The putative catalytic role of higher serotonin bioavailability in the clinical response to exposure and response prevention in obsessive-compulsive disorder

Objective: 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). Methods: 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. Results: 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. Conclusion: 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.

Alexithymia, suicidal ideation, and serum lipid levels among drug-naïve outpatients with obsessive-compulsive disorder

Objective: As obsessive-compulsive disorder (OCD) is a relatively common psychiatric disorder with a significant suicide risk, the individuation of potential biomarkers of suicidality, such as cholesterol levels, may enable recognition of at-risk subjects. Therefore, the aims of this study were to: 1) evaluate potential differences in clinical and laboratory parameters between patients with and without alexithymia and compare them with healthy controls; and 2) investigate which clinical and laboratory variables were associated with suicidal ideation. Methods: 79 drug-naïve adult outpatients with a DSM-IV diagnosis of OCD were recruited. Alexithymia was measured with the 20-item Toronto Alexithymia Scale (TAS-20), suicidal ideation was assessed with the Scale for Suicide Ideation, and depressive symptoms were evaluated with the Montgomery-Åsberg Depression Rating Scale (MADRS). Serum lipid levels of 40 healthy controls were also evaluated. Results: Alexithymic patients had altered serum lipid levels in comparison with non-alexithymics and healthy controls. Using a linear regression model, the presence of symmetry/ordering obsessions and compulsions, lower HDL-C levels, and difficulty in identifying feelings dimension of the TAS-20 were associated with higher suicidal ideation. Conclusions: Alexithymic individuals with OCD may exhibit dysregulation of the cholesterol balance, which in turn may be linked to suicidal ideation. Further prospective studies are required to elucidate this potential association. .