Abnormal white matter integrity in adolescents with internet addiction disorder: a tract-based spatial statistics study

Abstract

Background: Internet addiction disorder (IAD) is currently becoming a serious mental health issue around the globe. Previous studies regarding IAD were mainly focused on associated psychological examinations. However, there are few studies on brain structure and function about IAD. In this study, we used diffusion tensor imaging (DTI) to investigate white matter integrity in adolescents with IAD.

Methodology/principal findings: Seventeen IAD subjects and sixteen healthy controls without IAD participated in this study. Whole brain voxel-wise analysis of fractional anisotropy (FA) was performed by tract-based spatial statistics (TBSS) to localize abnormal white matter regions between groups. TBSS demonstrated that IAD had significantly lower FA than controls throughout the brain, including the orbito-frontal white matter, corpus callosum, cingulum, inferior fronto-occipital fasciculus, and corona radiation, internal and external capsules, while exhibiting no areas of higher FA. Volume-of-interest (VOI) analysis was used to detect changes of diffusivity indices in the regions showing FA abnormalities. In most VOIs, FA reductions were caused by an increase in radial diffusivity while no changes in axial diffusivity. Correlation analysis was performed to assess the relationship between FA and behavioral measures within the IAD group. Significantly negative correlations were found between FA values in the left genu of the corpus callosum and the Screen for Child Anxiety Related Emotional Disorders, and between FA values in the left external capsule and the Young's Internet addiction scale.

Conclusions: Our findings suggest that IAD demonstrated widespread reductions of FA in major white matter pathways and such abnormal white matter structure may be linked to some behavioral impairments. In addition, white matter integrity may serve as a potential new treatment target and FA may be as a qualified biomarker to understand the underlying neural mechanisms of injury or to assess the effectiveness of specific early interventions in IAD.

Figure 1. TBSS analysis of fractional anisotropy (FA) volumes.

Areas in red are regions where FA was significantly lower (p<0.01, corrected by TFCE) in adolescents with Internet addiction disorder (IAD) relative to normal controls without IAD. To aid visualization, regions showing reduced FA (red) are thickened using the tbss_fill script implemented in FSL. Results are shown overlaid on the MNI152-T1 template and the mean FA skeleton (green). The left side of the image corresponds to the right hemisphere of the brain.

Figure 2. Correlation analysis between fractional anisotropy (FA) and behavioral measures within the Internet addiction disorder (IAD) group.

To aid visualization, regions showing significant correlations (red) are thickened using the tbss_fill script implemented in FSL. Figure 2A shows FA values in the left genu of the corpus callosum correlates negatively with the Screen for Child Anxiety Related Emotional Disorders (SCARED) (r = −0.621, p = 0.008). Figure 2B shows FA values in the left external capsule correlates negatively with the Young's Internet addiction scale (YIAS) (r = −0.566, p = 0.018).