Brain correlates of response inhibition in Internet gaming disorder

The effect of reward learning on inhibitory control in internet gaming disorder: Evidence from behavioral and ERP

Reward dysregulation and deficits in inhibitory control significantly contribute to the development of internet gaming disorder (IGD). While prior research demonstrates that reward history influences individuals' inhibitory control, it remains unclear whether this effect extends to individuals with IGD. The primary aim of this study was to investigate whether individuals with IGD exhibit impairments in reward learning and whether prior reward learning influences their inhibitory control, using both behavioral and event-related potential (ERP) measures. This study first employed a probability selection task to examine potential impairments in reward learning among individuals with IGD. Next, a stop-signal task incorporating reward- and punishment-associated stimuli was used to further investigate the behavioral and electroencephalographic effects of prior reward learning on subsequent inhibitory control. Results revealed that during the reward-learning phase, the IGD group exhibited significantly longer response times than the control group in both the learning and transfer phases. Additionally, the feedback-related negativity amplitude in the IGD group was significantly lower than that in the control group. Conversely, the P3 wave amplitude induced by positive and negative feedback in the IGD group were significantly higher than in the control group. In the inhibitory control phase following reward learning, the Nogo-P3 wave amplitude in response to reward cues was significantly greater in the IGD group than in the control group. Moreover, within the IGD group, the Nogo-P3 wave amplitude evoked by reward cues was significantly larger than the amplitude evoked by loss cues. These findings suggest that reward learning is impaired in individuals with IGD and that stimuli with a prior reward history may compromise inhibitory control, potentially serving as a critical factor in addiction development in this population.

Influence of reinforcement learning on the inhibitory control of Internet gaming disorder

Reward processing dysfunction and inhibition control deficiency have been observed in Internet gaming disorder (IGD). However, it is still unclear whether the previous reinforcement learning depends on reward/punishment feedback influences on the cognitive inhibitory control of IGD. This study compared the differences between an IGD group and healthy people without game experiences in the probability selection task and the subsequent stop signal task by the method of behavioral experiments, in order to explore whether the reward learning ability is impaired in the IGD group. We also discuss the influence of previous reward learning on subsequent inhibition control. The results showed that (1) during the reward learning phase, the IGD group's accuracy was significantly lower than that of the control group; (2) compared with the control group, the IGD group's reaction times were longer in the transfer phase; (3) for no-go trials of the inhibitory control phase after reward learning, the accuracy of the reward-related stimulation in the IGD group was lower than that of punishment-related or neutral stimulation, but there was no significant difference among the three conditions in the control group. These findings indicated that the reinforcement learning ability of the IGD group was impaired, which further caused the abnormal response to reinforcement stimuli.

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.

Altered intrinsic neural timescales and neurotransmitter activity in males with tobacco use disorder

Previous researches of tobacco use disorder (TUD) has overlooked the hierarchy of cortical functions and single modality design separated the relationship between macroscopic neuroimaging aberrance and microscopic molecular basis. At present, intrinsic timescale gradient of TUD and its molecular features are not fully understood. Our study recruited 146 male subjects, including 44 heavy smokers, 50 light smokers and 52 non-smokers, then obtained their rs-fMRI data and clinical scales related to smoking. Intrinsic neural timescale (INT) method was performed to describe how long neural information was stored in a brain region by calculating the autocorrelation function (ACF) of each voxel to examine the difference in the ability of information integration among the three groups. Then, correlation analyses were conducted to explore the relationship between INT abnormalities and clinical scales of smokers. Finally, cross-modal JuSpace toolbox was used to investigate the association between INT aberrance and the expression of specific receptor/transporters. Compared to healthy controls, TUD subjects displayed decreased INT in control network (CN), default mode network (DMN), sensorimotor areas and visual cortex, and such trend of decreasing INT was more pronounced in heavy smokers. Moreover, various neurotransmitters (including dopaminergic, acetylcholine and μ-opioid receptors) were involved in the molecular mechanism of timescale decreasing and differed in heavy and light smokers. These findings supplied novel insights into the brain functional aberrance in TUD from an intrinsic neural dynamic perspective and confirm INT was a potential neurobiological marker. And also established the connection between macroscopic imaging aberrance and microscopic molecular changes in TUD.

Neural underpinnings of ethical decisions in life and death dilemmas in naïve and expert firefighters

When a single choice impacts on life outcomes, faculties to make ethical judgments come into play. Here we studied decisions in a real-life setting involving life-and-death outcomes that affect others and the decision-maker as well. We chose a genuine situation where prior training and expertise play a role: firefighting in life-threatening situations. By studying the neural correlates of dilemmas involving life-saving decisions, using realistic firefighting situations, allowed us to go beyond previously used hypothetical dilemmas, while addressing the role of expertise and the use of coping strategies (n = 47). We asked the question whether the neural underpinnings of deontologically based decisions are affected by expertise. These realistic life-saving dilemmas activate the same core reward and affective processing network, in particular the ventromedial prefrontal cortex, nucleus accumbens and amygdala, irrespective of prior expertise, thereby supporting general domain theories of ethical decision-making. We found that brain activity in the hippocampus and insula parametrically increased as the risk increased. Connectivity analysis showed a larger directed influence of the insula on circuits related to action selection in non-experts, which were slower than experts in non rescuing decisions. Relative neural activity related to the decision to rescue or not, in the caudate nucleus, insula and anterior cingulate cortex was negatively associated with coping strategies, in experts (firefighters) suggesting practice-based learning. This shows an association between activity and expert-related usage of coping strategies. Expertise enables salience network activation as a function of behavioural coping dimensions, with a distinct connectivity profile when facing life-rescuing dilemmas.

Neural Network Dynamics and Brain Oscillations Underlying Aberrant Inhibitory Control in Internet Addiction

Previous studies have reported a role of alterations in the brain's inhibitory control mechanism in addiction. Mounting evidence from neuroimaging studies indicates that its key components can be evaluated with brain oscillations and connectivity during inhibitory control. In this study, we developed an internet-related stop-signal task with electroencephalography (EEG) signal recorded to investigate inhibitory control. Healthy controls and participants with Internet addiction were recruited to participate in the internet-related stop-signal task with 19-channel EEG signal recording, and the corresponding event-related potentials and spectral perturbations were analyzed. Brain effective connections were also evaluated using direct directed transfer function. The results showed that, relative to the healthy controls, participants with Internet addiction had increased Stop-P3 during inhibitory control, suggesting that they have an altered neural mechanism in impulsive control. Furthermore, participants with Internet addiction showed increased low-frequency synchronization and decreased alpha and beta desynchronization in the middle and right frontal regions compared to healthy controls. Aberrant brain effective connectivity was also observed, with increased occipital-parietal and intra-occipital connections, as well as decreased frontal-paracentral connection in participants with Internet addiction. These results suggest that physiological signals are essential in future implementations of cognitive assessment of Internet addiction to further investigate the underlying mechanisms and effective biomarkers.

The Relationships between Effortful Control, Mind Wandering, and Mobile Phone Addiction Based on Network Analysis

BACKGROUND

The prevailing mobile phone use brought the problem of addiction, which might cause negative consequences. Effortful control and mind wandering were associated with addictive behavior. The present study aimed to investigate the dimension-level relationships between effortful control, mind wandering, and mobile phone addiction.

METHODS

A total of 1684 participants participated this study. The mobile phone addiction, effortful control, and mind wandering were measured through self-report scales, respectively. Dimension-level network of these psychological variables was estimated and bridge expected influence (BEI) values for each node was calculated.

RESULTS

Dimensions of mobile phone addiction, effortful control, and mind wandering exhibited distinct and complex links to each other. The node "activation control" exhibited the highest negative BEI value (BEI = -0.32), whereas "spontaneous thinking" showed the highest positive BEI value (BEI = 0.20).

CONCLUSIONS

Different dimensions of effortful control and mind wandering had varied yet significant connections with distinct dimensions of mobile phone addiction, facilitating understanding of the specific pathways underlying the three constructs. The identified dominant bridge nodes can provide potential targets for the intervention of mobile phone addiction.

Subregional prefrontal cortex recruitment as a function of inhibitory demand: an fMRI metanalysis

Convergent studies corroborated the idea that the right prefrontal cortex is the crucial brain region responsible for inhibiting our actions. However, which sub-regions of the right prefrontal cortex are involved is still a matter of debate. To map the inhibitory function of the sub-regions of the right prefrontal cortex, we performed Activation Likelihood Estimation (ALE) meta-analyses and meta-regressions (ES-SDM) of fMRI studies exploring inhibitory control. Sixty-eight studies (1684 subjects, 912 foci) were identified and divided in three groups depending on the incremental demand. Overall, our results showed that higher was the inhibitory demand based on the individual differences in performances, more the upper portion of the right prefrontal cortex was activated to achieve a successful inhibition. Conversely, a lower demand of the inhibitory function, was associated with the inferior portions of the right prefrontal cortex recruitment. Notably, in the latter case, we also observed activation of areas associated with working memory and responsible for cognitive strategies.

Understanding older adults' smartphone addiction in the digital age: empirical evidence from China

Background

Despite the fact that an increasing number of older adults are addicted to smartphones, the existing addiction literature still focuses primarily on adolescents. To address this issue, this study draws from the perspectives of subjective cognitive decline and family relationship conflict to examine older adults' smartphone addiction based on their key characteristics.

Methods

This study investigates the effects of subjective cognitive decline and family relationship conflict on older adults' smartphone addiction through a survey of 371 subjects in China.

Results

The results show that subjective cognitive decline and family relationship conflict affect older adults' smartphone addiction through a sense of alienation. In addition, older adults' perceived power moderates the relationship between alienation and smartphone addiction.

Discussion

This study offers new perspectives on the study of smartphone addiction from the perspective of older adults, and sheds light on how to improve the older adults' quality of life in their later years.

Abnormal psychological performance as potential marker for high risk of internet gaming disorder: An eye-tracking study and support vector machine analysis

Individuals with high risk of internet gaming disorder (HIGD) showed abnormal psychological performances in response inhibition, impulse control, and emotion regulation, and are considered the high-risk stage of internet gaming disorder (IGD). The identification of this population mainly relies on clinical scales, which are less accurate. This study aimed to explore whether these performances have highly accurate for discriminating HIGD from low-risk ones. Eye tracking based anti-saccade task, Barratt impulsiveness scale (BIS), and Wong and Law emotional intelligence scale (WLEIS) were used to evaluate psychological performances in 57 individuals with HIGD and 52 matched low risk of internet gaming disorder (LIGD). HIGD group showed significantly increased BIS total (t = −2.875, p = 0.005), attention (t = −2.139, p = 0.035), motor (t = −2.017, p = 0.046), and non-planning (t = −2.171, p = 0.032) scores, but significantly decreased WLEIS emotion regulation score (t = 2.636, p = 0.010) and correct rate of eye tracking anti-saccade task (t = 2.294, p = 0.024) compared with LIGD group. BIS total score was negatively correlated with the WLEIS total (r = −0.473, p < 0.001) and WLEIS emotion regulation (r = −0.366, p < 0.001) scores. A combination of the WLEIS emotion regulation score and the correct rate of anti-saccade task could discriminate HIGD from LIGD with 91.23% sensitivity, 82.69% specificity, and 87.16% accuracy. Participants with higher gaming hours daily were 40 times more likely to be high risk than their counterparts (p < 0.001). Hence, psychological performances were worse in HIGD. A combination of abnormal emotion regulation and response inhibition might be a potential marker to identify HIGD individuals.

Sexual Differences in Internet Gaming Disorder (IGD): From Psychological Features to Neuroanatomical Networks

Internet gaming disorder (IGD) has been included in the 2013 Diagnostic and Statistical Manual of Mental Disorders (DSM-5) as a condition in need of further study, and gaming disorder was recognized by the World Health Organization as a mental disorder in the International Classification of Disease (ICD-11) of 2018. IGD has different characteristics in the two sexes and is more prevalent in males than females. However, even if the female gamer population is constantly growing, the majority of available studies analyzed only males, or the data were not analyzed by sex. To better elucidate sex differences in IGD, we selectively reviewed research publications that evaluated IGD separately for males and females collected in approximately one hundred publications over the past 20 years. The available data in this narrative review indicate that IGD is strongly dimorphic by sex for both its psychological features and the involvement of different brain areas. Impulsivity, low self-control, anxiety, emotion dysregulation, and depression are some of the psychological features associated with IGD that show a sex dimorphism. At the same time, IGD and its psychological alterations are strongly correlated to dimorphic functional characteristics in relevant brain areas, as evidenced by fMRI. More research is needed to better understand sex differences in IGD. Animal models could help to elucidate the neurological basis of this disorder.

Meta-analysis of structural and functional brain alterations in internet gaming disorder

Background

Many neuroimaging studies have reported abnormalities in brain structure and function in internet gaming disorder (IGD). However, the findings were divergent. We aimed to provide evidence-based evidence of structural and functional changes in IGD by conducting a meta-analysis integrating these studies quantitatively.

Method

A systematic search was conducted in PubMed, ScienceDirect, Web of Science, and Scopus from January 1, 2010 to October 31, 2021, to identify eligible voxel-based morphometry (VBM) and functional magnetic resonance imaging (fMRI) studies. Brain alternations between IGD subjects and healthy controls (HCs) were compared using the anisotropic seed-based d mapping (AES-SDM) meta-analytic method. Meta-regression analysis was used to investigate the relationship between gray matter volume (GMV) alterations and addiction-related clinical features.

Results

The meta-analysis contained 15 VBM studies (422 IGD patients and 354 HCs) and 30 task-state fMRI studies (617 IGD patients and 550 HCs). Compared with HCs, IGD subjects showed: (1) reduced GMV in the bilateral anterior/median cingulate cortex, superior/inferior frontal gyrus and supplementary motor area; (2) hyperactivation in the bilateral inferior frontal gyrus, precentral gyrus, left precuneus, right inferior temporal gyrus and right fusiform; (3) hypoactivation in the bilateral lingual and the left middle frontal gyrus; and (4) both decreased GMV and increased activation in the left anterior cingulate. Furthermore, Meta-regression revealed that GMV reduction in left anterior cingulate were positively correlated with BIS-11 score [r = 0.725, p = 0.012(uncorrected)] and IAT score [r = 0.761, p = 0.017(uncorrected)].

Conclusion

This meta-analysis showed structural and functional impairments in brain regions related to executive control, cognitive function and reward-based decision making in IGD. Furthermore, multi-domain assessments captured different aspects of neuronal changes in IGD, which may help develop effective interventions as potential therapeutic targets.

Relationship between Resting-State Alpha Coherence and Cognitive Control in Individuals with Internet Gaming Disorder: A Multimodal Approach Based on Resting-State Electroencephalography and Event-Related Potentials

The human brain is constantly active, even at rest. Alpha coherence is an electroencephalography (EEG) rhythm that regulates functional connectivity between different brain regions. However, the relationships between resting-state alpha coherence and N2/P3 components associated with response inhibition and cognitive processes have not been investigated in addictive disorders. The present study investigated the relationships between alpha coherence during the resting state and N2/P3 components of event-related potentials during the Go/Nogo task in healthy controls (HCs) and patients with Internet gaming disorder (IGD). A total of 64 young adults (HC: n = 31; IGD: n = 33) participated in this study. Alpha coherence values at left fronto-central and bilateral centro-temporal electrode sites were significantly correlated with P3 latency in HCs, whereas inverse correlations were observed in patients with IGD. Furthermore, significant differences were observed in the correlation values between the groups. Our results suggest that patients with IGD lack dynamic interactions of functional connectivity between the fronto-centro-temporal regions during the resting state and the event-related potential (ERP) index during cognitive tasks. The findings of this study may have important implications for understanding the neurophysiological mechanisms linking resting-state EEG and task-related ERPs underlying IGD.

Sports Augmented Cognitive Benefits: An fMRI Study of Executive Function with Go/NoGo Task

Exercise is believed to have significant cognitive benefits. Although an array of experimental paradigms have been employed to test the cognitive effects on exercising individuals, the mechanism as to how exercise induces cognitive benefits in the brain remains unclear. This study explores the effect of dynamic neural network processing with the classic Go/NoGo task with regular exercisers. We used functional magnetic resonance imaging to analyze the brain activation of areas involved in executive function, especially inhibitory control. Nineteen regular joggers and twenty-one subjects as a control group performed the task, and their brain imaging data were analyzed. The results showed that at the attentive visual period, the frontal and parietal areas, including the prefrontal cortex, putamen, thalamus, lingual, fusiform, and caudate, were significantly enhanced in positive activities than the control group. On the other hand, in the following inhibitory control processing period, almost the same areas of the brains of the exercise group have shown stronger negative activation in comparison to the control group. Such dynamic temporal response patterns indicate that sports augment cognitive benefits; i.e., regular jogging increases the brain's visual attention and inhibitory control capacities.

Neural substrates of deficient cognitive control in individuals with severe internet gaming disorder

BACKGROUND AND AIMS

Internet gaming disorder (IGD) is rapidly becoming a worldwide health concern. The prefrontal-subcortical model of self-regulation emphasizes that an impaired prefrontal cognitive control system and an overwhelming subcortical reward-seeking system are both crucial factors in health problems, including addiction. This study focused on the cognitive control system of IGD, aiming to investigate whether cognitive control is altered and the underlying neural correlates in college students with IGD.

METHODS

Thirty college students with IGD and twenty-five matched healthy controls were asked to complete a stop-signal task that measures cognitive control while being monitored by functional magnetic resonance imaging (fMRI).

RESULTS

Compared to the controls, only the college students with severe IGD, rather than those with mild IGD, had deficient brain activity involved in inhibitory control and response execution (specifically, the inferior frontal gyrus, anterior cingulate cortex and primary motor cortex); this result implies that cognitive control deficits are closely linked to addiction severity in individuals with IGD. Regarding performance monitoring function, college students with IGD exhibited unabated behavioral and brain activity, as did the control group.

CONCLUSIONS

Combined with our previous finding that the subcortical reward system was enhanced in individuals with IGD, the present findings extend the prefrontal-subcortical model of self-regulation from the perspective of IGD in a college student population and thus provide useful insight for the effective prevention and treatment of IGD.

Effect of Acute Aerobic Exercise on Inhibitory Control of College Students with Smartphone Addiction

Background

Inhibitory control deficits may be one important cause for smartphone addiction. The available studies have shown that acute aerobic exercise may improve the inhibitory control. However, there is still lack of research on how regimens of an acute exercise affect this inhibitory control. The present study was to examine the effects of an acute aerobic exercise at three different exercise intensities on changes in the inhibitory control function including response inhibition and interference control in college students with smartphone addiction.

Methods

Participants (n = 30; age 20.03 ± 0.96 years) with smartphone addiction were identified by the Mobile Phone Addiction Tendency Scale for College Students and randomized to study 1 and study 2 with 15 individuals each. Fifteen participants in study 1 were tested by the Go/NoGo task to explore the response inhibition, while other fifteen in study 2 were tested by the Flanker task to examine the interference control. The participants in study 1 and 2 were randomly assigned to three groups (5 in each) with exercising at low, moderate, and high intensity. The individual response inhibition and interference control were measured before and after 30 minutes acute aerobic exercise, respectively.

Results

In study 1, the accuracy of NoGo stimulus after 30 minutes of acute aerobic exercise was significantly increased (p ≤ 0.001) while the response time (RT) of Go stimulus was significantly decreased (p ≤ 0.001). The largest changes occurred in the moderate-intensity group for the accuracy of NoGo stimulus (p=0.012) and for the RT of Go stimulus (p ≤ 0.001). The results in study 2 showed no significant change in all three groups after exercise.

Conclusions

30 minutes of acute aerobic exercise could effectively elicit changes of the response inhibition in college students with smartphone addiction. The largest improvement was observed in the moderate intensity of an acute aerobic exercise in college students with smartphone addiction.

Neurobiological mechanisms underlying internet gaming disorder

This review summarizes studies on the neurobiological correlates of internet gaming disorder (IGD), presently the most direct approach to analyzing the impact of digital technology and the internet on brain mechanisms. Brain imaging studies have shown that IGD shares, to a large extent, neurobiological alterations that are typical for other addictions, such as: (i) activation in brain regions associated with reward, as evident from cue exposure and craving studies and neurotransmitter systems studies that indicate an involvement of dopamine-mediated reward mechanisms; (ii) reduced activity in impulse control areas and impaired decision making; and (iii) reduced functional connectivity in brain networks that are involved in cognitive control, executive function, motivation, and reward. Moreover, there are structural changes, mainly reduction in gray-matter volume and white-matter density. Comorbidity studies indicate that executive control networks in attention deficit-hyperactivity disorder (ADHD) may increase the susceptibility to develop IGD. Most importantly, this review also outlines findings that show the effects of excessive use of screens, here referring to the playing of computer games, which activate many brain regions associated with cognitive, motor, and sensory function and not directly involved in other forms of addiction. This review describes and summarizes comprehensively the neurobiological correlates of addictive internet use in adolescents and young adults.
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Association of Extensive Video Gaming and Cognitive Function Changes in Brain-Imaging Studies of Pro Gamers and Individuals With Gaming Disorder: Systematic Literature Review

BACKGROUND

The World Health Organization announced the inclusion of gaming disorder (GD) in the International Classification of Diseases, 11th Revision, despite some concerns. However, video gaming has been associated with the enhancement of cognitive function. Moreover, despite comparable extensive video gaming, pro gamers have not shown any of the negative symptoms that individuals with GD have reported. It is important to understand the association between extensive video gaming and alterations in brain regions more objectively.

OBJECTIVE

This study aimed to systematically explore the association between extensive video gaming and changes in cognitive function by focusing on pro gamers and individuals with GD.

METHODS

Studies about pro gamers and individuals with GD were searched for in the PubMed and Web of Science databases using relevant search terms, for example, "pro-gamers" and "(Internet) gaming disorder." While studies for pro gamers were searched for without date restrictions, only studies published since 2013 about individuals with GD were included in search results. Article selection was conducted by following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines.

RESULTS

By following the PRISMA guidelines, 1903 records with unique titles were identified. Through the screening process of titles and abstracts, 86 full-text articles were accessed to determine their eligibility. A total of 18 studies were included in this systematic review. Among the included 18 studies, six studies included pro gamers as participants, one study included both pro gamers and individuals with GD, and 11 studies included individuals with GD. Pro gamers showed structural and functional alterations in brain regions (eg, the left cingulate cortex, the insula subregions, and the prefrontal regions). Cognitive function (eg, attention and sensorimotor function) and cognitive control improved in pro gamers. Individuals with GD showed structural and functional alterations in brain regions (eg, the striatum, the orbitofrontal cortex, and the amygdala) that were associated with impaired cognitive control and higher levels of craving video game playing. They also showed increased cortical thickness in the middle temporal cortex, which indicated the acquisition of better skills. Moreover, it was suggested that various factors (eg, gaming expertise, duration or severity of GD, and level of self-control) seemed to modulate the association of extensive video game playing with changes in cognitive function.

CONCLUSIONS

Although a limited number of studies were identified that included pro gamers and/or individuals who reported showing symptoms of GD for more than 1 year, this review contributed to the objective understanding of the association between extensive video game playing and changes in cognitive function. Conducting studies with a longitudinal design or with various comparison groups in the future would be helpful in deepening the understanding of this association.

The role of repetitive transcranial magnetic stimulation (rTMS) in the treatment of behavioral addictions: Two case reports and review of the literature

BACKGROUND

Several behaviors, besides consumption of psychoactive substances, produce short-term reward that may lead to persistent aberrant behavior despite adverse consequences. Growing evidence suggests that these behaviors warrant consideration as nonsubstance or "behavioral" addictions, such as pathological gambling, internet gaming disorder and internet addiction.

CASE PRESENTATION

Here, we report two cases of behavioral addictions (BA), compulsive sexual behavior disorder for online porn use and internet gaming disorder. A 57-years-old male referred a loss of control over his online pornography use, started 15 years before, while a 21-years-old male university student reported an excessive online gaming activity undermining his academic productivity and social life. Both patients underwent a high-frequency repetitive transcranial magnetic stimulation (rTMS) protocol over the left dorsolateral prefrontal cortex (l-DLPFC) in a multidisciplinary therapeutic setting. A decrease of addictive symptoms and an improvement of executive control were observed in both cases.

DISCUSSION

Starting from these clinical observations, we provide a systematic review of the literature suggesting that BAs share similar neurobiological mechanisms to those underlying substance use disorders (SUD). Moreover, we discuss whether neurocircuit-based interventions, such as rTMS, might represent a potential effective treatment for BAs.

Reduced frontostriatal functional connectivity and associations with severity of Internet gaming disorder

Cognitive, functional, and structural brain factors involving frontal executive and striatal reward networks have been implicated in Internet gaming disorder (IGD). However, frontostriatal network connectivity and its association with addiction severity are poorly understood in IGD. Resting-state fMRI data from 337 subjects (130 with IGD, 207 with recreational game use [RGU]) were collected. Striatal-cortical communications were measured with resting-state functional connectivity (FC) using coherent spontaneous fluctuations in the blood-oxygenation-level-dependent fMRI signal. Correlations were calculated between FC measures and IGD-related assessments (addiction severity and craving scores). Decreased FC was predominantly observed in IGD subjects, with IGD subjects showing decreased FC between the putamen and superior frontal gyrus (SFG), middle frontal gyrus (MFG), and inferior frontal gyrus (IFG) and the ventral striatum and IFG, superior temporal gyrus, and MFG. Disorder severity and craving scores were negatively correlated with FC between striatal and frontal brain regions. Associations between diminished FC in corticostriatal circuitry and clinical features (IGD craving, severity) suggest potential therapeutic targets for neuromodulation treatments. The extent to which frontostriatal circuits involving executive control over reward processes may be altered to treat IGD warrants additional study.

A neural mechanism of the relationship between impulsivity and emotion dysregulation in patients with Internet gaming disorder

Impulsivity and emotion dysregulation have been known to be risk factors for Internet gaming disorder (IGD), but their underlying neural mechanisms are not yet fully understood. Given that the prefrontal cortex has a key role in higher order cognition and addiction, the present study aimed to investigate emotional influences on response inhibition in situations with different cognitive demands. A total of 41 young male adults (20 with and 21 without IGD) were scanned while performing two versions of an emotional go/no-go task with demands on low and high working memory load. Patients with IGD showed a failure in response inhibition and increased activation of widespread brain regions, including prefrontal, motor-sensory, parietal, occipital, insula, and striatal regions across tasks. Among these regions, involvement of the dorsolateral prefrontal cortex and ventral striatum was observed only during the task with high demands on working memory. Moreover, it was also only during the high-load task that interaction between response inhibition and emotional states was observed in the dorsomedial prefrontal cortex, with observations revealing that its alteration in patients with IGD was associated with number of hours spent on Internet gaming. Our findings highlight a failure of response inhibition and dysfunction within the inhibitory control network. The special significance of our study is that dysfunctional dorsomedial prefrontal cortex may mediate abnormal emotional influences on response inhibition in patients with IGD.

Distinct patterns of prefrontal cortical disengagement during inhibitory control in addiction: A meta-analysis based on population characteristics

Prefrontal cortical dysfunctions underlying inhibitory control deficits in addiction are complex and likely dependent on population characteristics. Here, we conducted a meta-analysis to examine alterations in brain activations during response inhibition in addicted individuals. We characterized imaging findings based on substance use status, diagnosis, substance classes, and task performance. Results revealed in those with active drug addiction hypoactivation of the left dorsal anterior cingulate cortex (dACC) and right middle frontal gyrus (MFG), compared with healthy controls. Weakening of the dACC and MFG activations was particularly pronounced in nicotine users, respectively. Impaired task performance was also associated with diminished MFG activation. In contrast, abstinent users did not exhibit any significant differences compared with healthy controls. Those with behavioral addictions were characterized by higher midcingulate cortical activation. Thus, the neural disengagement during response inhibition in active drug addiction was limited to a small number of prefrontal cortical regions and dependent on population characteristics. Finally, the evidence for potential normalization of hypofrontality following substance use cessation highlights the benefits of abstinence in restoring cerebral functions.

Altered functional network activities for behavioral adjustments and Bayesian learning in young men with Internet gaming disorder

BACKGROUND AND AIMS

Deficits in cognitive control represent a core feature of addiction. Internet Gaming Disorder (IGD) offers an ideal model to study the mechanisms underlying cognitive control deficits in addiction, eliminating the confounding effects of substance use. Studies have reported behavioral and neural deficits in reactive control in IGD, but it remains unclear whether individuals with IGD are compromised in proactive control or behavioral adjustment by learning from the changing contexts.

METHODS

Here, fMRI data of 21 male young adults with IGD and 21 matched healthy controls (HC) were collected during a stop-signal task. We employed group independent component analysis to investigate group differences in temporally coherent, large-scale functional network activities during post-error slowing, the typical type of behavioral adjustments. We also employed a Bayesian belief model to quantify the trial-by-trial learning of the likelihood of stop signal - P(Stop) - a broader process underlying behavioral adjustment, and identified the alterations in functional network responses to P(Stop).

RESULTS

The results showed diminished engagement of the fronto-parietal network during post-error slowing, and weaker activity in the ventral attention and anterior default mode network in response to P(Stop) in IGD relative to HC.

DISCUSSION AND CONCLUSIONS

These results add to the literatures by suggesting deficits in updating and anticipating conflicts as well as in behavioral adjustment according to contextual information in individuals with IGD.

Effects of excessive violent video game playing on verbal memory: an event-related brain potentials study

The goal of the study was to investigate temporal dynamics of excessive violent game playing. We compared behavioral data and event-related potentials (ERPs) of excessive video game players (EVGPs, n = 21) and non-players (NPs, n = 21) using a classical learning, cued recall and recognition paradigm, featuring violent and non-violent words. During the recognition phase, EVGPs performed better for violent words, but worse for non-violent words compared to NPs. Also, EVGPs showed slower reaction times than NPs when responding to new violent words. We found significant group differences in parietal P300 and FN400 amplitudes. The EVGP group showed larger P300 amplitudes for violent words, and more negative FN400 amplitudes for new violent words compared to NPs. The results imply that EVGPs differ from NPs in their cognitive and ERP responses to violent and non-violent verbal stimuli. The cognitive processes of EVGPs are consistent with a model of attention and memory bias rather than with desensitization to violence.

The imbalance between goal-directed and habitual systems in internet gaming disorder: Results from the disturbed thalamocortical communications

BACKGROUND

Converging evidence has identified the imbalance between goal-directed systems and habitual systems in the addiction process. The thalamocortical loop plays an important role in the habitual/goal-directed system. However, little is known about the role of the thalamus in goal-directed and habitual systems in Internet gaming disorder (IGD) patients. This study investigated whether thalamocortical circuit was disrupted and how they affected goal-directed and habitual behaviors in IGD patients.

METHODS

This is a functional magnetic resonance imaging (fMRI) study. Twenty-five IGD patients and 25 matched recreational game users (RGUs) were scanned when they were in a resting state and were performing an instrumental learning task to obtain behavioral data related to habitual/goal-directed behavior. We used the whole-brain seed-based functional connectivity (FC) of the four thalamic nuclei (bilateral) and correlation analyses to examine the thalamocortical loop difference and relationship with habitual/goal-directed performance.

RESULTS

Compared with RGUs, IGD patients demonstrated significantly increased FC between the left midline nucleus (MN) and the right postcentral gyrus (PCG), and between the pulvinar and medial frontal gyrus (MFG). Correlation results showed that within the IGD group, the correct response rates of the participants to inconsistent stimulus-result pairs were positively correlated with the FC between the pulvinar and MFG. Inhibition-control scores were negatively correlated with the FC between the left MN and the PCG.

CONCLUSIONS

IGD patients showed disrupted thalamocortical communication that could further result in an imbalance between the goal-directed and habitual systems in IGD patients. These findings provide more information about the involvement of the thalamus in the pathophysiology of IGD, and as potential circuit-level biomarkers of IGD patients, these circuit alterations may be useful in treatment development and in monitoring treatment outcomes.

Impulsivity in heroin-dependent individuals: structural and functional abnormalities within frontostriatal circuits

High levels of impulsivity are a risk factor for the initiation of heroin use and a core behavioral characteristic of heroin dependence. Impulsivity also contributes to the maintenance of drug use and hinders effective therapy. Here we sought to identify neuroimaging markers of impulsivity in heroin-dependent individuals (HDI), with a focus on the nucleus accumbens (NAc), a key region implicated in impulsivity and drug addiction generally. Volume and resting-state functional connectivity (RSFC) differences of the bilateral NAc were investigated between 21 HDI and 21 age-, gender-, nicotine-, alcohol-matched healthy controls (HC). The neuroimaging results were then correlated with the Barratt Impulsivity Scales (BIS-11). Higher motor impulsivity (t = 2.347, p = 0.0253) and larger right NAc volume (F (1,38) = 4.719, p = 0.036) was observed in HDI. The right NAc volume was positively correlated with BIS total (r = 0.6196, p = 0.0239) /motor (r = 0.5921, p = 0.0330) scores in HC and BIS motor (r = 0.5145, p = 0.0170) score in HDI. A negative correlation was found between RSFC of the right NAc-bilateral superior frontal gyrus (SFG) and motor impulsivity in HDI (left: r=-0.6537, p = 0.0013; right: r=-0.6167, p = 0.0029) and HC (left: r=-0.6490,p = 0.0164; right: r=-0.6993, p = 0.0078). We aimed to reveal novel multimodality neuroimaging biomarkers of the higher impulsivity in HDI by focusing on the NAc and corresponding functional circuits. Higher motor impulsivity was observed in HDI. Furthermore, the volume of the right NAc and the RSFC strength of right NAc-SFG could be neuroimaging biomarkers for the severity of impulsivity in HDI. These potential biomarkers could be a target for novel treatments in HDI.

Monetary Reward Discounting, Inhibitory Control, and Trait Impulsivity in Young Adults With Internet Gaming Disorder and Nicotine Dependence

Internet Gaming Disorder (IGD) has been considered a potential behavioral or non-substance addiction that requires further investigation. Recognition of the commonalities between IGD and Substance Use disorders (SUD) would be of great help to better understand the basic mechanisms of addictive behaviors and excessive Internet gaming. However, little research has targeted a straightforward contrast between IGD and SUD on neuropsychological aspects. The present study thus aimed to explore the associations of reward processing and inhibitory control with IGD and nicotine dependence (ND) in young adults. Fifty-eight IGD and 53 ND individuals, as well as 57 age- and gender-matched healthy controls, were assessed with a series of measurements including the Delay-discounting Test (DDT), Probability Discounting Test (PDT), the Stroop Color-Word Task, a revised Go/No Go Task, and the Barratt Impulsiveness Scale (BIS-11). Multivariate analysis of variance (mANOVA) models revealed that both IGD and ND groups scored higher than healthy controls on the BIS-11 attentional, motor, and non-planning impulsiveness (Cohen's d = 0.41-1.75). Higher degrees of delay discounting on the DDT were also found in IGD and ND groups compared to healthy controls (Cohen's d = 0.53-0.69). Although IGD group did not differ from healthy controls on the PDT, ND group had a lower degree of probability discounting than healthy controls (Cohen's d = 0.55), suggesting a reduction in risk aversion. Furthermore, ND subjects showed a lower correct accuracy in the incongruent trials of the Stroop task than healthy controls (Cohen's d = 0.61). On the Go/No Go task, both IGD and ND groups had a lower correct accuracy in the No-Go trials than healthy controls (Cohen's d = 1.35-1.50), indicating compromised response inhibition. These findings suggested that IGD was linked to both anomalous reward discounting and dysfunctional inhibitory control, which was comparable with one typical SUD category (i.e., ND). This study might promote a better understanding of the pathogenesis of IGD as a potential addictive disorder similar to SUD.

Structural and Functional Brain Abnormalities in Internet Gaming Disorder and Attention-Deficit/Hyperactivity Disorder: A Comparative Meta-Analysis

Background: Patients with Internet gaming disorder (IGD) and attention-deficit/hyperactivity disorder (ADHD) have high comorbidity but it is still unknown whether these disorders have shared and distinctive neuroimage alterations. Objective: The aim of this meta-analysis was to identify shared and disorder-specific structural, functional, and multimodal abnormalities between IGD and ADHD. Methods: A systematic literature search was conducted for whole-brain voxel-based morphometry (VBM) and functional magnetic resonance imaging (fMRI) studies comparing people with IGD or ADHD with healthy controls. Regional gray matter volume (GMV) and fMRI differences were compared over the patient groups and then a quantitative comparison was performed to find abnormalities (relative to controls) between IGD and ADHD using seed-based d mapping meta-analytic methods. Result: The meta-analysis contained 14 IGD VBM studies (contrasts covering 333 IGDs and 335 HCs), 26 ADHD VBM studies (1,051 patients with ADHD and 887 controls), 30 IGD fMRI studies (603 patients with IGD and 564 controls), and 29 ADHD fMRI studies (878 patients with ADHD and 803 controls). Structurally, VBM analysis showed disorder-specific GMV abnormality in the putamen among IGD subjects and orbitofrontal cortex in ADHD and shared GMV in the prefrontal cortex. Functionally, fMRI analysis discovered that IGD-differentiating increased activation in the precuneus and shared abnormal activation in anterior cingulate cortex, insular, and striatum. Conclusion: IGD and ADHD have shared and special structural and functional alterations. IGD has disorder-differentiating structural alterations in the putamen and ADHD has alterations in the orbitofrontal cortex. Disorder-differentiating fMRI activations were predominantly observed in the precuneus among IGD subjects and shared impairing function connection was in the rewards circuit (including ACC, OFC, and striatum).

Cognitive Correlates in Gaming Disorder and Social Networks Use Disorder: a Comparison

Purpose of Review

This overview aims at summarizing studies, which investigated cognitive correlates of gaming disorder and of a problematic use of social networks by using behavioral experimental paradigms and brain imaging techniques.

Recent Findings

Based on theoretical models, inhibition/inhibitory control, attentional bias, executive functions, decision-making, and working memory capabilities have been identified as cognitive components, which are assumed to play a crucial role in the development and maintenance of an addictive behavior. A systematic search shows that various studies have already examined the involvement of different cognitive components in both types of potential addictive behaviors. However, the number of studies addressing cognitive correlates of social networks use disorder is very much lower compared with gaming disorder, even if there is a positive trend in terms of new publications in recent years.

Summary

Cognitive correlates have been frequently investigated in gaming disorder, as in many other disorders due to substance use or addictive behaviors. Studies on cognitive aspects involved in a problematic social networks use are still rare, but they are needed in order to further show if this phenomenon may also deserve a classification as addictive disorder. Interactions between different cognitive and affective processes are still understudied in both gaming disorder and problematic social networks use.

Altered brain network topology related to working memory in internet addiction

BACKGROUND AND AIMS

The working memory (WM) ability of internet addicts and the topology underlying the WM processing in internet addiction (IA) are poorly understood. In this study, we employed a graph theoretical framework to characterize the topological properties of the IA brain network in the source cortical space during WM task.

METHODS

A sample of 24 subjects with IA and 23 matched healthy controls (HCs) performed visual 2-back task. Exact Low Resolution Electromagnetic Tomography was adopted to project the pre-processed EEG signals into source space. Subsequently, Lagged phase synchronization was calculated between all pairs of Brodmann areas, the graph theoretical approaches were then employed to estimate the brain topological properties of all participants during the WM task.

RESULTS

We found better WM behavioral performance in IA subjects compared with the HCs. Moreover, compared to the HC group, more integrated and hierarchical brain network was revealed in the IA subjects in alpha band. And altered regional centrality was mainly resided in frontal and limbic lobes. In addition, significant relationships between the IA severity and the significant altered graph indices were found.

CONCLUSIONS

In conclusion, these findings provide evidence to support the notion that altered topological configuration may underline changed WM function observed in IA.

Shared gray matter alterations in individuals with diverse behavioral addictions: A voxel-wise meta-analysis

BACKGROUND AND AIMS

Numerous studies on behavioral addictions (BAs) have reported gray matter (GM) alterations in multiple brain regions by using voxel-based morphometry (VBM). However, findings are poorly replicated and it remains elusive whether distinct addictive behaviors are underpinned by shared abnormalities. In this meta-analysis, we integrated VBM studies on different BAs to investigate common GM abnormalities in individuals with BAs.

METHODS

Numerous studies on behavioral addictions (BAs) have reported gray matter (GM) alterations in multiple brain regions by using voxel-based morphometry (VBM). However, findings are poorly replicated and it remains elusive whether distinct addictive behaviors are underpinned by shared abnormalities. In this meta-analysis, we integrated VBM studies on different BAs to investigate common GM abnormalities in individuals with BAs.

RESULTS

Twenty studies including 505 individuals with BAs and 564 healthy controls met the inclusion criteria. Compared with healthy controls, individuals with BAs showed GM atrophy in the left anterior cingulate (extending to the left medial superior frontal gyrus and bilateral orbitofrontal gyrus), right putamen and right supplementary motor area. Subgroup analysis found heterogeneity in gender and subtypes of BAs. Meta-regression revealed that GM decreases in the left anterior cingulate and right supplementary motor area were positively correlated with addictive severity. Higher impulsivity was associated with smaller volume of the left anterior cingulate.

DISCUSSION AND CONCLUSIONS

Our findings on BAs were mainly derived from internet gaming disorder (IGD) and pathological gambling (PG) studies, preliminarily suggesting that GM atrophy in the prefrontal and striatal areas might be a common structural biomarker of BAs.

Impaired regulation of both addiction-related and primary rewards in individuals with internet gaming disorder

Poor executive function (EF) has been implicated in addictions. Among "hot" EFs (i.e., those involving motivations and emotions), poor regulation of craving has been proposed to underlie addiction development in substance-use disorders (SUDs), making such regulation a potential treatment target. However, regulation of craving remains poorly understood in internet gaming disorder (IGD). Additionally, prior studies of cold EFs (e.g., inhibition and cognitive flexibility under neutral conditions) in IGD have provided mixed results and mostly included only male subjects. We addressed these issues by instructing 54 participants (26 with IGD including males and females, and 28 control subjects) to perform a regulation-of-craving (ROC) task and a Stroop color-word-interference task. Compared to control subjects, individuals with IGD revealed deficits in regulation for both gaming- and food-related craving, but no differences in Stroop performance. The current study provides initial empirical support suggesting regulation impairments for both addiction-related and primary rewards among individuals with IGD. The findings are consistent with studies in SUDs, suggesting that impaired regulation of craving may be a relevant transdiagnostic construct across SUDs and behavioral addictions. The findings suggest targeting regulation of "hot" processes should be considered in IGD treatment development.

Internet addiction disorder detection of Chinese college students using several personality questionnaire data and support vector machine

With the unprecedented development of the Internet, it also brings the challenge of Internet Addiction (IA), which is hard to diagnose and cure according to the state-of-art research. In this study, we explored the feasibility of machine learning methods to detect IA. We acquired a dataset consisting of 2397 Chinese college students from the University (Age: 19.17 ± 0.70, Male: 64.17%) who completed Brief Self Control Scale (BSCS), the 11th version of Barratt Impulsiveness Scale (BIS-11), Chinese Big Five Personality Inventory (CBF-PI) and Chen Internet Addiction Scale (CIAS), where CBF-PI includes five sub-features (Openness, Extraversion, Conscientiousness, Agreeableness, and Neuroticism) and BSCS includes three sub-features (Attention, Motor and Non-planning). We applied Student's t-test on the dataset for feature selection and Support Vector Machines (SVMs) including C-SVM and ν-SVM with grid search for the classification and parameters optimization. This work illustrates that SVM is a reliable method for the assessment of IA and questionnaire data analysis. The best detection performance of IA is 96.32% which was obtained by C-SVM in the 6-feature dataset without normalization. Finally, the BIS-11, BSCS, Motor, Neuroticism, Non-planning, and Conscientiousness are shown to be promising features for the detection of IA.

Cognitive deficits in problematic internet use: meta-analysis of 40 studies

BACKGROUND

Excessive use of the internet is increasingly recognised as a global public health concern. Individual studies have reported cognitive impairment in problematic internet use (PIU), but have suffered from various methodological limitations. Confirmation of cognitive deficits in PIU would support the neurobiological plausibility of this disorder.

AIMS

To conduct a rigorous meta-analysis of cognitive performance in PIU from case-control studies; and to assess the impact of study quality, the main type of online behaviour (for example gaming) and other parameters on the findings.

METHOD

A systematic literature review was conducted of peer-reviewed case-controlled studies comparing cognition in people with PIU (broadly defined) with that of healthy controls. Findings were extracted and subjected to a meta-analysis where at least four publications existed for a given cognitive domain of interest.

RESULTS

The meta-analysis comprised 2922 participants across 40 studies. Compared with controls, PIU was associated with significant impairment in inhibitory control (Stroop task Hedge's g = 0.53 (s.e. = 0.19-0.87), stop-signal task g = 0.42 (s.e. = 0.17-0.66), go/no-go task g = 0.51 (s.e. = 0.26-0.75)), decision-making (g = 0.49 (s.e. = 0.28-0.70)) and working memory (g = 0.40 (s.e. = 0.20-0.82)). Whether or not gaming was the predominant type of online behaviour did not significantly moderate the observed cognitive effects; nor did age, gender, geographical area of reporting or the presence of comorbidities.

CONCLUSIONS

PIU is associated with decrements across a range of neuropsychological domains, irrespective of geographical location, supporting its cross-cultural and biological validity. These findings also suggest a common neurobiological vulnerability across PIU behaviours, including gaming, rather than a dissimilar neurocognitive profile for internet gaming disorder.

DECLARATION OF INTEREST

S.R.C. consults for Cambridge Cognition and Shire. K.I.'s research activities were supported by Health Education East of England Higher Training Special interest sessions. A.E.G.'s research has been funded by Innovational grant (VIDI-scheme) from ZonMW: (91713354). N.A.F. has received research support from Lundbeck, Glaxo-SmithKline, European College of Neuropsychopharmacology (ECNP), Servier, Cephalon, Astra Zeneca, Medical Research Council (UK), National Institute for Health Research, Wellcome Foundation, University of Hertfordshire, EU (FP7) and Shire. N.A.F. has received honoraria for lectures at scientific meetings from Abbott, Otsuka, Lundbeck, Servier, Astra Zeneca, Jazz pharmaceuticals, Bristol Myers Squibb, UK College of Mental Health Pharmacists and British Association for Psychopharmacology (BAP). N.A.F. has received financial support to attend scientific meetings from RANZCP, Shire, Janssen, Lundbeck, Servier, Novartis, Bristol Myers Squibb, Cephalon, International College of Obsessive-Compulsive Spectrum Disorders, International Society for Behavioral Addiction, CINP, IFMAD, ECNP, BAP, the World Health Organization and the Royal College of Psychiatrists. N.A.F. has received financial royalties for publications from Oxford University Press and payment for editorial duties from Taylor and Francis. J.E.G. reports grants from the National Center for Responsible Gaming, Forest Pharmaceuticals, Takeda, Brainsway, and Roche and others from Oxford Press, Norton, McGraw-Hill and American Psychiatric Publishing outside of the submitted work.

Meta-analyses of the functional neural alterations in subjects with Internet gaming disorder: Similarities and differences across different paradigms

Internet gaming disorder (IGD) has become a global public health concern due to its increasing prevalence and potential negative consequences. Researchers have sought to identify which brain regions are associated with this disorder. However, inconsistent results have been reported among studies due to the heterogeneity of paradigms and subjects. The present research aimed to combine the results of individual studies to provide a more coherent and powerful explanation. By selecting 40 studies utilizing a qualified whole-brain analysis, we performed a comprehensive series of meta-analyses that employed seed-based d mapping. We divided the existing experimental paradigms into 3 categories: game-related cue-reactivity, executive control, and risk-reward-related decision-making tasks. We divided all studies into three subgroups according to their paradigms. In cue-reactivity tasks, patients with IGD exhibited significant hyperactivation in the bilateral precuneus and bilateral cingulate and significant hypoactivation in the insula, but there were no differences in the striatum. In executive control tasks, patients with IGD displayed significant hyperactivation in the right superior temporal gyrus, bilateral precuneus, bilateral cingulate, and insula and hypoactivation in the left inferior frontal gyrus. In risky decision-making paradigms, IGD patients exhibited significant hyperactivation in the left striatum, right inferior frontal gyrus, and insula and hypoactivation in the left superior frontal gyrus, left inferior frontal gyrus, and right precentral gyrus. Our study aimed to discover the similarities among all studies and to explore the uniqueness of the different paradigms. This study further confirmed the critical role of reward circuitry and executive control circuitry in IGD but not under all conditions.

Neural correlates of inhibition and reward are negatively associated

Individuals with impulsive and addictive disorders, including drug addiction, binge eating/obesity, and problem gambling, exhibit both impaired control over behavior and heightened sensitivity to reward. However, it is not known whether such deviation in inhibitory and reward circuitry among clinical populations is a cause or consequence of the disorders. Recent evidence suggests that these constructs may be related at the neural level, and together, increase risk for engaging in maladaptive behaviors. The current study examined the degree to which brain function during inhibition relates to brain function during receipt of reward in healthy young adults who have not yet developed problem behaviors. Participants completed the stop signal task to assess inhibitory control and the doors task to assess reactivity to monetary reward (win vs loss) during functional magnetic resonance imaging (fMRI). Brain activation during response inhibition was negatively correlated with brain activation during reward. Specifically, less brain activation in right prefrontal regions during inhibition, including the right inferior frontal gyrus, middle frontal gyrus, and supplementary motor area, was associated with greater brain activation in left ventral striatum during receipt of monetary reward. Moreover, these associations were stronger in binge drinkers compared to non-binge drinkers. These findings suggest that the systems are related even before the onset of impulsive or addictive disorders. As such, it is possible that the association between inhibitory and reward circuitry may be a prospective marker of risk.

Differentiation between young adult Internet addicts, smokers, and healthy controls by the interaction between impulsivity and temporal lobe thickness

BACKGROUND AND AIMS

Internet addiction is a non-substance-related addiction disorder with progressively growing prevalence. Internet addiction, like substance-related addictions, has been linked with high impulsivity, low inhibitory control, and poor decision-making abilities. Cortical thickness measurements and trait impulsivity have been shown to have a distinct relationship in addicts compared to healthy controls. Thus, we test whether the cortical correlates of trait impulsivity are different in Internet addicts and healthy controls, using an impulsive control group (smokers).

METHODS

Thirty Internet addicts (15 females) and 60 age- and gender-matched controls (30 smokers, all young adults aged 19-28 years) were scanned using a 3T MRI scanner and completed the Barratt Impulsiveness Scale.

RESULTS

Internet addicts had a thinner left superior temporal cortex than controls. Impulsivity had a significant main effect on the left pars orbitalis and bilateral insula, regardless of group membership. We identified divergent relationships between trait impulsivity and thicknesses of the bilateral middle temporal, right superior temporal, left inferior temporal, and left transverse temporal cortices between Internet addicts and healthy controls. Further analysis with smokers revealed that the left middle temporal and left transverse temporal cortical thickness change might be exclusive to Internet addiction.

DISCUSSION

The effects of impulsivity, combined with a long-term exposure to some specific substance or stimuli, might result in different natures of relationships between impulsivity and brain structure when compared to healthy controls.

CONCLUSION

These results may indicate that Internet addiction is similar to substance-related addictions, such that inefficient self-control could result in maladaptive behavior and inability to resist Internet use.

Mapping Internet gaming disorder using effective connectivity: A spectral dynamic causal modeling study

OBJECTS

Understanding the neural basis underlying Internet gaming disorder (IGD) is essential for the diagnosis and treatment of this type of behavioural addiction. Aberrant resting-state functional connectivity (rsFC) of the default mode network (DMN) has been reported in individuals with IGD. Since rsFC is not a directional analysis, the effective connectivity within the DMN in IGD remains unclear. Here, we employed spectral dynamic causal modeling (spDCM) to explore this issue.

METHODS

Resting state fMRI data were collected from 64 IGD (age: 22.6 ± 2.2) and 63 well-matched recreational Internet game users (RGU, age: 23.1 ± 2.5). Voxel-based mean time series data extracted from the 4 brain regions within the DMN (medial prefrontal cortex, mPFC; posterior cingulate cortex, PCC; bilateral inferior parietal lobule, left IPL/right IPL) of two groups during the resting state were used for the spDCM analysis.

RESULTS

Compared with RGU, IGD showed reduced effective connectivity from the mPFC to the PCC and from the left IPL to the mPFC, with reduced self-connection in the PCC and the left IPL.

CONCLUSIONS

The spDCM could distinguish the changes in the functional architecture between two groups more precisely than rsFC. Our findings suggest that the decreased excitatory connectivity from the mPFC to the PCC may be a crucial biomarker for IGD. Future brain-based intervention should pay attention to dysregulation in the IPL-mPFC-PCC circuits.

Stress System Response and Decision Making in Heavy Episodic Users of Alcohol and Online Video Games

Objective: Few empirical studies have addressed stress system response and subsequent decision making in problematic online video game players who also consume alcohol. Method: Participants were randomly assigned to either receive a psychosocial stressor, including evaluated public speaking and mental arithmetic, or control condition. Salivary cortisol, cardiovascular and subjective responses were collected. Following, decision making was assessed using the Iowa Gambling Task. Results: In this sample of moderate internet gamers (N = 71; 45 male, 16.9% meeting suggested DSM-5 criteria for internet gaming disorder), 53.52% met gender-specific cut-points for heavy episodic drinking. Overall, participants in the TSST condition demonstrated elevated systolic and diastolic blood pressure, self-reported anxiety, and negative affect (ps < .05). However, response to the TSST was varied, particularly in individuals reporting binge internet gaming (6 h or more consecutive use in the last 30 d) who did not display the expected decline in positive affect in response to the TSST (p = .02). Differences in greater advantageous decision making between heavy episodic internet gaming participants in the stress condition, versus those reading a travel magazine, were also noted. These differences were not significant in participants reporting an absence of heavy episodic gaming behavior. Conclusions: These findings support the continued study of individuals who engage in problematic internet gaming behavior, particularly those who engage in heavy episodic use of alcohol.

Abnormal gray matter volume and impulsivity in young adults with Internet gaming disorder

Reduced executive control is one of the central components of model on the development and maintenance of Internet gaming disorder (IGD). Among the various executive control problems, high impulsivity has consistently been associated with IGD. We performed voxel-based morphometric analysis with diffeomorphic anatomical registration by using an exponentiated Lie algebra algorithm (DARTEL) to investigate the relationship of gray matter abnormalities to impulsivity in IGD. Thirty-one young male adults whose excessive Internet gaming began in early adolescence, and 30 age-matched male healthy controls were examined. IGD subjects showed smaller gray matter volume (GMV) in brain regions implicated in executive control, such as the anterior cingulate cortex and the supplementary motor area. The GMVs in the anterior cingulate cortex and the supplementary motor area were negatively correlated with self-reporting scales of impulsiveness. IGD subjects also exhibited smaller GMV in lateral prefrontal and parietal cortices comprising the left ventrolateral prefrontal cortex and the left inferior parietal lobule when compared with healthy controls. The GMVs in the left ventrolateral prefrontal cortex were negatively correlated with lifetime usage of Internet gaming. These findings suggest that gray matter abnormalities in areas related to executive control may contribute to high impulsivity of young adults with IGD. Furthermore, alterations in the prefrontal cortex were related with long-term excessive Internet gaming during adolescence.

Subregions of the Anterior Cingulate Cortex Form Distinct Functional Connectivity Patterns in Young Males With Internet Gaming Disorder With Comorbid Depression

Depression is one of the most common comorbid conditions in Internet Gaming Disorder (IGD). Although there have been many studies on the pathophysiology of IGD, the neurobiological basis underlying the close association between depression and IGD has not been fully clarified. Previous neuroimaging studies have demonstrated functional and structural abnormalities in the anterior cingulate cortex (ACC) in IGD patients. In this study, we explored functional connectivity (FC) abnormalities involving subregions of the ACC in IGD subjects with comorbid depression. We performed a resting state seed-based FC analysis of 21 male young adults with IGD with comorbid depression (IGDdep+ group, 23.6 ± 2.4 years), 22 male young adults without IGD with comorbid depression (IGDdep- group, 24.0 ± 1.6 years), and 20 male age-matched healthy controls (24.0 ± 2.2 years). ACC-seeded FC was evaluated using the CONN-fMRI FC toolbox. The dorsal ACC (dACC), the pregenual ACC (pgACC), and the subgenual ACC (sgACC) were selected as seed regions. Both IGD groups had stronger pgACC FC with the right precuneus, the posterior cingulate cortex, and the left inferior frontal gyrus/insula than the control group. The IGDdep+ group had stronger dACC FC with the left precuneus and the right cerebellar lobule IX than the control and IGDdep- groups. The IGDdep+ group also had weaker pgACC FC with the right dorsomedial prefrontal cortex and the right supplementary motor area and had weaker sgACC FC with the left precuneus, the left lingual gyrus, and the left postcentral gyrus than the other groups. The strength of the connectivity between the sgACC and the left precuneus correlated positively with a higher omission error rate in the continuous performance test in the IGDdep+ group. In addition, the IGDdep- group had stronger sgACC FC with the left dorsolateral prefrontal cortex than the other groups. Our findings suggest that young males with IGD comorbid with depression have FC alterations of the default mode network and diminished FC with the prefrontal cortex. This altered FC pattern may be involved in the close association of IGD and depression.

The Comorbidity Between Internet Gaming Disorder and Depression: Interrelationship and Neural Mechanisms

Internet gaming disorder (IGD) is characterized by cognitive and emotional deficits. Previous studies have reported the co-occurrence of IGD and depression. However, extant brain imaging research has largely focused on cognitive deficits in IGD. Few studies have addressed the comorbidity between IGD and depression symptoms and underlying neural mechanisms. Here, we systematically investigated this issue by combining a longitudinal survey study, a cross-sectional resting-state functional connectivity (rsFC) study and an intervention study. Autoregressive cross-lagged modeling on a longitudinal dataset of college students showed that IGD severity and depression are reciprocally predictive. At the neural level, individuals with IGD exhibited enhanced rsFC between the left amygdala and right dorsolateral prefrontal cortex (DLPFC), inferior frontal and precentral gyrus, compared with control participants, and the amygdala-frontoparietal connectivity at the baseline negatively predicted reduction in depression symptoms following a psychotherapy intervention. Further, following the intervention, individuals with IGD showed decreased connectivity between the left amygdala and left middle frontal and precentral gyrus, as compared with the non-intervention group. These findings together suggest that IGD may be closely associated with depression; aberrant rsFC between emotion and executive control networks may underlie depression and represent a therapeutic target in individuals with IGD. Registry name: The behavioral and brain mechanism of IGD; URL: https://www.clinicaltrials.gov/ct2/show/NCT02550405; Registration number: NCT02550405.