Liking, wanting, and the incentive-sensitization theory of addiction

The association between cannabis and alcohol co-use and momentary subjective effects: Risks for increasingly hazardous cannabis use

BACKGROUND

Co-use of cannabis and alcohol is associated with a higher prevalence of health-related, psychiatric, and psychosocial impairments. The aims of this study were to 1) examine the association between cannabis and alcohol co-use and subjective effects, 2) determine whether the time between cannabis and alcohol use is associated with subjective effects, and 3) examine whether subjective responses to co-use are associated with hazardous cannabis use over time.

METHODS

Young adults who co-used cannabis and alcohol (N = 155, 55.5 % women, Mean age=21 yo) completed baseline, six-month, and twelve-month assessments of hazardous cannabis use. Co-use and subjective effects were assessed across 21 days of EMA at baseline.

FINDINGS

Co-use was associated with greater momentary subjective intoxication, compared to cannabis- and alcohol-only, and stimulation and bad effects, compared to cannabis-only. Subjective intoxication was significantly higher for co-use within 0-90minutes compared to cannabis-only. Subjective intoxication was significantly higher for co-use within 0-120minutes compared to alcohol-only. Co-use within 0-30minutes was associated with significantly greater stimulation and bad effects, compared to cannabis-only use moments. The extent to which an individual becomes more intoxicated when co-using the greater the risk the individual had for increasing hazardous cannabis use six and twelve months later.

CONCLUSION

Findings indicate that co-use is associated with increased intoxication, compared to cannabis or alcohol use alone, and increased stimulation and bad effects, compared to cannabis use alone. Subjective responses to co-use in a naturalistic setting are important to consider when evaluating long-term risk of cannabis use among young adults.

The interplay between hypothalamic and brainstem nuclei in homeostatic control of energy balance

Energy balance and body weight are tightly regulated by homeostatic and hedonic systems of the brain. These systems are ultimately finely tuned by hypothalamic and extrahypothalamic neurocircuitry that modulate feeding and the appetite signalling cascade. The hypothalamus has been extensively researched and its role in homeostatic regulation of energy balance is well established. Later on, evidence indicated that extrahypothalamic signalling also has a critical role in regulation of body mass across the lifespan. One of these brain regions was the brainstem and specifically the dorsal vagal complex (DVC), which comprises of the area postrema (AP), nucleus of the solitary tract (NTS) and dorsal motor complex of the vagus (DMV). These brain stem nuclei were shown to also finely tune feeding behaviour through catecholaminergic, glutamatergic, and GABAergic signals. Moreover, these nuclei also receive afferent signals from the viscera through the gut, as well as humoral input from the bloodstream. Therefore, these brain stem nuclei are deemed as the port of entry where initial appetite-related signals are first conveyed and then modulated to the forebrain to hypothalamic and extrahypothalamic regions such as the arcuate nucleus (ARC) and parabrachial nucleus (PBN). Understanding the intricate interactions and projections between hypothalamic and brainstem nuclei is instrumental to comprehend energy balance regulation as a whole and to potentially address metabolic conditions such as diabetes and obesity. Further research in this area may lead to the development of targeted pharmacological and lifestyle intervention strategies that could lead to mitigation of metabolic disorders and/or promote a healthier body mass across the life span.

Unraveling the neural dichotomy of consensus and idiosyncratic experiences in short video viewing

Human experiences are inherently shaped by individual perspectives, leading to diverse interpretations of the same events. However, shared activities, such as communal film watching or sports viewing, underscore the dual nature of these experiences: collective joy arises through social interactions, while individual emotional responses are influenced by personal preferences. The neural mechanisms underlying this interplay between shared and idiosyncratic experiences, particularly in the context of reward processing, remain insufficiently explored. In this study, we investigated the neural basis of both communal enjoyment and individual anticipatory responses during short video viewing. Using functional MRI, we measured brain activity in participants as they watched 90 short videos and provided ratings of their reward expectations and experienced pleasure. By integrating intersubject correlation (ISC) and individual-specific analyses, we identified shared and unique neural activity patterns. Our findings reveal that synchronized activity within the default mode network (DMN) and reward-related regions underlies shared experiences of collective pleasure. In contrast, distinct activations in the frontal cortex and caudate nucleus were associated with personal preferences and reward anticipation, highlighting a neural dichotomy between communal enjoyment and individualized reward processing during digital media engagement.

Effects of GLP-1 Receptor Agonists in Alcohol Use Disorder

In the search for novel treatment strategies for alcohol use disorder (AUD), glucagon-like peptide-1 (GLP-1) receptor agonists (GLP-1RAs) approved for treating Type 2 diabetes and obesity have caught much attention. GLP-1 is a naturally occurring peptide produced in the small intestines and the brain, regulating plasma glucose levels and satiety. This focused review will report on the preclinical studies, case stories, register-based cohort studies, brain-imaging data and secondary analysis of clinical data supporting the role of GLP-1RAs as a novel treatment of AUD. Several clinical trials are ongoing, examining the potential effects of the GLP-1RA semaglutide in AUD.

Involvement of CB1R and CB2R Ligands in Sleep Disorders and Addictive Behaviors in the Last 25 Years

Over the last three decades, the decriminalization and legalization of therapeutic and recreational marijuana consumption have increased. Consequently, the availability of marijuana-based products associated with its therapeutic use has increased. These developments have stimulated research on cannabinoids involving a wide range of animal models and clinical trials. Also, it is reported that cannabinoids promote sleep in animal models and naïve human participants, and they seem to improve insomnia and sleep apnea in patients. However, evidence from rigorous clinical trials is needed. In addition, among several physiological processes, cannabinoid receptors modulate dopamine synthesis and release. In this regard, the side effects of marijuana and marijuana derivatives must not be ignored. The chronic consumption of marijuana could reduce dopamine responsivity, increase negative emotionality, and induce anhedonia. Research on the neurobiological changes associated with cannabinoid ligands in animal models, in regard to the consumption of both marijuana and marijuana-based compounds, must improve and the effectiveness of the therapeutic outcomes in clinical trials must be guaranteed. In this review, we include a detailed description of the mechanisms of action of cannabinoids on the brain and their impact on sleep disorders and addictive behaviors to emphasize the need to understand the potential risks and benefits of their therapeutic and recreational use. Evidence from basic research and clinical trials from papers published between 2000 and 2024 are included. The pharmacodynamics of these compounds is discussed in terms of sleep-wake regulation, drug addiction, and addictive behaviors.

The long-term associations of childhood parental loss with attachment, creativity, and epigenetic regulation

The loss of a parent during childhood is a profound event with enduring impacts on psychological and emotional development. This study investigates the long-term effects of childhood parental loss on attachment patterns and openness to experience, with a focus on the epigenetic modulation of the oxytocin and dopamine systems. The sample included 371 participants (51.2% women, ages 26-43), of whom 33 experienced parental loss during childhood. In those individuals who lost a parent, findings revealed comparably lower attachment avoidance and a DNA methylation profile associated with a potential for increased oxytocin activity. Additionally, a DNA methylation profile associated with a potential for heightened dopamine activity was identified in this group, aligning with greater creativity. These findings highlight the intricate interplay of genetic and environmental factors in fostering resilience and personal growth, shedding light on the roles of oxytocin and dopamine in social bonding and the potential for long-term adaptation following early-life trauma.

Current Advances in Behavioral Addictions: From Fundamental Research to Clinical Practice

Gambling disorder is the only behavioral addiction recognized as a clinical disorder in DSM-5, and Internet gaming disorder is included as a condition requiring further research. ICD-11 categorizes gambling and gaming disorders as disorders due to addictive behaviors. Additional behavioral addictions may include compulsive sexual behavior disorder, compulsive buying-shopping disorder, and problematic use of social media. This narrative review summarizes the current state of knowledge regarding these five (potential) disorders due to addictive behaviors. All five (potential) disorders are clinically relevant and prevalent. Behavioral addictions frequently co-occur with other mental and behavioral problems, such as depression, anxiety, and attention deficit hyperactivity disorder. Validated diagnostic instruments exist, with empirical support varying across conditions. No medications have approved indications from regulatory bodies for behavioral addictions, and cognitive-behavioral therapy has the most empirical support for efficacious treatment. Given that behavioral addictions are prevalent, frequently co-occur with psychiatric disorders, may often go undiagnosed and untreated, and have been linked to poorer treatment outcomes, active screening and treatment are indicated. Public health considerations should be expanded, and impacts of modern technologies should be investigated more intensively. Treatment optimization involving pharmacotherapy, psychotherapy, neuromodulation, and their combination warrants additional investigation.

Attentional Processing Biases in Young People With Binging and Purging Behavior

OBJECTIVE

Binging and purging are transdiagnostic features of eating disorders (EDs). Attentional biases (ABs) toward food and body shape cues and negative affect (NA) are associated with ED psychopathology. These ABs might also be present in people with subthreshold ED not meeting full diagnostic criteria. We investigated ABs to food and body shape cues and the interaction between ABs and NA in young people with binge/purge behavior (B/P group) and healthy controls (HC group). Our B/P sample consisted of individuals with threshold and subthreshold ED, including participants with BN, AN-R, and AN-B/P.

METHOD

We conducted two studies. Study 1 recruited n = 54 HC and n = 53 B/P participants aged 16-25, and Study 2 recruited n = 73 HC and n = 72 B/P participants. In Study 1, ABs toward food and body shape cues were compared between B/P versus HC participants using a pictorial dot-probe task. In Study 2, ABs were compared between B/P versus HC participants after NA induction using the Cyberball social exclusion task. Indexes of attentional engagement and disengagement were computed.

RESULTS

There was a main effect of cue type on attentional engagement at 0.2 s (p = 0.006,η p 2 $\eta _p^2$  = 0.075) and 2 s (p = 0.040,η p 2 $\eta _p^2$  = 0.043), and attentional disengagement at 2 s (p = 0.006,η p 2 $\eta _p^2$  = 0.077) in Study 1. Findings were not replicated following NA induction in Study 2. No main effect of group or group × cue type interaction was found.

DISCUSSION

Our results disagree with previous research supporting the importance of ABs toward food and body shape cues in young people with threshold and subthreshold EDs and suggest these might not constitute a relevant target in the treatment of ED behavior. However, due to a heterogeneous approach to measuring ABs and multiple types of AB being described in EDs, further research is needed to clarify whether ABs map onto transdiagnostic models of behavioral dysregulation.

Wanting and liking of Facebook functions and their correlation to problematic use

A key question about social media use is whether it constitutes an addiction. A possible frame of reference to investigate this question is the Incentive Sensitizations Theory (IST), as it provides a solid empirical background to understand the motivational and hedonic aspects of problematic behaviors. A central assumption of IST that addiction-related cues play a pivotal role in addictive behaviors has remained relatively understudied in the context of social media use. Given that social media platforms are multifaceted applications, the aim of this study was to explore motivational and hedonic responses associated with cues from different features of Facebook and their correlation with problematic use, analyzing survey data of 1436 respondents. The study primary focused on (1) the relationship between Facebook usage time/frequency, wanting and liking, and problematic use, and (2) the wanting and liking of 10 different Facebook notifications and their correlation to problematic use. Results aligned with predictions of IST, showing a positive correlation between wanting and usage time/frequency and problematic use, while marginal and inconsistent correlation was found with liking. Various Facebook functions contribute differently to its addictive potential, with social-communication features having the highest and general information features the lowest impact. In summary, the findings indicate that excessive Facebook use is primarily driven by compulsive tendencies rather than positive emotions. Although this study doesn't conclusively determine if Facebook use can turn into an addiction, it appears that there are strikingly similar dynamics to substance use within the self-reported reflection of the motivational and hedonic systems.

Associations between social networks, messaging apps, addictive behaviors, and sleep problems in adolescents: the EHDLA study

Objective

The current study aims to provide a comprehensive analysis of the relationships between social network (SN) use, messaging apps use, and addictive behaviors related to SNs, and sleep-related problems in a sample of Spanish adolescents.

Methods

This was a cross-sectional study using data from the Eating Healthy and Daily Life Activities (EHDLA) project, which involved adolescents aged 12-17 years from three secondary schools in Valle de Ricote (Region of Murcia, Spain). A sample of 632 adolescents was studied. The use of SN (i.e., Facebook, Twitter, Instagram, Snapchat or TikTok) or messaging applications (i.e., WhatsApp) was assessed via a scale including one item for each SN, in which adolescents were asked what type of SN they used and the usage profile of each SN. The Short Social Networks Addiction Scale-6 Symptoms (SNAddS-6S) was used to determine SN addictive behaviors. Generalized linear regression analyses with a negative binomial distribution were performed to determine the associations of SN use or SN addictive behaviors with sleep-related problems. These analyses were adjusted for age, sex, body mass index, socioeconomic level, physical activity, sedentary behavior, and adherence to the Mediterranean diet.

Results

Higher SN use was related to greater presence of sleep-related problems [prevalence ratio (PR) = 1.04; 95% confidence interval (CI) 1.01-1.07; p = 0.015]. Additionally, the higher the score on the addictive behaviors toward SN use scale was, the more sleep-related problems were identified (PR = 1.15; 95% Cl 1.09 to 1.21; p < 0.001). Specifically, only the use of Twitter was significantly associated with sleep-related problems (PR = 1.10; 95% Cl 1.01 to 1.21; p = 0.035). In terms of addictive behaviors related to SN use, mood modification, relapse, withdrawal, and conflict were significantly associated with sleep-related problems (mood modification: PR = 1.58; 95% CI 1.36 to 1.84; p < 0.001; relapse: PR = 1.24; 95% CI 1.07 to 1.43; p = 0.004; withdrawal: PR = 1.28; 95% CI 1.08 to 1.51; p = 0.004; conflict: PR = 1.19; 95% CI 1.01 to 1.39; p = 0.037).

Conclusion

Our results suggest a relationship between SN use, SN addictive behaviors, and sleep-related problems in adolescents. These cross-sectional results should be confirmed in longitudinal and intervention studies.

Academic motivation-achievement cycle and the behavioural pathways: A short-timeframe experiment with manipulated perceived achievement

BACKGROUND

The purported reciprocity between motivation and academic achievement in education has largely been supported by correlational data.

AIMS

Our first aim was to determine experimentally whether motivation and achievement are reciprocally related. The second objective was to investigate a potential behavioural mediation pathway between motivation and achievement by measuring the objective effort expended on learning. Finally, we studied the causality of these relations by analysing the dynamics between motivation and achievement (rather than examining them as individual constructs) when perceived achievement was experimentally manipulated.

SAMPLE(S)

The study employed a short-timeframe experiment in which 309 Dutch undergraduate students (Mage = 19.89, SD = 2.08) learned new English vocabulary.

METHODS

Their motivation, effort, and achievement were measured at multiple time points within one hour. Midway through the experiment, participants received manipulated feedback indicating an achievement decline, which was expected to influence their subsequent motivation, effort, and actual achievement. A random-intercept cross-lagged panel framework was employed to model how one construct influenced another over time.

RESULTS

We found a unilateral effect of achievement on motivation (i.e., no reciprocity), which remained stable across the time points. Our experimental manipulation partially supported a causal interpretation of the unilateral achievement→motivation pathway. Additionally, no mediation effect of effort was identified: motivation was not associated with effort, nor was effort linked to achievement.

CONCLUSIONS

Our findings underscore the importance of further exploration of behavioural mediation pathways, a broad operationalization of motivation, and the application of appropriate modelling strategies to investigate the motivation-achievement reciprocity.

Early postnatal NMDA receptor ablation in cortical interneurons impairs affective state discrimination and social functioning

Emotion recognition is fundamental for effective social interactions among conspecifics. Impairments in affective state processing underlie several neuropsychiatric disorders, including schizophrenia, although the neurobiological substrate of these deficits remains unknown. We investigated the impact of early NMDA receptor hypofunction on socio-affective behaviors. Male mice lacking NMDA receptors in GABAergic interneurons of cerebral and hippocampal cortices from an early postnatal age (interNMDAr-KO mutants) were evaluated in affective state discrimination, social preference and social novelty preference, hierarchy and dominance, aggression and territoriality, and long-term social interaction. We show that interNMDAr-KO mice failed to discriminate conspecifics based on their affective states, unlike control littermates, while exhibiting an intact preference for social stimuli over inanimate objects. This discrimination deficit was observed regardless of whether affective valences were manipulated positively or negatively, via a palatable reward or social defeat, respectively. Additionally, interNMDAr-KO mice failed to establish a normal social hierarchy, consistently assuming subordinate roles against control littermates, and presented an abnormal response to conspecifics in the resident-intruder test. Finally, mice lacking NMDA receptors in GABAergic interneurons exhibited social withdrawal following exposure to unfamiliar conspecifics in a custom setting designed to monitor social behavior over extended time periods. This deficit was reversed by subchronic clozapine treatment. Our study thoroughly assessed the impact of a pathophysiological manipulation relevant to schizophrenia on social behavior in mice. Overall, this study provides evidence demonstrating that altered NMDAr-dependent development of cortical and hippocampal interneurons impairs affective state discrimination and leads to deficits in social functioning and long-term sociality.

Does semaglutide reduce alcohol intake in Danish patients with alcohol use disorder and comorbid obesity? Trial protocol of a randomised, double-blinded, placebo-controlled clinical trial (the SEMALCO trial)

INTRODUCTION

Alcohol use disorder (AUD) is a massive burden for the individual, relatives and society. Despite this, the treatment gap is wide compared with other mental health disorders. Treatment options are sparse, with only three Food and Drug Administration (FDA)-approved pharmacotherapies. Glucagon-like peptide-1 (GLP-1) receptor agonists have shown promising effects in reducing alcohol consumption in preclinical experiments, and clinical trials are in high demand to investigate these potentially beneficial effects in patients diagnosed with AUD.

METHODS AND ANALYSIS

The effects of the once-weekly GLP-1 receptor agonist semaglutide will be investigated in a 26-week, randomised, placebo-controlled, double-blinded clinical trial. 108 patients diagnosed with AUD and comorbid obesity (body mass index (BMI)≥30 kg/m2)) will be randomised to treatment with either semaglutide or placebo in combination with cognitive behavioural therapy. A subgroup of the patients will have structural, functional and neurochemical brain imaging performed at baseline and after 26 weeks of treatment. The primary endpoint is the reduction in heavy drinking days, defined as days with excess consumption of 48/60 g of alcohol per day (women and men, respectively). Secondary endpoints include changes from baseline to week 26 in alcohol consumption, smoking status, quality of life, fibrosis-4 score, plasma concentration of phosphatidylethanol, brain gamma-aminobutyric acid (GABA) levels, alcohol cue reactivity, functional connectivity and white matter tract integrity.

STATUS

Recruitment started in June 2023.

ETHICS AND DISSEMINATION

The study is approved by the Ethics Committee of the Capital Region of Denmark, the Danish Board of Health and the Danish Data Protection Agency. All patients will sign the written consent form before being included in the trial. Results will be disseminated through peer-reviewed publications and conference presentations. After the results are published, all de-identified data will be available in the Mendeley database.

TRIAL REGISTRATION NUMBER

NCT05895643.

Adverse childhood experiences and suicidal ideation in patients with major depressive disorder: investigating the mediating role of emotional reactivity and probabilistic and reinforcement learning

OBJECTIVES

Major Depressive Disorder (MDD) is a severe and widespread psychiatric condition that affects individuals globally. Suicidal ideation is one of the key symptoms associated with this disorder. Numerous studies have explored the impact of adverse childhood experiences on the development of suicidal thoughts in adulthood. However, limited research focuses on the underlying mechanisms that mediate this relationship. Therefore, the present study aimed to investigate whether emotional reactivity, along with probabilistic and reinforcement learning (PRL), serves as a mediator in the relationship between adverse childhood experiences and suicidal ideation in Iranian patients with MDD.

METHOD

The study included 201 inpatients diagnosed with MDD hospitalized in various psychiatric wards across Shiraz, Iran. Participants were selected using a convenient sampling method. Data were collected through the Probabilistic Reward Task, the Emotional Reactivity Scale, the Beck Scale of Suicidal Ideation, and the Modified Adverse Childhood Experiences - International Questionnaire. The collected data were analyzed using Pearson's correlation test and structural equation modeling with SPSS and AMOS 26.

RESULTS

Adverse childhood experiences were found to have a direct and significant relationship with suicidal ideation (p < .001). Additionally, emotional reactivity and PRL served as significant mediators in the relationship between adverse childhood experiences and suicidal ideation.

CONCLUSION

Our findings indicate that various factors-including adverse childhood experiences, emotional reactivity, and PRL-contribute to the development of suicidal ideation in patients with major depressive disorder (MDD). Therefore, it is essential to consider these factors when developing therapeutic plans.

The effect of individual differences on Pavlovian conditioning in specific Internet-use disorders

The I-PACE model suggests that Internet-use disorders result from the interplay of individual vulnerabilities and cognitive and affective processes. As in substance use disorders, Pavlovian conditioning processes are attributed a key role. However, and despite progress in identifying individual vulnerabilities, factors influencing appetitive conditioning remain poorly understood. We therefore conducted a Pavlovian conditioning experiment in which individuals with risky as well as non-problematic use of either gaming or buying-shopping applications learned to associate different abstract stimuli with either gaming or buying-shopping. Regression analyses were used to identify individual characteristics influencing awareness of the experimental contingencies, speed of acquisition of awareness and the magnitude of the conditioned emotional responses regarding pleasantness and arousal ratings of the stimuli. Results demonstrated successful Pavlovian conditioning and an attentional bias towards reward-predicting cues. Awareness of the experimental contingencies was linked solely to cognitive abilities, while the speed of acquisition of awareness and the magnitude of conditioned responses was influenced by specific personality characteristics, experiences of compensation from using the application and severity of problematic use. Importantly, certain characteristics specifically predicted the magnitude of the conditioned response towards gaming, while others specifically predicted the response towards buying-shopping, highlighting differing vulnerabilities. These findings underscore the importance of targeted interventions and prevention strategies tailored to these specific vulnerability factors. Further implications and limitations are discussed.

Generalized cue reactivity in rat dopamine neurons after opioids

Cue reactivity is the maladaptive neurobiological and behavioral response upon exposure to drug cues and is a major driver of relapse. A widely accepted assumption is that drugs of abuse result in disparate dopamine responses to cues that predict drug vs. natural rewards. The leading hypothesis is that drug-induced dopamine release represents a persistently positive reward prediction error that causes runaway enhancement of dopamine responses to drug cues, leading to their pathological overvaluation. However, this hypothesis has not been directly tested. Here, we develop Pavlovian and operant procedures in male rats to measure firing responses within the same dopamine neurons to drug versus natural reward cues, which we find to be similarly enhanced compared to cues predicting natural rewards in drug-naive controls. This enhancement is associated with increased behavioral reactivity to the drug cue, suggesting that dopamine neuronal activity may still be relevant to cue reactivity, albeit not as previously hypothesized. These results challenge the prevailing hypothesis of cue reactivity, warranting revised models of dopaminergic function in opioid addiction, and provide insights into the neurobiology of cue reactivity with potential implications for relapse prevention.

Sex-associated differences in incentive salience and drinking behaviour in a rodent model of alcohol relapse

The ability of environmental cues to trigger alcohol-seeking behaviours is thought to facilitate problematic alcohol use. Individuals' tendency to attribute incentive salience to cues may increase the risk of addiction. We sought to study the relationship between incentive salience and alcohol addiction using non-preferring rats to model the heterogeneity of human alcohol consumption, investigating both males and females. Adult rats were subjected to the alcohol deprivation effect (ADE) paradigm, where they were given voluntary access to different alcohol solutions with repeated interruptions by deprivation and reintroduction phases over a protracted period (five Alcohol Deprivation Cycles). Before each Alcohol Deprivation Cycle, rats were tested in the Pavlovian Conditioned Approach (PCA) paradigm, which quantifies the individual salience toward a conditional cue and the reward, thus allowing us to trace the process of attributing incentive salience to reward cues. During the final Alcohol Deprivation Cycle (ADE5), animals were tested for compulsive-like behaviour using quinine taste adulteration. We investigated sex differences in drinking behaviour and PCA performance. We observed thatb females drank significantly more alcohol than males and displayed more sign-tracking (ST) behaviour in the PCA, whereas males showed goal-tracking (GT) behaviour. Furthermore, we found that high drinkers exhibited more ST behaviour. The initial PCA phenotype was correlated with later alcohol consumption. Our findings indicate a complex relationship between incentive salience and alcohol addiction and emphasize the importance of considering both sexes in preclinical research.

[Comparative Harm/Benefit Analysis of Various Psychotropic Substances from the Perspective of German Drug Users and Addiction Medicine Experts - A Contribution to Psychoeducation of Substance-Addicted Individuals and Restriction/Legalization Debates]

BACKGROUND

To date, we cannot find any current international comparative study on the assessment of a benefit/harm profile of various licit and illicit psychoactive substances conducted by adult drug users and addiction experts as well. Particularly, there is no study from the German-speaking area of Western Europe.

METHODS

In addition to the data already published by 101 German addiction medicine experts (published in this journal, [1]), we carried out interviews using a structured questionnaire with 100 German substance dependent users, residing in acute and rehabilitation clinical setting, to evaluate 34 psychoactive substances regarding their health and social harm potential for users and others as well as their potential benefit.

RESULTS

Both, users and experts estimated traditional illicit drugs, such as heroin, crack/cocaine and methamphetamine, to be particularly harmful. Synthetic cannabinoids, alcohol and benzodiazepines were in the upper midfield, cannabis and psychotropic mushrooms in the lower midfield, and gabapentinoids at the bottom of the harm rankings of both, users and experts. In comparison with the experts, the users estimated methadone and benzodiazepines to be significantly more harmful. In the benefit analysis, users rated traditional illicit drugs including cannabis and psychotropic mushrooms as well as nicotine as significantly more useful than the experts. In contrast to the experts (traditional illicit drugs), the users did not assess any substance as very harmful and very useless at the same time. Only a few users reported to have experiences with opioid analgesics which, however, did not differ between the users´ and experts´ harm/benefit-assessments. Neither users nor experts predicted cannabis-legalization to change the overall risk potential of cannabis. Specific cognitive valuation biases seemed to be prominent in both groups.

CONCLUSION

This study presents first harm/benefit assessments of psychotropic substances from the perspective of German addiction medicine experts and drug users. The results can be valuable to the psychoeducation of substance-addicted individuals and to current restriction or legalization debates.

The bioSocial Cognitive Theory of eating (bSCT-e): Applying and elaborating on a biopsychosocial substance use theory for food addiction

Obesity rates are increasing globally, and food addiction (FA1) may be an important contributing factor but there is a lack of understanding of the key psychological mechanisms that contribute to FA. The bioSocial Cognitive Theory (bSCT) proposes that substance use is predicted by biologically based personality traits and their influence on social cognitive mechanisms. While validated in substance use, bSCT has not been applied to a behavioural or non-substance addiction. However, the bSCT does not include a negative affective personality component, of which there is clear theoretical and empirical support as risk factors for FA. Thus, this study sought to test both the original bSCT model and an elaborated version related to eating (bSCT-e) that included direct and indirect punishment sensitivity pathways to identify the individual risk factors of FA. Data were collected from 204 university students (75.5% female; Mage = 24.82, SD = 9.17) via an online survey. Both original bSCT and bSCT-e models provided a good fit to the data, with the latter providing slightly better fit and accounting for more variance in FA. The findings suggest that individuals who are more reward driven and punishment sensitive hold exaggerated beliefs about the reinforcing and emotion regulation effects of eating, which may undermine eating control and increase risk of FA. This study provides potential new insights into the complex biopsychosocial mechanisms of FA, and points to potential intervention targets.

Dopamine D3 receptor mediates natural and methamphetamine rewards via regulating the expression of miR-29c in the nucleus accumbens of mice

The dopamine D3 receptor (D3R), principally confined to the nucleus accumbens (NAc), is involved in regulating natural and drug rewards; however, the molecular mechanisms underlying the associated process remain unclear. Earlier research has reported the concurrent influence of D3R and miR-29c expressed in the NAc on methamphetamine (METH)-induced reward behaviors and microglial activation, hinting at regulatory roles in reward processing. Herein, we performed viral manipulation-mediating D3R/miR-29c overexpression and inhibition in the whole NAc in male D3R knockout and wild-type mice to investigate this potential relationship. Behavioral responses to the rewarding stimuli were assessed using sucrose preference score, METH-induced locomotor sensitization, and METH-induced conditioned place preference tests. Overall, we observed a notable decrease in the behavioral response to sucrose and METH in D3R-deficient mice, accompanied by the downregulation of miR-29c expression in the NAc. Diminished responses to those rewarding stimuli in D3R-deficient mice primarily stemmed from the reduction of GSK3β activity and subsequent down-regulation of miR-29c in the NAc. Microglial activation in the NAc mediates the effect of D3R-miR-29c deficiency on the reward effects of sucrose and METH. Pharmacological suppression of microglial activity rescued the reduced response in mice lacking D3R-miR-29c in the NAc. Overall, this study revealed the mechanism by which D3R regulates both natural and drug rewards via miR-29c in the murine NAc, highlighting the role of the NAc D3R-miR-29c pathway as a critical regulator of rewards, and providing new insights into the role of NAc D3R-miR-29c in encoding rewarding experiences.

Exploring Individual Differences in Interoception Among Athletes Based on a Three-Dimensional Construct of Interoception

Previous studies demonstrated that sensorimotor training enhances interoceptive abilities. Athletes are highly engaged in performance-driven physical training and often incorporate-to varying degrees-sensorimotor training into their routines. In this study, we investigated the role of individual differences in interoception by comparing professional athletes of different performance levels and both sexes with recreational athletes and controls, applying a three-dimensional model of interoception. Twenty-six elite athletes, 52 recreational athletes, and 50 college students were recruited from national sports teams, local sports training centers, and local universities. We used the Multidimensional Assessment of Interoperative Awareness (MAIA), the Heartbeat Detecting Task (HDT), and a numeric rating scale based on HDT to measure interoceptive sensibility, accuracy, and awareness. At average, athletes showed significantly higher interoceptive sensibility, interoceptive accuracy, and interoceptive awareness than controls. Elite athletes reported significantly higher scores in all measures of interception compared to recreational athletes. Intriguingly, Non-Distracting for interoceptive sensibility was positively correlated with the level of experience in elite athletes. Male athletes had better interoceptive sensibility and interoceptive awareness compared to female athletes in the elite group, while no significant sex differences were detected in the other two groups. These results indicated that level of sport experience and sex are associated with differences in interoceptive accuracy, interoceptive sensibility, and interoceptive awareness. It also suggests that interoceptive ability is possibly an experience-dependent trait for athletic performance, which provides insight for improving sports performance through an approach of enhancing interoceptive ability.

Blunted neural response to real-life social reward anticipation in internet gaming disorder: An event-related potential study

Recent research indicates that individuals with Internet gaming disorder (IGD) exhibit impaired social reward processing, evidenced by reduced neural sensitivity to real-life social reward. The aim of the present study is to further investigate the impaired processing of social reward anticipation and reward consumption in individuals with IGD, and explore the relationship between these two components. Using a social incentive delay task with game-related and real-life versions, combined with event-related potential (ERP) technology, we examined 25 individuals with IGD and 25 matched healthy game players. The results showed that, at the behavioral level, individuals with IGD showed significantly slower reaction times to real-life target stimuli compared with game-related target stimuli, which is not observed in healthy controls. At the neural level, the Cue-P3 elicited by real-life incentive cues in individuals with IGD was significantly smaller than that elicited by game-related incentive cues. However, these effects were no longer significant after adding depression and anxiety scores as covariates. There was no significant difference in reward positivity (RewP) elicited between the two types of reward consumption. Furthermore, individuals with IGD showed a positive correlation between Cue-P3 elicited by game-related social incentive cue and RewP elicited by game-related social reward. However, this effect was not observed in the healthy controls. In conclusion, the present study suggests that the blunted allocation of motivated neural attention resources to real-life social incentive cues in individuals with IGD may be the key mechanism underlying their impaired social reward processing. This impairment may be influenced by the higher levels of depression and anxiety symptoms commonly observed in individuals with IGD.

The Incentive-Sensitization Theory of Addiction 30 Years On

The incentive-sensitization theory (IST) of addiction was first published in 1993, proposing that (a) brain mesolimbic dopamine systems mediate incentive motivation ("wanting") for addictive drugs and other rewards, but not their hedonic impact (liking) when consumed; and (b) some individuals are vulnerable to drug-induced long-lasting sensitization of mesolimbic systems, which selectively amplifies their "wanting" for drugs without increasing their liking of the same drugs. Here we describe the origins of IST and evaluate its status 30 years on. We compare IST to other theories of addiction, including opponent-process theories, habit theories of addiction, and prefrontal cortical dysfunction theories of impaired impulse control. We also address critiques of IST that have been raised over the years, such as whether craving is important in addiction and whether addiction can ever be characterized as compulsive. Finally, we discuss several contemporary phenomena, including the potential role of incentive sensitization in behavioral addictions, the emergence of addiction-like dopamine dysregulation syndrome in medicated Parkinson's patients, the role of attentional capture and approach tendencies, and the role of uncertainty in incentive motivation.

When the society dictates food search - Neural signalling underlying appetitive motivation in honey bees

In honey bees, appetitive motivation is primarily driven by the needs of the colony rather than individual needs. The regulation of appetitive behavior is achieved through the coordinated action of neuropeptides, hormones and biogenic amines, which integrate multiple signals to ensure appropriate appetitive responses. Dopamine signalling underpins a food-related wanting system that is sensitive to aversive experiences. The short neuropeptide F (sNPF) enhances appetitive responsiveness, food intake and behavioral and neural responsiveness to food-related odorants. Additionally, it facilitates appetitive learning and memory. On the contrary, tachykinin-related peptides (TRPs) inhibit appetitive responses. Physiological changes during the transition to the foraging state lead to distinct patterns of insulin and adipokinetic hormone (AKH) signaling, different from those seen in solitary insects, indicating that social life had significant consequences on the systems controlling appetitive motivation. Overall, studying the neural bases of appetitive behavior in bees reveals unique aspects that arise from their social lifestyle.

Neural and immune interactions linking early life stress and anhedonia

Early experiences of stress and adversity are associated with blunted reward sensitivity and altered reward learning. Meanwhile, anhedonia is characterized by impairments in reward processing, including motivation, effort, and pleasure. Early life stress (ELS) and anhedonia share psychological, behavioral, and neurobiological correlates, and the system-level interactions that give rise to anhedonia have yet to be fully appreciated. The proposed framework uses a multilevel, multisystem approach to aid in understanding neural-immune interactions that link ELS and anhedonia. The interactions linking anhedonia and ELS presented here include reduced reward sensitivity, alterations in hypothalamic-pituitary-adrenal (HPA) axis response, elevated inflammatory cytokines or physiological markers of stress, and blunted reward circuitry functioning along the mesocorticolimbic pathway. The clinical implications and areas for future research are also discussed. Ultimately, this research may inform the development of more specific and individualized treatments for anhedonia.

Attention to food stimuli in binge eating disorder: Electrophysiological evidence

Attentional biases towards food play an important role in the pathology of binge eating disorder (BED). Later stage electrophysiological potentials (P300, late positive potential) present promising markers of motivated attention with high temporal, albeit low spatial resolution. Complementing this, the N2pc is an earlier-latency component providing the possibility of more directly analyzing visuospatial attention. Therefore, we tested a group with BED (N = 60), as well as an overweight (OW; N = 28) and normal weight (NW; N = 30) group without BED in a Go/No-Go paradigm using food and nonfood distractor images. Only the OW group in exclusively the Go trials displayed a stronger spatial attention allocation towards nonfood distractors as evidenced by an increased N2pc amplitude. In the P300's time window, the OW group displayed no attentional bias towards food and the NW group only did so in the absence of a target. Solely the BED group allocated more motivated attention towards food distractors both in Go and No-Go trials. In the following late positive potential (LPP), the OW group exhibited a general attentional bias towards food distractors, while the BED group only did so in the absence of a target. These results are discussed in light of the incentive sensitization theory and a potential early attentional suppression of potent distractors.

Reward processing in young people with self-harm behaviour

Twenty percent of young people report a lifetime presence of self-harm (SH) behaviour, associated with negative health and functional outcomes. Understanding the underlying cognitive mechanisms is needed to develop targeted early interventions. Reward processing biases may underlie SH, aligning with accounts of the behaviour acquiring "addictive" characteristics. However, the specific nature of such biases remains unclear, particularly its relationship with negative affect (NA) that frequently triggers SH. In Study 1, we compared young people (aged 16-25) with SH to a group with NA but no SH history and a healthy control group on performance of a novel Incentive Delay Task (IDT), with SH-related (SH trials), positive social (social trials) or monetary images (money trials) as stimuli. In Study 2, a different sample of SH and HC participants completed the same IDT following NA induction via an online Trier Social Stress Test. For both studies, we hypothesised faster and more correct responses in the SH group than control groups on SH trials. Contradicting our hypothesis, there were no significant between-group differences in IDT performance on SH, social and money trials in either study. Certain SH characteristics (positive reinforcement, SH mental imagery, urge) were significantly correlated with better performance on SH trials in SH participants. Thus, broadly SH behaviour may not be underpinned by motivational biases towards SH-related cues or naturalistic rewards. Future studies should clarify whether incentivisation of SH-related cues instead explains individual differences in SH behaviour and its relation with treatment and prognosis.

Alcohol and cannabis use in daily lives of college-attending young adults: Does co-use correspond to greater reported pleasure?

Co-use of alcohol and cannabis is prevalent and linked with heightened risk for substance-related harms. The current study investigated the role of substance-related pleasure as a reinforcing factor for co-use relative to alcohol or cannabis use. Specifically, we used data from a 21-day diary study of college students to examine day-level associations between co-use and self-reported substance-related pleasure (any, level of pleasure). Participants were 237 college students (65 % female sex at birth, ages 18-24) who reported 1+ alcohol and cannabis co-use occasion. Participants completed daily surveys across 21 consecutive days about yesterday's substance use and experiences of pleasure, yielding 2,086 daily surveys involving alcohol and/or cannabis use. Multilevel models indicated that odds of substance-related pleasure were higher on days with co-use relative to days with single-substance use, and level of pleasure was higher on co-use days relative to cannabis but not alcohol use days. Pleasure may serve as a reinforcing property of co-use that may be related to continued use despite experience of negative consequences. Intensity of pleasure related to co-use appears to be largely driven by use of alcohol. However, given mixed findings concerning level of pleasure, individuals may report co-use increases feelings of pleasure but do not actually experience more pleasure. Pleasure may serve as a viable target in future prevention and intervention programming targeting co-use.

Stress-induced overeating behaviors explained from a (transitory) relief-learning perspective

People use various behaviors to cope with stressful events. These behaviors are mostly adaptive, as they allow a successful release of stress without impacting other aspects of life: How nice is it to have a break with a few spoons of that favorite ice cream during a hectic working day? However, when excessive consumption of high-sugar/salt ultra-processed food becomes the gateway to find relief from stress, eating loses this adaptive function and may escalate to binge eating, lead to obesity, and other medical conditions linked to overweight. Several etiological models attempt to explain stress-induced eating and excessive overeating behaviors characterizing these clinical conditions. The popular Emotional Eating Theory proposes that stress-related (over-)eating, a major predictor of obesity and diagnosed binge eating disorders, develops based on negative reinforcement learning since food consumption regulates the negative affective state associated with stressful circumstances. Differently, the prominent Incentive Sensitization Theory explains overeating, binge eating disorders (including bulimia), and obesity in terms of excessive amplification of reward 'wanting', which is thought to emerge from overexposure to obesogenic (food)cues. The several studies oriented by these theories have paved the way to better understand stress-related (over-)eating and its clinical excesses. However, a deep mechanistic understanding of how and why stress-induced (over-)eating can escalate till clinical forms of overeating remain elusive. A well-funded connection of the mechanisms proposed by the Emotional Eating Theory and the Incentive Sensitization Theory might address this etiological open question. To avoid erroneous arguments, it is however essential to first address the internal theoretical and methodological shortcomings of each theory and connected studies. These shortcomings stem from conceptual fallacies and poorly implemented designs, which might partially explain the 'high variability and low replicability' problem of empirical findings. Next, the formulation of a new integrative model could provide fresh insight into the deep learning and biological mechanisms of this escalation. A successful formalization of this model could then create the much-needed impact in clinical and preventive research since excessive overeating is a behavior hard to change once established. In this opinion paper, I propose to apply recent insights we gathered on the role of relief from the field of safety learning to stress (over-)eating. I will present a new relief-based model that, as a starting point, has the potential to connect the Emotional Eating Theory with the Incentive Sensitization Theory, setting the base for more integrative science.

Task goals shape the relationship between decision and movement speed

The speed at which we move is linked to the speed at which we decide to make these movements. Yet the principles guiding such relationship remain unclear: whereas some studies point toward a shared invigoration process boosting decision and movement speed jointly, others rather indicate a trade-off between both levels of control, with slower movements accompanying faster decisions. Here, we aimed 1) at further investigating the existence of a shared invigoration process linking decision and movement and 2) at testing the hypothesis that such a link is masked when detrimental to the reward rate. To this aim, we tested 62 subjects who performed the Tokens task in two experiments (separate sessions): experiment 1 evaluated how changing decision speed affects movement speed, whereas experiment 2 assessed how changing movement speed affects decision speed. In the latter experiment, subjects were encouraged to favor either decision speed (fast decision group) or decision accuracy (slow decision group). Various mixed model analyses revealed a coregulation of decision (urgency) and movement speed in experiment 1 and in the fast decision group of experiment 2 but not in the slow decision group, despite the fact that these same subjects displayed a coregulation effect in experiment 1. Altogether, our findings support the idea that coregulation occurs as a default mode but that this form of control is diminished or supplanted by a trade-off relationship, contingent on reward rate maximization. Drawing from these behavioral observations, we propose that multiple processes contribute to shaping the speed of decisions and movements.NEW & NOTEWORTHY The principles guiding the relationship between decision and movement speed are still unclear. In the present behavioral study involving two experiments conducted with 62 human subjects, we report findings indicating a relationship that varies as a function of the task goals. Coregulation emerges as a default mode of control that fades when detrimental to the reward rate, possibly because of the influence of other processes that can selectively shape the speed of our decisions or movements.

Aberrant encoding of event saliency in the orbitofrontal cortex following loss of the psychiatric-associated circular RNA, circHomer1

CircHomer1 is an activity-dependent circular RNA (circRNA) isoform produced from back-splicing of the Homer1 transcript. Homer1 isoforms are well-known regulators of homeostatic synaptic plasticity through post-synaptic density scaffold regulation. Homer1 polymorphisms have been associated with psychiatric diseases including schizophrenia (SCZ) and bipolar disorder (BD). Postmortem tissue from patients with SCZ and BD displayed reduced circHomer1 levels within the orbitofrontal cortex (OFC), a region that tracks event saliency important for modulating behavioral flexibility. While dysregulation of circHomer1 expression has recently been identified across multiple psychiatric and neurodegenerative disorders and is associated with impaired behavioral flexibility in mice, it is unknown whether circHomer1 can induce electrophysiological signatures relevant to cognitive dysfunction in these disorders. To examine the role of circHomer1 in neuronal signaling, we bilaterally knocked down circHomer1 in the OFC of C57BL/6 J male mice and recorded neural activity from the OFC during a touchscreen reversal learning task then measured molecular changes of synaptic regulators following knockdown. Knockdown of circHomer1 within the OFC induced choice-dependent changes in multiunit firing rate and local field potential coordination and power to salient stimuli during reversal learning. Further, these electrophysiological changes were associated with transcriptional downregulation of glutamatergic signaling effectors and behavioral alterations leading to impaired cognitive flexibility. CircHomer1 is a stable biomolecule, whose knockdown in rodent OFC produces lasting electrophysiological and transcriptional changes important for efficient reversal learning. This is, to our knowledge, the first demonstration of a psychiatric-associated circRNA contributing to electrophysiological, transcriptional, and behavioral alterations relevant to psychiatric phenotypes.

Tobacco Images Choice and its Association With Craving and Dependence in People Who Smoke Cigarettes

INTRODUCTION

Increased salience of drug-related cues over nondrug reinforcers can drive drug use and contribute to tobacco use disorder (TUD). An important scientific and clinical goal is to effectively measure this elevated drug-seeking behavior in TUD. However, most TUD assessments rely on self-reported cravings and cigarette consumption, not providing an objective measure of the impact of drug cues on biasing behavior toward drugs. The probabilistic image choice (PIC) task investigates the choice of viewing drug-related pictures as compared to other salient pictures (eg, pleasant and unpleasant). This study aimed to develop and validate the PIC task for TUD and evaluate the associations between behavioral choice and tobacco craving, daily cigarette consumption, quit attempts and motivation to quit, and nicotine dependence (the Fagerström score).

METHODS

We recruited 468 smokers and 121 nonsmokers using the Prolific online platform. Participants performed the PIC task twice (at a 1-month interval) and completed other measures relevant to TUD.

RESULTS

Compared to nonsmokers, tobacco smokers selected to view significantly more tobacco images and less pleasant (nondrug reinforcer) images, a profile that remained stable at retest. Individual differences in choice of tobacco as compared to pleasant images on the PIC task were associated with craving but not with the other tobacco dependence measures, suggesting that the task may serve as a behavioral proxy measure of drug "wanting" rather than of cumulative nicotine exposure or physical dependence.

CONCLUSIONS

These results suggest that the PIC task can be a valuable tool for objectively assessing craving-associated tobacco seeking in TUD.

IMPLICATIONS

Most of the current measures of TUD rely on self-reports of consumption, dependence, and craving, and do not take into consideration the role of drug-related cues in driving tobacco seeking. This study shows that the PIC task provides an objective, reliable proxy measure of tobacco image-seeking behavior in people who smoke cigarettes that is linked to craving (desire) for smoking but not to other measures of TUD. Therefore, the PIC task may be a useful complementary tool for the classification, diagnosis, and prognosis of TUD.

The Role of the Rat Prefrontal Cortex and Sex Differences in Decision-Making

The prefrontal cortex is critical for decision-making across species, with its activity linked to choosing between options. Drift diffusion models (DDMs) are commonly employed to understand the neural computations underlying this behavior. Studies exploring the specific roles of regions of the rodent prefrontal cortex in controlling the decision process are limited. This study explored the role of the prelimbic cortex (PLC) in decision-making using a two-alternative forced-choice task. Rats first learned to report the location of a lateralized visual stimulus. The brightness of the stimulus indicated its reward value. Then, the rats learned to make choices between pairs of stimuli. Sex differences in learning were observed, with females responding faster and more selectively to high-value stimuli than males. DDM analysis found that males had decreased decision thresholds during initial learning, whereas females maintained a consistently higher drift rate. Pharmacological manipulations revealed that PLC inactivation reduced the decision threshold for all rats, indicating that less information was needed to make a choice in the absence of normal PLC processing. μ-Opioid receptor stimulation of the PLC had the opposite effect, raising the decision threshold and reducing bias in the decision process toward high-value stimuli. These effects were observed without any impact on the rats' choice preferences. Our findings suggest that PLC has an inhibitory role in the decision process and regulates the amount of evidence that is required to make a choice. That is, PLC activity controls "when," but not "how," to act.

Dynamic overrepresentation of accumbal cues in food- and opioid-seeking rats after prenatal THC exposure

The increasing prevalence of cannabis use during pregnancy has raised medical concerns, primarily related to Δ9-tetrahydrocannabinol (THC), which readily crosses the placenta and affects fetal brain development. Previous research has identified dopaminergic alterations related to maternal THC consumption. However, the consequences that prenatal cannabis exposure (PCE) has on striatum-based processing during reward pursuit have not been determined. Here, we characterize PCE rats during food or opioid-maintained reward seeking. We find that the supramotivational phenotype of PCE rats is independent of value-based processing and is instead related to augmented reinforcing efficiency of opioid rewards. Our findings reveal that prenatal THC exposure leads to increased cue-evoked dopamine responses and an overrepresentation of effort-driven striatal encoding patterns. Recapitulating clinical findings, drug-related PCE adaptations were more pronounced in males, who showed increased vulnerability for relapse. Collectively, these findings indicate that prenatal THC exposure in male rats engenders a pronounced neurodevelopmental susceptibility to addiction-like disorders.

The Algorithmic Agent Perspective and Computational Neuropsychiatry: From Etiology to Advanced Therapy in Major Depressive Disorder

Major Depressive Disorder (MDD) is a complex, heterogeneous condition affecting millions worldwide. Computational neuropsychiatry offers potential breakthroughs through the mechanistic modeling of this disorder. Using the Kolmogorov theory (KT) of consciousness, we developed a foundational model where algorithmic agents interact with the world to maximize an Objective Function evaluating affective valence. Depression, defined in this context by a state of persistently low valence, may arise from various factors-including inaccurate world models (cognitive biases), a dysfunctional Objective Function (anhedonia, anxiety), deficient planning (executive deficits), or unfavorable environments. Integrating algorithmic, dynamical systems, and neurobiological concepts, we map the agent model to brain circuits and functional networks, framing potential etiological routes and linking with depression biotypes. Finally, we explore how brain stimulation, psychotherapy, and plasticity-enhancing compounds such as psychedelics can synergistically repair neural circuits and optimize therapies using personalized computational models.

Neurophysiological characteristics of reward processing in individuals at different levels of gaming

Altered reward processing has been repeatedly reported in Internet gaming disorder (IGD). However, it remains unclear whether these changes are linked to the severity of addictive symptoms or the extent of gaming experience. This study examined the neurophysiological responses regarding reward anticipation and consummation in individuals at different levels of gaming (including 22 casual gamers, 31 regular gamers, and 27 individuals with IGD) through a monetary incentive delay task. Three event-related potential components during reward anticipation-cue-related P300 (Cue-P3), contingent negative variation, and stimulus-preceding negativity (SPN)-and two during reward consummation-feedback-related negativity and feedback-related P300 (FB-P3)-were measured. We found that IGD individuals exhibited greater Cue-P3 but lower SPN amplitude compared to casual gamers, while regular gamers fell between the two without significant differences. Regressions indicated that more extensive gaming experience, rather than the severity of the symptoms, primarily contributed to the increased Cue-P3 in IGD. No group differences were found during reward consummation. Our results highlight disrupted reward anticipation processing in IGD, characterized by increased attention bias toward reward cues (Cue-P3) but diminished cognitive resources for reward anticipation (SPN) and emphasize the role of gaming experience in increased attention bias in IGD.

Cannabis cue-reactivity in cannabis use disorder: Diverging evidence in two distinct cannabis cultures

BACKGROUND

Cannabis policies and attitudes play a role in the development and presentation of cannabis use disorder (CUD), but it is unclear how these factors are related to biomarkers of addiction. The current study examined cross-cultural differences in cannabis attitudes, cannabis cue-reactivity in the brain and its associations with cannabis use measures and cannabis attitudes.

DESIGN

Cross-sectional fMRI study.

SETTING

The Netherlands (NL) and Texas (TX), USA.

PARTICIPANTS

104 cannabis users with CUD (44% female; NL-CUD = 54, TX-CUD = 50) and 83 non-using controls (52% female; NL-CON = 50, TX-CON = 33).

MEASUREMENTS

Self-reported positive (perceived benefits) and negative (perceived harms) cannabis attitudes and tactile cannabis cue-reactivity assessed using a 3T MRI scanner.

FINDINGS

While the CUD group overall was more positive and less negative about cannabis and reported higher craving, the TX-CUD group reported significantly more positive and less negative attitudes and less craving than the NL-CUD group. Cannabis cue-reactivity was observed in the CUD group in clusters including the precuneus, lateral occipital cortex, frontal medial cortex, nucleus accumbens, and thalamus. In the TX-CUD group, a positive association was observed between symptom severity and cue-induced craving and cannabis cue-reactivity in precuneus and occipital cortex clusters, while a negative association was observed in the NL-CUD group. In these clusters, individuals with more positive attitudes exhibited a positive association between craving and cue-reactivity and those with less positive attitudes exhibited a negative association. No associations with quantity of use were observed.

CONCLUSIONS

Cue-induced craving might be deferentially associated with cannabis cue-reactivity across distinct cannabis use environments.

Emotion Regulation Can Effectively Improve Decision-Making Behaviors of Individuals Who Use Methamphetamine

PURPOSE

Negative emotions can cause people to make irrational decisions, and decision-making disorders may lead individuals who use methamphetamine (meth) to relapse. Therefore, the current study was performed to investigate whether emotion regulation (ER) can improve negative emotions and thus improve decision-making behavior of individuals who use meth.

METHOD

Based on the Iowa Gambling Task, a three-factor mixed experimental design was used to examine the effects of cognitive reappraisal and expressive suppression strategies on negative emotions and decision-making behaviors of 157 individuals who use meth.

RESULTS

Cognitive reappraisal and expressive suppression were effective in reducing participants' negative emotions and improving decision-making behaviors. Specifically, two types of ER strategies were effective in improving decision-making abilities of participants with negative emotional distress, and cognitive reappraisal was more effective than expressive suppression.

CONCLUSION

Regarding cognitive reappraisal, female participants showed better decision-making behavior than males, which predicts that females who use meth might be more adept at using cognitive reappraisal. This finding suggests that mental health providers should aid substance users in managing their negative emotions and also pay attention to gender differences during the nursing process. [Journal of Psychosocial Nursing and Mental Health Services, 62(11), 27-34.].

Social addiction or nicotine addiction? The effect of smoking social motivation on inhibitory control under smoking social cues: Evidence from ERPs

INTRODUCTION

Previous studies and theoretical models suggest that the decreasing effect of smoking-related cues on inhibitory control in individuals who smoke is one of the underlying mechanisms of smoking behavior. However, many studies have overlooked the effects of other types of smoking-related cues, such as social cues. Moreover, previous studies have lacked investigation into whether this decreasing effect is influenced by internal factors. The present study aims to integrate behavioral and electrophysiological indicators to investigate the effect of smoking social cues on inhibitory control in individuals who smoke, as well as the moderating role of social motivations.

METHOD

In Experiment 1, a visual Go/NoGo paradigm with four types of backgrounds (neutral, neutral social, smoking object, and smoking social backgrounds) was used to record the error rates and reaction times of 32 participants who smoke. In Experiment 2, the Go/NoGo paradigm with two types of backgrounds (smoking object and smoking social backgrounds) was used to record the error rates, reaction times, and amplitudes of the N2 and P3 event-related potentials among 30 participants who smoke with varying degrees of primed smoking social motivation.

RESULTS

(1) Individuals who smoke had higher commission error rates and larger P3 amplitude under smoking social background than under smoking object background; (2) individuals who smoke with primed high smoking social motivation, rather than low motivation had higher commission error rates and larger P3 amplitude under smoking social background than under smoking object background.

CONCLUSIONS

Smoking social cues have a greater capacity to decrease inhibitory control in people who smoke than smoking object cues, and this decreasing effect is bolstered by smoking social motivation.

Single-nucleus RNA-sequencing of orbitofrontal cortex in rat model of methamphetamine-induced sensitization

The behavioral sensitization, characterized by escalated behavioral responses triggered by recurrent exposure to psychostimulants, involves neurobiological mechanisms that are brain-region and cell-type specific. Enduring neuroadaptive changes have been observed in response to methamphetamine (METH) within the orbitofrontal cortex (OFC), the cell-type specific transcriptional alterations in response to METH sensitization remain understudied. In this study, we utilized Single-nucleus RNA-sequencing (snRNA-seq) to profile the gene expression changes in the OFC of a rat METH sensitization model. The analyses of differentially expressed genes (DEGs) unveiled cell-type specific transcriptional reactions associated with METH sensitization, with the most significant alterations documented in microglial cells. Bioinformatic investigations revealed that distinct functional and signaling pathways enriched in microglia-specific DEGs majorly involved in macroautophagy processes and the activation of N-methyl-D-aspartate ionotropic glutamate receptors (NMDAR). To validate the translational relevance of our findings, we analyzed our snRNA-seq data in conjunction with a transcriptomic study of individuals with opioid use disorder (OUD) and a large-scale Genome-Wide Association Studies (GWAS) from multiple externalizing phenotypes related to drug addiction. The validation analysis confirmed the consistent expression changes of key microglial DEGs in human METH addiction. Moreover, the integration with GWAS data revealed associations between addiction risk genes and the DEGs observed in specific cell types, particularly microglia and excitatory neurons. Our study highlights the importance of cell-type specific transcriptional alterations in the OFC in the context of METH sensitization and their potential translational relevance to human drug addiction.

A Virtual In Vivo Dissection and Analysis of Socioaffective Symptoms Related to Cerebellum-Midbrain Reward Circuitry in Humans

Emerging research in nonhuman animals implicates cerebellar projections to the ventral tegmental area (VTA) in appetitive behaviors, but these circuits have not been characterized in humans. Here, we mapped cerebello-VTA white matter connectivity in a cohort of men and women using probabilistic tractography on diffusion imaging data from the Human Connectome Project. We uncovered the topographical organization of these connections by separately tracking from parcels of cerebellar lobule VI, crus I/II, vermis, paravermis, and cerebrocerebellum. Results revealed that connections between the cerebellum and VTA predominantly originate in the right cerebellar hemisphere, interposed nucleus, and paravermal cortex and terminate mostly ipsilaterally. Paravermal crus I sends the most connections to the VTA compared with other lobules. We discovered a mediolateral gradient of connectivity, such that the medial cerebellum has the highest connectivity with the VTA. Individual differences in microstructure were associated with measures of negative affect and social functioning. By splitting the tracts into quarters, we found that the socioaffective effects were driven by the third quarter of the tract, corresponding to the point at which the fibers leave the deep nuclei. Taken together, we produced detailed maps of cerebello-VTA structural connectivity for the first time in humans and established their relevance for trait differences in socioaffective regulation.

Blunted sensitivity to expected value during risky decision making in individuals with problematic pornography use

Background and aims

Neurobiological models of addiction posit that addiction manifests through an amplified salience towards addiction-associated stimuli and a diminished responsiveness to non-addiction-related incentives. However, existing research on reward processing in individuals with problematic pornography use (PPU) has primarily been limited to sexual cue reactivity.

Methods

In this event-related potential (ERP) study, we employed a risky decision-making task involving 30 individuals with PPU and 33 healthy controls (HCs) to examine the effects of PPU on non-pornographic (money) reward valuation.

Results

Compared to HCs, individuals with PPU exhibited compromised sensitivity to monetary rewards. Specifically, while the HC group demonstrated a differential response in late positive potential (LPP) amplitude to various expected value (EV) levels, this pattern was absent in the PPU group. This impairment was associated with poorer adaptive decision-making, as evidenced by PPU participants' inability to adjust risk choices based on changes in EV, leading to a propensity for riskier decisions in disadvantageous situations.

Discussion and conclusions

The findings of impaired monetary evaluation in individuals with PPU may potentially explain why they continually pursue pornographic rewards while showing insensitivity to other rewards in daily life. Consequently, treatment development strategies may prioritize improving sensitivity to non-pornographic rewards within this population.

Effect of exercise duration on toluene-induced locomotor sensitization in mice: a focus on the Renin Angiotensin System

RATIONALE

Exercise attenuates addictive behavior; however, little is known about the contribution of exercise duration to this positive effect. The Renin Angiotensin System (RAS) has been implicated both in addictive responses and in the beneficial effects of exercise; though, its role in the advantageous effects of exercise on toluene-induced addictive responses has not been explored.

OBJECTIVES

To evaluate the impact of different exercise regimens in mitigating the expression of toluene-induced locomotor sensitization and to analyze changes in RAS elements' expression at the mesocorticolimbic system after repeated toluene exposure and following voluntary wheel running in toluene-sensitized animals.

METHODS

Toluene-induced addictive-like response was evaluated with a locomotor sensitization model in mice. Toluene-sensitized animals had access to running wheels 1, 2, 4 or 24 h/day for 4 weeks; thereafter, locomotor sensitization expression was evaluated after a toluene challenge. RAS elements (ACE and ACE2 enzymes; AT1, AT2 and Mas receptors) expression was determined by Western blot in the VTA, NAc and PFCx of toluene-sensitized mice with and without exercise.

RESULTS

Individual differences in toluene-induced locomotor sensitization development were observed. Access to wheel running 1 and 2 h/day reduced but 4 and 24 h/day completely blocked locomotor sensitization expression. Repeated toluene exposure changed RAS elements' expression in the VTA, NAc and PFCx, while exercise mainly modified ACE and AT1 in air-exposed and toluene-sensitized mice.

CONCLUSIONS

Inhalant-exposed animals show different sensitization phenotypes. Exercise duration determined its efficacy to attenuate the addictive-like response. Toluene exposure and exercise each modified RAS, the latter also modifying toluene-induced changes.

Neural Correlates of the Attentional Bias Towards Subliminal Pornographic Cues in Individuals with Tendencies Toward Problematic Pornography Use: An ERP Study Using a Dot-Probe Task

Attentional bias toward addiction-related stimuli has been implicated in the development and maintenance of addiction disorders. Several previous studies have reported an attentional bias toward pornographic cues in individuals with problematic pornography use (PPU). Since attentional bias can occur without conscious awareness, the purpose of this study was to use electroencephalography to examine whether individuals with a high tendency for PPU exhibit attentional bias at the level of the preconscious processing. Event-related potentials (ERPs) were recorded while male participants with high (n = 24) and low (n = 23) levels of subclinical PPU performed a masked version of the dot-probe task measuring attentional bias toward subliminally presented pornographic stimuli. Behavioral data revealed that participants from both groups with high and low tendencies for PPU reacted faster to probes replacing pornographic images than to probes replacing neutral images. ERPs revealed that individuals with a high tendency for PPU exhibited larger probe-locked P1 amplitudes following masked pornographic images (valid condition) compared with masked neutral images (invalid condition). Additionally, PPU symptom severity correlated positively with the P1 amplitude difference between valid and invalid conditions. These results highlight the automaticity of attentional capture by pornographic stimuli and support the hypothesis of an addiction-related attentional bias during preconscious processes. The implication of these findings for understanding the clinical phenomenon of out-of-control addictive behavior are discussed.

Greater ventral striatal functional connectivity in cigarette smokers relative to non-smokers across a spectrum of alcohol consumption

Cigarette smoking is associated with elevated risk of disease and mortality and contributes to heavy healthcare-related economic burdens. The nucleus accumbens is implicated in numerous reward-related behaviors, including reinforcement learning and incentive salience. The established functional connectivity of the accumbens includes regions associated with motivation, valuation, and affective processing. Although the high comorbidity of cigarette smoking with drinking behaviors may collectively affect brain activity, there could be independent effects of smoking in alcohol use disorder that impact brain function and behavior. We hypothesized that smoking status, independent of alcohol use, would be associated with aberrations of nucleus accumbens functional connectivity to brain regions that facilitate reward processing, salience attribution, and inhibitory control. Resting state functional magnetic resonance imaging data from thirty-one nonsmokers and nineteen smoking individuals were analyzed using seed-based correlations of the bilateral accumbens with all other brain voxels. Statistical models accounted for drinks consumed per week. The smoking group demonstrated significantly higher functional connectivity between the left accumbens and the bilateral insula and anterior cingulate cortex, as well as hyperconnectivity between the right accumbens and the insula. Confirmatory analyses using the insula and cingulate clusters generated from the original analysis as seed regions reproduced the hyperconnectivity in smokers between the bilateral insular regions and the accumbens. In conclusion, smoking status had distinct effects on neural activity; hyperconnectivity between the accumbens and insula in smokers may reflect enhanced encoding of the reinforcing effects of smoking and greater orientation toward smoking-associated stimuli.

Understanding the shift to compulsion in addiction: insights from personality traits, social factors, and neurobiology

Compulsion stands as a central symptom of drug addiction; however, only a small fraction of individuals who use drugs exhibit compulsive characteristics. Differences observed in Sign-trackers (ST) and Goal-trackers (GT) during Pavlovian conditioning may shed light on individual variances in drug addiction. Here, we focus on the behavioral attributes, formation processes, and neural mechanisms underlying ST and how they drive addiction toward compulsivity in humans. We will explore addiction from three interconnected levels: individual personality traits, social factors, and neurobiology. Furthermore, we distinguish between the processes of sensitization and habituation within ST. These nuanced distinctions across various aspects of addiction will contribute to our understanding of the addiction development process and the formulation of targeted preventive strategies.

Neuroimaging Biomarkers in Addiction

As a neurobiological process, addiction involves pathological patterns of engagement with substances and a range of behaviors with a chronic and relapsing course. Neuroimaging technologies assess brain activity, structure, physiology, and metabolism at scales ranging from neurotransmitter receptors to large-scale brain networks, providing unique windows into the core neural processes implicated in substance use disorders. Identified aberrations in the neural substrates of reward and salience processing, response inhibition, interoception, and executive functions with neuroimaging can inform the development of pharmacological, neuromodulatory, and psychotherapeutic interventions to modulate the disordered neurobiology. Based on our systematic search, 409 protocols registered on ClinicalTrials.gov include the use of one or more neuroimaging paradigms as an outcome measure in addiction, with the majority (N=268) employing functional magnetic resonance imaging (fMRI), followed by positron emission tomography (PET) (N=71), electroencephalography (EEG) (N=50), structural magnetic resonance imaging (MRI) (N=35) and magnetic resonance spectroscopy (MRS) (N=35). Furthermore, in a PubMed systematic review, we identified 61 meta-analyses including 30 fMRI, 22 structural MRI, 8 EEG, 7 PET, and 3 MRS meta-analyses suggesting potential biomarkers in addictions. These studies can facilitate the development of a range of biomarkers that may prove useful in the arsenal of addiction treatments in the coming years. There is evidence that these markers of large-scale brain structure and activity may indicate vulnerability or separate disease subtypes, predict response to treatment, or provide objective measures of treatment response or recovery. Neuroimaging biomarkers can also suggest novel targets for interventions. Closed or open loop interventions can integrate these biomarkers with neuromodulation in real-time or offline to personalize stimulation parameters and deliver the precise intervention. This review provides an overview of neuroimaging modalities in addiction, potential neuroimaging biomarkers, and their physiologic and clinical relevance. Future directions and challenges in bringing these putative biomarkers from the bench to the bedside are also discussed.

The neural correlates of reinforcement sensitivity theory: A systematic review of the frontal asymmetry and spectral power literature

The original Reinforcement Sensitivity Theory (oRST) proposes two systems of approach (BAS) and avoidance (BIS) motivation to underpin personality and behavior. The revised-RST (rRST) model separates avoidance motivation into passive (BIS; anxiety) and active (FFFS; fear) systems. Prior research has attempted to map RST onto lateralized frontal asymmetry to provide a neurophysiological marker of RST. The main aim is to examine the relationships of the o/rRST scales with trait (baseline) and state (manipulated through experimental paradigms) frontal asymmetry. A systematic review was conducted, resulting in 158 studies designated to neuroimaging research. In total, 54 studies were included in this review using either frontal asymmetry or spectral power. The results were split into three main categories: resting frontal alpha asymmetry (N = 23), emotional induction and state-related frontal alpha asymmetry (N = 20), and spectral analysis (N = 16). Findings indicated that BAS was associated with enhanced left frontal asymmetry at baseline and during state-related paradigms. Findings for BIS were more inconsistent, especially at rest, suggesting that BIS, in particular, may require active engagement with the environment. Only 9 of the 54 papers included used the revised RST model, highlighting the need for more rRST research.

Strengthening Neuroplasticity in Substance Use Recovery Through Lifestyle Intervention

The incidence of substance use and behavioral addictions continues to increase throughout the world. The Global Burden of Disease Study shows a growing impact in disability-adjusted life years due to substance use. Substance use impacts families, communities, health care, and legal systems; yet, the vast majority of individuals with substance use disorders do not seek treatment. Within the United States, new legislation has attempted to increase the availability of buprenorphine, but the impact of substance use continues. Although medications and group support therapy have been the mainstay of treatment for substance use, lifestyle medicine offers a valuable adjunct therapy that may help strengthen substance use recovery through healthy neuroplastic changes.

Contextual factors associated with subjective effects of cannabis: A systematic review and meta-analysis

BACKGROUND

Cannabis is consumed in various social and environmental settings, and such contexts may be important predictors of subjective effects. The aim of this systematic review and meta-analysis was to examine the relationship between contextual factors and subjective effects of cannabis.

METHODS

A PRISMA-guided search of MEDLINE, Embase, PsycINFO, Global Health, and Google Scholar yielded 29 studies.

RESULTS

Study type (Ecological Momentary Assessment or Experimental) was a significant predictor of intoxication effects, and experimental studies had a greater pooled effect size (z =.296,95 % CI [.132,.478], p=.004) than Ecological Momentary Assessment (EMA) studies (z =.071,95 % CI [.011,.130], p =.02). Contextual conditions (environment, social group, expectancy, time of day, day of week) were not significant predictors of cannabis effects.

CONCLUSION

Findings did not point to a significant association between contextual conditions and subjective effects. However, as current literature is methodologically weak, it may be premature to conclude that subjective effects are not shaped by contextual factors. In view of policy and therapeutic implications, replications and study refinements are recommended.