The neurobiology of addiction

Alternative splicing in addiction

Addiction is a chronic and relapsing medical condition characterized by the compulsive use of drugs or alcohol despite harmful consequences. While transcriptional regulation has long been recognized for its role in addiction, recent genome-wide analyses have uncovered widespread alternative splicing changes that shift protein isoform diversity in multiple brain reward regions central to addiction. In this review, we discuss emerging research and evidence that alternative splicing is dysregulated in cocaine, alcohol, and opioid use disorders.

Treating Opioid Use Disorder and Opioid Withdrawal in the Context of Fentanyl

The opioid crisis, driven by illicitly manufactured fentanyl, presents significant challenges in treating opioid use disorder (OUD) and opioid withdrawal syndrome. Fentanyl is uniquely lethal due to its rapid onset and respiratory depressant effects, driving the surge in overdose deaths. This review examines the limitations of traditional diagnostic criteria like those of the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision (DSM-5-TR) and explores the potential of dimensional models such as the Hierarchical Taxonomy of Psychopathology (HiTOP) for a more nuanced understanding of OUD. Current treatments, including medications for OUD, are evaluated for efficacy in managing fentanyl-related OUD. Innovations in drug formulations and alternative induction methods are discussed to address the unique challenges posed by fentanyl. Psychotherapeutic and behavioral interventions, such as cognitive behavioral therapy and contingency management, are highlighted as crucial complements to pharmacotherapy. The review underscores the need for increased precision, comprehensive phenotyping, and advanced diagnostics to develop personalized treatment plans, all with the aim of improving patient outcomes and mitigating the societal impact of the opioid crisis.

Differences in fMRI-based connectivity during abstinence or interventions between heroin-dependent individuals and healthy controls

The substantial personal, societal, and economic impacts of opioid addiction drive research investigating how opioid addiction affects the brain, and whether therapies attenuate addiction-related metrics of brain function. Evaluating the connectivity between brain regions is a useful approach to characterise the effects of opioid addiction on the brain. This work is a systematic narrative review of studies investigating the effect of abstinence or interventions on connectivity in people who are dependent on heroin (HD) and healthy controls (HC). We found that HD typically showed weaker connectivity than HC between three functional networks: the Executive Control Network, Default Mode Network, and the Salience Network. Abstinence and Transcranial Magnetic Stimulation (TMS) both attenuated differences in connectivity between HD and HC, often by strengthening connectivity in HD. We observed that increased connectivity due to abstinence or TMS consistently related to decreased craving/risk of relapse. Using these findings, we present an "urge and action framework" relating therapeutic factors contributing to craving/relapse, connectivity results, and neurobiological models of HD. To inform future research, we critically assessed the impact of study design and analysis methods on study results. We conclude that the weaker between-network connectivity in HD and HC and its relationship to craving/relapse merits further exploration as a biomarker and target for therapeutic interventions.

Preclinical and clinical sex differences in the effects of alcohol on measures of brain dopamine: a systematic review

INTRODUCTION

Dopamine is involved in reward processing and plays a critical role in the development and progression of alcohol use disorder (AUD). However, little is known about the effect of sex on the relationship between dopamine and alcohol use/AUD. There is a critical need to identify the neurobiological mechanisms that contribute to sex differences in AUD to inform treatment approaches. This study aimed to review existing literature on sex differences in the effects of alcohol on brain dopamine measures in animals and individuals with heavy drinking/AUD.

METHODS

A systematic review was conducted using Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. PubMed was searched from inception to July 23rd, 2024.

RESULTS

Of the 1,412 articles identified, 10 met study criteria (1 human, 9 animal), including in vivo (two positron emission tomography, four microdialysis) and ex vivo (two liquid chromatography, two fast-scan cyclic voltammetry) studies. Six studies included an alcohol challenge; three showed that females had greater alcohol-induced dopamine release than males in the ventral striatum and frontal cortex, while three showed no sex-related differences. Notably, the latter three studies examined sex in a combined AUD/control group or measured dopamine levels days after alcohol exposure. Two studies that examined the effects of prenatal alcohol exposure showed that prenatal-alcohol-exposed male offspring versus sex-matched air-exposed controls had greater prefrontal cortical dopamine D1 receptor availability, and prenatal-alcohol-exposed female offspring versus sex-matched air-exposed controls had greater striatal dopamine concentration. Two studies investigating the mu-opioid receptor (MOR) regulation of alcohol-induced dopamine release showed a faster decline in females relative to males while the other study found females may be less dependent on MOR activity at lower doses of alcohol relative to higher doses.

CONCLUSIONS

This systematic review showed mixed results regarding sex differences in brain dopamine measures in alcohol-exposed animals and individuals with AUD, which may arise from differences in the timing, quantity, and duration of alcohol exposure, species, conditions, models, and techniques. More research examining the effect of sex on the relationship between alcohol use and brain dopamine measures is needed to enhance our understanding of AUD development, progression, and treatment in both females and males.

"Patients, Trauma Survivors, Sweethearts, or Troublemakers?": A Discourse Analysis of General Practitioners' and Pharmacists' Accounts of Clients on Opioid Substitution Treatment

Despite the high level of scientific support for the effectiveness of opioid substitution treatments (OSTs), individuals who rely on this treatment are a highly stigmatized population within healthcare settings. Previous studies mainly focused on the experiences of OST clients, while the perspective of medical professionals regarding OST remains largely unexplored. This study aims to investigate the discourse of pharmacists and general practitioners about OST through the lens of positioning theory. To explore their stance toward OST, semi-structured interviews were conducted with 30 pharmacists and general practitioners working in pharmacies, community health centers, private medical practices, prisons, and drug treatment services in Flanders, Belgium. The participants of this study discursively constructed four storylines to position themselves and OST clients, namely, a biomedical, psychodynamic, biopsychosocial, and moralizing storyline. These storylines are based on historical explanatory addiction models, and their use varies according to the participant's work setting. While the moralizing storyline was characterized by othering, stereotyping, and labeling, participants who applied the biopsychosocial storyline approached clients in a destigmatizing manner. To conclude, participants used the identified storylines to define the position of clients in OST, along with their related rights and duties. The dominant storyline thus shapes the view on and treatment of OST clients in a medical setting.

Expression of GDAP1 Gene Correlates With Alcohol Deprivation Effect

Alcohol addiction is a widespread disease, and the exact causes and consequences are still not fully determined. Neurotransmitters and neuronal circuits are not only the target structure of alcohol and responsible for its direct effects but also play a central role in the development of addiction. A gene that has been linked to alcohol use disorder in recent studies is the ganglioside-induced differentiation-associated protein 1 (GDAP1) gene. The present study focuses on the hippocampus, a brain region particularly vulnerable to alcohol and rich in Gdap1 gene expression. Using an established drinking model, alcohol drinking behavior was induced in adult male Long Evans rats. After 6 weeks of voluntary alcohol intake, followed by 2 weeks of deprivation, the animals were divided into two groups based on the alcohol deprivation effect (ADE). Gdap1 gene expression was measured with real-time PCR in the hippocampus. Results reveal significantly decreased mRNA expression in the high ADE group compared to the low ADE group. This decrease was specifically detected within the cornu ammonis 3 (CA3) region. Gdap1 expression in this region also negatively correlated with ADE in all animals. Taken together, results indicate that Gdap1 might not only be associated with alcohol consumption but might even play a role in alcohol dependence.

Role of Nanomedicine in Transforming Pharmacotherapy for Substance Use Disorder (SUD)

The field of nanomedicine offers revolutionary potential to reshape the discovery and development of therapeutics for diverse human diseases. However, its application has been limited in improving Substance Use Disorders (SUDs), which represent a profound public health crisis, including major types such as opioid, alcohol, stimulant, and cannabis use disorders. Pharmacotherapy, a cornerstone of SUD management, has reduced morbidity, mortality, and the societal impact of addiction, though its efficacy has ranged from none to moderate. Thus, there is a major unmet need to transform SUD pharmacotherapy to curb the epidemic of addiction. This article explores the potential roles of nanomedicine-inspired precision-targeted drug delivery, sustained release, and combination therapies to increase therapeutic efficacy and minimize side effects. Additionally, it discusses innovative mechanisms that align with the neurobiological complexities of addiction and synergistic approaches that integrate nanomedicine with behavioral interventions, device-based therapies, and emerging modalities such as immunotherapy and neurostimulation. Despite these advancements, barriers such as treatment accessibility, adherence challenges, and inequitable resource distribution persist, particularly in underserved populations. By harnessing the transformative capabilities of nanomedicine and integrating it into holistic, equitable, and personalized care frameworks, this review highlights a path forward to revolutionize the SUD pharmacotherapy landscape. The article underscores the need for continued nano-SUD pharmacotherapy research and the development of strategies to alleviate the substantial burden of addiction on individuals, families, and society.

A moderated mediation model in assessing links between rumination, emotional reactivity, and suicidal risk in alcohol use disorder

Introduction

Suicide is a major public health concern, particularly among people with alcohol use disorders (AUD). Rumination, as a dysfunctional emotion regulation strategy, and increased emotional reactivity may significantly influence suicide risk in this population.

Aim

The aim of this study was to assess whether different emotional reactivity mediate the association between ruminations and suicide risk, and whether AUD or control group (HC) status moderates these relationships.

Methods

A study was conducted with 152 participants, including 86 from AUD and 66 from HC. Self-report questionnaires measuring ruminations, emotional reactivity and suicide risk were used. Structural Equation Modeling, invariance analysis, and moderated mediation estimation were used in the analyses.

Results

The mediation analysis in the full sample revealed a significant indirect effect of rumination on suicide risk via emotional reactivity. Multi-group analysis indicated no significant differences in the mediation effect between the AUD and HC groups, with neither group showing a statistically significant indirect effect.

Conclusions

The findings indicate that emotional reactivity may serve as a key mechanism mediating the relationship between rumination and suicide risk. Therapeutic interventions should focus on reducing ruminations and emotion reactivity to effectively reduce suicide risk in this group. Further research is needed to better understand these mechanisms.

Teaching Knowledge and Empathy in Substance Use Disorder Through Enriched Education in the Neurobiology of Addiction: A Narrative Review on Addiction Education in Professional Schools

BACKGROUND

Addiction is a devastating chronic disease requiring significant resources and attention. Healthcare professionals have noted struggles in caring for patients with substance use disorder (SUD) due to stigma, perceived difficulties in dealing with patients, and issues with treatment compliance. Challenges in dealing with individuals with SUD may stem from an inadequate understanding of the disease and consequent misconceptions about patient behaviors. The type and extent of addiction education affect the depth of understanding of SUD and shape attitudes toward patients. In this review, we explore aspects of addiction education including examining curricular guidelines and educational strategies, especially regarding the neurobiology of addiction.

METHODS

We conducted a narrative review using online databases and search engines to identify studies related to addiction/SUD education with emphasis on the type and extent of neurobiological content.

RESULTS

Studies examining addiction education document deficiencies that may contribute to insufficiencies in SUD treatment and disrespectful treatment of individuals with SUD. There is also a lack of detail regarding the extent of the neurobiology of addiction education in professional core courses and curricular guidelines. Implementing a more detailed approach to addiction education with more comprehensive neurobiology is discussed along with strategies to motivate students to learn and appreciate these complex details.

CONCLUSIONS

While there are many aspects of addiction education, a solid foundation in the neurobiological mechanisms of addiction is important to establish an appreciation for the disease nature of addiction and the resulting behaviors of the individual. Teaching beyond the rewarding nature of addiction is essential to enable students to comprehend how the activation of survival stress systems and compromised decision-making affects the behavior of individuals with SUD. A more comprehensive understanding of addiction fosters more respect for individuals with SUD and creates potential for more opportunities for effective treatment.

Unveiling the Complexities of Medications, Substance Abuse, and Plants for Recreational and Narcotic Purposes: An In-Depth Analysis

The complexities surrounding the use of medications, substance abuse, and the recreational use of plants are multifaceted and warrant a comprehensive examination. This review highlights the complexities surrounding the consumption of chemical substances in excess or for non-medical purposes, obtained through legal prescriptions, over-the-counter purchases, or illicit means, with an emphasis on the predictive role of stressors and individual-level variables in the development of substance use disorders, as well as the influence of the regulatory environment on patterns of consumption. Additionally, the alarming escalation in the mortality rate associated with illicit drug and opioid overdoses is also underscored. The recreational use of prescription medications can lead to significant health risks, particularly when combined with other substances; therefore, the need for interventions and preventive measures to address substance abuse among various populations is imperative. Furthermore, novel insights on substance abuse addiction, exploring the neurobiological mechanisms underlying addiction, and discussing treatment approaches and interventions are elucidated. Advancements in technology for detecting substance abuse are also highlighted, displaying innovative tools for more effective identification and monitoring. In conclusion, the complexities of medications, substance abuse, and the recreational use of plants reveal a landscape marked by overlapping motivations and health implications. The distinction between medical and recreational use is critical for understanding user behavior and addressing public health concerns.

Art therapy's engagement of brain networks for enduring recovery from addiction

The field of addiction in its priority to save lives has emphasized harm reduction and medication therapies that have taken precedence over counseling and psychotherapy. The extensive mental health needs, traumatic histories and cognitive challenges of this population call for more availability of all treatments, but also in-depth treatment for the causes of the addiction. The prevalence of trauma is examined with regard to the challenge it presents in treatment for substance use disorder (SUD), and other comorbidities. Two case examples are offered that exemplify how art therapy expedites key information about underlying trauma. Art therapy is proposed as a treatment approach for SUD for its apparent activation of key neural networks that are also impacted by trauma, and its usefulness in engaging those who have cognitive challenges experientially. Quantitative research is cited that suggests art therapy's activation of the reward system, which may make art therapy useful in treating the stress and inhibition coefficients of addiction that map to neural networks of addiction. The need for additional empirical research is cited that may improve the efficiency and effectiveness of art therapy and mental health treatment.

Lack of Premeditation Mediates the Relationship Between Adverse Childhood Experiences and Posttraumatic Stress Disorder in Individuals in Residential Treatment for Substance Use Disorder

Objective: Adverse Childhood Events (ACEs) are associated with increased vulnerability for posttraumatic stress disorder (PTSD), but not everyone who experiences ACEs develops PTSD. Impulsivity has gained interest as a potential mediator between ACEs and PTSD, given that both PTSD and ACEs have been closely related to impulsivity. However, less is known about the relationship within the context of substance use disorder (SUD), a population highly vulnerable to co-occurring PTSD. This study examined whether impulsivity mediates the relationship between ACEs and PTSD symptoms in adults seeking residential treatment for substance use disorder (SUD). Methods: N = 134 consenting adults in residential treatment for SUD completed questionnaires measuring impulsivity (UPPS-P), ACEs (ACEs Scale), and PTSD symptoms (PCL-5). Regression models tested our hypotheses that ACEs would predict PTSD symptoms and that impulsivity would mediate this relationship. Results: Two-thirds of participants met the PCL-5 score threshold for a provisional diagnosis of PTSD. ACEs score and impulsivity were significant direct predictors of PTSD symptoms (coeff = 2.23, p < .001; coeff = 1.03, p < .001). Among UPPS-P subconstructs, only lack of premeditation emerged as a partial mediator (z = 2.14, p = 0.032). Conclusions: Individuals with SUD experience adverse and traumatic events at alarming rates and are at increased risk for PTSD. Our mediation finding suggests that impulsivity and especially lack of premeditation may be clinically relevant in the development or maintenance of PTSD symptoms among individuals with SUD.

Unveiling the power of optimism: Exploring behavioral and neuromolecular correlates of alcohol seeking and drinking in rats with biased judgement

Alcohol use disorder (AUD) is a common psychiatric condition with substantial global mortality. Despite extensive research into its pathophysiology, the cognitive predispositions driving alcohol dependence are less understood. This study explores whether biased cognition, specifically traits of optimism and pessimism, predicts susceptibility to alcohol-seeking behaviors using an animal model. Rats were initially tested for judgement bias through Ambiguous Cue Interpretation tests. Those identified as 'optimistic' or 'pessimistic' were further examined for their tendency to escalate alcohol intake using the intermittent access 2-bottle choice (2BC) paradigm. Additionally, we assessed how judgement bias influenced the development of compulsive alcohol-seeking behavior in a Seeking-Taking (ST) and Seeking-Taking Punishment tasks, alcohol-seeking motivation in the Progressive Ratio Schedule of Reinforcement paradigm, the speed of extinction, and reinstatement after abstinence. Neurochemical analyses were conducted to investigate trait-specific differences in neurotransmitter-related gene expression and receptor densities in the brain. We used TaqMan Gene Expression Array Cards to analyze expression levels of genes linked to serotonergic, dopaminergic, glutamatergic, and GABAergic pathways, and alcohol metabolism in various brain regions. Receptor densities for 5-HT1A, 5-HT2A, and D2 were measured using autoradiography analysis. Behaviorally, 'optimistic' rats showed significantly lower alcohol consumption in the 2BC paradigm compared to 'pessimistic' rats. This lowered intake correlated with decreased monoamine oxidase-A (Maoa) expression in the medial prefrontal cortex (mPFC) and increased metabotropic glutamate receptor 2 (Grm2) expression in the amygdala (Amy). Additionally, we observed significant interactions between judgement bias and alcohol intake in the expression of several genes in the mPFC, nucleus accumbens (Nacc), orbitofrontal cortex (OFC), and Amy, as well as in 5-HT2A receptor binding in the Nacc. Overall, these results suggest that optimism is linked to lower alcohol consumption and related neurochemical changes, indicating a potential cognitive mechanism in AUD risk.

Harm Reduction and Substance Use in Adolescents

This article discusses the use of substances among adolescents, the unacceptable overdose death rates they bear, and the relevant evidence-based harm reduction strategies available in primary care, including medications for opioid use disorder. Access to these medications, as well as to harm reduction strategies generally, is insufficient for adolescents. Many adolescents who use substances and who are most at risk for overdose regularly visit primary care, which is an appropriate setting for treatment and harm reduction delivery.

Impulsivity in ADHD and Borderline Personality Disorder: A Systematic Review of Gray and White Matter Variations

Introduction: Impulsivity is one of the overlapping symptoms common to borderline personality disorder (BPD) and attention deficit hyperactivity disorder (ADHD), but the neurobiological basis of these disorders remains uncertain. This systematic review aims to identify abnormalities in the gray and white matter associated with impulsivity in BPD and ADHD. Methods: We conducted a systematic search of the PubMed, Embase, and SCOPUS databases, adhering to PRISMA guidelines. Studies that investigated gray and white matter alterations in BPD or ADHD populations and their relationship with impulsivity were included. We reviewed information from 23 studies involving 992 participants, which included findings from structural MRI and DTI. Results: The review identified various nonhomogeneous changes associated with impulsivity in BPD and ADHD. BPD was mainly associated with abnormalities in the prefrontal cortex (PFC) and limbic areas, which correlated negatively with impulsivity. In contrast, impulsivity associated with ADHD was associated with structural changes in the caudate nucleus and frontal-striatal pathways. Despite the overlapping symptoms of impulsivity, the neurobiological mechanisms appeared to differ between the two disorders. Conclusions: These findings emphasize the distinct neurostructural correlates of impulsivity in BPD and ADHD. While both disorders show impulsivity as one of their main symptoms, the fundamental brain structures associated with this trait are different. BPD is primarily associated with abnormalities in the prefrontal cortex and limbic system, whereas the alterations seen in ADHD tend to focus on the caudate nucleus and frontostriatal pathways. Further research is needed to clarify these differences and their implications for treatment.

Adaptations in glutathione-based redox protein signaling pathways and alcohol drinking across species

Alcohol use disorder (AUD) is the most prevalent substance use disorder but there is incomplete knowledge of the underlying molecular etiology. Here, we examined the cytosolic proteome from the nucleus accumbens core (NAcC) of ethanol drinking rhesus macaques to identify ethanol-sensitive signaling proteins. The targets were subsequently investigated using bioinformatics, genetic, and pharmacological manipulations in mouse models of ethanol drinking. Of the 1000+ cytosolic proteins identified in our screen, 50 proteins differed significantly between control and ethanol drinking macaques. Gene Ontology analysis of the differentially expressed proteins identified enrichment in pathways regulating metabolic processes and proteasome activity. Because the family of Glutathione S-transferases (GSTs) was enriched in these pathways, validation studies targeted GSTs using bioinformatics and genetically diverse mouse models. Gstp1 and Gstm2 were identified in Quantitative Trait Loci and published gene sets for ethanol-related phenotypes (e.g., ethanol preference, conditioned taste aversion, differential expression), and recombinant inbred strains that inherited the C57BL/6J allele at the Gstp2 interval consumed higher amounts of ethanol than those that inherited the DBA/2J allele. Genetic deletion of Gstp1/2 led to increased ethanol consumption without altering ethanol metabolism or sucrose preference. Administration of the pharmacologic activator of Gstp1/2, carnosic acid, decreased voluntary ethanol drinking. Proteomic analysis of the NAcC cytosolic of heavy drinking macaques that were validated in mouse models indicate a role for glutathione-mediated redox regulation in ethanol-related neurobiology and the potential of pharmacological interventions targeting this system to modify excessive ethanol drinking.

Need for strategic communications and stakeholder engagement to advance acceptability of an overdose preventing vaccine targeting fentanyl

BACKGROUND

Fentanyl is a synthetic opioid, exposure to which has led to hundreds of thousands of overdose deaths. Novel vaccines are being developed that might protect against fentanyl overdose. Proactive attention to strategic communications and stakeholder engagement may smooth uptake of a novel vaccine given known challenges around vaccine hesitancy and concern for stigma related to substance use.

METHODS

Qualitative interviews (N = 74) with a purposive sample of adolescents/young adults with opioid use disorder (OUD), family members of persons with OUD, experts in substance use treatment and harm reduction, and community members were conducted and thematically analyzed to discern attitudes toward a fentanyl vaccine, and directions for communications and engagement.

RESULTS

Major themes reflected personal concerns for biomedical risk and system-level concerns for alignment and integration of an overdose preventing vaccine with prevailing beliefs about addiction and associated frameworks and philosophies for treatment and response.

CONCLUSION

Acceptability and implementation of a novel fentanyl vaccine targeting overdose will need precision communications that address biomedical, moral/spiritual, and structural perspectives about the nature of addiction. Education about the purpose and limits of a fentanyl vaccine, partnerships with diverse stakeholders from throughout the opioid response ecosystem and interweaving of a vaccine strategy into comprehensive prevention and treatment are recommended.

Gut Microbiota and DTI Microstructural Brain Alterations in Rodents Due to Morphine Self-Administration

The opioid epidemic is an evolving health crisis in need of interventions that target all domains of maladaptive changes due to chronic use and abuse. Opioids are known for their effects on the opioid and dopaminergic systems, in addition to neurocircuitry changes that mediate changes in behavior; however, new research lines are looking at complementary changes in the brain and gut. The gut-brain axis (GBA) is a bidirectional signaling process that permits feedback between the brain and gut and is altered in subjects with opioid use disorders. In this work, we determine longitudinal, non-invasive, and in-vivo complementary changes in the brain and gut in rodents trained to self-administer morphine for two weeks using MRI and 16S rDNA analysis of fecal matter. We assess the changes occurring during both an acute phase (early in the self-administration process, after two days of self-administration) and a chronic phase (late in the self-administration process, after two weeks of self-administration), with all measurements benchmarked against baseline (naïve, non-drug state). Rats were surgically implanted with an intravenous jugular catheter for self-administration of morphine. Rats were allowed to choose between an active lever, which delivers a single infusion of morphine (0.4 mg/kg/infusion), or an inactive lever, which had no consequence upon pressing. Animals were scanned in a 7T MRI scanner three times (baseline, acute, and chronic), and before scanning, fecal matter was collected from each rat. After the last scan session, a subset of animals was euthanized, and brains were preserved for immunohistochemistry analysis. We found early changes in gut microbiota diversity and specific abundance as early as the acute phase that persisted into the chronic phase. In MRI, we identified alterations in diffusivity indices both within subjects and between groups, showing a main effect in the striatum, thalamus, and somatosensory cortex. Finally, immunohistochemistry analyses revealed increased neuroinflammatory markers in the thalamus of rats exposed to morphine. Overall, we demonstrate that morphine self-administration shapes the brain and gut microbiota. In conclusion, gut changes precede the anatomical effects observed in MRI features, with neuroinflammation emerging as a crucial link mediating communication between the gut and the brain. This highlights neuroinflammation as a potential target in addressing the impacts of opioid use.

In vivo Evaluation of Antioxidant Activity of Chamomile Extract against Procyclidine-Induced Oxidative Stress: Potential Application in Cancer Prevention

The study aimed to investigate the effect of the aqueous extract of the chamomile plant on oxidative stress induced by procyclidine in rats. 30 rats were randomly divided into five groups, with 6 rats in each group. The first group was given distilled water only, while the second group was administered procyclidine (1 mg/kg body weight) in three doses daily for a period of 60 days. The third group was given procyclidine in the same doses as the second group for 30 days. Afterward, they were administered an aqueous extract of chamomile (300 mg/kg) for another 30 days. The fourth group was administered the aqueous extract (300 mg/kg) for 30 days. Subsequently, they were given procyclidine in the same doses as the second group for another 30 days. On the other hand, the fifth group was administered the aqueous extract of chamomile (300 mg/kg) for a period of 60 days to investigate the potential effects of the extract. Afterward, blood samples were drawn to measure various biological parameters, including Total Oxidant Status (TOS), Malondialdehyde (MDA), Aspartate Aminotransferase (AST), Alanine Transaminase (ALT), and Acetylcholinesterase (AChE) activity. Finally, an anatomical study was conducted on the kidneys, brain, and liver to enhance the research. The results displayed a significant increase in the levels of TOS, MDA, AST, ALT enzymes, and Ach-E activity in the second group compared to the first group. Groups 3 and 4 significantly decreased compared to the second group based on the same standards. In regard to Group 5, there are no significant moral differences between it and Group 1. Finally, this study demonstrated the importance of using chamomile extract as an antioxidant and its potential in cancer prevention against the oxidative stress induced by excessive doses of procyclidine. (p ≤ 0.005).

Chronic alcohol consumption alters sex-dependent BNST neuron function in rhesus macaques

Repeated alcohol drinking contributes to a number of neuropsychiatric diseases, including alcohol use disorder and co-expressed anxiety and mood disorders. Women are more susceptible to the development and expression of these diseases with the same history of alcohol exposure as men, suggesting they may be more sensitive to alcohol-induced plasticity in limbic brain regions controlling alcohol drinking, stress responsivity, and reward processing, among other behaviors. Using a translational model of alcohol drinking in rhesus monkeys, we examined sex differences in the basal function and plasticity of neurons in the bed nucleus of the stria terminalis (BNST), a brain region in the extended amygdala shown to be a hub circuit node dysregulated in individuals with anxiety and alcohol use disorder. We performed slice electrophysiology recordings from BNST neurons in male and female monkeys following daily "open access" (22 h/day) to 4% ethanol and water for more than one year or control conditions. We found that BNST neurons from control females had reduced overall current density, hyperpolarization-activated depolarizing current (Ih), and inward rectification, as well as higher membrane resistance and greater synaptic glutamatergic release and excitatory drive, than those from control males, suggesting that female BNST neurons are more basally excited than those from males. Chronic alcohol drinking produced a shift in these measures in both sexes, decreasing current density, Ih, and inward rectification and increasing synaptic excitation. In addition, network activity-dependent synaptic inhibition was basally higher in BNST neurons of males than females, and alcohol exposure increased this in both sexes, a putative homeostatic mechanism to counter hyperexcitability. Altogether, these results suggest that the rhesus BNST is more basally excited in females than males and chronic alcohol drinking produces an overall increase in excitability and synaptic excitation. These results shed light on the mechanisms contributing to the female-biased susceptibility to neuropsychiatric diseases including co-expressed anxiety and alcohol use disorder.

The influence of drug class on reward in substance use disorders

In the United States, the societal costs associated with drug use surpass $500 billion annually. The rewarding and reinforcing properties that drive the use of these addictive substances are typically examined concerning the neurobiological effects responsible for their abuse potential. In this review, terms such as "abuse potential," "drug," and "addictive properties" are used due to their relevance to the methodological, theoretical, and conceptual framework for understanding the phenomenon of drug-taking behavior and the associated body of preclinical and clinical literature. The use of these terms is not intended to cast aspersions on individuals with substance use disorders (SUD). Understanding what motivates substance use has been a focus of SUD research for decades. Much of this corpus of work has focused on the shared effects of each drug class to increase dopaminergic transmission within the central reward pathways of the brain, or the "reward center." However, the precise influence of each drug class on dopamine signaling, and the extent thereof, differs considerably. Furthermore, the aforementioned substances have effects on several neurobiological targets that mediate and modulate their addictive properties. The current manuscript sought to review the influence of drug class on the rewarding effects of each of the major pharmacological classes of addictive drugs (i.e., psychostimulants, opioids, nicotine, alcohol, and cannabinoids). Our review suggests that even subtle differences in drug effects can result in significant variability in the subjective experience of the drug, altering rewarding and other reinforcing effects. Additionally, this review will argue that reward (i.e., the attractive and motivational property of a stimulus) alone is not sufficient to explain the abuse liability of these substances. Instead, abuse potential is best examined as a function of both positive and negative reinforcing drug effects (i.e., stimuli that the subject will work to attain and stimuli that the subject will work to end or avoid, respectively). Though reward is central to drug use, the factors that motivate and maintain drug taking are varied and complex, with much to be elucidated.

Implications of Impulsivity on Criminal Behavior in Individuals With Substance Use Disorder

OBJECTIVE

Our aim was to analyze the association between criminal behavior and impulsivity in individuals with drug addiction and investigate whether impulsiveness mediates the relationship between drug use severity and legal problems.

METHODS

This cross-sectional study included 773 men diagnosed with addiction (295 alcohol users and 478 users of crack/polysubstance) while undergoing addiction treatment. The BIS-11 and ASI-6 were applied to assess impulsivity, criminal behavior, and drug use.

RESULTS

The prevalence of criminal behavior was 41.7% (n = 123) in alcohol users and 64.9% (n = 310) in users of crack/polysubstance. Earlier use of different substances and higher impulsivity scores were observed in individuals with criminal history. Mediation analyses revealed that impulsiveness acts as a mediator factor between substance use and criminal behavior, enhancing the severity of legal problems.

CONCLUSION

Our findings can help in deciding on tailored treatment strategies, focusing not only on substance use, but also on the prevention of social problems, criminality, and impulsivity.

Neuromodulation of safety and surprise in the early stages of infant development: affective homeostatic regulation in bodily and mental functions

Developing a sense of internal safety and security depends mainly on others: numerous neuromodulators play a significant role in the homeostatic process, regulating the importance of proximity to a caregiver and experiencing feelings that enable us to regulate our interdependence with our conspecifics since birth. This array of neurofunctional structures have been called the SEPARATION DISTRESS system (now more commonly known as the PANIC/ GRIEF system). This emotional system is mainly involved in the production of depressive symptoms. The disruption of this essential emotional balance leads to the onset of feelings of panic followed by depression. We will focus on the neuropeptides that play a crucial role in social approach behavior in mammals, which enhance prosocial behavior and facilitate the consolidation of social bonds. We propose that most prosocial behaviors are regulated through the specific neuromodulators acting on salient intersubjective stimuli, reflecting an increased sense of inner confidence (safety) in social relationships. This review considers the neurofunctional link between the feelings that may ultimately be at the base of a sense of inner safety and the central neuromodulatory systems. This link may shed light on the clinical implications for the development of early mother-infant bonding and the depressive clinical consequences when this bond is disrupted, such as in post-partum depression, depressive feelings connected to, addiction, neurofunctional disorders, and psychological trauma.

A Pilot Study: Treatment of High Alcohol Consumption in a Novel Minipig Model of Alcohol Use Disorder

Three medications are FDA approved in the US for treatment of Alcohol Use Disorder (AUD), and a few others are used off-label. Patient compliance and efficacy in the broader population are major hurdles for current AUD medications. As a consequence, there is an urgent need for improved pharmacotherapeutics to complement behavioral approaches. Here, we report pilot testing of a minocycline analog, 10-butylether minocycline (BEM, 10 mg/kg p.o.), in two female minipigs with free-choice drinking to intoxication for nearly two and a half years. Each pig met DSM-5 criteria for diagnosis of severe AUD, and BEM reduced both alcohol intake and preference. BEM is currently undergoing testing for approval as an Investigational New Drug by the FDA for AUD treatment.

Structural Features Influencing the Bioactive Conformation of Angiotensin II and Angiotensin A: Relationship between Receptor Desensitization, Addiction, and the Blood-Brain Barrier

The N-terminal portion of the octapeptide angiotensin II (DRVYIHPF; AngII), a vasopressor peptide that favorably binds to, and activates, AngII type 1 receptor (AT1R), has an important role in maintaining bioactive conformation. It involves all three charged groups, namely (i) the N-terminal amino group cation, (ii) the Asp sidechain anion and (iii) the Arg guanidino cation. Neutralization of any one of these three charged groups results in a substantial reduction (<5%) in bioactivity, implicating a specialized function for this cluster. In contrast, angiotensin A (ARVYIHPF; AngA) has reduced bioactivity at AT1R; however, replacement of Asp in AngII with sarcosine (N-methyl-glycine) not only restores bioactivity but increases the activity of agonist, antagonist, and inverse agonist analogues. A bend produced at the N-terminus by the introduction of the secondary amino acid sarcosine is thought to realign the functional groups that chaperone the C-terminal portion of AngII, allowing transfer of the negative charge originating at the C-terminus to be transferred to the Tyr hydroxyl-forming tyrosinate anion, which is required to activate the receptor and desensitizes the receptor (tachyphylaxis). Peptide (sarilesin) and nonpeptide (sartans) moieties, which are long-acting inverse agonists, appear to desensitize the receptor by a mechanism analogous to tachyphylaxis. Sartans/bisartans were found to bind to alpha adrenergic receptors resulting in structure-dependent desensitization or resensitization. These considerations have provided information on the mechanisms of receptor desensitization/tolerance and insights into possible avenues for treating addiction. In this regard sartans, which appear to cross the blood-brain barrier more readily than bisartans, are the preferred drug candidates.

Investigating the neurobiology of maternal opioid use disorder and prenatal opioid exposure using brain organoid technology

Over the past two decades, Opioid Use Disorder (OUD) among pregnant women has become a major global public health concern. OUD has been characterized as a problematic pattern of opioid use despite adverse physical, psychological, behavioral, and or social consequences. Due to the relapsing-remitting nature of this disorder, pregnant mothers are chronically exposed to exogenous opioids, resulting in adverse neurological and neuropsychiatric outcomes. Collateral fetal exposure to opioids also precipitates severe neurodevelopmental and neurocognitive sequelae. At present, much of what is known regarding the neurobiological consequences of OUD and prenatal opioid exposure (POE) has been derived from preclinical studies in animal models and postnatal or postmortem investigations in humans. However, species-specific differences in brain development, variations in subject age/health/background, and disparities in sample collection or storage have complicated the interpretation of findings produced by these explorations. The ethical or logistical inaccessibility of human fetal brain tissue has also limited direct examinations of prenatal drug effects. To circumvent these confounding factors, recent groups have begun employing induced pluripotent stem cell (iPSC)-derived brain organoid technology, which provides access to key aspects of cellular and molecular brain development, structure, and function in vitro. In this review, we endeavor to encapsulate the advancements in brain organoid culture that have enabled scientists to model and dissect the neural underpinnings and effects of OUD and POE. We hope not only to emphasize the utility of brain organoids for investigating these conditions, but also to highlight opportunities for further technical and conceptual progress. Although the application of brain organoids to this critical field of research is still in its nascent stages, understanding the neurobiology of OUD and POE via this modality will provide critical insights for improving maternal and fetal outcomes.

Rethinking Substance Use as Social History: Charting a Way Forward

Physicians have traditionally asked about substance use within the Social History section of the consultation note. Drawing on social science theory and using the authors' own experiences as generalists and addiction scholars, we consider the possible unintended harms associated with this approach. The inclusion of the substance use history within the Social History reproduces the discourse of substance use disorders as "life-style choices" rather than medical conditions, and reinforces stigma among healthcare workers through the attribution of personal responsibility for complications associated with problematic substance use. The ongoing placement of the substance use history within the Social History may lead to a failure to diagnose and make appropriate management plans for clients with substance use disorders. These missed opportunities may include inadequate withdrawal management leading to discharge before medically advised, insufficient use of evidence-based pharmacotherapy and psychotherapy, polypharmacy, medical complications, and repeated admissions to hospital. We argue instead that the Substance Use History should be a stand-alone section within the consultation note. This new section would reduce the invisibility of substance use disorders within our medical systems and model that these chronic medical conditions are amenable to prevention, treatment and harm reduction through the application of evidence-based practices.

Chronic alcohol consumption alters sex-dependent BNST neuron function in rhesus macaques

Repeated alcohol drinking contributes to a number of neuropsychiatric diseases, including alcohol use disorder and co-expressed anxiety and mood disorders. Women are more susceptible to the development and expression of these diseases with the same history of alcohol exposure as men, suggesting they may be more sensitive to alcohol-induced plasticity in limbic brain regions controlling alcohol drinking, stress responsivity, and reward processing, among other behaviors. Using a translational model of alcohol drinking in rhesus monkeys, we examined sex differences in the basal function and plasticity of neurons in the bed nucleus of the stria terminalis (BNST), a brain region in the extended amygdala shown to be a hub circuit node dysregulated in individuals with anxiety and alcohol use disorder. We performed slice electrophysiology recordings from BNST neurons in male and female monkeys following daily "open access" (22 hr/day) to 4% ethanol and water for more than one year or control conditions. We found that BNST neurons from control females had reduced overall current density, hyperpolarization-activated depolarizing current (Ih), and inward rectification, as well as higher membrane resistance and greater synaptic glutamatergic release and excitatory drive, than those from control males, suggesting that female BNST neurons are more basally excited than those from males. Chronic alcohol drinking produced a shift in these measures in both sexes, decreasing current density, Ih, and inward rectification and increasing synaptic excitation. In addition, network activity-dependent synaptic inhibition was basally higher in BNST neurons of males than females, and alcohol exposure increased this in both sexes, a putative homeostatic mechanism to counter hyperexcitability. Altogether, these results suggest that the rhesus BNST is more basally excited in females than males and chronic alcohol drinking produces an overall increase in excitability and synaptic excitation. These results shed light on the mechanisms contributing to the female-biased susceptibility to neuropsychiatric diseases including co-expressed anxiety and alcohol use disorder.

rTMS effects on urges and severity of tobacco use disorder operate independently of a retrieval-extinction component and involve frontal-striatal pathways

BACKGROUND

Although smoking remains a leading cause of preventable disease, the treatment options for smoking are limited. The present study evaluated the neural features underlying effects of repetitive transcranial magnetic stimulation (rTMS) for reducing smoking cravings. In addition, the efficacy of a simulated retrieval-extinction procedure to augment rTMS efficacy was examined.

METHODS

Sixty-one individuals with tobacco use disorder (TUD) were randomized into three groups: classic rTMS, retrieval rTMS (viewed smoking videos before rTMS), and sham rTMS. rTMS was performed on the left dorsolateral prefrontal cortex (DLPFC) over 5 days using a standard figure-8 coil. Smoking cravings and brain responses to smoking cues were measured before and after rTMS treatment. Changes in functional connectivity (FC) among different brain regions were calculated.

RESULTS

rTMS reduced smoking urges in TUD. Both active-rTMS groups demonstrated greater activations of the DLPFC, caudate, and bilateral insula relative to the sham group. Increased FC was observed between executive and reward network brain regions, and decreased FC was observed within reward network regions. Compared with standard rTMS, retrieval-extinction rTMS demonstrated similar outcomes and was associated with less activation of the medial frontal gyrus.

CONCLUSIONS

rTMS increased activations in brain regions implicated in executive control and reward processing. Strengthened prefrontal-striatal pathway suggests that rTMS enhanced top-down control over smoking cravings. The retrieval-extinction process, although associated with some different and multiple similar neural correlates as the standard rTMS, did not enhance cessation outcomes.

Processing abnormalities in monetary outcome evaluations among male individuals with opioid use disorder: evidence from feedback-related negativity

Background: Numerous studies have highlighted the pivotal role of alterations in the monetary reward system in the development and maintenance of substance use disorder (SUD). Although these alterations have been well documented in various forms of SUD, the electrophysiological mechanisms specific to opioid use disorder (OUD) remain underexplored. Understanding these mechanisms is critical for developing targeted interventions and advancing theories of addiction specific to opioid use.Objectives: To explore abnormalities in monetary reward outcome processing in males with OUD. We hypothesized that control individuals would show higher feedback-related negativity (FRN) to losses, unlike those in the OUD group, where FRN to losses and gains would not differ significantly.Methods: Fifty-seven participants (29 male individuals with OUD [heroin] and 28 male controls) were evaluated. A combination of the monetary incentive delay task (MIDT) and event-related potential (ERP) technology was used to investigate electrophysiological differences in monetary reward feedback processing between the OUD and healthy control groups.Results: We observed a significant interaction between group (control vs. OUD) and monetary outcome (loss vs. gain), indicated by p < .05 and η2p = 0.116. Specifically, control participants showed stronger negative FRN to losses than gains (p < .05), unlike the OUD group (p > .05).Conclusion: This study's FRN data indicate that males with OUD show altered processing of monetary rewards, marked by reduced sensitivity to loss. These findings offer electrophysiological insights into why males with OUD may pursue drugs despite potential economic downsides.

The Potential and Challenges of Genomics Informed Precision Care for Substance Use Disorders

Substance use disorders (SUDs) are complex brain disorders with heritability rooted in the interplay of multiple genetic factors, alongside significant environmental influences. Gaining insights into the genetic mechanisms that heighten SUD risk can guide precision care, specifically in the development of targeted tools for prevention, early intervention, and the discovery of therapeutic targets. Nurses are ideally placed to advance genomics-informed precision care for individuals with SUDs. To fulfill this role, they must be adequately prepared to assess the value and utility of current genomics knowledge, its limitations, and ways to incorporate this understanding into clinical practice, education, research, and health care policy. [Journal of Psychosocial Nursing and Mental Health Services, 62(3), 11-14.].

Exploring the Relationship between Diamine Oxidase and Psychotropic Medications in Fibromyalgia Treatment, Finding No Reduction in Diamine Oxidase Levels and Activity except with Citalopram

Background: Histamine intolerance manifests when there is an imbalance between the production of histamine and the body's capacity to metabolise it. Within the gastrointestinal tract, diamine oxidase (DAO) plays a pivotal role in breaking down ingested histamine. Insufficient levels of DAO have been linked to various diseases affecting the respiratory, cardiovascular, nervous, muscular, and digestive systems; some of these symptoms are evidenced in fibromyalgia syndrome. This underscores the crucial role of DAO in maintaining the histamine balance and highlights its association with diverse physiological systems and health conditions. The management of fibromyalgia commonly involves the use of psychotropic medications; however, their potential interactions with DAO remain not fully elucidated. Methods: This study delved into the influence of various psychotropic medications on DAO activity through in vitro experiments. Additionally, we explored their impact on the human intestinal cell line Caco-2, examining alterations in DAO expression at both the mRNA and protein levels along with DAO activity. Results: Notably, the examined drugs-sertraline, pregabalin, paroxetine, alprazolam, and lorazepam-did not exhibit inhibitory effects on DAO activity or lead to reductions in DAO levels. In contrast, citalopram demonstrated a decrease in DAO activity in in vitro assays without influencing DAO levels and activity in human enterocytes. Conclusions: These findings imply that a collaborative approach involving psychotropic medications and DAO enzyme supplementation for individuals with fibromyalgia and a DAO deficiency could offer potential benefits for healthcare professionals in their routine clinical practice.

Problematic social media use and vaping among Mexican-American college students

Introduction

Social media use and vaping nicotine are highly prevalent in the daily lives of young adults, especially among Mexican-American college students. The excessive and compulsive use of social media platforms, coupled with the urge to stay continuously connected, can lead to problematic social media use. To date, no studies have explored the impact of problematic social media use on the daily patterns of vaping among this vulnerable population.

Methods

In Spring 2023, we employed Ecological Momentary Assessment over a period of 14 days to collect real-time daily data on participants' social media use and vaping behaviors via a mobile phone-based application. Participants were 51 Mexican-American college students aged 18-25 years, 72.5% female, who were current vapers. We used generalized linear regression models to examine differences in vaping behaviors among participants with and without problematic social media use. All regression models adjusted for age, sex, and SES.

Results

Participants with problematic social media use vaped on an average of 5.9 days compared to 5.7 days reported by those without problematic social media use (p < .05). Problematic social media use is associated with more frequent daily vaping [b = 0.03; 95% CI: 0.02-0.05], increased number of days vaping [b = 0.14; 95% CI: 0.07-0.20], and vaping higher nicotine concentrations [b = 0.08; 95% CI: 0.03-0.14].

Conclusion

Results suggest that problematic social media use significantly increases the risk of daily vaping among Mexican-American college students. Findings highlight the need to strengthen digital resilience and social media literacy to help college students navigate and mitigate the risks of social media.

Resilience Phenotypes and Psychological Functioning among Individuals with Opioid Use Disorder

BACKGROUND

Opioid use disorder (OUD) is a heterogeneous disorder. However, there is a lack of deep phenotyping investigations focusing on important psychological constructs such as resilience that may impact OUD. The present study aimed to investigate the relationship between trait resilience and the five-factor model of personality (FFM) among individuals with opioid use disorder (OUD). We also explored whether the FFM and trait resilience form specific phenotypes associated with psychological functioning.

METHODS

This secondary analysis of an epigenetic study included participants of African ancestry (n = 72), an understudied population, who met DSM-5 criteria for OUD. Participants completed measures to assess personality traits, trait resilience, current and previous drug use, and psychological functioning (depression, anxiety, and stress).

RESULTS

Linear regression revealed a significant relationship between resilience (CD-RISC-25 score) and the FFM, R2 = 0.56, F(5,62) = 15.7, p<.001. Further, a two-cluster classification emerged as the optimal solution from the cluster analysis. Cluster 1 (n = 33, 45.8% of the sample) showed lower resilience (CD-RISC-25 score: M = 58.6, SD = 11.2) compared to Cluster 2 (n = 35, 48.6%; CD-RISC-25 score: M = 76.1, SD = 11.9). The "High-Resilience Cluster" (Cluster 2) was characterized by higher FFM traits of: Extraversion, Openness, Agreeableness, and Conscientiousness, and lower Neuroticism versus Cluster 1. Multivariate analysis of variance revealed statistically significant differences between the two resilience clusters concerning other psychological symptoms, Λ = 0.732, F(4, 50) = 7.05, p < 0.003.

CONCLUSIONS

These findings suggest associations between the FFM and trait resilience among individuals with OUD. Two distinct "resilience phenotypes" emerged, with high-resilience individuals displaying less stress, anxiety, and depressive symptoms. Results highlight the clinical importance of resilience as a potential target for intervention in people with OUD.

Dysregulation of the endogenous cannabinoid system following opioid exposure

Rates of opioid-related deaths and overdoses in the United States are at record-high levels. Thus, novel neurobiological targets for the treatment of OUD are greatly needed. Given the close interaction between the endogenous opioid system and the endocannabinoid system (ECS), targeting the ECS may have therapeutic potential in OUD. The various components of the ECS, including cannabinoid receptors, their lipid-derived endogenous ligands (endocannabinoids [eCBs]), and the related enzymes, present potential targets for developing new medications in OUD treatment. The purpose of this paper is to review the clinical and preclinical literature on the dysregulation of the ECS after exposure to opioids. We review the evidence of ECS dysregulation across various study types, exposure protocols, and measurement protocols and summarize the evidence for dysregulation of ECS components at specific brain regions. Preclinical research has shown that opioids disrupt various ECS components that are region-specific. However, the results in the literature are highly heterogenous and sometimes contradictory, possibly due to variety of different methods used. Further research is needed before a confident conclusion could be made on how exposure to opioids can affect ECS components in various brain regions.

Role of aldosterone and mineralocorticoid receptor (MR) in addiction: A scoping review

Preclinical and human studies suggest a role of aldosterone and mineralocorticoid receptor (MR) in addiction. This scoping review aimed to summarize (1) the relationship between alcohol and other substance use disorders (ASUDs) and dysfunctions of the aldosterone and MR, and (2) how pharmacological manipulations of MR may affect ASUD-related outcomes. Our search in four databases (MEDLINE, Embase, Web of Science, and Cochrane Library) indicated that most studies focused on the relationship between aldosterone, MR, and alcohol (n = 30), with the rest focused on opioids (n = 5), nicotine (n = 9), and other addictive substances (n = 9). Despite some inconsistencies, the overall results suggest peripheral and central dysregulations of aldosterone and MR in several species and that these dysregulations depended on the pattern of drug exposure and genetic factors. We conclude that MR antagonism may be a promising target in ASUD, yet future studies are warranted.

Abnormal frontostriatal connectivity and serotonin function in gambling disorder: A preliminary exploratory study

Background

The neurobiological mechanisms of gambling disorder are not yet fully characterized, limiting the development of treatments. Defects in frontostriatal connections have been shown to play a major role in substance use disorders, but data on behavioral addictions, such as gambling disorder, are scarce. The aim of this study was to 1) investigate whether gambling disorder is associated with abnormal frontostriatal connectivity and 2) characterize the key neurotransmitter systems underlying the connectivity abnormalities.

Methods

Fifteen individuals with gambling disorder and 17 matched healthy controls were studied with resting-state functional connectivity MRI and three brain positron emission tomography scans, investigating dopamine (18F-FDOPA), opioid (11C-carfentanil) and serotonin (11C-MADAM) function. Frontostriatal connectivity was investigated using striatal seed-to-voxel connectivity and compared between the groups. Neurotransmitter systems underlying the identified connectivity differences were investigated using region-of-interest and voxelwise approaches.

Results

Individuals with gambling disorder showed loss of functional connectivity between the right nucleus accumbens (NAcc) and a region in the right dorsolateral prefrontal cortex (DLPFC) (PFWE <0.05). Similarly, there was a significant Group x right NAcc interaction in right DLPFC 11C-MADAM binding (p = 0.03) but not in 18F-FDOPA uptake or 11C-carfentanil binding. This was confirmed in voxelwise analyses showing a widespread Group x right NAcc interaction in the prefrontal cortex 11C-MADAM binding (PFWE <0.05). Right NAcc 11C-MADAM binding potential correlated with attentional impulsivity in individuals with gambling disorder (r = -0.73, p = 0.005).

Discussion

Gambling disorder is associated with right hemisphere abnormal frontostriatal connectivity and serotonergic function. These findings will contribute to understanding the neurobiological mechanism and may help identify potential treatment targets for gambling disorder.

Longitudinal patterns of polysubstance use throughout adolescence: association with adult substance use and psychosocial outcomes controlling for preadolescent risk factors in a male cohort

PURPOSE

Inconsistent reports raise the question of the extent to which poor adult outcomes are associated with adolescent polysubstance use (PSU: alcohol, marijuana, other illicit drugs) above and beyond earlier risk factors.

METHODS

Early adulthood substance-related and psychosocial outcomes were examined in association with age 13 to 17 developmental patterns of PSU in boys from urban, low SES neighborhoods (N = 926). Three classes obtained by latent growth modeling described low/non-users (N = 565, 61.0%), lower risk PSU (later onset, occasional use, 2 ≤ substances; N = 223, 24.1%), and higher risk PSU (earlier onset, frequent use, 3 ≥ substances; N = 138, 14.9%). Preadolescent individual, familial and social predictors of adolescent PSU patterns were used as covariates.

RESULTS

Adolescent PSU contributed to both age-24 substance-related outcomes (frequency of alcohol, drug use, and getting drunk, risky behaviors under influence, and use-related problems) and psychosocial outcomes (no high school diploma, professional or financial strain, ASP symptoms, criminal record) over and above preadolescent risk factors. Controlling for preadolescent risk factors, adolescent PSU made a more important contribution to adult substance use outcomes (increasing the risk by about 110%) than to psychosocial outcomes (16.8% risk increase). PSU classes showed poorer adjustment for all age-24 substance use, and for various psychosocial outcomes than low/non-users. Higher risk polysubstance users also reported poorer outcomes than their lower risk peers for most substance use outcomes, and for professional or financial strain and criminal record.

CONCLUSION

Findings highlight the contribution of adolescent PSU in a dose-response fashion, over and above preadolescent risk factors, on both homotypic and heterotypic outcomes in early adulthood.

Neuropsychological functioning of patients with major depression or bipolar disorder comorbid to substance use disorders: A systematic review

Major depression disorder (MDD) and bipolar disorder (BD) are usual comorbidities in patients with substance use disorders (SUD), a condition known as dual disorder (DD). MDD, BD and SUD are associated with cognitive impairment, potentially leading to a greater functional impairment in the context of DD.

OBJECTIVES

To review the existing data on the cognitive impairment in DD patients with comorbid MDD or BD, considering the influence of the depressive symptomatology.

METHODS

Following the PRISMA protocol 19 studies were selected from the last 17 years, 13 of which focused on BD, five on MDD and one included both diagnoses.

RESULTS

Studies based in BD+SUD showed that the most affected cognitive domains were attention and executive functions, but not all of them found a greater impairment due to the comorbidity. While fewer studies were found for depression, MDD+SUD works point to a similar impairment cognitive pattern. Furthermore, depression improvement could be associated to better cognitive performance.

LIMITATIONS

More standardized research is needed regarding the influence of depression on cognitive performance of DD patients, especially on those with comorbid MDD. Factors such as main substance, abstinence, or MDD/BD-related variables should be considered. Unstudied factors, like gender or circadian rhythms, are proposed to improve knowledge in this area.

CONCLUSIONS

Current studies suggest that DD could potentiate cognitive impairment in BD, MDD and SUD. However, additional research is needed to improve the understanding of comorbidity to apply more individualized therapies in the treatment of these patients, considering the interference of their neurocognitive functioning.

Risk Factors of Suicidal Ideation in Iraqi Crystal Methamphetamine Users

Crystal methamphetamine, a potent psychostimulant, presents a complex clinical landscape. However, insights into the predisposing factors for suicidal tendencies among Iraqi users remain limited. Our study delves into these risks among 165 patients. Rigorous multivariable analysis was conducted, employing binary logistic regression, drawing from patients from Baghdad Medical City and Ibn-Rushd Teaching Hospital. Most participants were in their third decade (26.62 ± 0.53 years). Regarding suicidal ideation, our model demonstrated robust accuracy, supported by the Hosmer-Lemeshow goodness-of-fit test (NagelKerke's R2 = 0.49, accuracy = 79.4%, p = 0.885). Notably, chronic methamphetamine use exceeding a year (OR = 6.15, p = 0.001), absence of psychological trauma (OR = 4.58, p = 0.006), and incidence of visual hallucinations (OR = 4.52, p = 0.001) rendered users more susceptible to suicidal ideation. Furthermore, our investigation unveiled risk factors tied to psychotic features and withdrawal manifestations. The study underscores pivotal predictors of suicidal ideation, warranting interdisciplinary vigilance from psychiatrists, clinical psychologists, and social workers. By monitoring at-risk individuals, progression toward the intricate spectrum of suicide can be potentially averted. These findings illuminate the urgency of tailored interventions for crystal methamphetamine users, contributing to enhanced holistic care.

RGS6 negatively regulates inhibitory G protein signaling in dopamine neurons and positively regulates binge-like alcohol consumption in mice

BACKGROUND AND PURPOSE

Drugs of abuse, including alcohol, increase dopamine in the mesocorticolimbic system via actions on dopamine neurons in the ventral tegmental area (VTA). Increased dopamine transmission can activate inhibitory G protein signalling pathways in VTA dopamine neurons, including those controlled by GABAB and D2 receptors. Members of the R7 subfamily of regulator of G protein signalling (RGS) proteins can regulate inhibitory G protein signalling, but their influence on VTA dopamine neurons is unclear. Here, we investigated the influence of RGS6, an R7 RGS family memberthat has been implicated in the regulation of alcohol consumption in mice, on inhibitory G protein signalling in VTA dopamine neurons.

EXPERIMENTAL APPROACH

We used molecular, electrophysiological and genetic approaches to probe the impact of RGS6 on inhibitory G protein signalling in VTA dopamine neurons and on binge-like alcohol consumption in mice.

KEY RESULTS

RGS6 is expressed in adult mouse VTA dopamine neurons and it modulates inhibitory G protein signalling in a receptor-dependent manner, tempering D2 receptor-induced somatodendritic currents and accelerating deactivation of synaptically evoked GABAB receptor-dependent responses. RGS6-/- mice exhibit diminished binge-like alcohol consumption, a phenotype replicated in female (but not male) mice lacking RGS6 selectively in VTA dopamine neurons.

CONCLUSIONS AND IMPLICATIONS

RGS6 negatively regulates GABAB - and D2 receptor-dependent inhibitory G protein signalling pathways in mouse VTA dopamine neurons and exerts a sex-dependent positive influence on binge-like alcohol consumption in adult mice. As such, RGS6 may represent a new diagnostic and/or therapeutic target for alcohol use disorder.

Combining noninvasive brain stimulation with behavioral pharmacology methods to study mechanisms of substance use disorder

Psychotropic drugs and transcranial magnetic stimulation (TMS) are effective for treating certain psychiatric conditions. Drugs and TMS have also been used as tools to explore the relationship between brain function and behavior in humans. Combining centrally acting drugs and TMS has proven useful for characterizing the neural basis of movement. This combined intervention approach also holds promise for improving our understanding of the mechanisms underlying disordered behavior associated with psychiatric conditions, including addiction, though challenges exist. For example, altered neocortical function has been implicated in substance use disorder, but the relationship between acute neuromodulation of neocortex with TMS and direct effects on addiction-related behaviors is not well established. We propose that the combination of human behavioral pharmacology methods with TMS can be leveraged to help establish these links. This perspective article describes an ongoing study that combines the administration of delta-9-tetrahydrocannabinol (THC), the main psychoactive compound in cannabis, with neuroimaging-guided TMS in individuals with problematic cannabis use. The study examines the impact of the left dorsolateral prefrontal cortex (DLPFC) stimulation on cognitive outcomes impacted by THC intoxication, including the subjective response to THC and the impairing effects of THC on behavioral performance. A framework for integrating TMS with human behavioral pharmacology methods, along with key details of the study design, are presented. We also discuss challenges, alternatives, and future directions.

How, when, and to what degree do people with alcohol dependence recover their psychological wellbeing and quality of life? The Madrid Recovery Project

Introduction

The consensus on recovery from alcohol use disorder (AUD) has shifted toward encompassing psychological wellbeing and quality of life dimensions. However, few studies have explored the long-term recovery process and its dimensions, timing, styles, and modes. The aim of this study was to investigate the extent, timing, and process of psychological wellbeing and quality of life recovery in alcohol use disorder (AUD) patients, as well as the relationship with classic dimensions of AUD recovery.

Method

A cross-sectional study has been carried out with 348 participants with AUD, in different abstinence periods (1 month-28 years), and 171 control subjects. Participants underwent a psychological evaluation, which included self-informed measures of psychological wellbeing, quality of life, negative emotionality, and coping strategies related to alcohol consumption avoidance. Statistical analysis included linear and non-linear regression models between psychological dimensions and maintenance of abstinence, as well as matching the scores of the sample with AUD to those of controls. Scatter plots were used to explore inflection points. In addition, mean comparison tests were performed between participants with AUD and controls and by gender.

Results

In general, according to the regression models, there were pronounced increases in indices of wellbeing and coping strategies (and pronounced decreases in negative emotionality) during the first 5 years of abstinence, followed by less pronounced improvements. The matching of AUD subjects in wellbeing and negative emotionality indices with controls occurs at different times: (a) 1 year or less: physical health; (b) 1-4 years: psychological health; (c) 4-10 years: social relationships, wellbeing, and negative emotionality; and (d) more than 10 years: autonomy and self-acceptance. There are statistically significant differences by gender for the negative emotionality and physical health variables.

Conclusion

Recovery from AUD is a long process that involves improvements in wellbeing and quality of life. Four stages can be described in this process, with the most pronounced changes occurring during the first 5 years of abstinence. However, AUD patients take more time to obtain similar scores to controls in several psychological dimensions.

Psychiatric symptoms and intentions to quit smoking: How regularity and volume of cigarette consumption moderate the relationship

INTRODUCTION

Smoking prevalence is disproportionately higher in those with psychiatric symptoms. Smokers with psychiatric symptoms are less likely to have an intention to quit smoking and attain eventual smoking abstinence. This study presents the relationship between depressive/anxiety symptoms and the intention to quit smoking and related influencing factors.

METHODS

A cross-sectional study recruited 931 current smoking individuals covering two provinces in China in July 2022. The online survey comprised questions concerning sociodemographic characteristics, smoking conditions and psychiatric symptoms. Chi-squared analyses and moderation analyses were applied.

RESULTS

The proportion of smokers who had the intention to quit smoking within six months was 46.1%. In comparison with subjects without depressive/anxiety symptoms, individuals who had both psychiatric symptoms were less likely to have the intention to quit smoking (39.3% vs 49.8%, χ²=9.130, p=0.028). As for the moderating model of depression, the interaction term of depressive symptoms and smoking regularly was significant (β=0.554, t=3.260, p=0.001). For those who were occasional smokers, depressive symptoms significantly lowered their quitting intentions. The regularity of smoking similarly moderated the effect of anxiety symptoms on quitting intentions. When the number of cigarettes used weekly served as the moderator, the interaction of this number and depressive symptoms was significant, as well as for anxiety (p<0.001), indicating that the volume of cigarette consumption moderated the relationship between depressive/anxiety symptoms and intention to quit smoking.

CONCLUSIONS

Psychiatric symptoms were significant factors in reducing the willingness of smokers to quit smoking, and the effects were moderated by smokers' cigarette consumption conditions. Interventions are urged to enhance quitting intentions of these vulnerable smokers.

Impaired cognitive control moderates the relation between the attribution of incentive salience and severity of consumption in patients with methamphetamine dependence

BACKGROUND

Cognitive control and the attribution of incentive salience are two key neuropsychological processes proposed to explain substance use disorder (SUD). However, little is known about how they interact to influence the severity of drug use in people with SUD.

OBJECTIVE

To determine if cognitive control exerts a moderating effect on the relation between the attribution of salience to drug/reward-related cues and the severity of drug use in SUD cases.

METHOD

Sixty-nine SUD cases with methamphetamine as the main drug of consumption were selected and evaluated. Participants performed the Stroop, Go/No-Go, and Flanker tasks to identify a latent cognitive control factor, and the Effort-Expenditure for Reward task, as well as answering the Methamphetamine Incentive Salience Questionnaire to measure the attribution of incentive salience. Severity of drug use was determined by the KMSK scale and an exploratory clinical interview.

RESULTS

As expected, higher incentive salience attribution predicted greater severity of methamphetamine use. Unexpectedly, however, we found a moderating effect of impaired cognitive control on the relations between higher incentive salience scores and higher monthly drug use, and between younger age at onset of systematic drug use and higher incentive salience scores.

CONCLUSION

Results show the moderating role of cognitive control on the relation between incentive salience attribution and severity of drug use in SUD cases, and help explain the chronic, relapsing nature of addiction, knowledge necessary to develop more precise prevention and treatment strategies.

From Antidepressant Tianeptine to Street Drug ZaZa: A Narrative Review

Tianeptine is often incorrectly described as a selective serotonin reuptake inhibitor, but it actually is a µ-opioid receptor agonist with anxiolytic effects. It has been approved since the last 1980s in about 24 countries as a treatment for depression, but it was never cleared to market in the United States for this purpose. Nevertheless, tianeptine joined the billion-dollar US market of nootropics as ZaZa or Tianna Red and is widely available online and in small shops without a prescription, to the point that it has been nicknamed "gas station heroin." While the therapeutic dose range is about 25 to 50 mg/day, tianeptine abusers may take 100 times that amount. Tolerance occurs rapidly and users who seek to recapture the short-lived euphoric effects of the drug have to take more and more. Social media has peer-support sites for those trying to discontinue tianeptine. Tianeptine is associated with multiple side effects at high doses along with dependence, withdrawal symptoms, toxicity, respiratory depression, and even mortality. Agitation is more often a presenting symptom of withdrawal than toxicity. Tianeptine is often used by polysubstance drug abusers who may be unaware of the drug's dangers. Few clinicians are aware of tianeptine and most urine assays do not screen for it. Greater awareness is needed for this drug and steps must be taken as tianeptine or "gas station heroin" is emerging as a new public health threat.

Connecting Circuits with Networks in Addiction Neuroscience: A Salience Network Perspective

Human neuroimaging has demonstrated the existence of large-scale functional networks in the cerebral cortex consisting of topographically distant brain regions with functionally correlated activity. The salience network (SN), which is involved in detecting salient stimuli and mediating inter-network communication, is a crucial functional network that is disrupted in addiction. Individuals with addiction display dysfunctional structural and functional connectivity of the SN. Furthermore, while there is a growing body of evidence regarding the SN, addiction, and the relationship between the two, there are still many unknowns, and there are fundamental limitations to human neuroimaging studies. At the same time, advances in molecular and systems neuroscience techniques allow researchers to manipulate neural circuits in nonhuman animals with increasing precision. Here, we describe attempts to translate human functional networks to nonhuman animals to uncover circuit-level mechanisms. To do this, we review the structural and functional connections of the salience network and its homology across species. We then describe the existing literature in which circuit-specific perturbation of the SN sheds light on how functional cortical networks operate, both within and outside the context of addiction. Finally, we highlight key outstanding opportunities for mechanistic studies of the SN.

Neurotensin and Alcohol Use Disorders: Towards a Pharmacological Treatment

Harmful alcohol use is responsible for a group of disorders collectively named alcohol use disorders (AUDs), according to the DSM-5 classification. The damage induced by alcohol depends on the amount, time, and consumption patterns (continuous and heavy episodic drinking). It affects individual global well-being and social and familial environments with variable impact. Alcohol addiction manifests with different degrees of organ and mental health detriment for the individual, exhibiting two main traits: compulsive drinking and negative emotional states occurring at withdrawal, frequently causing relapse episodes. Numerous individual and living conditions, including the concomitant use of other psychoactive substances, lie in the complexity of AUD. Ethanol and its metabolites directly impact the tissues and may cause local damage or alter the homeostasis of brain neurotransmission, immunity scaffolding, or cell repair biochemical pathways. Brain modulator and neurotransmitter-assembled neurocircuitries govern reward, reinforcement, social interaction, and consumption of alcohol behaviors in an intertwined manner. Experimental evidence supports the participation of neurotensin (NT) in preclinical models of alcohol addiction. For example, NT neurons in the central nucleus of the amygdala projecting to the parabrachial nucleus strengthen alcohol consumption and preference. In addition, the levels of NT in the frontal cortex were found to be lower in rats bred to prefer alcohol to water in a free alcohol-water choice compared to wild-type animals. NT receptors 1 and 2 seem to be involved in alcohol consumption and alcohol effects in several models of knockout mice. This review aims to present an updated picture of the role of NT systems in alcohol addiction and the possible use of nonpeptide ligands modulating the activity of the NT system, applied to experimental animal models of harmful drinking behavior mimicking alcohol addiction leading to health ruin in humans.