Neural mechanisms of persistent avoidance in OCD: A novel avoidance devaluation study.

Obsessive-Compulsive Disorder (OCD) is characterized by repetitive avoidance behavior which is distressing and associated with marked impairment of everyday life. Recently, paradigms have been designed to explore the hypothesis that avoidance behavior in OCD is consistent with a formal conception of habit. Such studies have involved a devaluation paradigm, in which the value of a previously rewarded cue is altered so that avoidance is no longer necessary. We employed a rule-based avoidance task which included a devaluation, examining behavioral performance on the task and their neural correlates using functional MRI in groups of participants with OCD (n = 44) and healthy control participants (n = 46). Neuroimaging data were analyzed using a general linear model (GLM), modelling valued, devalued and control cues, as well as feedback events. First, while no overall effect of OCD was seen on devaluation performance, patients with longer illness duration showed poorer devaluation performance (χ2 = 13.84, p < 0.001). Reduced devaluation was related to impaired learning on the overtraining phase of the task, and to enhanced feedback activation in the caudate and parietal lobe during within-scanner retraining (T = 5.52, p_FWE = 0.003), across all participants. Second, a significant interaction effect was observed in the premotor cortex (F = 29.03, p_FWE = 0.007) coupled to the devalued cue. Activations were divergent in participants with OCD (lower activation) and healthy controls (higher activation) who did not change responding to the devalued cue following devaluation, and intermediate in participants who did change responding (T = 5.39, p_FWE = 0.003). Finally, consistent with previous work, medial orbitofrontal cortex activation coupled to valued cues was reduced in OCD compared to controls (T = 3.49, p_FWE = 0.009). The findings are discussed in terms of a prediction error-based model of goal-directed and habitual control: specifically, how goal-directed control might be diminished in OCD in favor of habits. They suggest that illness duration might be significant determinant of variation in impaired goal-directed learning in OCD, and be a factor relevant for understanding discrepancies across studies. Overall, the study shows the potential of conceptual replication attempts to provide complementary insights into compulsive behavior and its associated neural circuitry in OCD.

Deep Brain Stimulation for Obsessive-Compulsive Disorder: A Meta-Analysis of Treatment Outcome and Predictors of Response.

BACKGROUND: Deep brain stimulation (DBS) has been proposed as an alternative to ablative neurosurgery for severe treatment-resistant Obsessive-Compulsive Disorder (OCD), although with partially discrepant results probably related to differences in anatomical targetting and stimulation conditions. We sought to determine the efficacy and tolerability of DBS in OCD and the existence of clinical predictors of response using meta-analysis. METHODS: We searched the literature on DBS for OCD from 1999 through January 2014 using PubMed/MEDLINE and PsycINFO. We performed fixed and random-effect meta-analysis with score changes (pre-post DBS) on the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) as the primary-outcome measure, and the number of responders to treatment, quality of life and acceptability as secondary measures. FINDINGS: Thirty-one studies involving 116 subjects were identified. Eighty-three subjects were implanted in striatal areas--anterior limb of the internal capsule, ventral capsule and ventral striatum, nucleus accumbens and ventral caudate--27 in the subthalamic nucleus and six in the inferior thalamic peduncle. Global percentage of Y-BOCS reduction was estimated at 45.1% and global percentage of responders at 60.0%. Better response was associated with older age at OCD onset and presence of sexual/religious obsessions and compulsions. No significant differences were detected in efficacy between targets. Five patients dropped out, but adverse effects were generally reported as mild, transient and reversible. CONCLUSIONS: Our analysis confirms that DBS constitutes a valid alternative to lesional surgery for severe, therapy-refractory OCD patients. Well-controlled, randomized studies with larger samples are needed to establish the optimal targeting and stimulation conditions and to extend the analysis of clinical predictors of outcome.