Gray matter differences in the anterior cingulate and orbitofrontal cortex of young adults with Internet gaming disorder: Surface-based morphometry

Abstract

Background and aims Altered risk/reward decision-making is suggested to predispose individuals with Internet gaming disorder (IGD) to pursue short-term pleasure, despite long-term negative consequences. The anterior cingulate cortex (ACC) and the orbitofrontal cortex (OFC) play important roles in risk/reward decision-making. This study investigated gray matter differences in the ACC and OFC of young adults with and without IGD using surface-based morphometry (SBM). Methods We examined 45 young male adults with IGD and 35 age-matched male controls. We performed region of interest (ROI)-based analyses for cortical thickness and gray matter volume (GMV) in the ACC and OFC. We also conducted whole-brain vertex-wise analysis of cortical thickness to complement the ROI-based analysis. Results IGD subjects had thinner cortices in the right rostral ACC, right lateral OFC, and left pars orbitalis than controls. We also found smaller GMV in the right caudal ACC and left pars orbitalis in IGD subjects. Thinner cortex of the right lateral OFC in IGD subjects correlated with higher cognitive impulsivity. Whole-brain analysis in IGD subjects revealed thinner cortex in the right supplementary motor area, left frontal eye field, superior parietal lobule, and posterior cingulate cortex. Conclusions Individuals with IGD had a thinner cortex and a smaller GMV in the ACC and OFC, which are critical areas for evaluating reward values, error processing, and adjusting behavior. In addition, in behavioral control-related brain regions, including frontoparietal areas, they also had thinner cortices. These gray matter differences may contribute to IGD pathophysiology through altered risk/reward decision-making and diminished behavioral control.

Keywords: Internet gaming disorder; cortical thickness; gray matter volume; risk/reward decision-making; surface-based morphometry.

Figure 1.

Regions of interest (ROIs). ROIs were defined according to the Desikan–Killiany cortical atlas. ROIs for the anterior cingulate cortex (ACC) included both sides of the caudal ACC (green) and the rostral ACC (orange). ROIs for the orbitofrontal cortex (OFC) included both sides of the lateral OFC (red), medial OFC (blue), and the pars orbitalis (yellow)

Figure 2.

Correlation analysis for brain-behavior relationships. Partial correlation between cortical thickness in the right lateral orbitofrontal cortex (OFC) and cognitive impulsivity score of the Barratt Impulsiveness Scale (BIS) after controlling for covariates (age, IQ, BDI, BAI, and WURS). To depict partial correlation, variables were regressed onto covariates using a linear regression. Scatter plots were generated using calculated non-standardized residuals. The cortical thickness of the right lateral OFC significantly correlated with cognitive impulsivity in IGD subjects (r = −.333, p = .038)

Figure 3.

Whole-brain vertex-wise analysis of cortical thickness. A statistical threshold of p < .005 (uncorrected) was employed for a vertex-wise comparison. Compared with controls, subjects with IGD had a thinner cortex in the (A) right supplementary motor area (SMA; peak Talairach coordinate: X = 7, Y = 21, Z = 53; number of vertices: 271), (B) left frontal eye field (FEF; peak Talairach coordinate: X = −10, Y = 17, Z = 45; number of vertices: 224) and the left posterior cingulate cortex (PCC; peak Talairach coordinate: X = −9, Y = −30, Z = 40; number of vertices: 215), and (C) left superior parietal lobule (SPL; peak MNI coordinate: X = −15, Y = −62, Z = 61; number of vertices: 216)