Extracting the values of resting-state functional connectivity that correlate with a tendency of internet addiction

The number ofpatients with internet addiction disorder (IAD), especially among school-age children, is on the rise. Development ofobjective examination technique to assist the current diagnostic methods using medical interview and inquiry tests is desirable for detection of IAD at its early stage. In this study, we extracted the values off unctional connectivity (FC) that correlated with a tendency ofIAD, using resting-state functional magnetic resonance imaging (rs-fMRI) data. We recruited 40 males[mean age (SD): 21.9 (0.9) years] with no neurological disorders, conducted rs-fMRI recordings for 7 min 30 s, and administered five questionnaires including internet addiction test (IAT), to assess their mental states. The IAT scores ofall participants were in the range ofhealthy to a tendency ofIAD. The FC values were calculated using the cross-correlation oftimeseries signals in a low frequency band (0.017 to 0.09 Hz) between all possible connections ofbrain region pairs defined by Automated Anatomical Labeling (AAL). For each region pair, we calculated Pearsonʼs correlation coefficients “γ” between the FC values and the scores ofIAT as well as other inventories for psychological states, in all subjects. The “ γ” were subjects-cross-validated, and the FC ofthe survived region pairs were statistically assessed by correction ofmultiple comparison. Finally, we obtained some region pairs in which FC specifically correlated with the IAT scores, but not with other psychological scores. These pairs had mostly negative “γ” over long-distance connections across right and left brain hemispheres. The results suggested that the functional connectivity between specific brain regions was significantly degraded already at the stage prior to the onset of IAD. We expect that our connectivity method can be an objective tool for detecting a tendency of IAD to assist the present diagnostic methods.