A proof of concept study of tolcapone for pathological gambling: relationships with COMT genotype and brain activation

Advancements in addressing drug dependence: A review of promising therapeutic strategies and interventions

Substance dependence represents a pervasive global concern within the realm of public health. Presently, it is delineated as a persistent and recurrent neurological disorder stemming from drug-triggered neuroadaptations in the brain's reward circuitry. Despite the availability of various therapeutic modalities, there has been a steady escalation in the mortality rate attributed to drug overdoses. Substantial endeavors have been directed towards the exploration of innovative interventions aimed at mitigating cravings and drug-induced repetitive behaviors. Within this review, we encapsulate the most auspicious contemporary treatment methodologies, accentuating meta-analyses of efficacious pharmacological and non-pharmacological approaches: including gabapentin, topiramate, prazosin, physical exercise regimens, and cerebral stimulation techniques.

Prognosis of impulse control disorders in Parkinson's disease: a prospective controlled study

BACKGROUND

The long-term prognosis of impulsive compulsive disorders (ICD) remains poorly studied in Parkinson's disease (PD).

OBJECTIVE

Evaluating the natural history of ICD and its impact on PD symptoms including cognition and treatment adjustments.

MATERIALS AND METHODS

We assessed PD patients at baseline (BL) with (BL-ICD+) or without (BL-ICD-) ICD despite dopamine agonist (DA) exposure of > 300 mg levodopa-equivalent daily dose for > 12 months at baseline and after more than two years of follow-up. ICD were assessed using the Ardouin's Scale of Behaviors in PD (ASBPD), cognition using the Mattis scale, and PD symptoms using the UPDRS score. Treatment adjustments, DA withdrawal-associated symptoms, and ICDs social consequences were recorded.

RESULTS

149 patients were included (78 cases and 71 controls), mean duration of follow-up was 4.4 ± 1 years. At baseline, psychiatric disorders were more common among BL-ICD + (42.3 vs 12.3% among BL-ICD-, p < 0.01). At follow-up, 53.8% of BL-ICD + were not ICD-free while 21.1% of BL-ICD- had developed ICD. BL-ICD + more frequently experienced akinesia (21.8 vs 8.5%, p = 0.043) and rigidity worsening (11.5 vs 1.4%, p = 0.019) following therapeutic modifications. Decision to decrease > 50% DA doses (12.8 vs 1.4%, p = 0.019) or to withdraw DA (19.2 vs 5.6%, p = 0.025) was more frequently considered among BL-ICD+ . At follow-up, the prevalence of cognitive decline was lower among BL-ICD + (19.2 vs 37.1%, p = 0.025).

CONCLUSION

ICDs were associated with increased psychiatric burden at baseline and better cognitive prognosis. Most patients were still showing ICDs at the follow-up visit, suggesting ICD to be considered as a chronic, neuropsychiatric disorder.

Pharmacological management of gambling disorder: an update of the literature

INTRODUCTION

Gambling disorder (GD) is a mental health condition characterized by persistent and problematic betting behavior. GD generates distress and impairment, and treatment options include psychological and pharmacological interventions.

AREAS COVERED

This narrative review explores existing pharmacological treatments for GD. The following classes of medications were considered: opioid-receptor antagonists (e.g. naltrexone and nalmefene), serotonin reuptake inhibitors (e.g. fluvoxamine, paroxetine, sertraline, escitalopram, and citalopram), glutamatergic agents (e.g. N-acetylcysteine (NAC), acamprosate, and memantine), mood stabilizers (e.g. topiramate, carbamazepine, lithium), and other medications (e.g. modafinil, nefazodone, olanzapine, haloperidol, tolcapone, and bupropion).

EXPERT OPINION

Due to the limitations of the studies reviewed, solid conclusions regarding the optimal choice of pharmacotherapy for individuals with GD are challenging to draw at this time. Despite some medications, such as naltrexone and nalmefene, showing promising results, efficacy has varied across studies. The review highlights current gaps/limitations, including small sample sizes, limited diversity in participant demographics, the need for exploring different gambling subtypes and treatment responses, high placebo response rates, lack of longer-term longitudinal information, limited investigation of neurobiological correlates and co-occurring disorders, and the importance of implementation research. Further research is needed to address these gaps and explore additional medications, as well as interventions like neuromodulation.

Neural mechanisms linked to treatment outcomes and recovery in substance-related and addictive disorders

The present review focuses on potential neural mechanisms underlying recovery from psychiatric conditions characterised by impaired impulse control, specifically substance use disorders, gambling disorder, and internet gaming disorder. Existing treatments (both pharmacological and psychological) for these addictions may impact brain processes, and these have been evaluated in neuroimaging studies. Medication challenge and short-term intervention administration will be considered with respect to treatment utility. Main models of addiction (e.g., dual process, reward deficiency syndrome) will be considered in the context of extant data. Additionally, advanced analytic approaches (e.g., machine-learning approaches) will be considered with respect to guiding treatment development efforts. Thus, this narrative review aims to provide directions for treatment development for addictive disorders.

Dopaminergic dysfunction: Role for genetic & epigenetic testing in the new psychiatry

Reward Deficiency Syndrome (RDS), particularly linked to addictive disorders, costs billions of dollars globally and has resulted in over one million deaths in the United States (US). Illicit substance use has been steadily rising and in 2021 approximately 21.9% (61.2 million) of individuals living in the US aged 12 or older had used illicit drugs in the past year. However, only 1.5% (4.1 million) of these individuals had received any substance use treatment. This increase in use and failure to adequately treat or provide treatment to these individuals resulted in 106,699 overdose deaths in 2021 and increased in 2022. This article presents an alternative non-pharmaceutical treatment approach tied to gene-guided therapy, the subject of many decades of research. The cornerstone of this paradigm shift is the brain reward circuitry, brain stem physiology, and neurotransmitter deficits due to the effects of genetic and epigenetic insults on the interrelated cascade of neurotransmission and the net release of dopamine at the Ventral Tegmental Area -Nucleus Accumbens (VTA-NAc) reward site. The Genetic Addiction Risk Severity (GARS) test and pro-dopamine regulator nutraceutical KB220 were combined to induce "dopamine homeostasis" across the brain reward circuitry. This article aims to encourage four future actionable items: 1) the neurophysiologically accurate designation of, for example, "Hyperdopameism /Hyperdopameism" to replace the blaming nomenclature like alcoholism; 2) encouraging continued research into the nature of dysfunctional brainstem neurotransmitters across the brain reward circuitry; 3) early identification of people at risk for all RDS behaviors as a brain check (cognitive testing); 4) induction of dopamine homeostasis using "precision behavioral management" along with the coupling of GARS and precision Kb220 variants; 5) utilization of promising potential treatments include neuromodulating modalities such as Transmagnetic stimulation (TMS) and Deep Brain Stimulation(DBS), which target different areas of the neural circuitry involved in addiction and even neuroimmune agents like N-acetyl-cysteine.

Potential Biological Markers and Treatment Implications for Binge Eating Disorder and Behavioral Addictions

The reward system is highly relevant to behavioral addictions such as gambling disorder (GD), internet gaming disorder (IGD), and food addiction/binge eating disorder (FA/BED). Among other brain regions, the ventral striatum (VS) has been implicated in reward processing. The main objective of the present state-of-the-art review was to explore in depth the specific role of the VS in GD, IGD and FA/BED, understanding it as a possible biomarker of these conditions. Studies analyzing brain changes following interventions for these disorders, and especially those that had explored possible treatment-related changes in VS, are discussed. More evidence is needed on how existing treatments (both pharmacological and psychobehavioral) for behavioral addictions affect the activation of the VS and related circuitry.

Catechol-O-Methyltransferase Effects on Smoking: A Review and Proof of Concept of Sex-Sensitive Effects

Purpose of Review

This article reviews recent research on how catechol-O-methyltransferase (COMT) may impact cigarette smoking behavior, and how effects may be sex-sensitive. Preliminary data are presented on sex-sensitive effects of COMT on response to short-term abstinence in individuals who smoke.

Recent Findings

Although research is mixed, functional variants in the COMT gene have been linked with smoking behavior, cessation outcomes and nicotine abstinence-related symptoms. Our proof-of-concept preliminary data from a human laboratory study of individuals who smoke cigarettes found that those with the high COMT enzyme activity genotype (Val/Val) reported more severe smoking urges and withdrawal symptoms following overnight abstinence than Met carriers. These effects were present in women, but not in men and were abstinent-dependent, in that they dissipated following nicotine administration.

Summary

The preliminary data showing sex-sensitive pharmacogenetic effects may shed light on mechanisms contributing to sex differences in barriers to smoking cessation or potential sex-specific treatment options.

Effects of pharmacological and genetic regulation of COMT activity in alcohol use disorder: a randomized, placebo-controlled trial of tolcapone

Alcohol Use Disorder (AUD) is characterized by loss of control over drinking. Behavioral control is mediated, in part, by cortical dopamine signaling. Inhibition of catechol-O-methyltransferase (COMT), the enzyme primarily responsible for cortical dopamine inactivation, may increase cortical dopamine, especially among individuals with genetically mediated lower dopaminergic tone, such as COMT rs4680 (val158met) val-allele homozygotes. This study was a randomized, placebo-controlled, pharmacogenetic trial of the COMT inhibitor tolcapone. Ninety non-treatment-seeking AUD individuals were prospectively genotyped for rs4680 and randomized to tolcapone (200 mg t.i.d.) or placebo for 8 days. At baseline and on day 7, peripheral COMT activity was assayed, and participants completed an fMRI alcohol cue-reactivity task; on day 8, they completed a bar-lab paradigm. Primary outcomes were: (1) natural drinking during the medication period; (2) alcohol self-administration in the bar lab; and (3) alcohol cue-elicited cortical (right inferior frontal gyrus [rIFG]) and ventral striatal activation. At baseline, the rs4680 val-allele had an additive effect on COMT activity. Tolcapone, relative to placebo, reduced COMT activity in all genotype groups. COMT genotype moderated tolcapone's effect on drinking during the medication period and in the bar lab, such that tolcapone, relative to placebo, reduced drinking only among val-allele homozygotes. Tolcapone did not affect cue-elicited ventral striatal activation but reduced rIFG activation; less rIFG activation on day 7 was associated with less drinking during the medication period. Taken together, these data suggest that COMT inhibition may reduce drinking specifically among individuals genetically predisposed to excessive COMT activity and potentially low cortical dopamine tone.ClinicalTrials.gov identifier: NCT02949934 https://clinicaltrials.gov/ct2/show/NCT02949934.

Gambling disorder in minority ethnic groups

BACKGROUND

Although the data on racial/ethnic associations with gambling disorder are limited, studies suggest that ethnicity may have associations with both symptom severity and psychosocial impairment linked to gambling disorder. Based on the current literature, we hypothesized that there would be a difference in gambling symptom severity, and co-occurring disorders, as a function of racial-ethnic group.

METHODS

475 adults (mean age = 47.6 (±11.6) years; 54.3 % females) with gambling disorder who had participated in clinical trials on pharmacotherapy or psychotherapy were included. Participants were assessed for gambling severity, comorbidities, health issues, quality of life and psychosocial functioning. Participants who self-identified as Black, Asian or Minority Ethnic (BAME) were compared to those who self-identified as white Caucasian (non-BAME). Significance was defined as p < 0.01.

RESULTS

The BAME group had significantly earlier age of first gambling. The two groups did not differ significantly in terms of age when gambling first became problematic, disability, current gambling disorder symptom severity, previous suicide attempt(s), quality of life, percent of salary in past year lost to gambling, or likelihood of having received treatment for gambling disorder in the past, nor in terms of having used Gamblers Anonymous.

CONCLUSIONS

These data show that having gambling disorder and being from a minority racial-ethnic group was associated with significantly earlier age at first gambling, in clinical trial settings. Future work should further examine differences in the clinical features of gambling disorder in different minority groups in larger sample sizes, ideally also longitudinally, across a range of settings. Identification of the reasons/mechanisms for differences in earlier age of first gambling may lead to new public health and treatment targets to minimize gambling harms.

Update on Gambling Disorder

Gambling disorder (GD) is estimated to be experienced by about 0.5% of the adult population in the United States. The etiology of GD is complex and includes genetic and environmental factors. Specific populations appear particularly vulnerable to GD. GD often goes unrecognized and untreated. GD often co-occurs with other conditions, particularly psychiatric disorders. Behavioral interventions are supported in the treatment of GD. No medications have a formal indication for the GD, although clinical trials suggest some may be helpful. Noninvasive neuromodulation is being explored as a possible treatment. Improved identification, prevention, and treatment of GD are warranted.

Cortical dopamine reduces the impact of motivational biases governing automated behaviour

Motivations shape our behaviour: the promise of reward invigorates, while in the face of punishment, we hold back. Abnormalities of motivational processing are implicated in clinical disorders characterised by excessive habits and loss of top-down control, notably substance and behavioural addictions. Striatal and frontal dopamine have been hypothesised to play complementary roles in the respective generation and control of these motivational biases. However, while dopaminergic interventions have indeed been found to modulate motivational biases, these previous pharmacological studies used regionally non-selective pharmacological agents. Here, we tested the hypothesis that frontal dopamine controls the balance between Pavlovian, bias-driven automated responding and instrumentally learned action values. Specifically, we examined whether selective enhancement of cortical dopamine either (i) enables adaptive suppression of Pavlovian control when biases are maladaptive; or (ii) non-specifically modulates the degree of bias-driven automated responding. Healthy individuals (n = 35) received the catechol-o-methyltransferase (COMT) inhibitor tolcapone in a randomised, double-blind, placebo-controlled cross-over design, and completed a motivational Go NoGo task known to elicit motivational biases. In support of hypothesis (ii), tolcapone globally decreased motivational bias. Specifically, tolcapone improved performance on trials where the bias was unhelpful, but impaired performance in bias-congruent conditions. These results indicate a non-selective role for cortical dopamine in the regulation of motivational processes underpinning top-down control over automated behaviour. The findings have direct relevance to understanding neurobiological mechanisms underpinning addiction and obsessive-compulsive disorders, as well as highlighting a potential trans-diagnostic novel mechanism to address such symptoms.

Tolcapone in obsessive-compulsive disorder: a randomized double-blind placebo-controlled crossover trial

Despite the availability of evidence-based treatments for obsessive-compulsive disorder (OCD), not all patients experience sufficient benefit or are able to tolerate them. Tolcapone is a catechol-O-methyl-transferase (COMT) enzyme inhibitor that augments cortical dopaminergic transmission. Conduct a proof of concept study to examine whether a COMT inhibitor would reduce OCD symptoms to a greater extent than placebo. We conducted a randomized, placebo-controlled, double-blind crossover trial in adults with OCD (N = 20). Participants were assessed at baseline, after 2 weeks of tolcapone, and again after 2 weeks of placebo on measures of OCD symptom severity and psychosocial functioning. There was a 1-week washout period between the 2-week treatment phases. Two weeks of tolcapone was associated with significant improvement in OCD versus two weeks of placebo (t = 2.194, P = 0.0409). The mean percentage decreases in the total Yale-Brown obsessive-compulsive scale (YBOCS) scores for the entire sample over the corresponding 2-week period were 16.4% for tolcapone and 3.6% for placebo. These data indicate that brain penetrant COMT inhibitors merit further investigation as a candidate new treatment for OCD.

Central nervous system activities of extract Mangifera indica L

ETHNOBOTANICAL RELEVANCE

Leaves of Mangifera indica L. have folk-uses in tropical regions of the world as health teas, as a remedy for exhaustion and fatigue, as a vegetable, and as a medicine. Mangifera indica leaf extract (MLE) had previously been demonstrated to alter brain electrical activity in-vivo. The aim of the present series of studies was to investigate whether mangiferin, a major compound in leaves and in MLE, is responsible for the neurocognitive activity of MLE, and if the CNS activities of MLE have translational potential.

MATERIALS AND METHODS

MLE, tradename Zynamite, is produced by Nektium Pharma, Spain. Isolated mangiferin was tested in-vitro in radioligand binding and enzyme inhibition studies against 106 CNS targets. Changes in the electroencephalograms (EEG's) of MLE and mangiferin were recorded in-vivo from four brain regions. Two double blind randomized placebo-controlled crossover clinical trials were conducted, each with 16 subjects. At 90 min and at 60 min respectively, after oral intake of 500 mg MLE, EEG recordings, psychometric tests, mood state, and tolerability were studied.

RESULTS

Isolated mangiferin is a selective inhibitor of catechol-O-methyltransferase (COMT) with an IC50 of 1.1 μM, with no activity on the CNS targets of caffeine. Both mangiferin and MLE induce similar changes in long-term potentiation (LTP) in the hippocampus in-vitro, and induce a similar pattern of EEG changes in-vivo. In both translational clinical trials MLE was well tolerated, with no cardiovascular side-effects. In both studies MLE caused significant spectral changes in brain electrical activity in cortical regions during cognitive challenges, different to the attenuated spectral changes induced by caffeine. There were no significant changes in the psychometric tests other than reaction time for all groups. In the second study there was a trend to faster reaction time within group for MLE (p = 0.066) and the percentage improvement in reaction time for MLE compared to placebo was significant (p = 0.049). In the first study MLE improved all scores for Profile of Mood States (POMS), with the score for "fatigue" significantly improved (p = 0.015); in the second study the POMS score for "dejection" was improved in the caffeine group, p = 0.05.

CONCLUSIONS

Mangiferin is a COMT inhibitor of moderate potency and is the major CNS-active compound in MLE. Both mangiferin and MLE increase hippocampal LTP in-vitro, and induce a similar pattern of changes in brain electrical activity in-vivo. While the translational clinical trials of MLE are limited by being single dose studies in a small number of subjects, they provide the first clinical evidence that the extract is well tolerated with no cardiovascular side-effects, can induce changes in brain electrical activity, may give a faster reaction time, and decrease fatigue. These CNS activities support the reported folk-uses use of mango leaf tea as a substitute for tea and as a traditional remedy for fatigue and exhaustion. Extract Mangifera indica L., Zynamite, has nootropic potential, and larger clinical studies are needed to realise this potential.

Opioid and Dopamine Genes Interact to Predict Naltrexone Response in a Randomized Alcohol Use Disorder Clinical Trial

BACKGROUND

While the opiate antagonist, naltrexone, is approved for treating alcohol use disorder (AUD), not everyone who receives the medication benefits from it. This study evaluated whether the OPRM1 SNP rs1799971 interacts with the dopamine transporter gene DAT1/SLC6A3 VNTR rs28363170 or the catechol-O-methyltransferase (COMT) gene SNP rs4680 in predicting naltrexone response.

METHODS

Individuals who met DSM-IV alcohol dependence were randomly assigned to naltrexone (50 mg/d) or placebo based on their OPRM1 genotype (75 G-allele carriers and 77 A-allele homozygotes) and also genotyped for DAT1 VNTR (9 vs. 10 repeats) or COMT SNP (val/val vs. met carriers). Heavy drinking days (%HDD) were evaluated over 16 weeks and at the end of treatment. Effect sizes (d) for naltrexone response were calculated based on genotypes.

RESULTS

Naltrexone, relative to placebo, significantly reduced %HDD among OPRM1 G carriers who also had DAT1 10/10 (p = 0.021, d = 0.72) or COMT val/val genotypes (p = 0.05, d = 0.80), and to a lesser degree in those OPRM1 A homozygotes who were also DAT1 9-repeat carriers (p = 0.09, d = 0.70) or COMT met carriers (p = 0.03, d = 0.63). All other genotype combinations showed no differential response to naltrexone. Diarrhea/abdominal pain was more prominent in OPRM1 A homozygotes who were also DAT 9 or COMT met carriers.

CONCLUSIONS

These results suggest that individuals with AUD with a more opioid-responsive genotype (OPRM1 G carriers) respond better to naltrexone if they have genotypes indicating normal/less dopamine tone (DAT1 10,10 or COMT val,val), while those with a less responsive opioid-responsive genotype (OPRM1 A homozygotes) respond better to naltrexone if they have genotypes indicating greater dopamine tone (DAT1 9-repeat or COMT met carriers). These results could lead to more personalized AUD treatments.

Novel, non-nitrocatechol catechol-O-methyltransferase inhibitors modulate dopamine neurotransmission in the frontal cortex and improve cognitive flexibility

RATIONALE

Cognitive impairment is a primary feature of many neuropsychiatric disorders and there is a need for new therapeutic options. Catechol-O-methyltransferase (COMT) inhibitors modulate cortical dopaminergic function and have been proposed as potential cognitive enhancers. Unfortunately, currently available COMT inhibitors are not good candidates due to either poor blood-brain barrier penetration or severe toxicity.

OBJECTIVES

To address the need for safe, brain-penetrant COMT inhibitors, we tested multiple novel compounds in a set of preclinical in vivo efficacy assays in rats to determine their ability to inhibit COMT function and viability as potential clinical candidates.

METHODS

We measured the change in concentration of dopamine (DA) metabolites in cerebrospinal fluid (CSF) from the cisterna magna and extracellular fluid (ECF) from the frontal cortex produced by our novel compounds. Additionally, we tested the effects of our brain-penetrant COMT inhibitors in an attentional set-shifting assay (ASST). We benchmarked the performance of the novel COMT inhibitors to the effects produced by the known COMT inhibitor tolcapone.

RESULTS

We found that multiple COMT inhibitors, exemplified by LIBD-1 and LIBD-3, significantly modulated dopaminergic function measured as decreases in homovanillic acid (HVA) and increases in 3,4-Dihydroxyphenylacetic acid (DOPAC), two DA metabolites, in CSF and the frontal cortex. Additionally, we found that LIBD-1 significantly improved cognitive flexibility in the ASST, an effect previously reported following tolcapone administration.

CONCLUSIONS

These results demonstrate that LIBD-1 is a novel COMT inhibitor with promising in vivo activity and the potential to serve as a new therapy for cognitive impairment.

Dopamine and Risky Decision-Making in Gambling Disorder

Gambling disorder is a behavioral addiction associated with impairments in value-based decision-making and cognitive control. These functions are thought to be regulated by dopamine within fronto-striatal circuits, but the role of altered dopamine neurotransmission in the etiology of gambling disorder remains controversial. Preliminary evidence suggests that increasing frontal dopamine tone might improve cognitive functioning in gambling disorder. We therefore examined whether increasing frontal dopamine tone via a single dose of the catechol-O-methyltransferase (COMT) inhibitor tolcapone would reduce risky choice in human gamblers (n = 14) in a randomized double-blind placebo-controlled crossover study. Data were analyzed using hierarchical Bayesian parameter estimation and a combined risky choice drift diffusion model (DDM). Model comparison revealed a nonlinear mapping from value differences to trial-wise drift rates, confirming recent findings. An increase in risk-taking under tolcapone versus placebo was about five times more likely, given the data, than a decrease [Bayes factor (BF) = 0.2]. Examination of drug effects on diffusion model parameters revealed that an increase in the value dependency of the drift rate under tolcapone was about thirteen times more likely than a decrease (BF = 0.073). In contrast, a reduction in the maximum drift rate under tolcapone was about seven times more likely than an increase (BF = 7.51). Results add to previous work on COMT inhibitors in behavioral addictions and to mounting evidence for the applicability of diffusion models in value-based decision-making. Future work should focus on individual genetic, clinical and cognitive factors that might account for heterogeneity in the effects of COMT inhibition.

Common neurobiological and psychological underpinnings of gambling and substance-use disorders

Both psychological and neurobiological studies in gambling disorder have increased in the past 10-15 years. This review examines the current state of the literature, with a focus on recent magnetic resonance imaging (MRI) studies in gambling disorder. The review compares and contrasts findings across gambling and substance-use disorders. Additionally, features with arguably particular relevance to gambling disorder (e.g., "near-miss" processing) are described, as well as their relationship to choice behaviors. More broadly, the review informs on how these studies advance our understanding of brain-behavior relationships relating to decision-making and key features of addictive disorders.

Impulsivity moderates the effects of dopamine D2 and mixed D1-D2 antagonists in individuals with gambling disorder

BACKGROUND

The functional role of dopamine D1 and D2 receptors in gambling disorder (GD) remains unclear.

AIMS

This study aimed to investigate the role of D1 activation and the moderating effects of impulsivity, a trait linked with weaker D2-mediated inhibition of dopamine release, in GD subjects.

METHODS

Thirty (nine female) non-comorbid GD subjects with low (LI), moderate (MI), or high impulsivity (HI) received the preferential D2 antagonist haloperidol (HAL; 3 mg) or the mixed D1-D2 antagonist fluphenazine (FLU; 3 mg), on separate sessions before a 15-minute slot machine game or amphetamine (AMPH; 20 mg), in a placebo-controlled, double-blind, counterbalanced design.

RESULTS

On their own, HAL and FLU led to linear increases and decreases, respectively, in desire to gamble across increasing levels of impulsivity. The slot machine and AMPH each evoked an inverted-U pattern of desire to gamble across increasing impulsivity. HAL reversed this effect of the game, whereas FLU did not alter post-game desire. HAL and FLU decreased and increased psychostimulant-like effects of the game, respectively, in LI and MI subjects, but consistently reduced these effects in HI subjects. HAL also altered the salience of negative affective words on a reading task, such that greater salience of negative words coincided with lower post-game desire to gamble.

CONCLUSIONS

D1 receptors appear to gauge the incentive value of gambling in GD subjects. D1 activation has negative reinforcing effects in HI gamblers and positive reinforcing effects in LI gamblers. Medications that activate D1 could curtail chasing in HI gamblers. D1 blockade could benefit HI gamblers whose main concern is craving.

Gambling disorder

Gambling disorder is characterized by a persistent, recurrent pattern of gambling that is associated with substantial distress or impairment. The prevalence of gambling disorder has been estimated at 0.5% of the adult population in the United States, with comparable or slightly higher estimates in other countries. The aetiology of gambling disorder is complex, with implicated genetic and environmental factors. Neurobiological studies have implicated cortico-striato-limbic structures and circuits in the pathophysiology of this disorder. Individuals with gambling disorder often go unrecognized and untreated, including within clinical settings. Gambling disorder frequently co-occurs with other conditions, particularly other psychiatric disorders. Behavioural interventions, particularly cognitive-behavioural therapy but also motivational interviewing and Gamblers Anonymous, are supported in the treatment of gambling disorder. No pharmacological therapy has a formal indication for the treatment of gambling disorder, although placebo-controlled trials suggest that some medications, such as opioid-receptor antagonists, may be helpful. Given the associations with poor quality of life and suicide, improved identification, prevention, policy and treatment efforts are needed to help people with gambling disorder.

Pharmacological Treatments for Disordered Gambling: A Meta-analysis

Disordered gambling is a public health concern associated with detrimental consequences for affected individuals and social costs. Currently, opioid antagonists are considered the first-line treatments to reduce symptoms of uncontrolled gambling. Only recently, glutamatergic agents and combined pharmacological and psychological treatments have been examined appearing promising options for the management of gambling disorder. A multilevel literature search yielded 34 studies including open-label and placebo-controlled trials totaling 1340 participants to provide a comprehensive evaluation of the short- and long-term efficacies of pharmacological and combined treatments. Pharmacological treatments were associated with large and medium pre-post reductions in global severity, frequency, and financial loss (Hedges’s g: 1.35, 1.22, 0.80, respectively). The controlled effect sizes for the outcome variables were significantly smaller (Hedges’s g: 0.41, 0.11, 0.22), but robust for the reduction of global severity at short-term. In general, medication classes yielded comparable effect sizes independent of predictors of treatment outcome. Of the placebo controlled studies, results showed that opioid antagonists and mood stabilizers, particularly the glutamatergic agent topiramate combined with a cognitive intervention and lithium for gamblers with bipolar disorders demonstrated promising results. However, more rigorously designed, large-scale randomized controlled trials with extended placebo lead-in periods are necessary. Moreover, future studies need to monitor concurrent psychosocial treatments, the type of comorbidity, use equivalent measurement tools, include outcome variables according to the Banff, Alberta Consensus, and provide follow-up data in order to broaden the knowledge about the efficacy of pharmacological treatments for this disabling condition.

Efficacy of Pharmacological Interventions in Targeting Decision-Making Impairments across Substance and Behavioral Addictions

Decision-making impairments reflect tendencies towards risky or unwise choices as manifested by presence of psychiatric symptoms or cognitive impairment (e.g. representation of value, inhibitory control-response selection, learning). Such impairments are suggested by the hallmark symptoms of substance and behavioral addictions, which include escalation over time (of substance intake or a given behavior), lack of control, neglect of other domains of life, and cognitive distortions (such as ‘chasing losses’ in gambling disorder). Amongst the putative behavioral addictions, most epidemiological data exist for gambling disorder, which is now included in DSM-5 as a substance-related and addictive disorder. However, other disorders share parallels and may also constitute behavioral addictions, such as compulsive stealing (kleptomania), compulsive shopping, and compulsive sexual behavior. The current paper presents a narrative review of evidence for cognitive decision-making impairments in addictions, as well as pharmacological treatments of these disorders that may have relevance for improving decision-making. We find that objective decision-making deficits have been widely reported in patients with substance use disorders and gambling disorder, compared to controls. Decision-making in the other behavioral addictions is under-studied. Evidence-based pharmacological treatments for some of these addictive disorders, for example, opioid antagonists and glutamatergic agents, modulate neural systems playing key roles in decision-making. But clinical trials have seldom examined effects of such treatments on objective decision-making measures. Future research directions are discussed, including the need to include standardized outcome measures of decision-making (tasks and imaging) alongside traditional clinical measures, to better understand and enhance underlying treatment mechanisms.

Dopamine and Working Memory: Genetic Variation, Stress and Implications for Mental Health

At the molecular level, the neurotransmitter dopamine (DA) is a key regulatory component of executive function in the prefrontal cortex (PFC) and dysfunction in dopaminergic (DAergic) circuitry has been shown to result in impaired working memory (WM). Research has identified multiple common genetic variants suggested to impact on the DA system functionally and also behaviourally to alter WM task performance. In addition, environmental stressors impact on DAergic tone, and this may be one mechanism by which stressors confer vulnerability to the development of neuropsychiatric conditions. This chapter aims to evaluate the impact of key DAergic gene variants suggested to impact on both synaptic DA levels (COMT, DAT1, DBH, MAOA) and DA receptor function (ANKK1, DRD2, DRD4) in terms of their influence on visuospatial WM. The role of stressors and interaction with the genetic background is discussed in addition to discussion around some of the implications for precision psychiatry. This and future work in this area aim to disentangle the neural mechanisms underlying susceptibility to stress and their impact and relationship with cognitive processes known to influence mental health vulnerability.

Clinical neuropsychiatric considerations regarding nonsubstance or behavioral addictions

Over the past several decades, non-substance-use behaviors like gambling, gaming, and sex have received greater consideration as possible foci of addictions. In this article, I will review the recent history and current status of non-substance or behavioral addictions. A main focus will involve gambling and gambling disorder, given that the latter is currently the sole non-substance addictive disorder described in the main text of the current (fifth) edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5). Internet gaming disorder, currently in the DSM-5 section addressing conditions that may need additional research, will also be considered, as will the concept of Internet addiction. Compulsive sexual behaviors (including problematic pornography use) will be considered, particularly with respect to how behavioral addictions may be considered in the forthcoming 11th edition of the International Classification of Diseases (ICD-11).

How to measure monetary losses in gambling disorder? An evidence-based refinement

Diverse monetary measures have been utilized across different studies in gambling disorder (GD). However, there are limited evidence-based proposals regarding the best way to assess financial losses. We investigated how different variables of monetary losses correlate with validated assessments of gambling severity and overall functioning in a large sample of subjects with GD (n = 436). We found that relative monetary variables (i.e. when financial losses were evaluated in relation to personal income) showed the most robust correlations with gambling severity and overall psychosocial functioning. Percentage of monthly income lost from gambling was the variable with the best performance.

Differential COMT expression and behavioral effects of COMT inhibition in male and female Wistar and alcohol preferring rats

Polymorphisms of the catechol-O-methyl transferase (COMT) gene have been associated with alcoholism, suggesting that alterations in the metabolism of catecholamines may be a critical component of the neuropathology of alcoholism. In the current experiments, the COMT inhibitor tolcapone was utilized in an operant behavioral model of reinforcer-seeking and drinking to determine if this compound was capable of remediating the excessive seeking and drinking phenotype of the alcohol-preferring P rat. Tolcapone was administered to male and female alcohol-reinforced P and Wistar rats. Additionally, tolcapone was administered to male sucrose-reinforced P and Wistar rats to determine if its effects also extended to a natural reinforcer. Animals were trained to make an operant response that resulted in 20 min uninterrupted access to the reinforcer solutions. Tolcapone had no effect in female rats on either seeking or consumption of ethanol. However, reductions of both reinforcer seeking and consumption were observed in male P rats, but only of seeking in Wistars. In separate experiments, using reinforcer naïve male and female animals, COMT expression was assessed via Western Blot analysis. Sex differences in COMT expression were also observed, where male P rats exhibited a marked reduction in protein expression relative to females in the PFC. Sex differences were not observed for Wistars or in the striatum and hippocampus. These data complement our previous findings in which tolcapone reduced cue-evoked responses in P rats and further suggest clinical utility of COMT inhibitors in the treatment of addiction disorders, specifically in male high drinkers.

Comparison of brain connectivity between Internet gambling disorder and Internet gaming disorder: A preliminary study

Background and aims Given the similarities in clinical symptoms, Internet gaming disorder (IGD) is thought to be diagnostically similar to Internet-based gambling disorder (ibGD). However, cognitive enhancement and educational use of Internet gaming suggest that the two disorders derive from different neurobiological mechanisms. The goal of this study was to compare subjects with ibGD to those with IGD. Methods Fifteen patients with IGD, 14 patients with ibGD, and 15 healthy control subjects were included in this study. Resting-state functional magnetic resonance imaging data for all participants were acquired using a 3.0 Tesla MRI scanner (Philips, Eindhoven, The Netherlands). Seed-based analyses, the three brain networks of default mode, cognitive control, and reward circuitry, were performed. Results Both IGD and ibGD groups demonstrated decreased functional connectivity (FC) within the default-mode network (DMN) (family-wise error p < .001) compared with healthy control subjects. However, the IGD group demonstrated increased FC within the cognitive network compared with both the ibGD (p < .01) and healthy control groups (p < .01). In contrast, the ibGD group demonstrated increased FC within the reward circuitry compared with both IGD (p < .01) and healthy control subjects (p < .01). Discussion and conclusions The IGD and ibGD groups shared the characteristic of decreased FC in the DMN. However, the IGD group demonstrated increased FC within the cognitive network compared with both ibGD and healthy comparison groups.

An Analysis of Treatment-Seeking Behavior in Individuals with Gambling Disorder

Gambling disorder affects approximately 1.1-3.5% of the population, with the rates being higher in young adults. Despite this high prevalence, little is known regarding which pathological gamblers decide to seek treatment. This study sought to examine the differences in three groups of pathological gamblers: those who did not seek treatment (n = 94), those who sought therapy (n = 106) and those who sought medication therapy (n = 680). All subjects were assessed on a variety of measures including demographics, family history, gambling history, comorbid psychiatric disorders and an assortment of clinical variables such as the Quality of Life Inventory, Hamilton Depression and Anxiety Rating Scales, Yale Brown Obsessive Compulsive Scale for Pathologic Gambling (PG-YBOCS), Barratt Impulsiveness Scale, Eysenck Impulsiveness Questionnaire and select cognitive tasks. Those seeking treatment were more likely to be Caucasian, have lost more money in the past year due to gambling, and were more likely to have legal and social problems as a result of their gambling. Those seeking therapy or medical treatment also scored significantly higher on the PG-YBOCS. This study suggests that pathologic gamblers seeking treatment were more likely to exhibit obsessive-compulsive tendencies likely leading to the increased legal and social problems that exist in this group.

Clinical Concepts Emerging from fMRI Functional Connectomics

Recent advances in connectomics have led to a synthesis of perspectives regarding the brain's functional organization that reconciles classical concepts of localized specialization with an appreciation for properties that emerge from interactions across distributed functional networks. This provides a more comprehensive framework for understanding neural mechanisms of normal cognition and disease. Although fMRI has not become a routine clinical tool, research has already had important influences on clinical concepts guiding diagnosis and patient management. Here we review illustrative examples. Studies demonstrating the network plasticity possible in adults and the global consequences of even focal brain injuries or disease both have had substantial impact on modern concepts of disease evolution and expression. Applications of functional connectomics in studies of clinical populations are challenging traditional disease classifications and helping to clarify biological relationships between clinical syndromes (and thus also ways of extending indications for, or "re-purposing," current treatments). Large datasets from prospective, longitudinal studies promise to enable the discovery and validation of functional connectomic biomarkers with the potential to identify people at high risk of disease before clinical onset, at a time when treatments may be most effective. Studies of pain and consciousness have catalyzed reconsiderations of approaches to clinical management, but also have stimulated debate about the clinical meaningfulness of differences in internal perceptual or cognitive states inferred from functional connectomics or other physiological correlates. By way of a closing summary, we offer a personal view of immediate challenges and potential opportunities for clinically relevant applications of fMRI-based functional connectomics.

Right inferior frontal cortex activity correlates with tolcapone responsivity in problem and pathological gamblers

Failures of self-regulation in problem and pathological gambling (PPG) are thought to emerge from failures of top-down control, reflected neurophysiologically in a reduced capacity of prefrontal cortex to influence activity within subcortical structures. In patients with addictions, these impairments have been argued to alter evaluation of reward within dopaminergic neuromodulatory systems. Previously we demonstrated that augmenting dopamine tone in frontal cortex via use of tolcapone, an inhibitor of the dopamine-degrading enzyme catechol-O-methyltransferase (COMT), reduced delay discounting, a measure of impulsivity, in healthy subjects. To evaluate this potentially translational approach to augmenting prefrontal inhibitory control, here we hypothesized that increasing cortical dopamine tone would reduce delay discounting in PPG subjects in proportion to its ability to augment top-down control. To causally test this hypothesis, we administered the COMT inhibitor tolcapone in a randomized, double-blind, placebo-controlled, within-subject study of 17 PPG subjects who performed a delay discounting task while functional MRI images were obtained. In this subject population, we found that greater BOLD activity during the placebo condition within the right inferior frontal cortex (RIFC), a region thought to be important for inhibitory control, correlated with greater declines in impulsivity on tolcapone versus placebo. Intriguingly, connectivity between RIFC and the right striatum, and not the level of activity within RIFC itself, increased on tolcapone versus placebo. Together, these findings support the hypothesis that tolcapone-mediated increases in top-down control may reduce impulsivity in PPG subjects, a finding with potential translational relevance for gambling disorders, and for behavioral addictions in general.

Imaging the Gambling Brain

Neuroimaging studies examining the neurobiological basis of gambling disorder (GD) have increased over the past decade. Functional magnetic resonance imaging studies during appetitive cue and reward processing tasks demonstrate altered functioning in frontostriatal brain areas, including the ventral striatum and the ventromedial prefrontal cortex. Findings suggest differences in how the anticipation and outcome of rewards are processed in individuals with GD. Future research requires larger sample sizes and should include appropriate clinical reference groups. Overall, studies to date highlight a common pathophysiology between substance-based addictions and GD, the latter offering a unique condition in which to examine nonchemical factors in addiction.

A Preliminary Study of DBH (Encoding Dopamine Beta-Hydroxylase) Genetic Variation and Neural Correlates of Emotional and Motivational Processing in Individuals With and Without Pathological Gambling

Background and aims Corticostriatal-limbic neurocircuitry, emotional and motivational processing, dopaminergic and noradrenergic systems and genetic factors have all been implicated in pathological gambling (PG). However, allelic variants of genes influencing dopaminergic and noradrenergic neurotransmitters have not been investigated with respect to the neural correlates of emotional and motivational states in PG. Dopamine beta-hydroxylase (DBH) converts dopamine to norepinephrine; the T allele of a functional single-nucleotide polymorphism rs1611115 (C-1021T) in the DBH gene is associated with less DBH activity and has been linked to emotional processes and addiction. Here, we investigate the influence of rs1611115 on the neural correlates of emotional and motivational processing in PG and healthy comparison (HC) participants. Methods While undergoing functional magnetic resonance imaging, 18 PG and 25 HC participants, all European Americans, viewed gambling-, sad-, and cocaine-related videotapes. Analyses focused on brain activation differences related to DBH genotype (CC/T-carrier [i.e., CT and TT]) and condition (sad/gambling/cocaine). Results CC participants demonstrated greater recruitment of corticostriatal-limbic regions, relative to T-carriers. DBH variants were also associated with altered corticostriatal-limbic activations across the different videotape conditions, and this association appeared to be driven by greater activation in CC participants relative to T-carriers during the sad condition. CC relative to T-carrier subjects also reported greater subjective sadness to the sad videotapes. Conclusions Individual differences in genetic composition linked to aminergic function contribute significantly to emotional regulation across diagnostic groups and warrant further investigation in PG.

Psychiatric Conditions in Parkinson Disease: A Comparison With Classical Psychiatric Disorders

Psychiatric conditions often complicate the outcome of patients affected by Parkinson disease (PD), but they differ from classical psychiatric disorders in terms of underlying biological mechanisms, clinical presentation, and treatment response. The purpose of the present review is to illustrate the biological and clinical aspects of psychiatric conditions associated with PD, with particular reference to the differences with respect to classical psychiatric disorders. A careful search of articles on main databases was performed in order to obtain a comprehensive review about the main psychiatric conditions associated with PD. A manual selection of the articles was then performed in order to consider only those articles that concerned with the topic of the review. Psychiatric conditions in patients with PD present substantial differences with respect to classical psychiatric disorders. Their clinical presentation does not align with the symptom profiles represented by Diagnostic and Statistical Manual for Mental Disorders and International Classification of Diseases. Furthermore, psychiatry treatment guidelines are of poor help in managing psychiatric symptoms of patients with PD. Specific diagnostic tools and treatment guidelines are needed to allow early diagnosis and adequate treatment of psychiatric conditions in comorbidity with PD.

Effect of Pharmacological Interventions on the Fronto-Cingulo-Parietal Cognitive Control Network in Psychiatric Disorders: A Transdiagnostic Systematic Review of fMRI Studies

Executive function deficits, such as working memory, decision-making, and attention problems, are a common feature of several psychiatric disorders for which no satisfactory treatment exists. Here, we transdiagnostically investigate the effects of pharmacological interventions (other than methylphenidate) on the fronto-cingulo-parietal cognitive control network, in order to identify functional brain markers for future procognitive pharmacological interventions. Twenty-nine manuscripts investigated the effect of pharmacological treatment on executive function-related brain correlates in psychotic disorders (n = 11), depression (n = 4), bipolar disorder (n = 4), ADHD (n = 4), OCD (n = 2), smoking dependence (n = 2), alcohol dependence (n = 1), and pathological gambling (n = 1). In terms of impact on the fronto-cingulo-parietal network, the preliminary evidence for catechol-O-methyl-transferase inhibitors, nicotinic receptor agonists, and atomoxetine was relatively consistent, the data for atypical antipsychotics and anticonvulsants moderate, and interpretation of the data for antidepressants was hampered by the employed study designs. Increased activity in task-relevant areas and decreased activity in task-irrelevant areas were the most common transdiagnostic effects of pharmacological treatment. These markers showed good positive and moderate negative predictive value. It is concluded that fronto-cingulo-parietal activity changes can serve as a marker for future procognitive interventions. Future recommendations include the use of randomized double-blind designs and selective cholinergic and glutamatergic compounds.

COMT genotype, gambling activity, and cognition

Neuropsychological studies of adults with problem gambling indicate impairments across multiple cognitive domains. Catechol-O-methyltransferase (COMT) plays a unique role in the regulation of dopamine in the prefrontal cortex, and has been implicated in the cognitive dysfunction evident in problem gambling. This study examined adults with varying levels of gambling behavior to determine whether COMT genotype was associated with differences in gambling symptoms and cognitive functioning. 260 non-treatment-seeking adults aged 18-29 years with varying degrees of gambling behavior provided saliva samples for genotyping COMT val158met (rs4680). All subjects underwent clinical evaluations and neurocognitive assessment of decision-making, working memory, and impulsivity. The Val/Val COMT genotype was associated with the largest percentage of subjects with gambling disorder (31.8%), a rate significantly different from the Val/Met (13.2%) group (p = 0.001). The Val/Val COMT group was also associated with significantly more gambling disorder diagnostic criteria being met, greater frequency of gambling behavior, and significantly worse cognitive performance on the Cambridge Gamble Task (risk adjustment and delay aversion) and the Spatial Working Memory task (total errors). This study adds to the growing literature on the role of COMT in impulsive behaviors by showing that the Val/Val genotype was associated with specific clinical and cognitive elements among young adults who gamble, in the absence of differences on demographic measures and other cognitive domains. Future work should consider using genotyping to explore whether certain polymorphisms predict subsequent development of impulsive behaviors including gambling disorder, and treatment outcomes.

Dynamic network mechanisms of relational integration

A prominent hypothesis states that specialized neural modules within the human lateral frontopolar cortices (LFPCs) support "relational integration" (RI), the solving of complex problems using inter-related rules. However, it has been proposed that LFPC activity during RI could reflect the recruitment of additional "domain-general" resources when processing more difficult problems in general as opposed to RI specifically. Moreover, theoretical research with computational models has demonstrated that RI may be supported by dynamic processes that occur throughout distributed networks of brain regions as opposed to within a discrete computational module. Here, we present fMRI findings from a novel deductive reasoning paradigm that controls for general difficulty while manipulating RI demands. In accordance with the domain-general perspective, we observe an increase in frontoparietal activation during challenging problems in general as opposed to RI specifically. Nonetheless, when examining frontoparietal activity using analyses of phase synchrony and psychophysiological interactions, we observe increased network connectivity during RI alone. Moreover, dynamic causal modeling with Bayesian model selection identifies the LFPC as the effective connectivity source. Based on these results, we propose that during RI an increase in network connectivity and a decrease in network metastability allows rules that are coded throughout working memory systems to be dynamically bound. This change in connectivity state is top-down propagated via a hierarchical system of domain-general networks with the LFPC at the apex. In this manner, the functional network perspective reconciles key propositions of the globalist, modular, and computational accounts of RI within a single unified framework.

Genotype status of the dopamine-related catechol-O-methyltransferase (COMT) gene corresponds with desirability of "unhealthy" foods

The role of dopamine is extensively documented in weight regulation and food intake in both animal models and humans. Yet the role of dopamine has not been well studied in individual differences for food desirability. Genotype status of the dopamine-related catechol-O-methyltransferase (COMT) gene has been shown to influence dopamine levels, with greater COMT enzymatic activity in val/val individuals corresponding to greater degradation of dopamine. Decreased dopamine has been associated with poorer cognitive control and diminished goal-directed behavior in various behavioral paradigms. Additionally, dopaminergic-rich regions such as the frontal cortex and dorsal striatum have been shown to be important for supporting food-related decision-making. However, the role of dopamine, as assessed by COMT genotype status, in food desirability has not been fully explored. Therefore, we utilized an individual's COMT genotype status (n = 61) and investigated food desirability based on self-rated "healthy" and "unhealthy" food perceptions. Here we found val/val individuals (n = 19) have greater desirability for self-rated "unhealthy" food items, but not self-rated "healthy" food items, as compared to val/met (n = 24) and met/met (n = 18) individuals (p < 0.005). Utilizing an objective health measure for the food items, we also found val/val and val/met individuals have greater desirability for objectively defined "unhealthy" food items, as compared to met/met individuals (p < 0.01). This work further substantiates the role of dopamine in food-related behaviors and more specifically in relationship to food desirability for "unhealthy" food items.

The neural bases of cognitive processes in gambling disorder

Functional imaging is offering powerful new tools to investigate the neurobiology of cognitive functioning in people with and without psychiatric conditions like gambling disorder. Based on similarities between gambling and substance-use disorders in neurocognitive and other domains, gambling disorder has recently been classified in the Diagnostic and Statistical Manual of Mental Disorders (5th edn) (DSM-5) as a behavioral addiction. Despite the advances in understanding, there exist multiple unanswered questions about the pathophysiology underlying gambling disorder and the promise for translating the neurobiological understanding into treatment advances remains largely unrealized. Here we review the neurocognitive underpinnings of gambling disorder with a view to improving prevention, treatment, and policy efforts.

A functional network perspective on response inhibition and attentional control

Inferior frontal cortex (IFC) modules that inhibit dominant behaviours are a popular feature in theories of cognitive dysfunction. However, the paradigms on which these theories are based fail to distinguish between inhibitory and non-inhibitory cognitive demands. Here we use four novel fMRI variants of the classic stop-signal task to test whether the IFC houses unique inhibitory modules. Our results demonstrate that IFC sub-regions are not functionally unique in their sensitivities to inhibitory cognitive demands, but instead form components of spatially distributed networks. These networks are most strongly activated when infrequent stimuli are being processed, regardless of behavioural inhibitory demands, and when novel tasks are being acquired, as opposed to when routine responses must be suppressed. We propose that there are no inhibitory modules within the frontal lobes and that behavioural inhibition is an emergent property of spatially distributed functional networks, each of which supports a broader class of cognitive demands.

The right inferior frontal cortex has long been thought to house a neural module that inhibits dominant behaviours. Using brain imaging, Erika-Florence et al. demonstrate that this inhibition is in fact an emergent property of multiple neural networks that support broader classes of cognitive processes.

Treatment of Gambling Disorders

Preclinical and clinical research implicate several neurotransmitter systems in the pathophysiology of gambling disorder (GD). In particular, neurobiological research suggests alterations in serotonergic, dopaminergic, glutamatergic and opioidergic functioning. The relative efficacy of medications targeting these systems remains a topic of ongoing research, and there is currently no Food and Drug Administration (FDA) approved medication with an indication for GD. Considering co-occurring disorders may be particularly important when devising a treatment plan for GD: extant data suggest that the opioid antagonist naltrexone may by the most effective form of current pharmacotherapy for GD, particularly for individuals with a co-occurring substance-use disorder (SUD) or with a family history of alcoholism. In contrast, lithium or other mood stabilizers may be most effective for GD for patients presenting with a co-occurring bipolar-spectrum disorder (BSD). Further, serotonin reuptake inhibitors (SRIs) may be efficacious in reducing GD symptoms for individuals also presenting with a (non-BSD) mood or anxiety disorder. Finally, elevated rates of GD (and other Impulse Control Disorders; ICDs) have been noted among individuals with Parkinson's Disease (PD), and clinicians should assess for vulnerability to GD when considering treatment options for PD. Reducing levodopa or dopamine agonist (DA) dosages may partially reduce GD symptoms among patients with co-occurring PD. For GD patients not willing to consider drug treatment, n-acetyl cysteine or behavioral therapies may be effective. Ongoing research into the effectiveness of combined behavioral and pharmacotherapies is being conducted; thus combined treatments should also be considered.

"Killing Two Birds with One Stone": Alcohol Use Reduction Interventions with Potential Efficacy in Enhancing Self-Control

We review interventions with empirical support for reducing alcohol use and enhancing self-control. While any intervention that decreases drinking could improve self-control, we focus here on interventions with evidence of direct benefit for both indications. Although no intervention yet shows strong evidence for dual efficacy, multiple interventions have strong evidence for one indication and solid or suggestive evidence for the other. Among pharmacotherapies, opioid antagonists currently have the best evidence for reducing alcohol use and enhancing self-control. Nicotinic partial agonist varenicline also appears to be efficacious for alcohol use and self-control. Many psychosocial and behavioral interventions (e.g., cognitive behavioral therapy, contingency management, mindfulness training) may have efficacy for both indications based on purported mechanisms of action and empirical evidence. Cognitive bias modification and neurophysiological interventions have promise for alcohol use and self-control as well and warrant further research. We offer several other suggestions for future research directions.

Hypoconnectivity and hyperfrontality in retired American football players

Recent research has raised concerns about the long-term neurological consequences of repetitive concussive and sub-concussive injuries in professional players of American Football. Despite this interest, the neural and psychological status of retired players remains unknown. Here, we evaluated the performances and brain activation patterns of retired National Football League players (NFL alumni) relative to controls using an fMRI-optimised neuropsychological test of executive function. Behaviourally, the NFL alumni showed only modest performance deficits on the executive task. By contrast, they showed pronounced hyperactivation and hypoconnectivity of the dorsolateral frontal and frontopolar cortices. Critically, abnormal frontal-lobe function was correlated with the number of times that NFL alumni reported having been removed from play after head injury and was evident in individual players. These results support the hypothesis that NFL alumni have a heightened probability of developing executive dysfunction and suggest that fMRI provides the most sensitive biomarker of the underlying neural abnormality.