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Brazilian Journal of Psychiatry

Print version ISSN 1516-4446On-line version ISSN 1809-452X


SAMPAIO, Thiago; LIMA, Cristiane; CORREGIARI, Fabio  and  BERNIK, Marcio. The putative catalytic role of higher serotonin bioavailability in the clinical response to exposure and response prevention in obsessive-compulsive disorder. Rev. Bras. Psiquiatr. [online]. 2016, vol.38, n.4, pp.287-293.  Epub Oct 17, 2016. ISSN 1516-4446.


Exposure and response prevention (ERP) is effective to treat obsessive-compulsive disorder (OCD), but the lack of tolerance to the aversion nature of exposure techniques results in a high drop-out rate. There have been reports of a generic stress endurance effect of serotonin (5-HT) in the central nervous system (CNS) which might be explained by suppression of defensive fixed action patterns. Previous studies have proposed that higher baseline 5-HT concentration and slow decrease in concentration during drug treatment of OCD were predictors of good clinical response to 5-HT reuptake inhibitors. The objective of this study was to investigate whether pre-treatment platelet rich plasma (PRP) 5-HT concentration is associated with latency of treatment response and final response to an ERP protocol for obsessive-compulsive disorder (OCD).


Thirty adult and treatment-free OCD patients were included in an 8-week, 16-session ERP protocol. 5-HT concentration was determined at baseline and after treatment. Patients with a reduction ≥30% on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) at the end of ERP were defined as responders.


A positive correlation between baseline 5-HT concentration and reduction of symptoms on the Y-BOCS was observed after 4 weeks. Baseline 5-HT concentration was not correlated with clinical response after 8 weeks of ERP, possibly due to the similar though delayed clinical response of patients with lower (compared to those with higher) baseline 5-HT concentration. Patients with higher 5-HT baseline concentration also showed more improvement in depressive symptoms with treatment.


The present results partially support the hypothesis of a stress endurance effect of 5-HT in OCD patients. According to the literature, fast onset responders possibly have more or larger 5-HT containing neurons, higher endogenous 5-HT synthesis or lower monoamine oxidase activity; all these hypotheses remain to be investigated.

Keywords : Behavior therapy; biological markers; stress; neurophysiology; obsessive-compulsive disorder.

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