Neural Activity During the Stop Signal Task, a Disinhibition Task, Predicts Relapse in Cocaine-Dependent Patients
Vo, Lan Chi Le
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BACKGROUND: Relapse is a prevalent phenomenon in addiction. Impaired inhibitory control is associated with relapse and is a significant predictor of cocaine use and treatment retention. OBJECTIVE: Functional magnetic resonance imaging (fMRI) was used to examine the association between BOLD response during the Stop Signal Task (SST, a measure of inhibitory control), and time to relapse in cocaine-dependent patients. METHODS: Forty-nine 2-4 weeks abstinent cocaine-dependent participants were assessed and then followed weekly for up to 26 weeks as outpatients. Relapse was defined as any use of cocaine during the follow up period. The patients were categorized into 27 individuals in the relapse group (relapsed within 30 days) and 22 in the non-relapse group (did not relapse at 30 days). BOLD response during successful inhibition ("StopSuccess") during SST was compared between groups (z>2.3, p=0.05). Regions of interest (ROIs) were also identified using mean percent BOLD signal change in the combined patient group. Percent BOLD change values were calculated within the significantly activated voxels during StopSuccess (voxel-based analysis, P = 0.15). Identified clusters were used in discriminant analysis through the Statistical Product and Service Solutions software to predict group membership. RESULTS: Consistent with our hypothesis, the study found BOLD changes during the SST that were able to predict those who relapse from those who did not. Specifically, the left lateral occipital cortex exhibited greater BOLD activation in the relapse group than the non-relapse group. On the other hand, the relapse group had lower BOLD activation in the left lateral orbitofrontal cortex and left anterior insula. Using discriminant analysis, these two regions of interest were able to classify 76.9% of individuals into their respective groups correctly with cross-validation. CONCLUSION: The left lateral occipital cortex, left lateral orbitofrontal cortex and left anterior insula can be used to identify those at risk of relapse and offer insights into mechanisms of relapse.