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

Neurobiological outcomes of cognitive behavioral therapy for obsessive-compulsive disorder: A systematic review

Introduction

Obsessive-compulsive disorder (OCD) is characterized by recurrent distressing thoughts and repetitive behaviors, or mental rituals performed to reduce anxiety. Recent neurobiological techniques have been particularly convincing in suggesting that cortico-striatal-thalamic-cortico (CSTC) circuits, including orbitofrontal cortex (OFC) and striatum regions (caudate nucleus and putamen), are responsible for mediation of OCD symptoms. However, it is still unclear how these regions are affected by OCD treatments in adult patients. To address this yet open question, we conducted a systematic review of all studies examining neurobiological changes before and after first-line psychological OCD treatment, i.e., cognitive-behavioral therapy (CBT).

Methods

Studies were included if they were conducted in adults with OCD and they assessed the neurobiological effects of CBT before and after treatment. Two databases were searched: PsycINFO and PubMed for the time frame up to May 2022.

Results

We obtained 26 pre-post CBT treatment studies performed using different neurobiological techniques, namely functional magnetic resonance imaging (fMRI), Positron emission tomography (PET), regional cerebral blood flow (rCBF), 5-HT concentration, magnetic resonance imaging (MRI), magnetic resonance spectroscopy (MRS), Electroencephalography (EEG). Neurobiological data show the following after CBT intervention: (i) reduced activations in OFC across fMRI, EEG, and rCBF; (ii) decreased activity in striatum regions across fMRI, rCBF, PET, and MRI; (iii) increased activations in cerebellum (CER) across fMRI and MRI; (iv) enhanced neurochemical concentrations in MRS studies in OFC, anterior cingulate cortex (ACC) and striatum regions. Most of these neurobiological changes are also accompanied by an improvement in symptom severity as assessed by a reduction in the Y-BOCS scores.

Conclusion

Cognitive-behavioral therapy seems to be able to restructure, modify, and transform the neurobiological component of OCD, in addition to the clinical symptoms. Nevertheless, further studies are necessary to frame the OCD spectrum in a dimensional way.

Monoamine abnormalities in the SAPAP3 knockout model of obsessive-compulsive disorder-related behaviour

Obsessive-compulsive disorder (OCD) is a leading cause of illness-related disability, but the neural mechanisms underlying OCD symptoms are unclear. One potential mechanism of OCD pathology is monoamine dysregulation. Because of the difficulty of studying monoamine signalling in patients, animal models offer a viable alternative to understanding this aspect of OCD pathophysiology. We used HPLC to characterize post-mortem monoamine levels in lateral orbitofrontal cortex (OFC), medial OFC, medial prefrontal cortex and dorsal and ventral striatum of SAPAP-3 knockout (KO) mice, a well-validated model of compulsive-like behaviours in OCD. As predicted from previous studies, excessive grooming was significantly increased in SAPAP-3 KO mice. Overall levels of the serotonin metabolite 5-hydroxyindoleacetic acid (HIAA) and the ratio of 5HIAA/serotonin (serotonin turnover) were increased in all cortical and striatal regions examined. In addition, dihydroxyphenylacetic acid/dopamine ratio was increased in lateral OFC, and HVA/dopamine ratio was increased in lateral and medial OFC. No baseline differences in serotonin or dopamine tissue content were observed. These data provide evidence of monoaminergic dysregulation in a translational model of OCD symptoms and are consistent with aberrant cortical and striatal serotonin and dopamine release/metabolism in SAPAP-3 KO mice. These results are guiding ongoing experiments using circuit and cell-type specific manipulations of dopamine and serotonin to determine the contributions of these monoaminergic systems to compulsive behaviours, and serve here as a touchstone for an expanded discussion of these techniques for precise circuit dissection.This article is part of the discussion meeting issue 'Of mice and mental health: facilitating dialogue between basic and clinical neuroscientists'.

Concomitant treatment with sertraline and social skills training improves social skills acquisition in social anxiety disorder: A double-blind, randomized controlled trial

Objectives

To examine whether: (1) sertraline (SER) + psychotherapy is superior to psychotherapy alone; (2) group cognitive-behavioural therapy (GCBT) is superior to group psychodynamic therapy (GPT) and (3) SER+GCBT or SER+GPT is superior to Placebo (PLA)+GCBT or PLA+GPT in social anxiety disorder (SAD).

Methods

A double-blind randomized controlled trial. Participants were assigned either to: SER+GCBT (n = 34); SER+GPT (n = 36); PLA+GCBT (n = 36) or PLA+GPT (n = 41) for 20 weeks. SER (or PLA) was administered at doses from 50 to 200 mg/d. Primary measures were both categorial: remission (CGI score≤2), response of social symptoms (≥50% reduction in Scale of Avoidance and Social Discomfort (SASD)); and continuous: reduction of SASD and Multidimensional Scale of Social Expression(M-MSSE).

Results

SER exhibited better improvement of social anxiety symptoms rate than PLA (25.73% vs. 9.46%, P < .05). Neither GCBT differed from GPT (12.33% vs. 22.54%, P = .11) nor SER+GCBT from PLA+GCBT (17.65% vs. 7.69%, P = .20). However, SER+GPT was superior to PLA+GPT (33.33%, vs. 11.43%, P < .05). M-MSSE had superior improvement for SER+GCBT vs PLA+GCBT (P < .01) but not for SER+GPT vs. PLA+GPT (P = .80). SASD scores improvement were greater for SER than PLA (P < .01) and for SER+GCBT vs. PLA+GCBT (P < .05), but neither GCBT differed from GPT(P = .60) nor SER+GPT differed from PLA+GPT (P = .09).

Conclusions

In overall, SER+psychotherapy was superior to psychotherapy alone. SER potentiated GCBT by enhancing social skills acquisition.

Trial registration

ISRCTN 57551461.