TRH and bipolar disorder: TRH-induced transient mood elevation is especially interesting as stimulation initiation in DBS for OCD is associated with mood elevation and hypomanic symptoms, also lasting for several days (Luigjes J et al. Hypomania as side effect of DBS in psychiatric patients, submitted).2 Therefore, we hypothesize on the basis of the present findings that TRH secretion may be a major determinant of the transient mood changes during DBS for the treatment of OCD.