A review of the genetic basis of problematic Internet use

A review of the genetic basis of problematic Internet use. Anna Maria Werling, Edna Grünblatt. Current Opinion in Behavioral Sciences, Volume 46, August 2022, 101149. https://doi.org/10.1016/j.cobeha.2022.101149

Highlights

• PUI is an increasing problem in mental health around the globe.

• PUI shares some clinical similarities with other substance-related disorders.

• Candidate genes of the serotonergic and dopaminergic pathways have been found in PUI.

• Promising multifaceted approaches, include genotyping/phenotyping, and polygenetics.

• Transcriptomics and epigenomics may support research, expanding the knowledge of PUI.

Abstract: Problematic Internet use (PUI) has become of increasing interest in mental health. Despite the rising number of PUI in all ages, the exact underpinning etiology is still missing. There is increasing evidence that, in particular, genetic, environmental, and personality factors are involved in the development and maintenance of PUI. However, the neurobiological mechanism of PUI has not been yet extensively investigated, and still reports conflicting results. Previous studies have focused on candidate genes, mainly of the serotonergic, dopaminergic, or acetylcholinergic pathways known partly as risk factors in other substance-use disorders. This review focuses on preexisting literature on the genetic basis of PUI, and implications for future research approaches to fill the gap of its etiology. Understanding the exact etiology and potential genetic mechanism is the basis for a better understanding of PUI and future therapy implications.

Keywords: Problematic Internet useInternet-use disorderInternet addictiongaming disordergambling disordergenegeneticsenvironmentgenome-wide association studySNPstranscriptomicepigenomicpolygenic risk factorbehavioural traitsepigenetic

Genetic evidence for problematic Internet use

PUI is regarded as a multidimensional syndrome with overlapping symptoms for substance-related and addictive disorders [1] and impulse-control disorders 11, 124, 130. The syndrome comprises characteristic symptoms, such as impaired control about the use of the Internet, mental engagement with the Internet, symptoms resulted by reduced use such as craving and withdrawal, increasing the amount of use, failed attempts to reduce the Internet use, lying about the extent of the use, loss of interest in activities, difficulties with relationships, and negative psychosocial consequences (e.g. 11, 42, 133, 158, 157). Recently, two new diagnoses of behavioral addictions were added to Chapter 6 of ICD-11 [147]: GD and gambling disorder. Both diagnoses are characterized by a persistent or recurrent pattern of gaming behavior online or offline. Additionally, all three criteria have to be fulfilled, impaired control over play, priority of games over other interests and activities of life, and continuation of gaming, despite negative consequences and impairments in various life areas. Furthermore, the pattern of gaming has to be seen for at least for 12 months, or less when the symptoms are severe. These criteria seem to have been used to date as a blueprint for other PUI behaviors, and in genetic studies. Owing to its above-mentioned characteristic symptoms for alcohol or drug addiction, experts suspect a vulnerability to PUI/IA to be associated with a genetic predisposition [130]. However, in contrast to other forms of addictive behavior (such as gambling and psychoactive substance abuse), only little research has investigated genetic risk factors in PUI. However, growing evidence reveals that behavioral addictions such as IA or compulsive Internet use resemble other substance-related addictions in different views [41] and they probably share similar neurobiological underpinnings. Twin studies to date have demonstrated a moderate-to-high heritability of substance use and addiction [139]. Surprisingly, with regard to the increasing research of PUI, studies exploring the genetic background of PUI are rather limited. Up to date, only few studies have investigated the heritability in PUI 82, 84 and resulted in 40% up to nearly 70% 47, 87, 141. Based on twin studies, some individuals are more susceptible to PUI than others due to their genetic vulnerabilities. Various types of (behavioral) addictions such as substance abuse and gambling have already shown significant gene-loci association, identifying successfully genetic markers 118, 143, 49•, 61. To investigate the interplay between genetic and environmental influences, some studies also focused on specific facets as potential mediating sources such as self-directedness or self-regulation [47]. Here, the heritability varies from being negligible up to explaining 44% of the variation [47]. Other samples investigated the sole genetic role and revealed a highly genetic role up to 68% in a Turkish sample of young twin pairs [31]. Other studies also demonstrated a genetic influence with 41–48% 141, 87, or 58% in girls and 66% for boys 82, 84. Other studies investigating mobile-phone use showed moderate heritabilities for various aspects of its use (such as talk and text frequency) and varied from 34% to 60% [94] or IGD from 48% to 66% [64]. Other studies show that the heritability for compulsive Internet disorder for boys is the same with girls [141]. Interestingly, comparing heritability between adults and adolescents, heritability estimates for adults were lower, and for some assessment scales, genetic influence was even negligible compared with adolescents [47]. This shows that the genetic contribution may change over the life span.