SEROTONIN CHALLENGE NORMALIZES DEFICITS IN EXECUTIVE FUNCTIONING IN PATIENTS WITH OBSESSIVE-COMPULSIVE DISORDER (OCD)

ObjectiveAssessing the potential of serotonin challenge for altering executive functions in OCD, OCD relatives and controls.BackgroundExecutive planning and response inhibition problems are common in OCD, yet the role of serotonin in these is unclear. Pharmacological challenge can elicit an u2018endophenotypeu2019 existing in patients and relatives. Therefore, we assessed the potential of serotonin challenge for altering specific executive functions in OCD patients, relatives and controls.Materials and MethodsA randomized crossover study assessed effects of single-dose escitalopram / placebo on executive planning and response inhibition in 24 patients, 13 relatives and 28 controls. One-touch Stockings of Cambridge (OTS) and Stop-Signal Task (SST) performances were assessed. ResultsOn executive planning, there was a significant effect of group (p=0.05) and a trend towards significant group x treatment interaction (p=0.07). Post hoc tests showed: (i) patients and relatives were impaired versus controls (p=0.04, p=0.03); (ii) escitalopram was associated with improved executive planning in OCD (p=0.01), but not in other groups (both p>0.1). There were no main effect of group or group x treatment interactions for response inhibition (both p>0.1). ConclusionsExecutive planning did not differ between OCD patients and relatives while differences between these two groups and controls were significant. Escitalopram challenge normalized executive planning dysfunction in OCD, providing support for SSRIu2019s potential role in normalizing planning deficits of fronto-striatal circuitry typical of OCD. Lack of effects on response inhibition is consistent with a role for other neurochemical systems in this function, notably noradrenaline, as found in non-OCD work.