Pretreatment brain activation during stroop task is associated with outcomes in cocaine-dependent patients

Abstract

Background: Cognitive behavioral and related therapies for cocaine dependence may exert their effects, in part, by enhancing cognitive control over drug use behavior. No prior studies have systematically examined the neural correlates of cognitive control as related to treatment outcomes for cocaine dependence.

Methods: Twenty treatment-seeking cocaine-dependent individuals performed a Stroop color-word interference task while undergoing functional magnetic resonance imaging (fMRI) prior to initiating treatment. The primary outcome measures were percent of urine drug screens negative for cocaine, percent days abstinent, and treatment retention. Correlations between regional brain activation during Stroop task performance and treatment outcome measures were analyzed.

Results: During Stroop performance, individuals activated brain regions similar to those reported in nonaddicted individuals, including the anterior cingulate cortex, dorsolateral prefrontal cortex, parietal lobule, insula, and striatum. Activations at treatment onset correlated differentially with specific outcomes: longer duration of self-reported abstinence correlated with activation of ventromedial prefrontal cortex, left posterior cingulate cortex, and right striatum; percent drug-free urine screens correlated with striatal activation; and treatment retention correlated with diminished activation of dorsolateral prefrontal cortex. A modest correlation between Stroop effect and treatment retention was found.

Conclusions: The functions of specific brain regions underlying cognitive control relate differentially to discrete outcomes for the treatment of cocaine dependence. These findings implicate neurocircuitry underlying cognitive control in behavioral treatment outcome and provide insight into the mechanisms of behavioral therapies for cocaine dependence. They also suggest neural activation patterns during cognitive control tasks are more sensitive predictors of treatment response than behavioral measures.

Figure 1. Regional brain activation during Stroop task performance correlates with treatment outcome measures

Brain slice correlation images of regional activation as denoted numerically in Table 3 (left side of figure) with corresponding percent signal change (right side of figure). A) percent cocaine negative urine toxicology over the course of treatment (p < 0.005), B and C) longest duration of self-reported cocaine abstinence (p < 0.005), and D) total weeks in treatment (p < 0.01). Red/white indicates areas of positive correlations between the indicated outcome measure and increased BOLD signal changes in the incongruent vs. congruent contrast. Blue/Green indicates areas of negative correlations between the indicated outcome measure and increased BOLD signal changes in the incongruent vs. congruent contrast. Numbers indicate Z axis MNI coordinates. Right side of brain is on the right.