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

Learning and memory processes in behavioural addiction: A systematic review

Similar to addictive substances, addictive behaviours such as gambling and gaming are associated with maladaptive modulation of key brain areas and functional networks implicated in learning and memory. Therefore, this review sought to understand how different learning and memory processes relate to behavioural addictions and to unravel their underlying neural mechanisms. Adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we systematically searched four databases - PsycINFO, PubMed, Scopus, and Web of Science using the agreed-upon search string. Findings suggest altered executive function-dependent learning processes and enhanced habit learning in behavioural addiction. Whereas the relationship between working memory and behavioural addiction is influenced by addiction type, working memory aspect, and task nature. Additionally, long-term memory is incoherent in individuals with addictive behaviours. Consistently, neurophysiological evidence indicates alterations in brain areas and networks implicated in learning and memory processes in behavioural addictions. Overall, the present review argues that, like substance use disorders, alteration in learning and memory processes may underlie the development and maintenance of behavioural addictions.

A preliminary study on the association of single nucleotide polymorphisms and methylation of dopamine system-related genes with psychotic symptoms in patients with methamphetamine use disorder

Methamphetamine use disorder (MAUD) can substantially jeopardize public security due to its high-risk social psychology and behaviour. Given that the dopamine reward system is intimately correlated with MAUD, we investigated the association of single nucleotide polymorphisms (SNPs), as well as methylation status of dopamine receptor type 4 (DRD4), catechol-O-methyltransferase (COMT) genes, and paranoid and motor-impulsive symptoms in MAUD patients. A total of 189 MAUD patients participated in our study. Peripheral blood samples were used to detect 3 SNPs and 35 CpG units of methylation in the DRD4 gene promoter region and 5 SNPs and 39 CpG units in the COMT gene. MAUD patients with the DRD4 rs1800955 C allele have a lower percentage of paranoid symptoms than those with the rs1800955 TT allele. Individuals with paranoid symptoms exhibited a reduced methylation degree at a particular DRD4 CpG2.3 unit. The interaction of the DRD4 rs1800955 C allele and the reduced DRD4CpG2.3 methylation degree were associated with a lower occurrence of paranoid symptoms. Meanwhile, those with the COMT rs4818 CC allele had lower motor-impulsivity scores in MAUD patients but greater COMT methylation levels in the promoter region and methylation degree at the COMT CpG 51.52 unit. Therefore, based only on the COMT rs4818 CC polymorphism, there was a negative correlation between COMT methylation and motor-impulsive scores. Our preliminary results provide a clue that the combination of SNP genotype and methylation status of the DRD4 and COMT genes serve as biological indicators for the prevalence of relatively high-risk psychotic symptoms in MAUD patients.

A systematic review and meta-analysis of risky decision-making in specific domains of problematic use of the internet: Evidence across different decision-making tasks

This systematic review summarizes empirical evidence on risky decision-making (objective risk and ambiguity) in specific domains of problematic use of the internet (PUI) focusing on online addictive behaviors. We conducted a pre-registered (PROSPERO: CRD42020188452) PubMed search for PUI domains: gaming, social-network use, online buying-shopping, online pornography use, and unspecified PUI. We used the Newcastle-Ottawa Scale for quality assessment. Relevant studies were identified only for gaming (n = 19), social-network use (n = 8), unspecified PUI (n = 7), and online gambling (n = 1). The meta-analyses included 25 studies (2498 participants) comparing PUI and control groups regarding decision-making performance under objective risk and ambiguity. Across PUI domains, individuals with PUI compared to control participants showed more disadvantageous decision-making in measures of objective risk (g = -0.42 [-0.69, -0.16], p = .002) but not ambiguity (g = -0.22 [-0.47, -0.04], p = .096). PUI domain and gender were significant moderators. In the risk domain, effects were particularly present in gaming disorder, especially in exclusively male samples. Overall, the paucity of empirical studies in the considered area necessitates further research to identify probable gender- and disorder-specific cognitive relationships.

Advances in problematic usage of the internet research - A narrative review by experts from the European network for problematic usage of the internet

Global concern about problematic usage of the internet (PUI), and its public health and societal costs, continues to grow, sharpened in focus under the privations of the COVID-19 pandemic. This narrative review reports the expert opinions of members of the largest international network of researchers on PUI in the framework of the European Cooperation in Science and Technology (COST) Action (CA 16207), on the scientific progress made and the critical knowledge gaps remaining to be filled as the term of the Action reaches its conclusion. A key advance has been achieving consensus on the clinical definition of various forms of PUI. Based on the overarching public health principles of protecting individuals and the public from harm and promoting the highest attainable standard of health, the World Health Organisation has introduced several new structured diagnoses into the ICD-11, including gambling disorder, gaming disorder, compulsive sexual behaviour disorder, and other unspecified or specified disorders due to addictive behaviours, alongside naming online activity as a diagnostic specifier. These definitions provide for the first time a sound platform for developing systematic networked research into various forms of PUI at global scale. Progress has also been made in areas such as refining and simplifying some of the available assessment instruments, clarifying the underpinning brain-based and social determinants, and building more empirically based etiological models, as a basis for therapeutic intervention, alongside public engagement initiatives. However, important gaps in our knowledge remain to be tackled. Principal among these include a better understanding of the course and evolution of the PUI-related problems, across different age groups, genders and other specific vulnerable groups, reliable methods for early identification of individuals at risk (before PUI becomes disordered), efficacious preventative and therapeutic interventions and ethical health and social policy changes that adequately safeguard human digital rights. The paper concludes with recommendations for achievable research goals, based on longitudinal analysis of a large multinational cohort co-designed with public stakeholders.

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.