Double-blind naltrexone and placebo comparison study in the treatment of pathological gambling

Dopamine and Opioid Neurotransmission in Behavioral Addictions: A Comparative PET Study in Pathological Gambling and Binge Eating

Although behavioral addictions share many clinical features with drug addictions, they show strikingly large variation in their behavioral phenotypes (such as in uncontrollable gambling or eating). Neurotransmitter function in behavioral addictions is poorly understood, but has important implications in understanding its relationship with substance use disorders and underlying mechanisms of therapeutic efficacy. Here, we compare opioid and dopamine function between two behavioral addiction phenotypes: pathological gambling (PG) and binge eating disorder (BED). Thirty-nine participants (15 PG, 7 BED, and 17 controls) were scanned with [¹¹C]carfentanil and [¹⁸F]fluorodopa positron emission tomography using a high-resolution scanner. Binding potentials relative to non-displaceable binding (BP_ND) for [¹¹C]carfentanil and influx rate constant (K_i) values for [¹⁸F]fluorodopa were analyzed with region-of-interest and whole-brain voxel-by-voxel analyses. BED subjects showed widespread reductions in [¹¹C]carfentanil BP_ND in multiple subcortical and cortical brain regions and in striatal [¹⁸F]fluorodopa K_i compared with controls. In PG patients, [¹¹C]carfentanil BP_ND was reduced in the anterior cingulate with no differences in [¹⁸F]fluorodopa K_i compared with controls. In the nucleus accumbens, a key region involved in reward processing, [¹¹C]Carfentanil BP_ND was 30-34% lower and [¹⁸F]fluorodopa K_i was 20% lower in BED compared with PG and controls (p<0.002). BED and PG are thus dissociable as a function of dopaminergic and opioidergic neurotransmission. Compared with PG, BED patients show widespread losses of mu-opioid receptor availability together with presynaptic dopaminergic defects. These findings highlight the heterogeneity underlying the subtypes of addiction and indicate differential mechanisms in the expression of pathological behaviors and responses to treatment.

A Guide to Medications Inducing Salivary Gland Dysfunction, Xerostomia, and Subjective Sialorrhea: A Systematic Review Sponsored by the World Workshop on Oral Medicine VI

BACKGROUND

Medication-induced salivary gland dysfunction (MISGD), xerostomia (sensation of oral dryness), and subjective sialorrhea cause significant morbidity and impair quality of life. However, no evidence-based lists of the medications that cause these disorders exist.

OBJECTIVE

Our objective was to compile a list of medications affecting salivary gland function and inducing xerostomia or subjective sialorrhea.

DATA SOURCES

Electronic databases were searched for relevant articles published until June 2013. Of 3867 screened records, 269 had an acceptable degree of relevance, quality of methodology, and strength of evidence. We found 56 chemical substances with a higher level of evidence and 50 with a moderate level of evidence of causing the above-mentioned disorders. At the first level of the Anatomical Therapeutic Chemical (ATC) classification system, 9 of 14 anatomical groups were represented, mainly the alimentary, cardiovascular, genitourinary, nervous, and respiratory systems. Management strategies include substitution or discontinuation of medications whenever possible, oral or systemic therapy with sialogogues, administration of saliva substitutes, and use of electro-stimulating devices.

LIMITATIONS

While xerostomia was a commonly reported outcome, objectively measured salivary flow rate was rarely reported. Moreover, xerostomia was mostly assessed as an adverse effect rather than the primary outcome of medication use. This study may not include some medications that could cause xerostomia when administered in conjunction with others or for which xerostomia as an adverse reaction has not been reported in the literature or was not detected in our search.

CONCLUSIONS

We compiled a comprehensive list of medications with documented effects on salivary gland function or symptoms that may assist practitioners in assessing patients who complain of dry mouth while taking medications. The list may also prove useful in helping practitioners anticipate adverse effects and consider alternative medications.

Similarities and Differences in Neurobiology

Substance addiction is a chronic, relapsing brain disease characterized by compulsive drug seeking and use despite harmful consequences. Non-substance addiction is defined recently that people may compulsively engage in an activity despite any negative consequences to their lives. Despite differences with respect to their addictive object, substance addiction and non-substance addiction may share similarities with respect to biological, epidemiological, clinical, genetic and other features. Here we review the similarities and differences in neurobiology between these two addictions with a focus on dopamine, serotonin, opioid, glutamate and norepinephrine systems. Studies suggest the involvement of all these systems in both substance addiction and non-substance addiction while differences may exist with respect to their contributions.

Treatment modalities for patients with gambling disorder

BACKGROUND

Gambling disorder (GD) is defined as persistent and recurrent problematic gambling behavior leading to clinically significant impairment or distress. The prevalence of GD has been shown to be 1.2-7.1% in the general population. GD can severely impact on personal and vocational wellbeing as well as lead to financial problems, and has been known to be difficult to treat. This review describes the available pharmacotherapy/psychosocial treatments for GD patients, and summarizes data on the effectiveness of these GD treatments.

METHODS

This review refers to newly as well as previously published studies and guidelines.

RESULTS

The description of pharmacotherapy mainly focuses on opioid receptor antagonists, selective serotonin reuptake inhibitors, and mood stabilizers. Psychosocial treatments/strategies mainly include cognitive behavioral therapy, motivational interviewing, and Gamblers Anonymous. We also introduce relatively novel treatment modalities.

CONCLUSIONS

This review can help clinicians to decide treatment plans for their GD patients. In addition, it can be used as a reference for designing future research.

Naltrexone: A Pan-Addiction Treatment?

Addiction is a major public health problem with few efficacious and safe treatments. The goal of this review is to provide an evidence-based assessment of the therapeutic role of the opioid antagonist naltrexone across the addiction spectrum-substance-based and behavioral. The PubMed database was searched for randomized, placebo-controlled clinical trials that investigated the oral or intramuscular long-acting formulation of naltrexone in substance use disorders or behavioral addictions such as pathological gambling, kleptomania, and trichotillomania. Thirty-nine efficacy studies were retrieved, covering alcohol use disorder (n = 22), opioid use disorder (n = 6), nicotine use disorder (n = 5), stimulant use disorder (n = 2), gambling disorder (n = 2), trichotillomania (n = 1), and kleptomania (n = 1). Despite the very different presentations within and between both addiction categories, the data, as a whole, show consistency in favor of naltrexone's relative efficacy and safety. Given the potential benefit and good tolerability revealed in the studies, the high morbidity associated with addiction, and the dearth of alternate treatments, naltrexone would seem like an underutilized treatment option. Further, naltrexone's seemingly broad anti-addiction efficacy supports a shared role for brain opioid pathways in the pathophysiology of addiction, broadly defined. More studies investigating the efficacy and tolerability of naltrexone and other opioid modulators are warranted. Studies should also further examine the effect of combining psychotherapy with naltrexone, as well as the potential role of naltrexone in treating comorbid addictions.

White matter tract integrity in treatment-resistant gambling disorder

BACKGROUND

Gambling disorder is a relatively common psychiatric disorder recently re-classified within the DSM-5 under the category of 'substance-related and addictive disorders'.

AIMS

To compare white matter integrity in patients with gambling disorder with healthy controls; to explore relationships between white matter integrity and disease severity in gambling disorder.

METHOD

In total, 16 participants with treatment-resistant gambling disorder and 15 healthy controls underwent magnetic resonance imaging (MRI). White matter integrity was analysed using tract-based spatial statistics.

RESULTS

Gambling disorder was associated with reduced fractional anisotropy in the corpus callosum and superior longitudinal fasciculus. Fractional anisotropy in distributed white matter tracts elsewhere correlated positively with disease severity.

CONCLUSIONS

Reduced corpus callosum fractional anisotropy is suggestive of disorganised/damaged tracts in patients with gambling disorder, and this may represent a trait/vulnerability marker for the disorder. Future research should explore these measures in a larger sample, ideally incorporating a range of imaging markers (for example functional MRI) and enrolling unaffected first-degree relatives of patients.

Evaluating the Impact of Naltrexone on the Rat Gambling Task to Test Its Predictive Validity for Gambling Disorder

Gambling Disorder has serious consequences and no medications are currently approved for the treatment of this disorder. One factor that may make medication development difficult is the lack of animal models of gambling that would allow for the pre-clinical screening of efficacy. Despite this, there is evidence from clinical trials that opiate antagonists, in particular naltrexone, may be useful in treating gambling disorder. To-date, the effects of naltrexone on pre-clinical models of gambling have not been evaluated. The purpose of the present study was to evaluate the effects of naltrexone in an animal model of gambling, the rat gambling task (rGT), to determine whether this model has some predictive validity. The rGT is a model in which rats are given a choice of making either a response that produces a large reward or a small reward. The larger the reward, the greater the punishment, and thus this task requires that the animal inhibit the ‘tempting’ choice, as the smaller reward option produces overall the most number of rewards per session. People with gambling disorder chose the tempting option more, thus the rGT may provide a model of problem gambling. It was found that naltrexone improved performance on this task in a subset of animals that chose the ‘tempting’, disadvantageous choice, more at baseline. Thus, the results of this study suggest that the rGT should be further investigated as a pre-clinical model of gambling disorder and that further investigation into whether opioid antagonists are effective in treating Gambling Disorder may be warranted.

Congruence Couple Therapy for Pathological Gambling: A Pilot Randomized Controlled Trial

A multi-site pilot randomized controlled trial of Congruence Couple Therapy (CCT) for problem gambling was conducted in Ontario and Alberta, Canada from 2009 to 2011. The purpose was to assess the feasibility of a full trial and to identify methodological modifications to enhance future trials. The sample (N = 30; 15 couples) consisted of 66% male gamblers and 34% female. Mean age of sample was 49.1 years. Baseline mean DSM-IV gambling score was 8.7/10. Retention of the treatment couples was 89% at 2-month follow-up. Retention of control couples was 78%. A randomized controlled design compared the status of couples in treatment condition to control condition. Treatment couples received 12-week CCT while control couples received three brief check-ins over 12 weeks. No significant difference was found between treatment and control group at baseline on all measures. At (1) week 12 post-treatment, and (2) week 20 follow-up, significant treatment effects were found for gambling symptoms (p = 0.008; p = 0.041), mental distress (p = 0.001; p = 0.035), and family systems function (p = 0.023; p = 0.054) between treatment and control group. Within group changes for treatment couples over time were significant for mental distress (p = 0.000), dyadic adjustment (p = 0.002), and family systems function (p = 0.000). On similar measures, control group showed non-significant improvement. Future methodological changes, advantages and disadvantages of multi-site partnerships with community treatment agencies are discussed. Of interest is that control participants showed unintended improvement. CCT as a treatment was favourably accepted by counselors, problem gamblers and their spouses. Positive outcome trends ranging from small to large effect size on key measures indicate that a full-scaled trial will require approximately 140 couples and is an investment worth pursuing.

Opioid antagonists in broadly defined behavioral addictions: a narrative review

INTRODUCTION

Naltrexone (NTX), a mu-opioid receptor antagonist, has been approved for the treatment of alcoholism and opioid dependence. More recently, however, NTX and a related drug, nalmefene (NMF), have also shown positive results for the treatment of gambling disorders.

AREAS COVERED

In this study, we reviewed the trials testing the effect of opioid antagonists (OA) in gambling disorders and in other broadly defined behavioral addictions, including selected DSM-5 disruptive, impulse-control, and conduct disorders, obsessive-compulsive and related disorders, eating disorders, and other conditions not currently recognized by official classification schemes. We found six randomized controlled trials (RCTs) of OA in gambling disorder, two RCTs of OA in trichotillomania (hair pulling disorder), two RCTs of OA in binge eating disorder, and one RCT of OA for kleptomania. We also reviewed case reports on hypersexual disorder, compulsive buying and skin picking disorders.

EXPERT OPINION

The reviewed data supported the use of OA, namely NTX and NMF, in gambling disorder (both) and kleptomania (NTX). We did not find enough evidence to support the use of NTX or NMF in trichotillomania (hair pulling disorder), excoriation (skin-picking) disorder, compulsive buying disorder, hypersexual disorder, or binge eating disorder.

Gambling disorder in financial markets: Clinical and treatment-related features

BACKGROUND AND AIMS

To date, few studies have examined the clinical manifestation of disordered gamblers in financial markets. This study examined the differences in the clinical and treatment-related features of gambling disorder between financial markets and horse races.

METHODS

Subjects who met the DSM-IV criteria for pathological gambling (PG) and who sought treatment were assessed by retrospective chart review. One hundred forty-four subjects were included in this sample, which consisted of the following groups: financial markets (n = 45; 28.6%) and horse races (n = 99; 71.4%).

RESULTS

Multiple similar manifestations were found between the groups, including severity of PG, age of PG onset, amounts of gambling debts, drinking days per week, depressive mood, duration of seeking treatment after the onset of PG, and treatment follow-up duration. However, disordered gamblers who invested in the financial market were significantly more likely to be educated (p = 0.003), live with their spouses (p = 0.007), have full-time jobs (p = 0.006), and they were more likely to participate in the first type of gambling than the horse races group (p<0.001). Furthermore, the financial markets group received the anti-craving medication less often than the horse races group (p = 0.04).

DISCUSSION AND CONCLUSIONS

These findings suggest that disordered gamblers in financial markets show different socio-demographic, clinical and treatment-related features compared with the horse race gamblers, despite a similar severity of gambling disorder. Understanding these differential manifestations may provide insight into prevention and treatment development for specific types of gambling.

Possible role of a dysregulation of the endogenous opioid system in antisocial personality disorder

Around half the inmates in prison institutions have antisocial personality disorder (ASPD). A recent theory has proposed that a dysfunction of the endogenous opioid system (EOS) underlies the neurobiology of borderline personality disorder (BPD). In the present theoretical paper, based on a comprehensive database and hand search of the relevant literature, this hypothesis is extended to ASPD, which may be the predominant expression of EOS dysfunction in men, while the same pathology underlies BPD in women. According to evidence from human and animal studies, the problematic behaviours of persons with antisocial, callous, or psychopathic traits may be seen as desperate, unconscious attempts to stimulate their deficient EOS, which plays a key role in brain reward circuits. If the needs of this system are not being met, the affected persons experience dysphoric mood, discomfort, or irritability, and strive to increase binding of endogenous opioids to receptors by using the rewarding effects of aggression by exertion of physical or manipulative power on others, by abusing alcohol or substances that have the reward system as target, by creating an "endorphin rush" by self-harm, by increasing the frequency of their sexual contacts, or by impulsive actions and sensation seeking. Symptoms associated with ASPD can be treated with opioid antagonists like naltrexone, naloxone, or nalmefene.

Endogenous Opioid Signaling in the Medial Prefrontal Cortex is Required for the Expression of Hunger-Induced Impulsive Action

Opioid transmission and dysregulated prefrontal cortex (PFC) activity have both been implicated in the inhibitory-control deficits associated with addiction and binge-type eating disorders. What remains unknown, however, is whether endogenous opioid transmission within the PFC modulates inhibitory control. Here, we compared intra-PFC opioid manipulations with a monoamine manipulation (d-amphetamine), in two sucrose-reinforced tasks: progressive ratio (PR), which assays the motivational value of an incentive, and differential reinforcement of low response rates (DRLs), a test of inhibitory control. Intra-PFC methylnaloxonium (M-NX, a limited diffusion opioid antagonist) was given to rats in a 'low-drive' condition (2-h food deprivation), and also after a motivational shift to a 'high-drive' condition (18-h food deprivation). Intra-PFC DAMGO (D-[Ala2,N-MePhe4, Gly-ol]-enkephalin; a μ-opioid agonist) and d-amphetamine were also tested in both tasks, under the low-drive condition. Intra-PFC M-NX nearly eliminated impulsive action in DRL engendered by hunger, at a dose (1 μg) that significantly affected neither hunger-induced PR enhancement nor hyperactivity. At a higher dose (3 μg), M-NX eliminated impulsive action and returned PR breakpoint to low-drive levels. Conversely, intra-PFC DAMGO engendered 'high-drive-like' effects: enhancement of PR and impairment of DRL performance. Intra-PFC d-amphetamine failed to produce effects in either task. These results establish that endogenous PFC opioid transmission is both necessary and sufficient for the expression of impulsive action in a high-arousal, high-drive appetitive state, and that PFC-based opioid systems enact functionally unique effects on food impulsivity and motivation relative to PFC-based monoamine systems. Opioid antagonists may represent effective treatments for a range of psychiatric disorders with impulsivity features.

Compulsive sexual behavior: a review of the literature

BACKGROUND AND AIMS

Compulsive sexual behavior (CSB) is a common disorder featuring repetitive, intrusive and distressing sexual thoughts, urges and behaviors that negatively affect many aspects of an individual's life. This article reviews the clinical characteristics of CSB, cognitive aspects of the behaviors, and treatment options.

METHODS

We reviewed the literature regarding the clinical aspects of CSB and treatment approaches.

RESULTS

The literature review of the clinical aspects of CSB demonstrates that there is likely a substantial heterogeneity within the disorder. In addition, the treatment literature lacks sufficient evidence-based approaches to develop a clear treatment algorithm.

CONCLUSIONS

Although discussed in the psychological literature for years, CSB continues to defy easy categorization within mental health. Further research needs to be completed to understand where CSB falls within the psychiatric nosology.

SCRATCH THAT!—Two case reports of scratch-card gambling disorder

Gambling disorder is a common, clinically relevant condition that impacts significantly one's life. Given that approved pharmacological interventions are lacking, it is crucial to readily identify these cases to provide available interventions in psychiatric care services. Here, we present two uncommon cases of unique scratch-card gambling disorder, a specific type of pathological gambling that could be increasing as availability of these games are growing.

Bipolar disorder and gambling disorder comorbidity: current evidence and implications for pharmacological treatment

BACKGROUND

The co-occurrence of bipolar disorder (BD) and gambling disorder (GD), though of clinical and public health importance, is still scarcely investigated. Comorbid BD-GD subjects experience a more severe course of illness and poorer treatment outcome, due to a range of clinical and psychosocial factors that collectively impede remission and recovery. The aim of our paper is to review the role of pharmacotherapy in the treatment of comorbid BD-GD, in order to support clinical decisions according to the best available evidence.

METHODS

A qualitative systematic review of studies on pharmacological treatment in comorbid BD-GD was performed. A comprehensive literature search of online databases, bibliographies of published articles and gray literature was conducted. Data on efficacy, safety and tolerability were extracted and levels of evidence were assessed. We also provide a brief overview of current epidemiological, neurobiological and clinical findings, with the intention of proposing a dimensional approach to the choice of available drugs.

RESULTS

The only drug with a high level of evidence is lithium. Considering the inclusion of GD in DSM-5 'Substance-related and Addictive Disorders' category, we discuss the use of other drugs with a high level of evidence currently used in BD subjects with co-occurring substance use disorders.

LIMITATIONS

Only few clinical trials are available and the population is limited; therefore no conclusive evidence can be inferred.

CONCLUSIONS

Further randomized controlled trials are required to evaluate the efficacy of pharmacological treatment strategies in large samples of patients with comorbid BD-GD. Also, attempts should be made to identify other shared clinical and psychopathological domains that are amenable to treatment.

Should pathological gambling and obesity be considered addictive disorders? A factor analytic study in a nationally representative sample

OBJECTIVE

Pathological gambling (PG) is now aligned with substance use disorders in the DSM-5 as the first officially recognized behavioral addiction. There is growing interest in examining obesity as an addictive disorder as well. The goal of this study was to investigate whether epidemiological data provide support for the consideration of PG and obesity as addictive disorders.

METHOD

Factor analysis of data from a large, nationally representative sample of US adults (N=43,093), using nicotine dependence, alcohol dependence, drug dependence, PG and obesity as indicators. It was hypothesized that nicotine dependence, alcohol dependence and drug use dependence would load on a single factor. It was further hypothesized that if PG and obesity were addictive disorders, they would load on the same factor as substance use disorders, whereas failure to load on the addictive factor would not support their conceptualization as addictive disorders.

RESULTS

A model with one factor including nicotine dependence, alcohol dependence, drug dependence and PG, but not obesity, provided a very good fit to the data, as indicated by CFI=0.99, TLI=0.99 and RMSEA=0.01 and loadings of all indicators >0.4.

CONCLUSION

Data from this study support the inclusion of PG in a latent factor with substance use disorders but do not lend support to the consideration of obesity, as defined by BMI, as an addictive disorder. Future research should investigate whether certain subtypes of obesity are best conceptualized as addictive disorders and the shared biological and environmental factors that account for the common and specific features of addictive disorders.

Age of pathological gambling onset: clinical and treatment-related features

OBJECTIVES

This study examined differences in the clinical and treatment-related features of pathological gambling (PG) on the basis of the age of PG onset among pathological gamblers who sought treatment.

METHODS

A total of 702 male outpatients with a primary diagnosis of PG and who were treated in a clinical practice were assessed by retrospective chart review. We selected the age of 25 years and younger as the threshold for "group 1." We then stratified the participants into 4 groups on the basis of the age of PG onset in 10-year intervals. Analysis of covariance with a covariant of age and the Pearson χ test were used for analyses.

RESULTS

We found that the earlier-onset gamblers were less likely to be escape type (P < 0.05), used significantly more Internet-based gambling (P < 0.001), and were less likely to engage in nonstrategic gambling (P < 0.05) than the later-onset gamblers. In addition, the earlier-onset gamblers took anticraving medication, such as naltrexone, significantly more often (P < 0.05), and sought treatment significantly more slowly after the onset of PG than the later-onset group (P < 0.01). Regarding adherence to treatment, however, there was no significant difference among the 4 groups on the basis of the age of PG onset.

CONCLUSIONS

The age of PG onset is associated with several important clinical and treatment features. More studies are needed to advance prevention and treatment strategies for each age group.

Safety and tolerability of as-needed nalmefene in the treatment of alcohol dependence: results from the Phase III clinical programme

OBJECTIVE

To investigate safety and tolerability of nalmefene for reduction of alcohol consumption in alcohol-dependent patients.

METHODS

Pooled data from three randomized, placebo-controlled studies (two 6-month; one 12-month) of 18 mg nalmefene (as-needed use) in alcohol-dependent patients looking at the total population (placebo n = 824, nalmefene n = 1123) and patients with high/very high drinking risk levels at screening and randomization (target population: placebo n = 374, nalmefene n = 450).

RESULTS

In the study, 62.7% of patients on placebo and 74.7% on nalmefene in the total population had treatment-emergent adverse events (TEAEs). Fourty-seven (5.9%) on placebo and 149 (13.0%) on nalmefene dropped out due to TEAEs. Thirty-five (4.4%) on placebo and 57 (5.0%) on nalmefene had serious adverse events. Tolerability and safety were similar in the target population and total population. Most frequent TEAEs were transient, mainly occurring at treatment initiation. There was no difference in tolerability and safety if nalmefene was taken daily or intermittently; no signal of increased risk of suicide-related behavior with nalmefene. The higher incidence of psychiatric events in the nalmefene group was mainly due to the TEAE of confusional state.

CONCLUSIONS

Although there was a higher incidence of TEAEs and TEAEs leading to dropout, nalmefene was well-tolerated and no major safety issues were identified.

Past-year gambling behaviour among patients receiving opioid substitution treatment

BACKGROUND

Substance abuse and gambling problems are associated, however, studies on gambling problems among opioid substitution treatment (OST) patients are scarce. The aims of this study are to explore the association of gender, age, treatment medication and treatment program with gambling behaviour, including gambling participation and gambling problems, among OST patients.

FINDINGS

All OST patients (n = 244) in three Finnish outpatient clinics were recruited in March - April 2014. The response rate was 64.3%. OST programs included two choices of orientation (rehabilitative/harm reduction) and two choices for treatment medication (methadone/buprenorphine-naloxone). Of 144 respondents, 70.1% had gambled during the past year and 12.5% were identified as potential past-year problem gamblers. Gambling was statistically significant more commonly among males (79.8%) compared with females (53.7%). Similarly patients in the rehabilitative program gambled (75.9%) more than those in the harm reduction program (50.0%). Gender, age, treatment medication or treatment program was not associated with past-year gambling problems.

CONCLUSIONS

Gambling participation of the OST patients seemed to be somewhat similar compared with the Finnish general population, but gambling problems were more common among OST patients. Gender and age may not be very strong indicators of risk while screening problem gamblers among OST patients. Institution of a problem gambling screening program is recommended, and additional intervention for gambling problems should be implemented for that need as a part of OST.

Gambling disorder and other behavioral addictions: recognition and treatment

Addiction professionals and the public are recognizing that certain nonsubstance behaviors--such as gambling, Internet use, video-game playing, sex, eating, and shopping--bear resemblance to alcohol and drug dependence. Growing evidence suggests that these behaviors warrant consideration as nonsubstance or "behavioral" addictions and has led to the newly introduced diagnostic category "Substance-Related and Addictive Disorders" in DSM-5. At present, only gambling disorder has been placed in this category, with insufficient data for other proposed behavioral addictions to justify their inclusion. This review summarizes recent advances in our understanding of behavioral addictions, describes treatment considerations, and addresses future directions. Current evidence points to overlaps between behavioral and substance-related addictions in phenomenology, epidemiology, comorbidity, neurobiological mechanisms, genetic contributions, responses to treatments, and prevention efforts. Differences also exist. Recognizing behavioral addictions and developing appropriate diagnostic criteria are important in order to increase awareness of these disorders and to further prevention and treatment strategies.

Behavioral addictions: a novel challenge for psychopharmacology

Although addictive syndromes have been traditionally related to substance-use disorders, during the last few decades a novel addictive group, including the so-called "behavioral or no-drug addictions," has been recognized and has attracted increasing attention for its relevant social impact. This group includes pathological gambling, compulsive shopping, TV/Internet/social network/videogame addictions, workaholism, sex and relationship addictions, orthorexia, and overtraining syndrome. Substance and behavioral addictions show similar phenomenological features, such as craving, dependence, tolerance, and abstinence, and perhaps they share a common possible pathophysiology. It is, however, controversial whether all or at least some of them should be considered real disorders or just normal, albeit extreme, behaviors. The aim of this article is to review current data on pharmacological treatment of behavioral addictions. As no specific and validated treatment algorithms are currently available, only an improved knowledge on their psychopathological, clinical, and neurobiological features may have relevant implications for more focused preventive and therapeutic strategies.

Effects of systemic opioid receptor ligands on ethanol- and sucrose seeking and drinking in alcohol-preferring (P) and Long Evans rats

The endogenous opioid system has been implicated in mediating the reinforcing effects of ethanol (EtOH). Naltrexone (NTX), an opioid antagonist with concentration-dependent selectivity for the mu receptor, naltrindole (NTI), a selective delta receptor antagonist, and U50,488H, a selective kappa receptor agonist were examined in both alcohol-preferring (P) and nonselected (Long Evans (LE)) rats to determine whether they differentially affected the seeking and consumption of EtOH and sucrose. Using the sipper-tube model, rats reinforced with either 2% sucrose or 10% EtOH were injected with vehicle and either NTI (2.5, 5.0, or 10.0 mg/kg), U50 (2.5, 5.0, or 10.0 mg/kg), low-dose NTX (0.1, 0.3, or 1.0 mg/kg), or high-dose NTX (1.0, 3.0, or 10.0 mg/kg). Subsequent intakes (consummatory) or lever responses (seeking) were assessed. Overall, NTI, U50, and NTX attenuated intake and responding for sucrose and EtOH, with EtOH-reinforced P rats being the most sensitive to the effects of NTI on intake and seeking. U50 treatment decreased intake and seeking in both P and LE rats but did not selectively reduce EtOH intake or seeking in either line. P rats were more sensitive than LE rats to lower doses of NTX, and these doses more selectively attenuated responding for EtOH than sucrose. Higher doses of NTX suppressed intake and responding across both lines and reinforcers. These results suggest that drugs selective for the opioid receptors may be good pharmacotherapeutic targets, particularly in those with an underlying genetic predisposition for greater EtOH preference/intake.

Pharmacological means of reducing human drug dependence: a selective and narrative review of the clinical literature

Substance abuse or addictive disorder is a global problem. A greater understanding of the associated changes in brain pathophysiology supports the notion that pharmacological treatments are part of the necessary treatment options. Craving is a core symptom of addictive disorder. It refers to a strong desire to use drugs again either to re-experience positive effects or to diminish negative experiences. Currently there are a number of medicines that are effective in the treatment of addictive disorders. These medications can either be for substitution (same pharmacological effect as the abused substance) or anticraving (decrease the craving of the abused substance). In this MEDLNE based review, specific compounds (naltrexone, acamprosate, topiramate, disulfiram, baclofen, N-acetylcysteine and bupropion) were selected that are known to diminish desire to use (anticraving effect) and that have been trialled for a number of different substance addictive disorders. Their therapeutic potential in clinical practice is discussed in light of their efficacy.

Pharmacological treatments in pathological gambling

Pathological gambling (PG) is a relatively common and often disabling psychiatric condition characterized by intrusive urges to engage in deleterious gambling behaviour. Although common and financially devastating to individuals and families, there currently exist no formally approved pharmacotherapeutic interventions for this disorder. This review seeks to examine the history of medication treatments for PG. A systematic review of the 18 double-blind, placebo-controlled pharmacotherapy studies conducted for the treatment of pathological gambling was conducted. Study outcome and the mean dose of medication administered was documented in an effort to determine a preferred medication choice in this population. A variety of medication classes have been examined in the treatment of PG with varying results. Antidepressants, atypical antipsychotics and mood stabilizers have demonstrated mixed results in controlled clinical trials. Although limited information is available, opioid antagonists and glutamatergic agents have demonstrated efficacious outcomes, especially for individuals with PG suffering from intense urges to engage in the behaviour. Given that several studies have demonstrated their efficacy in treating the symptoms associated with PG, opioid antagonists should be considered the first line treatment for PG at this time. Most published studies, however, have employed relatively small sample sizes, are of limited duration and involve possibly non-representative clinical groups (e.g. those without co-occurring psychiatric disorders). Response measures have varied across studies. Heterogeneity of PG treatment samples may also complicate identification of effective treatments. Identification of factors related to treatment response will help inform future studies and advance treatment strategies for PG.

Naltrexone for impulse control disorders in Parkinson disease: a placebo-controlled study

OBJECTIVE

Impulse control disorders (ICDs) in Parkinson disease (PD) are common and can be difficult to manage. The objective of this study was to determine the efficacy and tolerability of naltrexone, an opioid antagonist, for the treatment of ICDs in PD.

METHODS

Patients with PD (n = 50) and an ICD were enrolled in an 8-week, randomized (1:1), double-blind, placebo-controlled study of naltrexone 50-100 mg/d (flexible dosing). The primary outcome measure was response based on the Clinical Global Impression-Change score, and the secondary outcome measure was change in symptom severity using the Questionnaire for Impulsive-Compulsive Disorders in Parkinson's Disease-Rating Scale (QUIP-RS) ICD score.

RESULTS

Forty-five patients (90%) completed the study. The Clinical Global Impression-Change response rate difference favoring naltrexone in completers was 19.8% (95% confidence interval [CI] -8.7% to 44.2%). While this difference was not significant (odds ratio=1.6, 95% CI 0.5-5.2, Wald χ2 [df]=0.5 [1], p=0.5), naltrexone treatment led to a significantly greater decrease in QUIP-RS ICD score over time compared with placebo (regression coefficient for interaction term in linear mixed-effects model=-7.37, F[df]=4.3 [1, 49], p=0.04). The estimated changes in QUIP-RS ICD scores from baseline to week 8 were 14.9 points (95% CI 9.9-19.9) for naltrexone and 7.5 points (95% CI 2.5-12.6) for placebo.

CONCLUSIONS

Naltrexone treatment was not efficacious for the treatment of ICDs in PD using a global assessment of response, but findings using a PD-specific ICD rating scale support further evaluation of opioid antagonists for the treatment of ICD symptoms in PD.

CLASSIFICATION OF EVIDENCE

This study provides Class I evidence that in patients with PD and an ICD, naltrexone does not significantly increase the probability of achieving response. However, the study lacked the precision to exclude an important difference in response rates.

Gambling disorder during dopamine replacement treatment in Parkinson's disease: a comprehensive review

Gambling Disorder (GD) is characterized by “the failure to resist gambling impulses despite severe personal, family or occupational consequences”. In the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-V), GD replaces the DSM-IV diagnosis of Pathological Gambling (PG). GD estimated prevalence ranges between 0.4% and 3.4% within the adult population and it seems to be more common in patients with Parkinson's disease (PD). In this population, GD recently has become more widely recognized as a possible complication of dopamine agonist (DA) therapy. This association has aroused great interest for the dramatic impact GD has on patients' quality of life. Management of PG in patients with PD could be demanding. It is based on patient and caregiver education, modification of dopamine replacement therapy, and in some cases psychoactive drug administration. In this review article, the authors provide an overview of GD pathogenesis during DA therapy as well as a summary of available treatment options.

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.

The latest achievements in the pharmacotherapy of gambling disorder

Gambling disorder (GD) is becoming increasingly prevalent both among adults and adolescents. Unfortunately, this disorder is largely underestimated, while it can still lead to serious social and personal consequences, including criminal behavior or suicide attempts. In the past, the only means of treating gambling were psychobehavioral therapies. Nowadays, this disorder could also respond to many drugs from different classes such as opioid antagonists, serotonin selective reuptake inhibitors, mood stabilizers, atypical antipsychotics or glutamatergic agents. This review presents current pharmacological strategies and the results of clinical trials evaluating the efficacy of pharmacotherapy for GD. It also discusses the importance of distinguishing different pathological gambler subtypes such as impulsive, obsessive-compulsive and addictive subtypes as this may have serious pharmacological implications.

Getting a grip on problem gambling: what can neuroscience tell us?

In problem gamblers, diminished cognitive control and increased impulsivity is present compared to healthy controls. Moreover, impulsivity has been found to be a vulnerability marker for the development of pathological gambling (PG) and problem gambling (PrG) and to be a predictor of relapse. In this review, the most recent findings on functioning of the brain circuitry relating to impulsivity and cognitive control in PG and PrG are discussed. Diminished functioning of several prefrontal areas and of the anterior cingulate cortex (ACC) indicate that cognitive-control related brain circuitry functions are diminished in PG and PrG compared to healthy controls. From the available cue reactivity studies on PG and PrG, increased responsiveness towards gambling stimuli in fronto-striatal reward circuitry and brain areas related to attentional processing is present compared to healthy controls. At this point it is unresolved whether PG is associated with hyper- or hypo-activity in the reward circuitry in response to monetary cues. More research is needed to elucidate the complex interactions for reward responsivity in different stages of gambling and across different types of reward. Conflicting findings from basic neuroscience studies are integrated in the context of recent neurobiological addiction models. Neuroscience studies on the interface between cognitive control and motivational processing are discussed in light of current addiction theories.

Clinical implications: We suggest that innovation in PG therapy should focus on improvement of dysfunctional cognitive control and/or motivational functions. The implementation of novel treatment methods like neuromodulation, cognitive training and pharmacological interventions as add-on therapies to standard treatment in PG and PrG, in combination with the study of their effects on brain-behavior mechanisms could prove an important clinical step forward towards personalizing and improving treatment results in PG.

Impulse control disorders in Parkinson's disease: an overview from neurobiology to treatment

Parkinson's disease (PD) is the second most common neurodegenerative brain disorder and is characterized by motor symptoms such as tremor, bradykinesia, rigidity and postural instability. A majority of the patients also develop non-motor symptoms. Impulse control disorders (ICD) are behavioural changes that often fail to be detected in clinical practice. The prevalence of ICD in PD varies widely from 6.1 to 31.2 % and treatment with dopaminergic medication is considered to be the greatest risk factor. Management consists mainly of reducing dopaminergic medication. In our experience, ICD has a tremendous impact on the quality of life of the patients and their families and should therefore not be disregarded. Studies addressing the role of ICD in PD caregiver strain are imperative. We attempt to give a comprehensive overview of the literature on the complicated neurobiology of ICD and discuss risk factors, genetic susceptibility, screening modalities and management.

"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.

Pharmacotherapy of pathological gambling: review of new treatment modalities

Pathological gambling is classified in the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition as an impulse-control disorder. In the International Classification of Diseases of the WHO, pathological gambling is coded under the heading of 'Habit and Impulse Disorders'. Pathological gambling is a chronic, progressive disorder, which has a prevalence of 1-3.4% among western civilizations. The enormous personal and social consequences of this disorder include a high rate of suicide attempts, job loss, marital and family problems, legal problems, and criminal behavior. Recent studies have demonstrated that pathological gambling patients respond well to treatment with selective serotonin reuptake inhibitors, mood stabilizers and opioid antagonists. These findings support the idea that pathological gambling and other disorders of impulse control may be conceptualized as part of the obsessive-compulsive spectrum disorders or addictive disorders. This article will discuss possible treatment strategies according to different behavior patterns in pathological gambling and also remind the physicians who intend to treat this disorder of the possible diagnosis of pathological gambling.

Working memory and affective decision-making in addiction: a neurocognitive comparison between heroin addicts, pathological gamblers and healthy controls

BACKGROUND

Cognitive deficits are observed both in heroin dependence and in pathological gambling (PG) on various tasks. PG, as a non-substance addiction, is free of toxic consequences of drug use. Therefore a direct neurocognitive comparison of heroin addicts and pathological gamblers helps dissociate the consequences of chronic heroin use on cognitive function from the cognitive vulnerabilities that predispose addiction.

METHODS

A case-control design was used, comparing 58 abstinent heroin addicts, 58 pathological gamblers, and 60 healthy controls on working memory and affective decision-making functions. Working memory was assessed using the Self-ordered Pointing Test (SOPT). Affective decision-making was measured by the Iowa Gambling Task (IGT).

RESULTS

Heroin addicts performed significantly worse both on the IGT and on the SOPT, compared to healthy controls. Pathological gamblers performed worse on the IGT than healthy controls, but did not differ from controls on the SOPT. Years of heroin use were negatively correlated with working memory and affective decision-making performance in heroin addicts, while severity of gambling was not significantly correlated with any task performance in pathological gamblers.

CONCLUSIONS

Our findings indicate that deficits in affective decision-making shared by heroin dependence and PG putatively represent vulnerabilities to addiction and that working memory deficits detected only in heroin addicts may be identified as heroin-specific harmful effects.

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

Pathological gambling (PG) is a disabling disorder experienced by 1-3% of adults, and empirically validated treatments are lacking. Perturbations of prefrontal-dependent cognitive functions are implicated in the pathophysiology of PG. The enzyme catechol-O-methyl-transferase (COMT) is responsible for degradation of dopamine in the cortices and thereby is known to regulate such cognitive functions and their neural substrates. The objective of this study was to determine whether tolcapone, a COMT inhibitor, improves symptoms of PG and to explore whether such effects are dependent on COMT val-158-met polymorphism status and relate to concomitant changes in fronto-parietal activation. Twenty-four individuals with PG were enrolled in an 8-week trial of oral tolcapone (100mg/day titrated to 100mg thrice/day) and 12 undertook pre- and post-treatment fMRI to examine brain activation during an executive planning task in a pre-defined fronto-parietal network. At baseline, patients with PG showed fronto-parietal under-activation versus controls during executive planning. Treatment was associated with statistically significant reductions on PG-Yale Brown Obsessive Compulsive Scale (PG-YBOCS), the extent of which correlated significantly with augmentation of planning-related fronto-parietal activation. Symptom improvement was also significantly more pronounced in subjects with the val/val COMT polymorphism. Tolcapone improved PG symptoms, and the extent of symptomatic improvement was significantly related to augmentation of fronto-parietal activation (fMRI probe) and COMT status. Objective genetic and fMRI markers hold promise in the search for targeting treatment and elucidating brain mechanisms associated with optimal clinical outcomes.

Opioidergic and dopaminergic manipulation of gambling tendencies: a preliminary study in male recreational gamblers

Gambling is characterized by cognitive distortions in the processing of chance and skill that are exacerbated in pathological gambling. Opioid and dopamine dysregulation is implicated in pathological gambling, but it is unclear whether these neurotransmitters modulate gambling distortions. The objective of the current study was to assess the effects of the opioid receptor antagonist naltrexone and the dopamine D2 receptor antagonist haloperidol on gambling behavior. Male recreational gamblers (n = 62) were assigned to receive single oral doses of naltrexone 50 mg, haloperidol 2 mg or placebo, in a parallel-groups design. At 2.5 h post-dosing, participants completed a slot machine task to elicit monetary wins, "near-misses," and a manipulation of personal choice, and a roulette game to elicit two biases in sequential processing, the gambler's fallacy and the hot hand belief. Psychophysiological responses (electrodermal activity and heart rate) were taken during the slot machine task, and plasma prolactin increase was assessed. The tasks successfully induced the gambling effects of interest. Some of these effects differed across treatment groups, although the direction of effect was not in line with our predictions. Differences were driven by the naltrexone group, which displayed a greater physiological response to wins, and marginally higher confidence ratings on winning streaks. Prolactin levels increased in the naltrexone group, but did not differ between haloperidol and placebo, implying that naltrexone but not haloperidol may have been functionally active at these doses. Our results support opioid modulation of cognition during gambling-like tasks, but did not support the more specific hypothesis that naltrexone may act to ameliorate cognitive distortions.

A targeted review of the neurobiology and genetics of behavioural addictions: an emerging area of research

This review summarizes neurobiological and genetic findings in behavioural addictions, draws parallels with findings pertaining to substance use disorders, and offers suggestions for future research. Articles concerning brain function, neurotransmitter activity, and family history and (or) genetic findings for behavioural addictions involving gambling, Internet use, video game playing, shopping, kleptomania, and sexual activity were reviewed. Behavioural addictions involve dysfunction in several brain regions, particularly the frontal cortex and striatum. Findings from imaging studies incorporating cognitive tasks have arguably been more consistent than cue-induction studies. Early results suggest white and grey matter differences. Neurochemical findings suggest roles for dopaminergic and serotonergic systems, but results from clinical trials seem more equivocal. While limited, family history and genetic data support heritability for pathological gambling and that people with behavioural addictions are more likely to have a close family member with some form of psychopathology. Parallels exist between neurobiological and genetic and family history findings in substance and nonsubstance addictions, suggesting that compulsive engagement in these behaviours may constitute addictions. To date, findings are limited, particularly for shopping, kleptomania, and sexual behaviour. Genetic understandings are at an early stage. Future research directions are offered.