8 We therefore reanalyzed the original platelet 5-HT data of Flament et al, using season and diagnosis as grouping variables. The subjects and methods of this study have been previously described in detail.1 As seen in the Figure, there was a significant seasonal difference in platelet 5-HT concentration in the normal controls (analysis of variance, P≤.0002), but not in the patients with OCD or the total group. Post hoc differences persisted between summer and winter, and between summer and spring, in the controls (P≤.05, Bonferroni t test). These seasonal differences were significant in the male controls, but not