Epigenetics of generalized internet use disorder including data on overuse of social media: a closer look at the SLC6A4, NR3C1 and OXT genes

BACKGROUND: Only few studies so far have investigated the molecular underpinnings of Internet Use Disorders (IUD), which can shed light on the neurochemical basis of excessive online behaviors. There are even less epigenetic studies in this research field, and longitudinal evidence is even more scarce. METHODS: The present study investigated in n = 83 depressed patients and n = 83 healthy controls potential links between DNA-methylation of three candidate genes (serotonin transporter gene SLC6A4, glucocorticoid receptor gene NR3C1 and gene coding for oxytocin OXT) known to play a role in affective disorders and self-reported excessive Internet and problematic social media use over a two-week period. RESULTS: In depressed patients, we found a significant positive association between problematic social media use, IUD tendencies in general, craving and methylation of a CpG site in NR3C1. In healthy controls, we found a significant positive association between social support and methylation of a CpG site in OXT. Further we found that higher social media addiction tendencies were associated with decreasing differences in methylation of OXT over a two-week period in both the group of depressed patients and healthy controls. However, this effect was small and the confidence interval contained zero. CONCLUSIONS: Our findings might provide first preliminary indications that NR3C1 and OXT might be involved in overuse of social media. However, small effect sizes and complex interaction effects require replication in larger samples with longitudinal measurements over a longer time period.