Abstract
BackgroundInternet addiction has become increasingly recognized as a mental disorder, though its neurobiological basis is unknown. This study used functional neuroimaging to investigate whole-brain functional connectivity in adolescents diagnosed with internet addiction. Based on neurobiological changes seen in other addiction related disorders, it was predicted that connectivity disruptions in adolescents with internet addiction would be most prominent in cortico-striatal circuitry.MethodsParticipants were 12 adolescents diagnosed with internet addiction and 11 healthy comparison subjects. Resting-state functional magnetic resonance images were acquired, and group differences in brain functional connectivity were analyzed using the network-based statistic. We also analyzed network topology, testing for between-group differences in key graph-based network measures.ResultsAdolescents with internet addiction showed reduced functional connectivity spanning a distributed network. The majority of impaired connections involved cortico-subcortical circuits (∼24% with prefrontal and ∼27% with parietal cortex). Bilateral putamen was the most extensively involved subcortical brain region. No between-group difference was observed in network topological measures, including the clustering coefficient, characteristic path length, or the small-worldness ratio.ConclusionsInternet addiction is associated with a widespread and significant decrease of functional connectivity in cortico-striatal circuits, in the absence of global changes in brain functional network topology.
Highlights
Internet addiction has been increasingly recognized both in public and the scientific community worldwide [1], though it is a relatively new condition and its psychopathological characteristics and neurobiological mechanisms remain poorly understood
No significant difference was found in age and intelligence quotient (IQ) between the two groups, and Young Internet Addiction Scale (YIAS) score was significantly higher in internet addiction group (Table 1)
Group Differences in Functional Connectivity The network-based statistic (NBS) identified a single network showing significantly (p,0.05, family-wise error (FWE)-corrected) decreased connectivity in adolescents with internet addiction compared to controls
Summary
Internet addiction has been increasingly recognized both in public and the scientific community worldwide [1], though it is a relatively new condition and its psychopathological characteristics and neurobiological mechanisms remain poorly understood. Using positron emission tomography (PET), Kim et al (2011) found decreased dopamine D2 receptor availability in bilateral caudate and right putamen [6], and Hou et al (2012) using single photon emission computed tomography (SPECT) found decreased striatal dopamine transporter expression level in adults with internet addiction [7]. These findings accord with current theoretical models of addiction disorders, comprising substance addiction and behavioral addiction (e.g., pathological gambling), which emphasize pathology of fronto-striatal circuitry [8], as well as the insula [9,10]. Based on neurobiological changes seen in other addiction related disorders, it was predicted that connectivity disruptions in adolescents with internet addiction would be most prominent in cortico-striatal circuitry
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