Brain structures and activity during a working memory task associated with internet addiction tendency in young adults: A large sample study.

Saeid Sadeghi,Bita Shalani,Daniele Magistro,Kohei Sakaki,Yuko Sassa,Sugiko Hanawa,Ryoichi Yokoyama,Susumu Yokota,Tsuyoshi Araki,Shigeyuki Ikeda,Yuka Kotozaki,Yasuyuki Taki,Atsushi Sekiguchi,Rui Nouchi,Seishu Nakagawa,Kunio Iizuka,Takayuki Nozawa,Ryuta Kawashima,Hikaru Takeuchi,Carlos Makoto Miyauchi

doi:10.1371/journal.pone.0259259

Abstract

The structural and functional brain characteristics associated with the excessive use of the internet have attracted substantial research attention in the past decade. In current study, we used voxel-based morphometry (VBM) and multiple regression analysis to assess the relationship between internet addiction tendency (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 gray matter volume (GMV) of right supramarginal gyrus (rSMG) and significant negative correlations with white matter volume (WMV) 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 working memory (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 women. These results indicate that IAT is associated with (a) increased GMV in rSMG, which is involved in phonological processing, (b) decreased WMV 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.

Highlights

The internet is a necessity in many lives [1]
Whole-brain analyses of rGMV showed significant effects of interaction between sex and the internet addiction tendency (IAT) scores in the area spreading around the left anterior insula and left lentiform. This interaction was moderated by positive correlation in women. These results indicate that IAT is associated with (a) increased GMV in rSMG, which is involved in phonological processing, (b) decreased WMV in areas of frontal, sublobar, and temporal lobes, which are involved in response inhibition, and (c) reduced taskinduced deactivation of the default-mode network (DMN), indicative of altered attentional allocation
There was no significant difference in mean age between sexes, but independent sample t-tests revealed a significant difference in the IAT score

Summary

Introduction

The internet is a necessity in many lives [1]. More than half of the world’s population are internet users [2, 3]. Excessive internet use is associated with negative psychological consequences such as poor life satisfaction [4, 5], anxiety and aggression [6, 7], low self-esteem and depression [8, 9], and alcohol abuse [10, 11]. Physical health problems such as sleep problems [12,13,14] and social functioning impairments such as poor academic performance [15, 16] are other negative consequences of excessive internet use. Some studies have indicated that internet users show working memory (WM) deficits compare to individuals without such behaviors [19,20,21,22]

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