Brain Structures and Activity During a Working Memory Task Associated with Internet Addiction Tendency in Young Adults

Abstract

\n An increasing number of young people use internet excessively over the last decades, which leads to adverse impacts on individuals and society. The structural and functional brain characteristics associated with the excessive use of the internet have attracted substantial research attention in the past decade; however, due to the small sample sizes of past studies, many findings are inconsistent. Also, the relationship between internet addiction tendency (IAT) and regional brain activity during working memory (WM), a critical cognitive function governing learned behavior, has not been explored. In current study, we used voxel-based morphometry (VBM) and multiple regression analysis to assess the relationship between IAT score and regional gray and white matter volumes (rGMVs and rWMVs) and brain activity during a WM task in a large sample of healthy young adults (n= 1,154, mean age, 20.71 ± 1.78 years).We found a significant positive correlation between IAT score and GMV of right supramarginal gyrus (rSMG) and significant negative correlations with WMVs of right temporal lobe (sub-gyral and superior temporal gyrus), right sublobar area (extra-nuclear and lentiform nucleus), right cerebellar anterior lobe, cerebellar tonsil, right frontal lobe (inferior frontal gyrus and sub-gyral areas), and the pons. Also, IAT was significantly and positively correlated with brain activity in the default-mode network (DMN), medial frontal gyrus, medial part of the superior frontal gyrus, and anterior cingulate cortex) during a 2-back WM task. Moreover, whole-brain analyses of rGMV showed significant effects of interaction between sex and the IAT scores in the area spreading around the left anterior insula and left lentiform. This interaction was moderated by positive correlation in females.These results indicate that IAT is associated with (a) increased GMV in rSMG, which is involved in phonological processing, (b) decreased WMVs in areas of frontal, sublobar, and temporal lobes, which are involved in response inhibition, and (c) reduced task-induced deactivation of the DMN, indicative of altered attentional allocation.