Dopamine genes and reward dependence in adolescents with excessive internet video game play

Association between the Taq1A polymorphism and problematic media use in preadolescent children

Objective

Problematic media use (PMU) is addiction-like media use. No study has examined if genetic factors for addiction relate to PMU during childhood. This study tested the association between genetic risk factors for addiction and PMU among 9-to-12-year-olds.

Method

Data were from a cohort of 9-to-12-year-olds recruited from Northern New England, 2018-2022, for a study examining obesity risk among children. Two polymorphisms related to dopaminergic (ANNK1 rs1800497 [the Taq1A polymorphism] and COMT rs4680) and one related to nicotinic (CHRNA4 rs1044396) pathways that were previously associated with internet addiction or internet video game addiction in adolescents and young adults were genotyped. Parent-reported PMU for children was measured with a validated nine-item scale (range for final scores: 1 to 5); higher scores indicate more severe PMU.

Results

Among children (n = 180; 43.9% female; 90.0% white, non-Hispanic; 82.2% of parents were college graduates), the median PMU score was 2.22 (IQR: 1.78, 2.78). In a linear regression model adjusted for child age, sex, European ancestry, and parent education, there was an additive association between the number of Taq1A1 alleles and PMU among children. Specifically, geometric mean PMU scores were 8.6% greater for each additional copy of the Taq1A1 allele (p = 0.030; R 2 = 5.2%). No other polymorphisms were statistically associated with PMU at the p < 0.05 level.

Conclusion

These preliminary findings suggest that a genetic predisposition to reduced dopamine sensitivity as indicated by the Taq1A polymorphism may relate to PMU in early adolescence. Findings need confirmation in larger samples.

The mediating effects of mobile phone use on ADHD and educational outcomes: a two-step Mendelian randomisation study

Objective

This study investigates the potential mediating role of mobile phone screen time in the causal relationships between Attention-deficit/hyperactivity disorder (ADHD) and educational attainment. Our analysis explores both the effect of ADHD on educational outcomes and the reverse, i.e., the influence of educational attainment on ADHD risk.

Method

A two-sample Mendelian randomisation (MR) analysis was conducted using genetic instruments from genome-wide association studies (GWAS) of European populations. We employed a two-step MR approach to assess the causal effects between ADHD, mobile phone screen time (both frequency and duration), and educational outcomes, including years of full-time education and college completion. Data from public genome-wide association studies encompassing European populations with sample sizes ranging from 55,374 to 470,941 were utilised.

Results

We found significant causal associations between childhood ADHD and educational attainment, partially mediated by mobile phone screen time. Childhood ADHD was negatively linked to years of full-time education (IVW: OR = 0.93, 95% CI = 0.90-0.97, p = 0.000) and college completion (IVW: OR = 0.97, 95% CI = 0.95-0.98, p = 0.000). Mobile phone use frequency mediated 19.3% of the effect on full-time education (β = -0.158) and 11.9% on college completion (β = -0.084). The duration of phone use mediated 64.8% of the effect on college completion (β = -0.054). When ADHD was the outcome, phone use duration mediated -22.45% of full-time education effects (β = 0.426) and -19.62% of college completion (β = 0.433).

Conclusion

Different MR models reveal the complex mediation role of mobile phone use frequency and duration between ADHD and educational attainment, varying by educational outcome type. Frequency mediates the link between childhood ADHD and full-time education/college completion, while duration significantly impacts ADHD when higher education is the outcome. The notable mediation effect of duration on ADHD underscores the need for further study into screen time's influence on ADHD and academic achievement across stages.

Biomarkers of Internet Gaming Disorder-A Narrative Review

Since game mechanics and their visual aspects have become more and more addictive, there is concern about the growing prevalence of Internet gaming disorder (IGD). In the current narrative review, we searched PubMed and Google Scholar databases for the keywords "igd biomarker gaming" and terms related to biomarker modalities. The biomarkers we found are grouped into several categories based on a measurement method and are discussed in the light of theoretical addiction models (tripartite neurocognitive model, I-PACE). Both theories point to gaming-related problems with salience and inhibition. The first dysfunction makes an individual more susceptible to game stimuli (raised reward seeking), and the second negatively impacts resistance to these stimuli (decreased cognitive control). The IGD patients' hypersensitivity to reward manifests mostly in ventral striatum (VS) measurements. However, there is also empirical support for a ventral-to-dorsal striatal shift and transition from goal-directed to habitual behaviors. The deficits in executive control are demonstrated in parameters related to the prefrontal cortex (PFC), especially the dorsolateral prefrontal cortex (DLPFC). In general, the connection of PFC with reward under cortex nuclei seems to be dysregulated. Other biomarkers include reduced P3 amplitudes, high-frequency heart rate variability (HRV), and the number of eye blinks and saccadic eye movements during the non-resting state. A few studies propose a diagnostic (multimodal) model of IGD. The current review also comments on inconsistencies in findings in the nucleus accumbens (NAcc), anterior cingulate cortex (ACC), and precuneus and makes suggestions for future IGD studies.

Adolescent Internet Gaming Disorder and sensitivity to money and social rewards

Internet Gaming Disorder (IGD) is a behavioural addiction characterised by excessive exposure to addictive stimuli, resulting in reduced sensitivity of the brain's reward system towards everyday rewards. Online game addiction is prevalent among adolescents; however, it remains unclear if there are variations in reward processing patterns among adolescents with online game addiction. We compared differences in sensitivity to two types of rewards between patients with IGD and patients with Recreational Game Use (RGU) using the Monetary Incentive Delay (MID) paradigm and the Social Incentive Delay (SID) paradigm (Experiment 1). Additionally, we used a mixed reward latency paradigm, including both monetary and social rewards, to further explore the processing characteristics of IGD towards a mixture of these two rewards (Experiment 2). There were significant differences in the sensitivity of IGD and RGU to monetary and social rewards. Adolescents with IGD had significantly shorter reaction times to the four mixed rewards compared to RGU, while no significant differences were found between groups regarding sensitivity to specific individual rewards. However, the simultaneous presence of two rewards affected the processing speed and preference of adolescents with IGD. The reward processing characteristics observed in adolescents with online gaming disorder show specificity concerning the type and presentation of rewards, providing a theoretical foundation for diagnosing and treating adolescent online gaming addiction.

Cure for tantrums? Longitudinal associations between parental digital emotion regulation and children's self-regulatory skills

Introduction

Parents often use digital devices to regulate their children's negative emotions, e.g., to stop tantrums. However, this could hinder child development of self-regulatory skills. The objective of the study was to observe bidirectional longitudinal associations between parents' reliance on digital devices to regulate their child's emotions and self-regulatory tendencies (anger/frustration management, effortful control, impulsivity).

Methods

Parents (N = 265) filled out the Child Behavior Questionnaire-Short Form and the Media Assessment Questionnaire twice: the initial assessment (T1) took place in 2020 (mean child age = 3.5 years old), and follow-up (T2) occurred a year later in 2021 (mean child age = 4.5 years old).

Results

Higher occurrence of parental digital emotion regulation (PDER) in T1 predicts higher anger and lower effortful control in T2, but not impulsivity. Higher anger in T1, but not impulsivity and effortful control, predicts higher PDER in T2.

Discussion

Our results suggest that parents of children with greater temperament-based anger use digital devices to regulate the child's emotions (e.g., anger). However, this strategy hinders development of self-regulatory skills, leading to poorer effortful control and anger management in the child.

Genetic Aspects of Problematic and Risky Internet Use in Young Men-Analysis of ANKK1, DRD2 and NTRK3 Gene Polymorphism

BACKGROUND

Internet addiction disorder (IAD) is characterized by an excess of uncontrolled preoccupations, urges, or behaviors related to computer use and Internet access that culminate in negative outcomes or individual distress. PIU includes excessive online activities (such as video gaming, social media use, streaming, pornography viewing, and shopping). The aim of this study was to analyze the association of gene polymorphisms that may influence the severity of risky behaviors in young men with the frequency of Internet use. We speculate that there are individual differences in the mechanisms of Internet addiction and that gene-hormone associations may represent useful biomarkers for subgroups of individuals.

MATERIALS AND METHODS

The study was conducted in a sample of 407 adult males. Subjects were asked to complete the Problematic Internet Use Test (PIUT). Serum was analyzed to determine concentrations of luteinizing hormone (LH), follicle stimulating hormone (FSH), testosterone (TT), sex hormone binding protein (SHBG), dehydroepiandrosterone sulfate (DHEA-S), estradiol (E2), prolactin (PRL), insulin (I), serotonin (5-HT), and dopamine (DA), as well as DRD2, ANKK1, and NTRK3 gene polymorphisms.

RESULTS

In the analysis of the ANKK1 gene, there was a specific association between ANKK1 polymorphisms and PRL and 5-HT blood concentrations. There was also an association between the ANKK1 polymorphisms and LH and DA concentrations. When analyzing the DRD2 gene polymorphism, we found that in the group with a moderate level of Internet dependence, there was an association between both the G/GG and GG/GG polymorphisms and FSH concentration.

CONCLUSIONS

Our study found that there may be an association between the NTRK3 gene polymorphism and PIU. The polymorphisms of ANKK1 and DRD2 genes may be factors that influence the concentrations of hormones (PRL, 5-HT, DA) that are associated with the results obtained in PIU.

Neurobiological risk factors for problematic social media use as a specific form of Internet addiction: A narrative review

Problematic social media use (PSMU) is a behavioral addiction, a specific form of problematic Internet use associated with the uncontrolled use of social networks. It is typical mostly for modern adolescents and young adults, which are the first generations fully grown up in the era of total digitalization of society. The modern biopsychosocial model of the formation of behavioral addictions, postulating the impact of a large number of biological, psychological, and social factors on addictive behavior formation, may be quite applicable to PSMU. In this narrative review, we discussed neurobiological risk factors for Internet addiction with a focus on current evidence on the association between PSMU and structural/ functional characteristics of the brain and autonomic nervous system, neurochemical correlations, and genetic features. A review of the literature shows that the vast majority of the mentioned neurobiological studies were focused on computer games addiction and generalized Internet addiction (without taking into account the consumed content). Even though a certain number of neuroimaging studies have been conducted for PSMU, there is practically no research on neuropeptide and genetic associations for PSMU to date. This fact points to the extremely high relevance of such studies.

A Bibliometric Analysis of Research into Internet Gaming Disorders in Korea

After the concept of "Internet addiction" was first proposed in 2004, "Internet gaming disorder" (IGD) was included in the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) as a disorder requiring further research. IGD is prevalent in South Korea, and many studies have been conducted on the disorder. Previous studies have helped in understanding various aspects of IGD, but a comprehensive understanding of the research trends is required to identify research gaps. Therefore, we conducted a bibliometric review of all published IGD studies in South Korea. For the identification of articles, the Web of Science database was used. Data analysis was performed using Biblioshiny. A total of 330 publications were included in the analysis. The average number of citations per document was 17.12. These publications were written by a total of 658 authors, and the number of coauthors per document was 5.07. The years with the most publications were 2018 (n = 57), 2017 (n = 45), and 2019 (n = 40). The top three journals containing publications were the Journal of Behavioral Addictions (n = 46), Frontiers in Psychiatry (n = 19), and Psychiatry Investigation (n = 14). In a keyword analysis (apart from "IGD", "internet addiction", and "addiction"), the keywords "adolescent" (n = 31), "self-control" (n = 11), and "impulsivity" (n = 11) were included. T. This bibliometric analysis explores and summarizes the publications on IGD in South Korea. The results are expected to provide researchers with insights for further studies into IGD.

Cognitive, Emotional, Behavioral and Physiological Evaluation of the Relationship Between Brain and Gut Microbiota

The aim of this study is to examine the effect of gut microbiota on brain functions, mood and psychiatric disorders such as depression, anxiety and behavioral addictions, neurotransmitter levels, cognitive processes such as self-control, decision making and delayed gratification. In this context, the relevant literature was reviewed and the findings were evaluated. The relationships of the bidirectional communication between the brain-gut axis with cognitive, emotional, behavioral and physiological processes were explained with a diagram. As a result, although more research is needed on this subject, it has been observed that the brain-gut axis is bidirectionally established through neural, stress, endocrine and immune systems. In this bidirectional communication process, there are interactions in the context of cognitive, emotional, behavioral and other physiological factors. These factors both individually enter into bidirectional relationships with the brain and gut microbiota and are affected by the bidirectional communication between the brain and gut.

Molecular genetic associations between a prominent serotonin transporter gene polymorphism (5-HTTLPR/rs25531) and individual differences in tendencies toward autistic traits and generalized internet use disorder in China and Germany

BACKGROUND

The serotonin transporter polymorphism 5-HTTLPR is an extensively investigated genetic marker of autistic traits or autism spectrum disorder, and recently has also been studied in the realm of internet use disorder (IUD), yet the findings remain controversial. Therefore, the present study aimed to explore associations between 5-HTTLPR (also including SNP rs25531) and autistic traits/IUD tendencies and to assess whether the relationship between autistic traits and IUD tendencies varies by this genetic marker in participants from China and Germany.

METHODS

A total of 540 Chinese and 563 German subjects were genotyped for 5-HTTLPR/rs25531 and completed the Adult Autism Spectrum Quotient questionnaire and the short version of the Internet Addiction Test.

RESULTS

Carriers of the low expressing S'S' genotype (S, L_G ) showed significantly higher levels of autistic traits than the high expressing allele (e.g. L_A ) carriers in both samples. There was no significant effect of 5-HTTLPR/rs25531 on IUD either in the Chinese or Germany samples, whereas positive correlations between autistic traits and IUD varied by 5-HTTLPR/rs25531 genotypes and also differed between Chinese and German samples. In the Chinese sample, positive correlations were mainly driven by S'S' and S'L' carriers, while they were mainly determined by S'L' and L'L' carriers in the German sample. Further analyses revealed that the associations between autistic traits and IUD tended in parts to be more strongly pronounced in the complete German sample compared to the complete Chinese sample, and also varied depending on 5-HTTLPR/rs25531 genotypes (in S'S' carriers: China > Germany; in S'L' and L'L' carriers: China < Germany; both in terms of more positive associations).

CONCLUSIONS

Our findings suggest carriers of low expressing alleles (S, L_G ) are more likely to show higher autistic traits in both Chinese and German samples. Furthermore, the present work shows that both 5-HTTLPR/rs25531 and cultural differences might be of relevance to understand associations between autistic traits and IUD tendencies, but this needs to be further backed up.

Longer screen time utilization is associated with the polygenic risk for Attention-deficit/hyperactivity disorder with mediation by brain white matter microstructure

BACKGROUND

Attention-deficit/hyperactivity disorder (ADHD) has been reported to be associated with longer screen time utilization (STU) at the behavioral level. However, whether there are shared neural links between ADHD symptoms and prolonged STU is not clear and has not been explored in a single large-scale dataset.

METHODS

Leveraging the genetics, neuroimaging and behavioral data of 11,000+ children aged 9-11 from the Adolescent Brain Cognitive Development cohort, this study investigates the associations between the polygenic risk and trait for ADHD, STU, and white matter microstructure through cross-sectionally and longitudinal analyses.

FINDINGS

Children with higher polygenic risk scores for ADHD tend to have longer STU and more severe ADHD symptoms. Fractional anisotropy (FA) values in several white matter tracts are negatively correlated with both the ADHD polygenic risk score and STU, including the inferior frontal-striatal tract, inferior frontal-occipital fasciculus, superior longitudinal fasciculus and corpus callosum. Most of these tracts are linked to visual-related functions. Longitudinal analyses indicate a directional effect of white matter microstructure on the ADHD scale, and a bi-directional effect between the ADHD scale and STU. Furthermore, reduction of FA in several white matter tracts mediates the association between the ADHD polygenic risk score and STU.

INTERPRETATION

These findings shed new light on the shared neural overlaps between ADHD symptoms and prolonged STU, and provide evidence that the polygenic risk for ADHD is related, via white matter microstructure and the ADHD trait, to STU.

FUNDING

This study was mainly supported by NSFC and National Key R&D Program of China.

Interaction Effects of DRD2 Genetic Polymorphism and Interpersonal Stress on Problematic Gaming in College Students

Problematic gaming has become a public concern, influenced both by genetic factors and stressful environments. Studies have reported the effects of dopamine-related genes and interpersonal stressors on problematic gaming, but gene and environment interaction (G × E) studies have not been conducted. In this study, we investigated the interaction effects of dopamine receptor D2 (DRD2) polymorphisms and interpersonal stress on problematic gaming and the mediating effect of avoidant coping to reveal the mechanism of the G × E process. We recruited 168 college students (mean age = 22; male 63.1%) and genotyped their DRD2 C957T (rs6277) and Taq1 (rs1800497) polymorphisms. The results of the mediated moderation analysis showed that, when experiencing interpersonal stressors, individuals with both the C957T T allele and the Taq1 A1 allele showed more elevated problematic gaming scores than non-carriers. Moreover, the interaction effect of the combined DRD2 polymorphisms and interpersonal stress was significantly mediated by avoidant coping. These findings suggest that the influence of interpersonal stress on problematic gaming can be changed as a function of DRD2 genotypes, which may be because of the avoidant coping styles of C957T T allele and Taq1 A1 allele carriers in response to stress.

A bidirectional association between internet addiction and depression: A large-sample longitudinal study among Chinese university students

BACKGROUND

Internet addiction (IA) is associated with adverse consequences, especially for younger people. Evidence indicates that IA is associated with depression, but no studies have yet investigated potential common vulnerability between them.

METHODS

IA (measured by the Young's 20-item Internet Addiction Test Scale) and depressive symptoms (measured by the Patient Health Questionnaire-9 Scale) among 12 043 undergraduates were surveyed at baseline and at a respective 12 month follow-up for each participant. Application of a cross-lagged panel model approach (CLPM) revealed an association between IA and depression after adjusting for demographic variables.

RESULTS

Rates of baseline IA and depression were 5.47% (95% CI: 5.07%, 5.88%) and 3.85% (95% CI: 3.51%, 4.20%), respectively; increasing to 9.47% (95% CI: 8.94%, 9.99%) and 5.58% (95% CI: 5.17%,5.99%), respectively, at follow-up. Rates of new-incidences of IA and depression over 12 months were 7.43% (95% CI: 6.95%, 7.91%) and 4.47% (95% CI: 4.09%, 4.84%), respectively. Models in the present analysis revealed that baseline depression had a significant net-predictive effect on follow-up IA, and baseline IA had a significant net-predictive effect on follow-up depression.

LIMITATIONS

The follow-up survey response rate was moderate (54.69%) in this analysis of university students. Moreover, the IAT-20 scale did not allow differentiate between specific forms of Internet activity.

CONCLUSIONS

Common vulnerability and bidirectional cross-causal effects may both contribute to the association between IA and depression, with common vulnerability likely playing a more significant role than cross-causal effects.

A Literature Review on the Efficacy and Related Neural Effects of Pharmacological and Psychosocial Treatments in Individuals With Internet Gaming Disorder

OBJECTIVE

Internet gaming disorder (IGD) has attracted considerable attention as a serious mental and public health issue worldwide. Currently, there are no established treatment guidelines for IGD. Herein, we review the latest findings on the efficacy and related neural effects of pharmacological and psychosocial treatments for individuals with IGD.

METHODS

A database search of relevant studies published between 2007 and 2020 was conducted using PubMed and Google Scholar. Twenty-seven studies were reviewed for current evidence related to the efficacy and neural effects of pharmacological and psychosocial IGD treatments.

RESULTS

Pharmacological studies suggest that bupropion may play a significant role in IGD. Additionally, nuclear imaging studies on IGD have demonstrated functional impairment of the dopamine system, providing a neurobiological basis for the efficacy of dopamineenhancing drugs. Among the various psychosocial interventions, current evidence suggests that cognitive behavioral therapy may be an effective intervention for IGD. Cognitive behavioral therapy and bupropion were found to influence resting-state functional connectivity within the cortico-subcortical circuit and default mode network, suggesting a possible neural mechanism. Innovative approaches, including virtual reality treatment, residential camps, voluntary abstinence, and transcranial direct current stimulation, have shown promising results. However, methodological limitations, such as the absence of proper controls, small sample sizes, short duration, inconsistency of inclusion criteria across studies, and self-report measures of outcome, hamper conclusions regarding the efficacy of treatments.

CONCLUSION

Ongoing basic research and clinical trials overcoming these limitations could add to the existing knowledge on IGD and contribute to the development of evidence-based treatments.

The Relationship between Internet Addiction, Internet Gaming and Anxiety among Medical Students in a Malaysian Public University during COVID-19 Pandemic

The internet has become an important medium for learning and communication during the COVID-19 pandemic, particularly for university students. Nevertheless, an increase in internet usage could predispose people to internet addiction (IA) and internet gaming (IG). Equally, there is concern that anxiety levels have increased during the pandemic. The aim of this study is to determine the prevalence of IA and IG, and their associations with anxiety among medical students during the pandemic. Data were collected during the second wave of the “Conditional Movement Control Order” (CMCO) in Malaysia between 12 November and 10 December 2020. A total of 237 students participated through proportionate stratified random sampling in this cross-sectional study. They completed a set of online questionnaires which consisted of a sociodemographic profile, the Malay version of the internet addiction test (MVIAT), the Malay version of the internet gaming disorder-short form (IGDS9-SF) and the Malay version of the depression, anxiety and stress scale (DASS-21). The prevalence of IA and internet gaming disorder (IGD) were 83.5% and 2.5%, respectively. A multiple logistic regression showed that those in pre-clinical years had a greater risk of anxiety than those in clinical years [(AOR) = 2.49, p-value 0.01, 95% CI = 1.22–5.07]. In contrast, those who scored high on IA were protected against anxiety [AOR = 0.100, p-value 0.03, 95% CI = 0.01–0.76)]. In conclusion, IA was highly prevalent during the COVID-19 pandemic and its high usage might serve as a protective factor against anxiety among the medical students in this study sample.

Editorial Perspective: Missing the forest for the trees - how the focus on digital addiction and gaming diverted attention away from wider online risks

Despite the many ways in which Internet-related technologies can affect psychology, research into the Internet's mental health consequences has disproportionately focussed on the narrow topics of online addiction and the closely related Internet gaming disorder. Over two decades into the online revolution, the Internet is being blamed for dramatic transformations, including a rise in extremism, social polarization and weakened democracies. In trying to understand how these shifts could have happened, or how they might be contained, society looks to mental health experts - after all, it is the interaction between technology and human psychology that is encouraging certain behaviours online and discouraging others. The field, however, has precious little to offer by way of explanations. To no small degree, this is due to the tendency to approach online psychological problems primarily through the addiction framework. The result has been to blind us to other important traits and phenomena that are playing out online and on social media, including impulsivity, aggression, inattention, narcissism and the psychological meaning of living in a postprivacy world. The article covers historical aspects of how the addiction model came to dominate the field; some insufficiently heeded early warning signals about other online ills and the big price society is paying today for this approach. We end with a call for a significant broadening of the focus of research when it comes to online psychopathology.

Understanding internet gaming addiction in clinical practice

Internet gaming disorder (IGD) is a condition in which the individual is preoccupied with playing online video games and unable to regulate this behaviour, resulting in adverse physical and psychological consequences. Although there is some debate about whether IGD is an addiction or a coping mechanism, global evidence indicates that the condition is increasing in prevalence with recent advances in technology and its higher penetration into routine life. Male children and adolescents located in East Asian countries are at higher risk than others in the world. Attention-deficit hyperactivity disorder, depression and anxiety are typically associated with IGD. Given the continuing ambiguity regarding the diagnosis and screening tools for the disorder, it has become all the more relevant for mental health practitioners and academics to attend to this condition and develop evidence-based treatments. This review summarises both the existing evidence for the disorder and the debates that surround it.

Video Game Addictive Symptom Level, Use Intensity, and Hedonic Experience: An Empirical Analysis of a Novel Survey Instrument (Preprint)

Background

The effects of behavioral addiction to video games has received increasing attention in the literature, given increased use intensity among subgroups of video game players.

Objective

This study seeks to empirically determine the relationship between intensity of video gaming and hedonic experience of the player.

Methods

We conducted a survey of 835 individuals who regularly play video games to determine the relationship between intensity of use and hedonic experience. We divided the sample into quartiles by self-reported video game addictive symptom level (from the Internet Gaming Disorder Scale) and conducted polynomial regressions separately for each quartile.

Results

We found that the higher video game addictive symptom level groups experienced a U-shaped (curvilinear) relationship between hedonic experience and intensity of play, whereas groups with lower video game addictive symptom levels exhibited no such relationship. The coefficients for the highest addictive symptom level group (quartile 4) for marginal effects for hours played per week and hours played per week squared were significantly negative (P=.005) and significantly positive (P=.004), respectively.

Conclusions

Our results are consistent with sensitization and tolerance theories, which suggest that high-symptom groups experience frustration and disappointment until they achieve excessive dopamine release, at which point their hedonic experience is expected to improve with additional play. Conversely, low-symptom groups experience no such fall-and-rise pattern. This result is consistent with the outcome that members of the latter group play the game for the direct experience, such that their hedonic experience is more directly related to events occurring in the game than to the increasingly elusive pursuit of excessive dopamine release. We also find that high-symptom groups spend substantially more time and money to support video game use and are much more likely to engage in video game use at the expense of other important activities, such as working, sleeping, and eating.

Biochemical Correlates of Video Game Use: From Physiology to Pathology. A Narrative Review

In the last few decades, video game playing progressively became a widespread activity for many people, in childhood as well in adulthood. An increasing amount of literature has focused on pathological and non-pathological correlates of video game playing, with specific attention towards Internet Gaming Disorder (IGD). While many neurobiological studies in this field were based on neuroimaging, highlighting structural and functional brain changes among video game users, only a limited number of studies investigated the presence of biochemical correlates of video gaming. The present work aims to summarize and review the available literature about biochemical changes linked to video game use in IGD patients as well as non-pathological users, and the differences in between. Results may shed light on risks and benefits of video games, providing directions for further research on IGD treatment and, on other hand, on the potential role of video games in therapeutic or preventive protocols for specific conditions.

Non-Substance Addiction in Childhood and Adolescence

BACKGROUND

Around 5.8% of adolescents and 2.8% of young adults have an Internet-related disorder. These figures underline the widespread concerns in our society regarding the potential dangers and risks associated with Internet and digital media use.

METHODS

Selective literature search for records on Internet-related disorders in children and adolescents.

RESULTS

Internet-related disorders are now viewed as belonging to the behavioral addiction. Research has revealed similarities to substance-related disorders. There are often associations with other mental illnesses such as depression, anxiety, attention deficit/hyperactivity disorder, and personality disorders, as well as disturbed sleep patterns, increased risk taking, nicotine abuse, an unbalanced diet, and lack of exercise. Female adolescents are statistically significantly more often affected than male adolescents (7.1% versus 4.5%). The German STICA study, the first randomized controlled trial worldwide, demonstrated that cognitive behavioral therapy was effective compared with a waiting group (odds ratio 10.10, 95% confidence interval [3.69; 27.65]).

CONCLUSION

Internet-related disorders have not yet been conclusively conceptualized and operationalized. Further work is urgently required to refine the concepts of both the illness and and its treatment.

Predicting Stock Market Performance

Abstract. Gender and personality traits influence risk proneness in the context of financial decisions. However, most studies on this topic have relied on either self-report data or on artificial measures of financial risk-taking behavior. Our study aimed to identify relevant trading behaviors and personal characteristics related to trading success. N = 108 Caucasians took part in a three-week stock market simulation paradigm, in which they traded shares of eight fictional companies that differed in issue price, volatility, and outcome. Participants also completed questionnaires measuring personality, risk-taking behavior, and life stress. Our model showed that being male and scoring high on self-directedness led to more risky financial behavior, which in turn positively predicted success in the stock market simulation. The total model explained 39% of the variance in trading success, indicating a role for other factors in influencing trading behavior. Future studies should try to enrich our model to get a more accurate impression of the associations between individual characteristics and financially successful behavior in context of stock trading.

Validation and Adaptation of the Brief Self-Control Scale With Spanish Adolescents: Factorial Structure and Evidences of Reliability, Validity, and Factor Invariance Across Gender and Age

During adolescence, the difficulty to control impulses is especially notable. The Brief Self-Control Scale has been used in different countries for years to study associations between self-control and other variables. However, its factor structure is not completely clear, and it is necessary to have a scale with psychometric assurances that evaluates self-control in adolescents. The aim of this study was to examine the factorial structure of the Brief Self-Control Scale and to provide evidences of reliability, validity, and factor invariance across gender and age in a sample of Spanish adolescents. Participants were 693 adolescents from Southeastern Spain, aged 13 to 18 years. Data supported an excellent fit to a two-dimensional model and evidences of reliability, validity and factor invariance across gender and age were obtained. This study provides new data on the two-dimensionality of self-control. The need of this tool becomes increasingly relevant to the susceptibility of new emerging addictions, such as mobile phones or internet.

Genetics of OCD and Related Disorders; Searching for Shared Factors

Obsessive compulsive disorder (OCD) and several other obsessive-compulsive related disorders (OCRDs) including hoarding disorder, body dysmorphic disorder (BDD), skin picking disorder, trichotillomania and the newly arising public health conditions of online gaming and gambling disorders, under the umbrella of Problematic Usage of the Internet (PUI), not only share some common phenotypes, but there is evidence to suggest share some genetic risk factors. The simple fact that these disorders segregate within families points to this notion. However, the current data are still scarce. This chapter focuses on identifying the shared genetic factors. To address this question, a systematic review of the literature investigating genetic findings in OCD and OCRDs including PUI was conducted, with a focus on their genetic similarities. Greater knowledge of the specific genetic risks shared among OCRDs would be expected to open new avenues in the understanding of the biological mechanisms causing the development of these phenotypes, as well as provide opportunities to develop new animal and cellular models testing new therapy avenues.

Molecular genetics of neurotransmitters and neuropeptides involved in Internet use disorders including first insights on a potential role of hypothalamus' oxytocin hormone

This chapter covers the phenomenon of Internet use disorders (IUDs) and putative associations with different neurotransmitter and neuropeptide systems. Genes coding for such messengers can be seen as an important starting point in the complicated quest to understand human behavior including new phenomena such as IUDs. Therefore, a special focus of this chapter will lie on individual differences in molecular genetic underpinnings of neurotransmitter and neuropeptide systems and their associations with individual differences in tendencies towards IUDs. By shedding light on these associations, putative predisposing molecular genetic factors for the emergence and maintenance of IUDs can be carved out. Therefore, first an introduction to IUDs and a model that can guide research on putative associations of IUDs with different specific neurotransmitters and neuropeptides will be presented. Subsequently, twin studies on the heritability of IUDs are reviewed. Finally, studies on differences in molecular genetic predispositions and their associations with differences in IUDs will be presented and discussed, including targets related to the dopaminergic and serotonergic system as well as the hypothalamic neuropeptide oxytocin. The chapter closes with a conclusion about what is already known and what needs to be investigated in future studies to gain further insights into putative associations between molecular genetic markers and IUDs.

Exercise-Based Interventions for Internet Addiction: Neurobiological and Neuropsychological Evidence

With the increase in the number of internet users, the problems associated with excessive internet use have become increasingly obvious. Internet addiction can alter neurobiology, and its symptoms can be alleviated through exercise, but whether exercise exerts these effects through neurobiological pathways is unclear. Here, we reviewed the neurobiological mechanisms of exercise-based interventions against internet addiction by searching PubMed and Google Scholar for relevant research using such keywords as “exercise”, “internet addiction”, “hypothalamic-pituitary-adrenal axis”, “neurotrophin”, and “dopamine”. This review summarizes advances in our understanding of the neurobiological processes through which exercise can reduce internet addiction, and our analysis strengthens the idea that exercise-based interventions can be effective in this regard. The available evidence suggests that exercise can increase the levels of neurotrophic factors, cortisol, and neurotransmitters; improve the morphology of specific parts of the central nervous system, such as by stimulating hippocampal neurogenesis; protect the autonomic nervous system; and control the reward urge. In other words, exercise appears to mitigate internet addiction by regulating the neurobiology of the central and autonomic nervous systems. In this way, exercise-based interventions can be recommended for reducing internet addiction.

Problematic internet use: an exploration of associations between cognition and COMT rs4818, rs4680 haplotypes

OBJECTIVE

Problematic internet users suffer from impairment in a variety of cognitive domains. Research suggests that COMT haplotypes exert differential effects on cognition. We sought to investigate differences in the genetic profiles of problematic internet users and whether those could shed light on potential cognitive differences.

METHODS

We recruited 206 non-treatment seeking participants with heightened impulsive traits and obtained cross-sectional demographic, clinical, and cognitive data as well as the genetic haplotypes of COMT rs4680 and rs4818. We identified 24 participants who presented with problematic internet use (PIU) and compared PIU and non-PIU participants using one-way analysis of variance (ANOVA) and chi square as appropriate.

RESULTS

PIU was associated with worse performance on decision making, rapid visual processing, and spatial working memory tasks. Genetic variants were associated with altered cognitive performance, but rates of PIU did not statistically differ for particular haplotypes of COMT.

CONCLUSION

This study indicates that PIU is characterized by deficits in decision making and working memory domains; it also provides evidence for elevated impulsive responses and impaired target detection on a sustained attention task, which is a novel area worth exploring further in future work. The effects observed in the genetic influences on cognition of PIU subjects imply that the genetic heritable components of PIU may not lie within the genetic loci influencing COMT function and cognitive performance; or that the genetic component in PIU involves many genetic polymorphisms each conferring only a small effect.

Parenting paused: Pathological video game use and parenting outcomes

For most people, playing video games is a normal recreational activity, with little disruption to gamers' emotional, social, or physical health and well-being. However, for a small percentage of gamers, video gaming can become pathological (Fam, 2018). Substantial research has examined pathological gaming in teens and young adults (Cheng, Cheung, & Wang, 2018; Choo, Gentile, Sim, Khoo, & Liau, 2010), yet pathological gaming in adults (c.f. Holgren, 2017), especially in the context of parenthood, has been relatively ignored. The current study sought to address this limitation by studying associations between pathological gaming characteristics and parenting outcomes in a sample of men and women who have had a child in the last year. Fathers spent more time than mothers playing video games and displayed more pathological video gaming tendencies. Pathological gaming for mothers and fathers was related to increased depressive symptoms. Depressive symptoms mediated the relationship between pathological gaming and decreased feelings of parental efficacy, perceived parental competence, increased parenting stress, and increased perceived impact of parenting. Pathological video game playing was also directly related to decreased feelings of parental efficacy for mothers and fathers. Implications of the results and directions for future research are discussed.

Increase of orexin A in the peripheral blood of adolescents with Internet gaming disorder

BACKGROUND AND AIMS

Overindulgence in Internet gaming, which is related to rapid development of the online game industry, can cause a psychiatric disorder known as Internet gaming disorder (IGD). The number of adolescents with IGD is on the rise in countries with developed Internet technologies, such as South Korea. Therefore, it is important to develop biomarkers to detect patients at high risk of IGD. This study investigated expression levels of proteins in the blood of adolescents to provide insight into the development of biomarkers.

METHODS

We collected blood samples from 73 subjects [40 healthy adolescents (Internet gaming control, IGC) and 33 adolescents with IGD] between 13:00 and 15:00. We analyzed the expression levels of orexin A, oxytocin, cortisol, melatonin, BDNF, sICAM-1, RANTES, and NCAM using multiplex assay kits.

RESULTS

Orexin A was significantly (p = .016) elevated in the IGD group and the expression levels of melatonin tended to be higher (p = .055) in the IGD group. On the other hand, increased Internet gaming time in the IGD group was negatively correlated (p = .041) with expression of BDNF. On the contrary, sICAM-1 associated with inflammation exhibited the tendency of the positive correlation (p = .073) with Internet gaming time in the IGD group.

DISCUSSION AND CONCLUSIONS

We identified elevation of orexin A in the peripheral blood of adolescents with IGD and a negative correlation between Internet gaming time and BDNF in adolescents with IGD. Our results provide useful information to understand the pathophysiology of IGD in adolescents.

Differences in associations between problematic video-gaming, video-gaming duration, and weapon-related and physically violent behaviors in adolescents

Seemingly mixed findings have been reported on possible relationships between video-gaming and violent or aggressive behaviors. Given the prevalence of gaming in adolescents and potential harms associated with violent behaviors, relationships between problematic gaming, gaming engagement, and risk behaviors involving weapons and physical violence require further research. This study examined in a large sample of high-school students the relationships between problem-gaming severity, gaming duration, and violence-related measures including weapon-carrying, having been threatened by someone with a weapon, perceived insecurity, physical fights and serious fights leading to injuries. Potential moderation by sensation-seeking and impulsivity was also tested. Participants were 3,896 Connecticut high-school adolescents. Chi-square, logistic regression, and moderation models were conducted. Adolescents with at-risk/problem gaming, compared to low-risk and non-gaming adolescents, reported more weapon-carrying, having been threatened with weapons, feeling unsafe at school, and serious fighting leading to injury. Among those reporting gaming, weekly time spent gaming was associated with problem-gaming severity. Those with longer (versus shorter) gaming durations were more likely to report weapon-carrying and feeling unsafe at school. Sensation-seeking moderated associations between at-risk/problem gaming and weapon-carrying frequency. Associations between gaming quantity and problem-gaming severity and measures of weapon-carrying and physical violence in adolescents suggest that understanding further their mechanistic relationships may be important in promoting safer developmental trajectories for youth. Future longitudinal studies may provide important insight into the etiologies underlying these relationships and such information may help develop more effective prevention and intervention strategies.

Hypometabolism and altered metabolic connectivity in patients with internet gaming disorder and alcohol use disorder

Internet gaming disorder (IGD) has become the subject of growing concern as an addictive behavior and has been compared with substance/non-substance-related addiction. Although IGD show clinical impairments and social dysfunction, neurobiological alterations in IGD have not been clearly elucidated. We used ¹⁸F-fluorodeoxyglucose PET to investigate differences in glucose metabolism and metabolic connectivity in young men [thirty-six patients with IGD, twenty-six patients with alcohol use disorder (AUD) and thirty-nine healthy controls (HC)]. Compared with the HC, IGD showed hypometabolism in the anterior cingulate cortex (ACC), temporal, frontal, parietal and striatum and AUD exhibited hypometabolism in the occipital, temporal and parietal lobule. Furthermore, IGD showed negative correlations between the ACC and game duration and between the orbitofrontal cortex and impulsivity. Also, IGD had lower metabolic connectivity between temporal and limbic regions and between the motor area and occipital region. And AUD showed greater metabolic connectivity between the orbitofrontal and parietal regions, and between the somatosensory or parietal and temporal regions, but lower metabolic connectivity in the fronto-striatal or fronto-limbic regions. Our results provide evidences that hypometabolism and altered metabolic connectivity in IGD might be related to the abnormal sensory function by longtime gaming and dysfunction of impulsive/motivational states.

Research progress and debates on gaming disorder

Gaming disorder has become a significant issue in mental healthcare. While gaming is an important form of entertainment, excessive gaming may cause serious consequences for players. At present, there are still controversies in the academic community concerning the public health problems related to gaming disorder. This article attempts to expound the definition, epidemiology, aetiology, diagnosis, treatment and prevention of gaming disorder, in order to contribute to future conceptualization of gaming disorder.

Diagnostic and Classification Considerations Regarding Gaming Disorder: Neurocognitive and Neurobiological Features

Video gaming and Internet use have become a part of the everyday lives of many individuals, especially during adolescence. Given the health concerns related to problematic gaming behaviors, gaming disorder (GD) has been included in the version of the 11th edition of The International Classification of Diseases (ICD-11) ratified by the secretariat of the World Health Organization. Given these considerations and others (including debate regarding the most appropriate classification of GD and how best to prevent and treat the condition), there is a need for further research into GD. Specifically, we suggest that researching intermediate phenotypes focusing on cognitive and neurobiological function may help clarify GD's relationships to other addictive disorders and more accurately define their relationships with core and associated features of GD. Overlaps in neural activity, cognitive functioning, and other features suggest that GD shares similarities with gambling and substance-use disorders and may best be classified as an addictive disorder. Individuals with GD differ from those with regular game use (RGU) on neurocognitive levels. However, concerns have been raised with respect to the differences between GD and substance-use disorders in certain dimensional features, such as tolerance. Additionally, it has been argued that differences between GD and RGU may not be fully captured by nomenclature systems like the ICD-11. Nonetheless, individuals seek treatment for help with GD, despite the limited data available for effective treatments. As more data are gathered from investigations of GD, they should be translated into refining criteria for GD and optimizing interventions.

Neurobiological Risk Factors for the Development of Internet Addiction in Adolescents

The sudden appearance and spread of Internet addiction in adolescent populations, in association with the rapid escalation of consumed Internet content and the broad availability of smartphones and tablets with Internet access, is posing a new challenge for classical addictology which requires urgent solutions. Like the majority of other psychopathological conditions, pathological Internet addiction depends upon a group of multifactor polygenic conditions. For each specific case, there is a unique combination of inherited characteristics (nervous tissue structure, secretion, degradation, and reception of neuromediators), and many are extra-environment factors (family-related, social, and ethnic-cultural). One of the main challenges in the development of the bio-psychosocial model of Internet addiction is to determine which genes and neuromediators are responsible for increased addiction susceptibility. This information will herald the start of a search for new therapeutic targets and the development of early prevention strategies, including the assessment of genetic risk levels. This review summarizes the literature and currently available knowledge related to neurobiological risk factors regarding Internet addiction in adolescents. Genetic, neurochemical and neuroimaging data are presented with links to actual pathogenetic hypotheses according to the bio-psychosocial model of IA forming.

Bio-psychosocial factors of children and adolescents with internet gaming disorder: a systematic review

Previous large-scale studies suggest that internet gaming disorder (IGD) among children and adolescents has become an important public concern. Minors are known to be particularly susceptible to problematic internet gaming use owing to age-related underdevelopment of cognitive control. It has been shown that precursors of addictions appear during adolescence; therefore, prevention efforts must be established targeting minors who have their first experience with addictive substances and behaviors during pubescence. Since the DSM-5 classification of IGD in 2013, studies on IGD have drastically increased in number. Thus, we performed an updated review of studies of IGD in children and adolescents to assess the clinical implications of IGD. The search included all publication years, using PubMed, MEDLINE, and PsycINFO. Across studies, the presence of IGD had a negative effect on sleep and schoolwork in minors. Additionally, family factors, including the quality of parent-child relationships, were important social factors in minors with IGD. Brain imaging studies indicate that impaired cognitive control in minors with IGD is associated with abnormal function in the prefrontal cortex and striatum. Persistent pathological online game use from childhood may aggravate abnormal brain function; therefore, preventive care and early intervention are increasingly important. Although extant research supports the effectiveness of cognitive behavioral therapy for minors with IGD, effective psychological intervention for minors with IGD is an urgent issue that requires further research. This review, which presents updated findings of IGD in minors, is expected to contribute to the development of future research and be useful in clinical practice in the field of child and adolescent psychiatry.

Little video-gaming in adolescents can be protective, but too much is associated with increased substance use

BACKGROUND

Studies have demonstrated inconsistent results regarding the association between video gaming time and substance use in teenagers. Understating intricacies of this association can help with substance use reduction in teenagers.

OBJECTIVES

This study aimed to untangle this complex relationship by theorizing and examining a U-shaped association.

METHODS

We analyzed two large samples (n₁ = 7313 [52.5% female] and n₂ = 8079 [51.6% female]) of 8th and 10th graders in the United States. Substance use was operationalized as the sum of self-reported number of lifetime use instances of 14 unprescribed substances. Video game use time (hours per week) was self-reported on a 1 (none) to 9 (40+) scale. Common covariates/risk factors were included.

RESULTS

Consistently across datasets, partial-correlation between squared video gaming time and substance use (r = .10, p < .001 in 2014 and r = .08, p < .001 in 2015) supported the hypothesized u-shaped association. Analysis of covariance revealed that teenagers playing video games for 1-5 h a week report on significantly fewer instances of substance use compared with non-gamers (p < .001-.007). Post hoc analyses revealed that those who play at least 30 h per week report on significantly (p < .001) more instances of substance use (3.92 in 2014 and 3.38 in 2015) compared with teenagers playing video games for 1-5 h a week (2.17 in 2015 and 1.96 in 2015).

CONCLUSIONS

Video gaming time and substance use follow a u-shaped association; light video gaming can be protective in terms of substance use, while too much video gaming is associated with increased substance use.

Genetic association of human Corticotropin-Releasing Hormone Receptor 1 (CRHR1) with Internet gaming addiction in Korean male adolescents

BACKGROUND

The number of people with Internet gaming addiction (IGA) is increasing around the world. IGA is known to be associated with personal characteristics, psychosocial factors, and physiological factors. However, few studies have examined the genetic factors related to IGA. This study aimed to investigate the association between IGA and stress-related genetic variants.

METHODS

This cross-sectional study was conducted with 230 male high school students in a South Korean city. We selected five stress-related candidate genes: DAT1, DRD4, NET8, CHRNA4, and CRHR1. The DAT1 and DRD4 genes were genotyped by polymerase chain reaction, and the NET8, CHRNA4, and CRHR1 genes were genotyped by pyrosequencing analysis. We performed a Chi-square test to examine the relationship of these five candidate genes to IGA.

RESULTS

Having the AA genotype and the A allele of the CRHR1 gene (rs28364027) was associated with higher odds of belonging to the IGA participant group (p = .016 and p = .021, respectively) than to the non-IGA group. By contrast, the DAT1, DRD4, NET8, and CHRNA4 gene polymorphisms showed no significant difference between the IGA group and control group.

CONCLUSIONS

These results indicate that polymorphism of the CRHR1 gene may play an important role in IGA susceptibility in the Korean adolescent male population. These findings provide a justification and foundation for further investigation of genetic factors related to IGA.

Manifesto for a European research network into Problematic Usage of the Internet

The Internet is now all-pervasive across much of the globe. While it has positive uses (e.g. prompt access to information, rapid news dissemination), many individuals develop Problematic Use of the Internet (PUI), an umbrella term incorporating a range of repetitive impairing behaviours. The Internet can act as a conduit for, and may contribute to, functionally impairing behaviours including excessive and compulsive video gaming, compulsive sexual behaviour, buying, gambling, streaming or social networks use. There is growing public and National health authority concern about the health and societal costs of PUI across the lifespan. Gaming Disorder is being considered for inclusion as a mental disorder in diagnostic classification systems, and was listed in the ICD-11 version released for consideration by Member States (http://www.who.int/classifications/icd/revision/timeline/en/). More research is needed into disorder definitions, validation of clinical tools, prevalence, clinical parameters, brain-based biology, socio-health-economic impact, and empirically validated intervention and policy approaches. Potential cultural differences in the magnitudes and natures of types and patterns of PUI need to be better understood, to inform optimal health policy and service development. To this end, the EU under Horizon 2020 has launched a new four-year European Cooperation in Science and Technology (COST) Action Programme (CA 16207), bringing together scientists and clinicians from across the fields of impulsive, compulsive, and addictive disorders, to advance networked interdisciplinary research into PUI across Europe and beyond, ultimately seeking to inform regulatory policies and clinical practice. This paper describes nine critical and achievable research priorities identified by the Network, needed in order to advance understanding of PUI, with a view towards identifying vulnerable individuals for early intervention. The network shall enable collaborative research networks, shared multinational databases, multicentre studies and joint publications.

Behavioral Addictions as Mental Disorders: To Be or Not To Be?

Should excessive and problematic engagement in nonsubstance use behaviors be mental disorders? The fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) repositioned gambling disorder in the substance use disorders section and introduced Internet gaming disorder in the research appendix; the International Classification of Diseases (ICD-11) is also considering it. This article outlines pros and cons of considering behavioral addictions as mental disorders and also reviews the DSM-5 decision-making processes. It focuses on three conditions: gambling disorder, Internet gaming disorder (IGD), and Internet addiction (IA). We detail assessment methods and prevalence rates for these conditions and outline psychiatric comorbidities, demographic and biological risk factors, and promising treatment approaches. We also briefly discuss other putative behavioral addictions: eating/food, sex, exercise, shopping, and tanning "addictions." Overall, data are inconclusive, and consistent terminology and methodology are needed to define and evaluate these conditions more fully prior to considering them mental disorders.

Development of an effective virtual environment in eliciting craving in adolescents and young adults with internet gaming disorder

Internet gaming disorder (IGD) is a new disorder that warrants further investigation, as recently noted in the research criteria of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. Offering controlled environments that increase cue-induced craving, virtual reality cue-exposure therapy has been shown to be effective for some addiction disorders. To assess the feasibility of virtual reality for patients with IGD, this study aimed to develop virtual environments that represent risk situations for inducing craving, and assess the effect of virtual reality in cue reactivity. A total of 64 male adolescents and young adults (34 with IGD and 30 without) were recruited for participation. We developed a virtual internet café environment and the participants were exposed to four different tasks. As the primary feasibility outcome, cravings were measured with a visual analogue scale measuring current urge to play a game after exposure to each task. The virtual internet café induced significantly greater cravings in patients with IGD compared to controls. Additionally, patients exhibited a significantly higher acceptance rate of an avatar's invitation to play a game together than that of controls. In IGD, craving response to the tasks was positively associated with the symptom severity score as measured by Young's Internet Addiction Test. These findings reveal that virtual reality laden with complex game-related cues could evoke game craving in patients with IGD and could be used in the treatment of IGD as a cue-exposure therapy tool for eliciting craving.

Circulating MicroRNA Expression Levels Associated With Internet Gaming Disorder

BACKGROUND

Addictive use of the Internet and online games is a potential psychiatric disorder termed Internet gaming disorder (IGD). Altered microRNA (miRNA) expression profiles have been reported in blood and brain tissue of patients with certain psychiatric disorders and suggested as biomarkers. However, there have been no reports on blood miRNA profiles in IGD.

METHODS

To discover IGD-associated miRNAs, we analyzed the miRNA expression profiles of 51 samples (25 IGD and 26 controls) using the TaqMan Low Density miRNA Array. For validation, we performed quantitative reverse transcription PCR with 36 independent samples (20 IGD and 16 controls).

RESULTS

Through discovery and independent validation, we identified three miRNAs (hsa-miR-200c-3p, hsa-miR-26b-5p, hsa-miR-652-3p) that were significantly downregulated in the IGD group. Individuals with all three miRNA alterations had a much higher risk of IGD than those with no alteration [odds ratio (OR) 22, 95% CI 2.29-211.11], and the ORs increased dose dependently with number of altered miRNAs. The predicted target genes of the three miRNAs were associated with neural pathways. We explored the protein expression of the three downstream target genes by western blot and confirmed that expression of GABRB2 and DPYSL2 was significantly higher in the IGD group.

CONCLUSION

We observed that expressions of hsa-miR-200c-3p, hsa-miR-26b-5p, and hsa-miR-652-3p were downregulated in the IGD patients. Our results will be helpful to understand the pathophysiology of IGD.

The association between the nicotinic acetylcholine receptor α4 subunit gene (CHRNA4) rs1044396 and Internet gaming disorder in Korean male adults

The primary aim of this study was to investigate the genetic predisposition of Internet gaming disorder (IGD), and the secondary aim was to compare the results to those of alcohol dependence (AD). Two independent case-control studies were conducted. A total of 30 male participants with IGD, diagnosed according to the 5^th edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria, and 30 sex-matched controls participated in study 1. We designed targeted exome sequencing (TES) to test for 72 candidate genes that have been implicated in the pathogenesis of addiction. The genes included seven neurotransmitter (dopamine, serotonin, glutamate, r-aminobutyric acid (GABA), norepinephrine, acetylcholine, and opioid) system genes. A total of 31 male in-patients with AD and 29 normal male controls (NC) were enrolled in study 2. The same 72 genes included in study 1 and ten additional genes related to alcohol-metabolic enzyme were selected as the target genes, and we identified the genetic variants using the same method (TES). The IGD group had a lower frequency of the T allele of rs1044396 in the nicotinic acetylcholine receptor alpha 4 subunit (CHRNA4), and this variant represents a protective allele against IGD. However, we did not find a significant difference in the polymorphisms of the 72 genes that encode neurotransmitter systems between the AD and NC groups. This study demonstrated that rs1044396 of CHRNA4 was significantly associated with IGD.

Tolerance in Internet gaming disorder: A need for increasing gaming time or something else?

Background and aims The criterion of tolerance in DSM-5 Internet gaming disorder (IGD) refers to a need for increasing time spent gaming. However, this focus on "need for gaming time" may overlook some of the broader motivations, outcomes, or effects of gaming that underlie excessive play. This study aimed to explore regular and problematic gamers' experiences and perceptions of tolerance in IGD. Methods An online survey of 630 adult gamers yielded 1,417 text responses to open-ended questions. A thematic analysis of 23,373 words was conducted to extract dominant themes. Results Participants reported that they increasingly desired game items, status, or story progress as they became more involved or invested in games. As players develop higher standards of play in games, an increasing number of potential reward outcomes may have diminishing mood-modifying effects. None of the participants, including those with self-reported IGD, explicitly referred to a need for increasing time spent gaming. Discussion and conclusions These results suggest that players may be motivated by preferences for specific goals or reinforcers in games rather than wanting an amount of time spent gaming. Thus, problematic gaming may involve a need for completion of increasingly intricate, time-consuming, or difficult goals to achieve satisfaction and/or reduce fears of missing out. Further research is needed to determine whether these cognitive and motivational factors related to gaming stimuli should extend or replace the concept of tolerance in IGD or be considered as separate but related processes in disordered gaming.

Merging Theoretical Models and Therapy Approaches in the Context of Internet Gaming Disorder: A Personal Perspective

Although, it is not yet officially recognized as a clinical entity which is diagnosable, Internet Gaming Disorder (IGD) has been included in section III for further study in the DSM-5 by the American Psychiatric Association (APA, 2013). This is important because there is increasing evidence that people of all ages, in particular teens and young adults, are facing very real and sometimes very severe consequences in daily life resulting from an addictive use of online games. This article summarizes general aspects of IGD including diagnostic criteria and arguments for the classification as an addictive disorder including evidence from neurobiological studies. Based on previous theoretical considerations and empirical findings, this paper examines the use of one recently proposed model, the Interaction of Person-Affect-Cognition-Execution (I-PACE) model, for inspiring future research and for developing new treatment protocols for IGD. The I-PACE model is a theoretical framework that explains symptoms of Internet addiction by looking at interactions between predisposing factors, moderators, and mediators in combination with reduced executive functioning and diminished decision making. Finally, the paper discusses how current treatment protocols focusing on Cognitive-Behavioral Therapy for Internet addiction (CBT-IA) fit with the processes hypothesized in the I-PACE model.

Neurobiological findings related to Internet use disorders

In the last 10 years, numerous neurobiological studies have been conducted on Internet addiction or Internet use disorder. Various neurobiological research methods - such as magnetic resonance imaging; nuclear imaging modalities, including positron emission tomography and single photon emission computed tomography; molecular genetics; and neurophysiologic methods - have made it possible to discover structural or functional impairments in the brains of individuals with Internet use disorder. Specifically, Internet use disorder is associated with structural or functional impairment in the orbitofrontal cortex, dorsolateral prefrontal cortex, anterior cingulate cortex, and posterior cingulate cortex. These regions are associated with the processing of reward, motivation, memory, and cognitive control. Early neurobiological research results in this area indicated that Internet use disorder shares many similarities with substance use disorders, including, to a certain extent, a shared pathophysiology. However, recent studies suggest that differences in biological and psychological markers exist between Internet use disorder and substance use disorders. Further research is required for a better understanding of the pathophysiology of Internet use disorder.

New developments in brain research of internet and gaming disorder

There is evidence that the neural mechanisms underlying Internet Gaming Disorder (IGD) resemble those of drug addiction. Functional Magnetic Resonance Imaging (fMRI) studies of the resting state and measures of gray matter volume have shown that Internet game playing was associated with changes to brain regions responsible for attention and control, impulse control, motor function, emotional regulation, sensory-motor coordination. Furthermore, Internet game playing was associated with lower white matter density in brain regions that are involved in decision-making, behavioral inhibition and emotional regulation. Videogame playing involved changes in reward inhibitory mechanisms and loss of control. Structural brain imaging studies showed alterations in the volume of the ventral striatum that is an important part of the brain's reward mechanisms. Finally, videogame playing was associated with dopamine release similar in magnitude to those of drugs of abuse and lower dopamine transporter and dopamine receptor D₂ occupancy indicating sub-sensitivity of dopamine reward mechanisms.

Internet addiction and its facets: The role of genetics and the relation to self-directedness

A growing body of research focuses on problematic behavior patterns related to the use of the Internet to identify contextual as well as individual risk factors of this new phenomenon called Internet addiction (IA). IA can be described as a multidimensional syndrome comprising aspects such as craving, development of tolerance, loss of control and negative consequences. Given that previous research on other addictive behaviors showed substantial heritability, it can be expected that the vulnerability to IA may also be due to a person's genetic predisposition. However, it is questionable whether distinct components of IA have different etiologies. Using data from a sample of adult monozygotic and dizygotic twins and non-twin siblings (N=784 individuals, N=355 complete pairs, M=30.30years), we investigated the magnitude of genetic and environmental influences on generalized IA as well as on specific facets such as excessive use, self-regulation, preference for online social interaction or negative consequences. To explain the heritability in IA, we further examined the relation to Self-Directedness as potential mediating source. Results showed that relative contributions of genetic influences vary considerable for different components of IA. For generalized IA factors, individual differences could be explained by shared and non-shared environmental influences while genetic influences did not play a role. For specific facets of IA and private Internet use in hours per week, heritability estimates ranged between 21% and 44%. Bivariate analysis indicated that Self-Directedness accounted for 20% to 65% of the genetic variance in specific IA facets through overlapping genetic pathways. Implications for future research are discussed.