MRI Study On Functional Connectivity Density And Structural Correlates Of Impulsivity In Adolescents With Internet Gaming Disorder

Part One Functional Connectivity Density Alters in Adolescents with Internet Gaming DisorderObjective:To investigate alteration of resting-state functional connectivity density(rsFCD)in the adolescents with internet gaming disorder(IGD).Methods:Rest-stating functional magnetic resonance imaging(f MRI) examinations were performed on 27 male adolescents with IGD and 35 age- and education-matched male healthy controls(HCs) in our study. The attention network test(ANT) and the visual working memory test(VWMT) were used to evaluate visual attention and visual spacial working memory in all subjects.Rest-stating f MRI data of all participants were analyzed and global, short- and long-range rsFCD maps were obtained. The intergroup differences in global, short-,and long-range rsFCD were compared using voxel-wise two-sample t-test in SPM8(P < 0.05, Alpha Sim correction). Clinical/behavioral performances were compared using a two-sample t-test in SPSS 18.0 and the significance level was set at P < 0.05.Clusters with altered rsFCD in the IGD adolescents were defined as regions of interest(ROIs). Correlations between the mean rsFCD wihtin these ROIs and clinical/behavioral variables were further tested using the Pearson's correlation analysis in SPSS 18.0. Significance level was set at P < 0.05.Result:(1) The comparison of clinical/cognitive variablesOnline game playing time(hours/day) and Young's online internet addiction test(IAT) score was significantly higher in the IGD group than in the HCs(P < 0.05).There was no significant intergroup difference in behavioral performances(visual working memory and attention)(P > 0.05).(2) The comparison of rsFCDThe IGD adolescents exhibited higher global rsFCD in the left superior frontal cortex(SFC), the left middle frontal cortex(MFC) and the right inferior temporal cortex/fusiform(ITC/fusiform), and higher long-range rsFCD in the left SFC, the bilateral MFC and the right ITC/fusiform compared with the HCs(P < 0.05,Alpha Sim). There was no significant intergroup difference in short-range rsFCD.(3) Association between rsFCD and clinical/cognitive variablesThe IGD adolescents showed significant negative correlations between global/long-range rsFCD of the left MFC and IAT score(r =-0.477, P = 0.012; r =-0.436, P = 0.048). In addition, long-range rsFCD of the left MFC positively correlated with accuracy rate of the VWMT(VWMT_AR)(r = 0.441, P = 0.046);long-range rsFCD of the right MFC negatively correlated with average reaction time of the ANT(ANT_RT)(r =-0.467, P = 0.014) and with average reaction time of the VWMT(VWMT_RT)(r =-0.611, P = 0.003) in the IGD adolescents.Conclusion:The IGD adolescents showed increased rsFCD in the brain areas involved in working memory, spatial orientation and attention processing, which indicated that increased rsFCD may be a compensatory mechanism for maintaining the normal behavioral performance in IGD adolescents.Part Two Altered Structural Correlates of Impulsivity in Adolescents with Internet Gaming DisorderObjective:We aimed to explore the relationship between gray matter volume(GMV) and impulsivity in the IGD adolescents.Methods:Structure magnetic resonance imaging(MRI) was performed on 25 male adolescents with IGD and 27 age- and education-matched male healthy controls(HCs)in our study. The Barratt impulsiveness scale-11(BIS-11) was used to measure impulsivity of all participants.High resolution anatomical images of all participants were processed using voxel-based morphometry(VBM) analysis. We introduced a general linear model in SPM to characterize the intergroup differences in correlations between GMV and BIS-11 score(uncorrected P < 0.005; cluster size > 200 voxels). Intergroup differences in BIS-11 score and other clinical variables were compared using two-sample t-test in SPSS18.0. The significance level set at P < 0.05.Clusters with altered correlations between GMV and BIS-11 score in the IGD adolescents were defined as ROIs. The correlations between average GMV of these ROIs and BIS-11 score in each group were further tested using the Pearson's correlation analysis in SPSS 18.0. The significance level was set at P < 0.05.Result:(1) The comparison of clinical/cognitive variablesOnline game playing time(hours/day), IAT score and BIS-11 score was significantly higher in IGD group than in the HCs(P < 0.05).(2) The comparison of structural correlates of impulsivityThe IGD adolescents had lower correlations between BIS-11 score and GMV in the right dorsomedial prefrontal cortex(dm PFC), the bilateral orbitofrontal cortex(OFC)/insula, the right amygdala and the left fusiform cortex(uncorrected P < 0.005;cluster size > 200 voxels).(3) Association between GMV of ROIs and BIS-11 scoreROI-based correlation analysis showed significant positive correlations between GMV of all these clusters and BIS-11 score in the HCs(P < 0.05), while no significant correlation was found in the IGD group.Conclusion:Our findings demonstrated that dysfunction of these brain areas involved in the behavior inhibition, attention and emotion regulation might contribute to impulse control problems in the IGD adolescents.