Caudate nucleus volume mediates the link between glutamatergic neurotransmission and problematic smartphone use in youth

Subjective well-being can be predicted by caudate volume and promotion focus

It is well-known that the caudate nucleus is associated with motivational behaviors and subjective well-being. However, no longitudinal studies have examined the relationship between brain structure, behavioral orientations, and subjective well-being. This study analyzes data from our previous longitudinal study to examine whether future subjective well-being can be predicted by the volume of the caudate nucleus. We also examined whether behavioral orientation, based on the regulatory focus theory showing two orientations-promotion and prevention focus-was related to the volume of the caudate nucleus. Voxel-based morphometry analysis indicated that the left caudate volume was positively associated with rating scores for future subjective well-being and promotion orientation. Further, mediation analysis indicated that promotion orientation significantly mediated the relationship between future subjective well-being and left caudate volume. The findings indicate that future subjective well-being can be predicted by the volume of the left caudate nucleus, and that this relationship is mediated by promotion focus orientation.

Genes associated with cortical thickness alterations in behavioral addiction

Behavioral addiction (BA) is a conceptually new addictive phenotype characterized by compulsive reward-seeking behaviors despite adverse consequences. Currently, its underlying neurogenetic mechanism remains unclear. Here, this study aimed to investigate the association between cortical thickness (CTh) and genetic phenotypes in BA. We conducted a systematic search in five databases and extracted gene expression data from the Allen Human Brain Atlas. Meta-analysis of 10 studies (343 addicted individuals and 355 controls) revealed that the BA group showed thinner CTh in the precuneus, postcentral gyrus, orbital-frontal cortex, and dorsolateral prefrontal cortex (P < 0.005). Meta-regression showed that the CTh in the precuneus and postcentral gyrus were negatively associated with the addiction severity (P < 0.0005). More importantly, the CTh phenotype of BA was spatially correlated with the expression of 12 genes (false discovery rate [FDR] < 0.05), and the dopamine D2 receptor had the highest correlation (rho = 0.55). Gene enrichment analysis further revealed that the 12 genes were involved in the biological processes of behavior regulation and response to stimulus (FDR < 0.05). In conclusion, our findings demonstrated the thinner CTh in cognitive control-related brain areas in BA, which could be associated with the expression of genes involving dopamine metabolism and behavior regulation.

The Effects of Digital Addiction on Brain Function and Structure of Children and Adolescents: A Scoping Review

The escalating prevalence of studies investigating digital addiction (DA) and its detrimental impact on the human brain's structure and functionality has been noticeable in recent years. Yet, an overwhelming majority of these reviews have been predominantly geared towards samples comprising college students or adults and have only inspected a single variant of DA, such as internet gaming disorder, internet addiction disorder, problematic smartphone use, tablet overuse, and so forth. Reviews focusing on young children and adolescents (ages 0-18), or those which amalgamate various types of DA, are decidedly scarce. Given this context, summarizing the effects of DA on brain structure and functionality during the vital developmental stage (0-18 years) is of immense significance. A scoping review, complying with the PRISMA extension for such reviews, was conducted to amalgamate findings from 28 studies spanning a decade (2013-2023) and to examine the influence of assorted forms of DA on the brains of children and adolescents (0-18 years). The synthesized evidence indicated two primary results: (1) DA exerts harmful effects on the structure and functionality of the brains of children and adolescents, and (2) the prefrontal lobe is the region most consistently reported as impacted across all research. Furthermore, this review discerned a notable void of studies investigating the neural indices of digital addiction, along with a shortage of studies focusing on young children (0-6 years old) and longitudinal evidence. This research could provide the necessary theoretical basis for the thwarting and intervention of digital addiction, a measure indispensable for ensuring healthy brain development in children and adolescents.

High intensity interval training exercise increases dopamine D2 levels and modulates brain dopamine signaling

Background

Previous research has outlined the health benefits of exercise including its therapeutic potential for substance use disorders (SUD). These data have already been utilized and it is now common to find exercise as part of SUD treatment and relapse prevention programs. However, we need to better understand different exercise regimens and determine which would be the most beneficial for SUDs. Recently, high intensity interval training (HIIT) has gained attention in comparison with aerobic and resistance exercise. Little is known regarding the neurobiological mechanisms of HIIT, including its effects on dopamine signaling and receptor levels in the brain. The present study examined the effects of chronic HIIT exercise on dopamine signaling as measured by dopamine type 1-like receptor (D1R)-like, dopamine type 2-like receptor (D2R)-like, and tyrosine hydroxylase (TH) quantification in the brains of male and female rats as measured by [3H] SCH 23390 and [3H] spiperone autoradiography, and TH-immunoreactive optical density values.

Methods

Rats were separated in two groups: sedentary and HIIT exercise. Exercise was on a treadmill for 30 min daily (10 3 min cycles) for six weeks with progressive speed increased up to 0.8 mph (21.5 m/min).

Results

Results showed for D2R-like binding, a significant effect across the ventral caudate putamen (V CPU) between sexes, such that mean D2R-like binding was 14% greater for males than females. In the nucleus accumbens shell (Nac Shell), the HIIT Exercise rats showed 16% greater D2R-like binding as compared to the sedentary rats. No significant effects of HIIT exercise were found across groups for brain D1R-like binding levels or TH expression.

Conclusion

These results suggest that HIIT exercise can modulate dopamine signaling by way of increased D2R. These findings support the premise that HIIT exercise plays an important role in dopamine signaling and, may provide a potential mechanism for how HIIT exercise can impact the brain and behavior.

Association between mobile phone addiction, chronotype and nonsuicidal self-injury among adolescents: A large-scale study in China

BACKGROUND

Nonsuicidal self-injury (NSSI) is a serious public health and clinical problem, particularly for adolescents, and may link to problematic smartphone use (PSU) and chronotype. This study examines the independent and interaction effects of PSU and chronotype on NSSI among adolescents and identified gender differences in these associations.

METHODS

A total of 21,357 students aged 11-19 were recruited using stratified cluster sampling across five representative provinces in China and completed standard questionnaires to record details of PSU, chronotype, and NSSI.

RESULTS

A total of 38.1 % of students reported having engaged in NSSI and 17.7 % had PSU. PSU and chronotype were significantly associated with NSSI among adolescents, and this relationship was stronger in females. Interaction analysis indicated that E-type and PSU were interactively associated with increased risks of NSSI.

CONCLUSION

The findings suggest that E-type and PSU can increase the risk of NSSI both independently and interactively. Therefore, they should be considered in intervention programs for NSSI, especially for females.

Neuroimaging the effects of smartphone (over-)use on brain function and structure-a review on the current state of MRI-based findings and a roadmap for future research

The smartphone represents a transformative device that dramatically changed our daily lives, including how we communicate, work, entertain ourselves, and navigate through unknown territory. Given its ubiquitous availability and impact on nearly every aspect of our lives, debates on the potential impact of smartphone (over-)use on the brain and whether smartphone use can be "addictive" have increased over the last years. Several studies have used magnetic resonance imaging to characterize associations between individual differences in excessive smartphone use and variations in brain structure or function. Therefore, it is an opportune time to summarize and critically reflect on the available studies. Following this overview, we present a roadmap for future research to improve our understanding of how excessive smartphone use can affect the brain, mental health, and cognitive and affective functions.

Structural and Functional Neural Correlates in Individuals with Excessive Smartphone Use: A Systematic Review and Meta-Analysis

Background: Despite known association of internet addiction with a reduced brain volume and abnormal connectivity, the impact of excessive smartphone use remains unclear. Methods: PubMed, Embase, ClinicalTrial.gov, and Web of Science databases were systematically searched from inception to July 2022 using appropriate keywords for observational studies comparing differences in brain volumes and activations between excessive smartphone users and individuals with regular use by magnetic resonance imaging. Results: Of the 11 eligible studies retrieved from 6993 articles initially screened, seven and six evaluated brain volumes and activations, respectively. The former enrolled 421 participants (165 excessive smartphone users vs. 256 controls), while the latter recruited 276 subjects with 139 excessive smartphone users. The results demonstrated a smaller brain volume in excessive smartphone users compared to the controls (g = −0.55, p < 0.001), especially in subcortical regions (p < 0.001). Besides, the impact was more pronounced in adolescents than in adults (p < 0.001). Regression analysis revealed a significant positive association between impulsivity and volume reduction. Regarding altered activations, the convergences of foci in the declive of the posterior lobe of cerebellum, the lingual gyrus, and the middle frontal gyrus were noted. Conclusions: Our findings demonstrated a potential association of excessive smartphone use with a reduced brain volume and altered activations.

Impact of smartphone overuse on 1-year severe depressive symptoms and momentary negative affect: Longitudinal and experience sampling findings from a representative epidemiological youth sample in Hong Kong

Smartphone overuse can have detrimental impacts on youth mental health. How it may be longitudinally associated with depressive symptoms and functioning, and with daily momentary affect, remains to be investigated. A total of 3,033 young people were consecutively recruited from a large-scale epidemiological youth mental health study in Hong Kong. A subsample (n = 936) was followed-up after 1 year, with experience sampling data collected from 177 participants. Separate multivariable logistic regression models were applied to examine the prospective associations between smartphone overuse and depressive symptoms, with multilevel models fitted to examine its associations with momentary affect. The prevalence of smartphone overuse in the Hong Kong youth population was 29.3%. Smartphone overuse was significantly associated with more depressive symptoms and functional impairments both cross-sectionally and longitudinally. The associations between smartphone overuse and 1-year depressive symptoms were significant, even when accounting for baseline symptoms, social media use, and other risk and protective factors. Baseline depressive symptoms, in contrast, were not associated with 1-year smartphone overuse after adjusting for baseline smartphone overuse. Smartphone overuse was also significantly associated with higher levels of momentary negative affect, even when accounting for depressive symptoms. Strategies to mitigate the impact of smartphone overuse can have important long-term implications.