Neural Correlates of Impaired Cognitive Control in Individuals with Methamphetamine Dependence: An fMRI Study

Abstract

Impaired cognitive and behavioral control has often been observed in people who use methamphetamine (MA). However, a comprehensive understanding of the neural substrates underlying these impairments is still lacking. The goal of the present study was to study the neural correlates of impaired cognitive control in individuals with MA dependence according to DSM-IV criteria. Eighteen individuals with MA dependence and 21 healthy controls were investigated using Stroop task, fMRI, and an impulsivity questionnaire. Overall, patients were found to have significantly poorer accuracy on the Stroop task and higher self-rated impulsivity. Comparing brain activations during the task, decreased activation in the dorsolateral prefrontal cortex (DLPFC), anterior midcingulate cortex (aMCC), and dorsal striatum was observed in individuals with MA dependence, compared to healthy controls. Altered fMRI signal in DLPFC and aMCC significantly correlated with impaired behavioral task performance in individuals with MA dependence. Furthermore, significantly lower and pronounced brain activations in the MA group were additionally detected in several sensory cortical regions, i.e., in the visual, auditory, and somatosensory cortices. The results of the current study provide evidence for the negative impact of chronic crystal meth consumption on the proper functioning of the fronto-cingulate and striatal brain regions, presumably underlying the often-observed deficits in executive functions in individuals with MA use disorder. As a new finding, we also revealed abnormal activation in several sensory brain regions, suggesting the negative effect of MA use on the proper neural activity of these regions. This blunted activation could be the cause of the observed deficits in executive functions and the associated altered brain activation in higher-level brain networks.

Keywords: Stroop task; anterior cingulate cortex; cognitive control; crystal meth; dorsal striatum; fMRI; functional magnetic resonance imaging; methamphetamine dependence disorder; prefrontal cortex; visual cortex.

Figure 1

Significant group differences (healthy controls vs. individuals with MA dependence) in brain activation during the incongruent Stroop task condition (voxel-level: p < 0.001 uncorr., cluster-level: corrected according to expected voxels per cluster ≥ 16). The bar graphs depict parameter estimates extracted from the significant cluster in the left DLPFC, aMCC, and V1. (a) Averaged parameter estimates, and standard error extracted from the significant cluster in the left DLPFC (local maximum: x = −37, y = 36, z = 18, cluster size = 65); (b) averaged parameter estimates and standard error extracted from the significant cluster in the V1 (local maximum: x = 8, y = −73, z = 16, cluster size = 3482); (c) averaged parameter estimates and the standard error extracted from the significant cluster in the aMCC (local maximum: x = 10, y = 4, z = 32, cluster size = 45). Abbreviations: HC, healthy controls; MA, individuals with methamphetamine dependence; DLPFC, dorsolateral prefrontal cortex; VLPFC, ventrolateral prefrontal cortex; aMCC, anterior midcingulate cortex; V1, primary visual cortex; V2, secondary visual cortex; SMA, supplementary motor area.

Figure 2

The scatterplot depicts significantly positive correlations between the fMRI signal in the aMCC (individuals with MA dependence: r = 0.57, p < 0.01), left DLPFC (individuals with MA dependence: r = 0.57, p < 0.01), and the total number of correct responses in individuals with methamphetamine dependence (MA; blue color) and healthy controls (HC; red color).