A preliminary investigation of Stroop-related intrinsic connectivity in cocaine dependence: associations with treatment outcomes

Abstract

Background: Cocaine-dependent individuals demonstrate neural and behavioral differences compared to healthy comparison subjects when performing the Stroop color-word interference test. Stroop measures also relate to treatment outcome for cocaine dependence. Intrinsic connectivity analyses assess the extent to which task-related regional brain activations are related to each other in the absence of defining a priori regions of interest. Objective: This study examined 1) the extent to which cocaine-dependent and non-addicted individuals differed on measures of intrinsic connectivity during fMRI Stroop performance; and 2) the relationships between fMRI Stroop intrinsic connectivity and treatment outcome in cocaine dependence. Methods: Sixteen treatment-seeking cocaine-dependent patients and matched non-addicted comparison subjects completed an fMRI Stroop task. Between-group differences in intrinsic connectivity were assessed and related to self-reported and urine-toxicology-based cocaine-abstinence measures. Results: Cocaine-dependent patients vs. comparison subjects showed less intrinsic connectivity in cortical and subcortical regions. When adjusting for individual degree of intrinsic connectivity, cocaine-dependent vs. comparison subjects showed relatively greater intrinsic connectivity in the ventral striatum, putamen, inferior frontal gyrus, anterior insula, thalamus and substantia nigra. Non-mean-adjusted intrinsic-connectivity measures in the midbrain, thalamus, ventral striatum, substantia nigra, insula and hippocampus negatively correlated with measures of cocaine abstinence. Conclusion: The diminished intrinsic connectivity in cocaine-dependent vs. comparison subjects suggests poorer communication across brain regions during cognitive-control processes. In mean-adjusted analyses, the cocaine-dependent group displayed relatively greater Stroop-related connectivity in regions implicated in motivational processes in addictions. The relationships between treatment outcomes and connectivity in the midbrain and basal ganglia suggest that connectivity represents a potential treatment target.

• Addiction
• cocaine dependence
• cognitive control
• functional magnetic resonance imaging
• intrinsic connectivity
• Stroop color-word interference test
• treatment outcome

Acknowledgments

Supported by P50DA09241 (KMC), R01DA020908 (MNP), P20DA027844 (MNP), R01EB009666 (RTC), Connecticut Department of Mental Health and Addiction Services, and the Connecticut Mental Health Center. E. E. DeVito is supported by K12DA031050 (Mazure, PI) from NIDA, NIAAA, Office of Research on Women's Health (ORWH) and NIH Office of the Director (OD). M. R. Mitchell is supported by T32DA007238 (Petrakis, PI).