Psychiatry. Behavioral addictions debut in proposed DSM-V

Brain dopaminergic system changes in drug addiction: a review of positron emission tomography findings

Dopamine (DA) is considered crucial for the rewarding effects of drugs of abuse, but its role in addiction remains unclear. Positron emission tomography (PET) is the first technology used for in vivo measurement of components of the dopaminergic system in the human brain. In this article, we review the major findings from PET imaging studies on the involvement of DA in drug addiction, including presynaptic DA synthesis, vesicular monoamine transporter 2, the DA transporter, and postsynaptic DA receptors. These results have corroborated the role of DA in addiction and increased the understanding of its underlying mechanisms.

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.

A model-based analysis of impulsivity using a slot-machine gambling paradigm

Impulsivity plays a key role in decision-making under uncertainty. It is a significant contributor to problem and pathological gambling (PG). Standard assessments of impulsivity by questionnaires, however, have various limitations, partly because impulsivity is a broad, multi-faceted concept. What remains unclear is which of these facets contribute to shaping gambling behavior. In the present study, we investigated impulsivity as expressed in a gambling setting by applying computational modeling to data from 47 healthy male volunteers who played a realistic, virtual slot-machine gambling task. Behaviorally, we found that impulsivity, as measured independently by the 11th revision of the Barratt Impulsiveness Scale (BIS-11), correlated significantly with an aggregate read-out of the following gambling responses: bet increases (BIs), machines switches (MS), casino switches (CS), and double-ups (DUs). Using model comparison, we compared a set of hierarchical Bayesian belief-updating models, i.e., the Hierarchical Gaussian Filter (HGF) and Rescorla-Wagner reinforcement learning (RL) models, with regard to how well they explained different aspects of the behavioral data. We then examined the construct validity of our winning models with multiple regression, relating subject-specific model parameter estimates to the individual BIS-11 total scores. In the most predictive model (a three-level HGF), the two free parameters encoded uncertainty-dependent mechanisms of belief updates and significantly explained BIS-11 variance across subjects. Furthermore, in this model, decision noise was a function of trial-wise uncertainty about winning probability. Collectively, our results provide a proof of concept that hierarchical Bayesian models can characterize the decision-making mechanisms linked to the impulsive traits of an individual. These novel indices of gambling mechanisms unmasked during actual play may be useful for online prevention measures for at-risk players and future assessments of PG.

Relationships that compulsive buying has with addiction, obsessive-compulsiveness, hoarding, and depression

BACKGROUND AND OBJECTIVES

Compulsive buying has been associated with addiction, depression, and obsessive-compulsive disorder, as well as hoarding. The present study investigated the relationship that compulsive buying (CB) has with 'addictive' (i.e., sensitivity to reward), obsessive-compulsive, and depressive phenomena, after controlling for hoarding, substance dependence, manic, and Borderline Personality Disorder symptoms.

METHODS

87 participants from a community population completed the online questionnaires for the study, however 70 participants (M=29.19, SD=10.45; 70% were female) were used in the analyses because of exclusion criteria.

RESULTS

As expected, CB measures correlated with hoarding, depression, sensitivity to reward, and, but less so, obsessive-compulsive measures. Sensitivity to reward was the most important predictor of CB severity, compared to obsessive-compulsive and depression symptoms. Hoarding was also an important predictor of CB severity.

LIMITATIONS

Small sample size meant gender comparisons could not be made, and the use of a novel, communicated questionnaire meant that interpretation should be considered conservatively.

CONCLUSIONS

Overall, findings suggest that CB may be most closely related to the phenomena associated with addiction (an increased sensitivity to reward), rather than obsessive-compulsive or depression symptoms. Hoarding and reward sensitivity perhaps might separate compulsive buying from ordinary and recreational shopping.

Factor structure of the Internet Addiction Scale and its associations with psychiatric symptoms for Korean adolescents

In this paper, we explore underlying factors of Internet Addiction Scale (IAS) and examine how the dimensions of the IAS relate to psychiatric symptoms in Korean adolescents. Exploratory factor analysis with a sample of N = 1,722 consisted of 13-15 year old Korean adolescents identified three distinctive factors of IAS and they were labeled 'time management', 'withdrawal behaviors' and 'neglect work'. Then, multiple regression models were applied to assess the association between each factor and eight psychological problems, which were evaluated by Youth Self Report. The overall IAS was significantly associated with Somatic, Immature, Thought, Attention, Delinquent and Aggressive behaviors. However, three factor scores showed different association patterns and indicated multidimensional aspects of problematic Internet use.

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.

Environmental factors selectively impact co-occurrence of problem/pathological gambling with specific drug-use disorders in male twins

AIMS

Multiple forms of drug abuse/dependence frequently co-occur with problem/pathological gambling (PPG). The current study examines the extent to which genetic and environmental factors contribute to their co-occurrence.

DESIGN

Bivariate models investigated the magnitude and correlation of genetic and environmental contributions to problem/pathological gambling and its co-occurrence with nicotine dependence, cannabis abuse/dependence and stimulant abuse/dependence.

SETTING

Computer-assisted telephone interviews in the community.

PARTICIPANTS

Participants were 7869 male twins in the Vietnam Era Twin Registry, a USA-based national twin registry.

MEASUREMENTS

Life-time DSM-III-R diagnoses for problem/pathological gambling, nicotine dependence, cannabis abuse/dependence and stimulant abuse/dependence were determined using the Diagnostic Interview Schedule.

FINDINGS

All drug-use disorders displayed additive genetic and non-shared environmental contributions, with cannabis abuse/dependence also displaying shared environmental contributions. Both genetic [genetic correlation rA  = 0.22; 95% confidence interval (CI) = 0.10-0.34] and non-shared environmental components (environmental correlation rE  = 0.24; 95% CI = 0.10-0.37) contributed to the co-occurrence of problem/pathological gambling and nicotine dependence. This pattern was shared by cannabis abuse/dependence (rA  = 0.32; 95% CI = 0.05-1.0; rE  = 0.36; 95% CI = 0.16-0.55) but not stimulant abuse/dependence (SAD), which showed only genetic contributions to the co-occurrence with problem/pathological gambling (rA  = 0.58; 95% CI = 0.45-0.73).

CONCLUSIONS

Strong links between gambling and stimulant-use disorders may relate to the neurochemical properties of stimulants or the illicit nature of using 'hard' drugs such as cocaine. The greater contribution of environmental factors to the co-occurrence between problem/pathological gambling and 'softer' forms of drug abuse/dependence (cannabis, tobacco) suggest that environmental interventions (perhaps relating to availability and legality) may help to diminish the relationship between problem/pathological gambling and tobacco- and cannabis-use disorders.

A case of withdrawal psychosis from internet addiction disorder

Similar to substance use disorder, patients with Internet addiction disorder (IAD) show excessive use, tolerance and withdrawal symptoms. We report a case of a patient with withdrawal psychosis who showed persecutory delusion and disorganized behaviors in addition to common withdrawal symptoms such as agitation and irritability. A 25-year-old male developed a full-blown psychotic episode within one day after discontinuing an Internet game that he had been playing for at least eight hours a day for two years. Upon admission, he had no abnormal brain imaging findings and laboratory tests. With antipsychotic medication (quetiapine up to 800 mg), his psychotic symptoms rapidly subsided and after four days of treatment, he no longer showed any signs of psychosis. This case report suggests that brief psychosis can develop during withdrawal from long-term excessive use of an Internet and the central pathology beneath the IAD is more likely a form of addiction than impulse control.

The functional anatomy of impulse control disorders

Impulsive–compulsive disorders such as pathological gambling, hypersexuality, compulsive eating, and shopping are side effects of the dopaminergic therapy for Parkinson’s disease. With a lower prevalence, these disorders also appear in the general population. Research in the last few years has discovered that these pathological behaviors share features similar to those of substance use disorders (SUD), which has led to the term “behavioral addictions”. As in SUDs, the behaviors are marked by a compulsive drive toward and impaired control over the behavior. Furthermore, animal and medication studies, research in the Parkinson’s disease population, and neuroimaging findings indicate a common neurobiology of addictive behaviors. Changes associated with addictions are mainly seen in the dopaminergic system of a mesocorticolimbic circuit, the so-called reward system. Here we outline neurobiological findings regarding behavioral addictions with a focus on dopaminergic systems, relate them to SUD theories, and try to build a tentative concept integrating genetics, neuroimaging, and behavioral results.

[Substance-related and addictive disorders in the DSM-5]

This paper concerns the revised classification of Substance-Related and Addictive Disorders in the fifth edition of the American Psychiatric Association's (APA) Diagnostic and Statistical Manual of Mental Disorders (DSM-5). In DSM-5, substance use disorders are diagnosed on a continuum of severity specified by explicit operationalized diagnostic criteria. "Gambling disorder" is the only behavioral addiction added to the DSM. Furthermore, preliminary criteria for "Caffeine Use Disorder" and "Internet Gaming Disorder" have now been defined in the manual. Adopting the DSM-5 criteria catalogue within the German treatment system for children and adolescents with substance use disorders or at risk for developing substance use disorders would be of great significance. Since the diagnostic threshold is lower, more patients would be eligible for treatment. Thus, early intervention in the area of substance use disorders should be strengthened, a development that appears to be highly desirable from the perspective of child and adolescent psychiatry. The current Section III diagnoses, with their now comprehensive diagnostic criteria, facilitate more internationally compatible research.

Description of internet addiction among Chilean medical students: a cross-sectional study

OBJECTIVE

Internet addiction (IA) has been described as an emerging behavior related to the development of new technologies, with scarce studies on the subject and none involving medical students. The Internet Addiction Test (IAT) is a screening instrument used to detect IA worldwide, which was published in 1998 and inspired by the DSM-IV criteria for pathologic gambling. The objective of this study aims to measure the prevalence of IA in Chilean medical students and its possible association with demographic variables and depressive symptoms.

METHODS

First- to fifth-year undergraduate medical students at a medical school in Santiago de Chile answered a self-administered survey that included demographic data, the IAT scale, and the Goldberg's General Health Questionnaire (GHQ-12) to screen for IA and depressive symptoms, respectively.

RESULTS

Three hundred eighty-four students participated, achieving a response rate of 69.8 %, of which 11.5 % were classified as problematic users according to the IAT. The authors found a statistical association between positive results on the IAT and positive scores on the GHQ-12, as well as with the male gender.

CONCLUSION

In this first study of IA in medical students, the authors found a rate of incidence similar to what has been published in the literature focusing on college students. Additionally, there was a positive association between emotional symptoms and other abuse behaviors.

The relationship between recent stressful life events, personality traits, perceived family functioning and internet addiction among college students

Internet addiction (IA) is an emerging social and mental health issue among youths. Analysis of risk factors, as well as their interactions, is crucial for understanding the development of IA. This study investigated the relationship between recent stressful life events, personality traits, perceived family functioning and IA in 892 college students. Subjects were classified into categories (non-addicted, mild IA or severe IA) using the Chen Internet Addiction Scale. Stressful life events, personality traits and family functioning were assessed using the Adolescent Self-Rating Life Events Checklist, the Eysenck Personality Questionnaire, and the Family Adaptability and Cohesion Scale, respectively. The results indicated that compared with non-addicted subjects, subjects with severe IA (9.98%) had lower family functioning, lower extraversion, higher neuroticism and psychoticism, and more stressful life events, and subjects with mild IA (11.21%) had higher neuroticism and more health and adaptation problems. Neuroticism and health and adaptation problems were potential predictors of IA. An interaction effect between psychoticism and total life stress on IA was also found. These findings highlight the role of personality traits and life stress and their interactions in college students' IA. Further research should explore the mechanisms underlying the interaction effect of psychoticism with life stress on IA.

Relationships between problematic internet use and problem-gambling severity: findings from a high-school survey

With the popularity of Internet use among adolescents, there is concern that some youth may display problematic or addictive patterns of Internet use. Although excessive patterns of Internet use was considered for inclusion in the DSM-5 with pathological gambling and substance-use disorders in a category of addictive disorders, it was determined that more research was needed on Internet-use behaviors before such actions be further considered and possibly undertaken. The present study is the first to investigate whether at-risk/problematic Internet use (ARPIU) may moderate the strength of association between problem-gambling severity and gambling-related characteristics and health and well-being measures in adolescents. Survey data from 1884 Connecticut high-school student stratified by Internet use (ARPIU vs. non-ARPIU) were examined in bivariate analyses and logistic regression models. Gambling-related characteristics and health and well-being measures were mostly positively associated with problem-gambling severity in both Internet use groups. Interaction odds ratio revealed that the strength of the associations between problem-gambling severity and marijuana, alcohol and caffeine use were stronger amongst the non-ARPIU compared to the ARPIU group, suggesting that the relationships between these substance use behaviors and problem gambling may be partially accounted for by ARPIU. Future studies should examine the extent to which preventative interventions targeting both problematic Internet use and problem gambling may synergistically benefit measures of health and reduce risk-taking behaviors in adolescence.

Psychometric properties of the Cannabis Abuse Screening Test in Hungarian samples of adolescents and young adults

AIM

The aim of our study was to analyze psychometric properties of the Cannabis Abuse Screening Test (CAST).

METHODS

Our sample comprised Hungarian high school (n = 476; male 56.3%; mean age 19.0 years, SD = 0.65 years) and college students (n = 439; male 65.1%; mean age 23.9 years, SD = 1.56 years) who reported cannabis use in the past year. The sample covered the five biggest universities of Hungary. Besides the CAST, participants responded to the Munich-Composite International Diagnostic Interview. Factor structure was analyzed by a confirmatory factor analysis. Receiver operating characteristic curve analysis was made to assess cut-off scores. Data collection took place in 2010.

RESULTS

CAST proved to be a reliable (Cronbach's α 0.71 and 0.76) one-dimensional measure. Regarding both cannabis dependence and cannabis use disorders, a cut-off of 2 points proved to be ideal in both samples, resulting in optimal specificity, negative predictive values and accuracy, but less than optimal positive predictive values (dependence) and low sensitivity (cannabis use disorder).

DISCUSSION AND CONCLUSIONS

In line with former results, the CAST proved to be an adequate measure for the screening of cannabis-related problems among adolescents and young adults in an Eastern European country where this scale has not been studied before.

Argentine tango: Another behavioral addiction?

BACKGROUND

Behavioral addiction is an emerging concept based on the resemblance between symptoms or feelings provided by drugs and those obtained with various behaviors such as gambling, etc. Following an observational study of a tango dancer exhibiting criteria of dependence on this dance, we performed a survey to assess whether this case was unique or frequently encountered in the tango dancing community.

METHODS

We designed an online survey based on both the DSM-IV and Goodman's criteria of dependence; we added questions relative to the positive and negative effects of tango dancing and a self-evaluation of the degree of addiction to tango. The questionnaire was sent via Internet to all the tango dancers subscribing to "ToutTango", an electronic monthly journal. The prevalence of dependence was analyzed using DSM-IV, Goodman's criteria and self-rating scores separately.

RESULTS

1,129 tango dancers answered the questionnaire. Dependence rates were 45.1, 6.9 and 35.9%, respectively, according to the DSM-IV, Goodman's criteria and self-rating scores. Physical symptoms of withdrawal were reported by 20% of the entire sample and one-third described a strong craving for dancing. Positive effects were high both in dependent and non-dependent groups and were markedly greater than negative effects. Long practice of tango dancing did not modify the dependence rate or reduce the level of positive effects.

CONCLUSIONS

Tango dancing could lead to dependence as currently defined. However, this dependence is associated with marked and sustained positive effects whilst the negative are few. Identifying the precise substratum of this dependence needs further investigation.

A role for pharmacotherapy in the treatment of "internet addiction"

The advent of the Internet is among the most significant changes in recent decades and has greatly affected the entire range of human experience. However, it has, in turn, led to the emergence of psychopathological features of addiction linked to its use. Literature on the clinical management of the distress related to Internet use systematically measures up to an evolving nosography, with ambiguous definitions of the phenomenon and a diversity of diagnostic, prognostic, and therapeutic criteria. To date, case studies on "Internet addiction" treatment are rather limited, and no standard clinical treatment protocols exist. With regard to pharmacological treatment options, empirical or anecdotal assessments are mostly referred to. The aim of this article was to review current literature on Internet addiction treatment and assess the extent to which specific pharmacological interventions alleviate these patients' symptomatic burden, to propose a rationale that may guide the therapeutic approach. To this end, we also explored pharmacological interventions that target patterns of comorbidity and underlying psychopathological dimensions shared with other behavioral or substance addictions.

Neurobiology of gambling behaviors

For many, gambling is a recreational activity that is performed periodically without ill effects, but for some, gambling may interfere with life functioning. A diagnostic entity, pathological gambling (PG), is currently used to define a condition marked by excessive and problematic gambling. In this review, the current status of understanding of the neurobiologies of gambling and PG is described. Multiple neurotransmitter systems (norepinephrine, serotonin, dopamine, opioid and glutamate) and brain regions (ventral striatum, ventromedial prefrontal cortex, insula, among others) have been implicated in gambling and PG. Considerations for future directions in gambling research, with a view towards translating neurobiological advances into more effective prevention and treatment strategies, are discussed.

Does psychopathology in childhood predict internet addiction in male adolescents?

This study investigated childhood psychopathology and Internet addiction in adolescents. Initial assessment data were obtained from 1998 to 1999, and a follow-up assessment was performed in 2006, when the original subjects entered middle school. Personal information for the 524 male subjects was obtained from the original data. The subjects were evaluated with the Korean version of the child behavior checklist, which was administered to the children's parents. Demographic and psychosocial factors were also evaluated. Children were reassessed with the self-reported Korea Internet Addiction Scale. Our results indicated that 3.6 % of the subjects had Internet addiction, and revealed a significant relationship between withdrawal and anxiety/depression and future Internet addiction. The results suggest that withdrawal and anxiety/depression during childhood should be considered in the etiology of problematic Internet use in boys. Accordingly, clinicians should consider anxiety/depression and withdrawal during childhood to prevent Internet addiction.

Heterogeneity of compulsive buyers based on impulsivity and compulsivity dimensions: a latent profile analytic approach

Despite the recognition that compulsive buyers are not one homogenous group, there is a dearth of theory-guided empirical investigation. Furthermore, although compulsivity and impulsivity are used as major psychiatric criteria for diagnosing compulsive buyers, these dimensions have rarely been considered in assessing the heterogeneity issue. We fill this gap by applying the motivation shift model of addiction to compulsive buying and empirically assessing the heterogeneity issue in the bi-dimensional space represented by the buying impulsivity and compulsivity dimensions. These hypotheses were tested with latent profile analysis based on survey data (N=445). Consistent with the hypothesis, we identified the cluster of buyers with high buying compulsivity and impulsivity ("compulsive-impulsive buyers"), the cluster of buyers with low buying compulsivity and high impulsivity ("impulsive excessive buyers"), and the cluster of ordinary buyers. Furthermore, it was found that disparate clusters of buyers exhibit unique dispositional tendencies. Theoretical contributions and policy implications of the findings are discussed as well.

Addressing the question of disorder-specific risk factors of internet addiction: a comparison of personality traits in patients with addictive behaviors and comorbid internet addiction

Uncontrolled use of the internet has been reported to affect the lives of some users in a negative way. According to epidemiological studies, about 1% of the general population is showing signs of internet addiction. Since internet addiction is becoming a growing health concern, research on potential risk factors is becoming more important in order to develop strategies for prevention and to adopt therapeutic treatment. Although there are some studies investigating personality traits in internet addiction, most of these studies are based on samples of healthy subjects. In this research project, we compared personality profiles of a sample of patients in different rehabilitation centers. 70 patients with an addiction disorder that additionally met the criteria for internet addiction were compared to 48 patients suffering from alcohol dependence. Besides Big Five personality traits, we also assessed depressive symptoms. It was shown that patients with comorbid internet addiction can be discriminated from other patients by higher neuroticism and lower extraversion as well as lower conscientiousness. After controlling for depressive symptoms, lower conscientiousness especially turned out to be a disorder-specific risk factor. As internet addiction is related to unique patterns of personality traits and can be discriminated from alcohol dependence, treatment approaches are needed that meet the specific requirements of patients with internet addiction.

Neurobiological considerations in understanding behavioral treatments for pathological gambling

Pathological gambling (PG), a disorder currently categorized as an impulse-control disorder but being considered as a nonsubstance addiction in Diagnostic and Statistical Manual of Mental Disorders (5th ed.) discussions, represents a significant public health concern. Over the past decade, considerable advances have been made with respect to understanding the biological underpinnings of PG. Research has also demonstrated the efficacies of multiple treatments, particularly behavioral therapies, for treating PG. Despite these advances, relatively little is known regarding how biological measures, particularly those assessing brain function, relate to treatments for PG. In this article, we present a conceptual review focusing on the neurobiology of behavioral therapies for PG. To illustrate issues related to study design, we present proof-of-concept preliminary data that link Stroop-related brain activations prior to treatment onset to treatment outcome in individuals with PG receiving a cognitive-behavioral treatment incorporating aspects of imaginal desensitization and motivational interviewing. We conclude with recommendations about current and future directions regarding how to incorporate and translate biological findings into improved therapies for individuals with nonsubstance and substance addictions.

Cybersex addiction: Experienced sexual arousal when watching pornography and not real-life sexual contacts makes the difference

Background and aims Cybersex addiction is discussed controversially, while empirical evidence is widely missing. With respect to its mechanisms of development and maintenance Brand et al. (2011) assume that reinforcement due to cybersex should lead to the development of cue-reactivity and craving explaining recurrent cybersex use in the face of growing but neglected negative consequences. To support this hypothesis, two experimental studies were conducted. Methods In a cue-reactivity paradigm 100 pornographic cues were presented to participants and indicators of sexual arousal and craving were assessed. The first study aimed at identifying predictors of cybersex addiction in a freely recruited sample of 171 heterosexual males. The aim of the second study was to verify the findings of the first study by comparing healthy (n = 25) and problematic (n = 25) cybersex users. Results The results show that indicators of sexual arousal and craving to Internet pornographic cues predicted tendencies towards cybersex addiction in the first study. Moreover, it was shown that problematic cybersex users report greater sexual arousal and craving reactions resulting from pornographic cue presentation. In both studies, the number and subjective quality of real-life sexual contacts were not associated to cybersex addiction. Discussion The results support the gratification hypothesis, which assumes reinforcement, learning mechanisms, and craving to be relevant processes in the development and maintenance of cybersex addiction. Poor or unsatisfying sexual real-life contacts cannot sufficiently explain cybersex addiction. Conclusions Positive reinforcement in terms of gratification plays a major role in cybersex addiction.

From passive overeating to "food addiction": a spectrum of compulsion and severity

A psychobiological dimension of eating behaviour is proposed, which is anchored at the low end by energy intake that is relatively well matched to energy output and is reflected by a stable body mass index (BMI) in the healthy range. Further along the continuum are increasing degrees of overeating (and BMI) characterized by more severe and more compulsive ingestive behaviours. In light of the many similarities between chronic binge eating and drug abuse, several authorities have adopted the perspective that an apparent dependence on highly palatable food-accompanied by emotional and social distress-can be best conceptualized as an addiction disorder. Therefore, this review also considers the overlapping symptoms and characteristics of binge eating disorder (BED) and models of food addiction, both in preclinical animal studies and in human research. It also presents this work in the context of the modern and "toxic" food environment and therein the ubiquitous triggers for over-consumption. We complete the review by providing evidence that what we have come to call "food addiction" may simply be a more acute and pathologically dense form of BED.

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.

Phenomenology and treatment of behavioural addictions

Behavioural addictions are characterized by an inability to resist an urge or drive resulting in actions that are harmful to oneself or others. Behavioural addictions share characteristics with substance and alcohol abuse, and in areas such as natural history, phenomenology, and adverse consequences. Behavioural addictions include pathological gambling, kleptomania, pyromania, compulsive buying, compulsive sexual behaviour, Internet addiction, and binge eating disorder. Few studies have examined the efficacy of pharmacological and psychological treatment for the various behavioural addictions, and therefore, currently, no treatment recommendations can be made.

Reliability and validity of the Korean version of the internet addiction test among college students

We developed a Korean translation of the Internet Addiction Test (KIAT), widely used self-report for internet addiction and tested its reliability and validity in a sample of college students. Two hundred seventy-nine college students at a national university completed the KIAT. Internal consistency and two week test-retest reliability were calculated from the data, and principal component factor analysis was conducted. Participants also completed the Internet Addiction Diagnostic Questionnaire (IADQ), the Korea Internet addiction scale (K-scale), and the Patient Health Questionnaire-9 for the criterion validity. Cronbach's alpha of the whole scale was 0.91, and test-retest reliability was also good (r = 0.73). The IADQ, the K-scale, and depressive symptoms were significantly correlated with the KIAT scores, demonstrating concurrent and convergent validity. The factor analysis extracted four factors (Excessive use, Dependence, Withdrawal, and Avoidance of reality) that accounted for 59% of total variance. The KIAT has outstanding internal consistency and high test-retest reliability. Also, the factor structure and validity data show that the KIAT is comparable to the original version. Thus, the KIAT is a psychometrically sound tool for assessing internet addiction in the Korean-speaking population.

Genome-wide association study of a quantitative disordered gambling trait

Disordered gambling is a moderately heritable trait, but the underlying genetic basis is largely unknown. We performed a genome-wide association study (GWAS) for disordered gambling using a quantitative factor score in 1312 twins from 894 Australian families. Association was conducted for 2 381 914 single-nucleotide polymorphisms (SNPs) using the family-based association test in Merlin followed by gene and pathway enrichment analyses. Although no SNP reached genome-wide significance, six achieved P-values < 1 × 10(-5) with variants in three genes (MT1X, ATXN1 and VLDLR) implicated in disordered gambling. Secondary case-control analyses found two SNPs on chromosome 9 (rs1106076 and rs12305135 near VLDLR) and rs10812227 near FZD10 on chromosome 12 to be significantly associated with lifetime Diagnostic and Statistical Manual of Mental Disorders, fourth edition pathological gambling and South Oaks Gambling Screen classified probable pathological gambling status. Furthermore, several addiction-related pathways were enriched for SNPs associated with disordered gambling. Finally, gene-based analysis of 24 candidate genes for dopamine agonist-induced gambling in individuals with Parkinson's disease suggested an enrichment of SNPs associated with disordered gambling. We report the first GWAS of disordered gambling. While further replication is required, the identification of susceptibility loci and biological pathways will be important in characterizing the biological mechanisms that underpin disordered gambling.

The D2/3 dopamine receptor in pathological gambling: a positron emission tomography study with [11C]-(+)-propyl-hexahydro-naphtho-oxazin and [11C]raclopride

AIMS

Pathological gambling (PG) shares diagnostic features with substance use disorder (SUD), but the neurochemical mechanisms underlying PG are poorly understood. Because dopamine (DA), a neurotransmitter implicated in reward and reinforcement, is probably involved, we used positron emission tomography (PET) to test whether PG is associated with abnormalities in D2 and D3 receptor levels, as observed in SUD.

DESIGN

Case-control study comparing PG to healthy control (HC) subjects.

SETTING

Academic research imaging centre.

PARTICIPANTS

Thirteen non-treatment-seeking males meeting DSM-IV criteria for PG, and 12 matched HC (11 of whom completed PET).

MEASUREMENTS

Two PET scans (one with the D3 receptor preferring agonist [11C]-(+)-propyl-hexahydro-naphtho-oxazin (PHNO) and the other with [11C]raclopride) to assess D(2/3) DA receptor availability, and behavioural measures (self-report questionnaires and slot-machine game) to assess subjective effects and relationships to PET measures.

FINDINGS

Binding of both radiotracers did not differ between groups in striatum or substantia nigra (SN) (all P > 0.1). Across PG, [11C]-(+)-PHNO binding in SN, where the signal is attributable primarily to D3 receptors, correlated with gambling severity (r = 0.57, P = 0.04) and impulsiveness (r = 0.65, P = 0.03). In HC, [11C]raclopride binding in dorsal striatum correlated inversely with subjective effects of gambling (r = -0.70, P = 0.03) and impulsiveness (r = -0.70, P = 0.03).

CONCLUSIONS

Unlike with substance use disorder, there appear to be no marked differences in D2 /D3 levels between healthy subjects and pathological gamblers, suggesting that low receptor availability may not be a necessary feature of addiction. However, relationships between [11C]-(+)-PHNO binding and gambling severity/impulsiveness suggests involvement of the D3 receptor in impulsive/compulsive behaviours.

Shared genetic vulnerability for disordered gambling and alcohol use disorder in men and women: evidence from a national community-based Australian Twin Study

Disordered gambling (DG) will soon be included along with the substance use disorders in a revised diagnostic category of the Diagnostic and Statistical Manual of Mental Disorders DSM-5 called 'Substance Use and Addictive Disorders'. This was premised in part on the common etiologies of DG and the substance use disorders. Using data from the national community-based Australian Twin Registry, we used biometric model fitting to examine the extent to which the genetic liabilities for DG and alcohol use disorder (AUD) were shared, and whether this differed for men and women. The effect of using categorical versus dimensional DG and AUD phenotypes was explored, as was the effect of using diagnoses based on the DSM-IV and the proposed DSM-5 diagnostic criteria. The genetic correlations between DG and AUD ranged from 0.29 to 0.44. There was a significantly larger genetic correlation between DG and AUD among men than women when using dimensional phenotypes. Overall, about one-half to two-thirds of the association between DG and AUD was due to a shared genetic vulnerability. This study represents one of the few empirical demonstrations of an overlap in the genetic risk for DG and another substance-related addictive disorder. More research is needed on the genetic overlap between DG and other substance use disorders, as well as the genetic overlap between DG and other (non-substance-related) psychiatric disorders.

[Gambling addiction]

Extensive coherent clinical, psychopathological, neurobiological and genetic similarities with substance-related addictions justify the forthcoming classification of gambling addiction under the new category "Substance Use and Addictive Disorders" in the DSM-5. Thus, gambling addiction can be regarded as the prototype of behavioral addiction. In general it should be kept in mind that isolated gambling forms are associated with varying addictive potential due to specific situational and structural game characteristics. High rates of indebtedness, suicidality, social isolation and gambling-related crime often accompany pathological gambling. As a consequence gambling addiction represents a mental disorder with a significant economic burden. In Germany 12-month prevalence rates for problem gambling in adulthood range from 0.24 % to 0.64  % and for pathological gambling from 0.20 % to 0.56 %. Because gambling products rank among the so-called demeriting (i.e. potentially harmful) social activities, player and youth protection measures to prevent gambling disorders and associated crime should be best regulated as a state monopoly.

Fronto-striatal dysregulation in drug addiction and pathological gambling: Consistent inconsistencies?

Alterations in appetitive processing are central to the major psychological theories of addiction, with differential predictions made by the reward deficiency, incentive salience, and impulsivity hypotheses. Functional MRI has become the chief means of testing these predictions, with experiments reliably highlighting disturbances at the level of the striatum, medial prefrontal cortex, and affiliated regions. However, demonstrations of hypo-reactivity and hyper-reactivity of this circuitry in drug addicted groups are reported in approximately equal measure. Similar findings are echoed in the emergent neuroimaging literature on pathological gambling, which has recently witnessed a coming of age. The first aim of this article is to consider some of the methodological aspects of these experiments that could influence the observed direction of group-level effects, including the baseline condition, trial structure and timing, and the nature of the appetitive cues (drug-related, monetary, or primary rewards). The second aim is to highlight the conceptual traction that is offered by pathological gambling, as a model of a ‘toxicity free’ addiction and an illness where tasks of monetary reinforcement afford a more direct mapping to the abused commodity. Our conclusion is that relatively subtle decisions in task design appear capable of driving group differences in fronto-striatal circuitry in entirely opposing directions, even with tasks and task variants that look ostensibly similar. Differentiation between the psychological theories of addiction will require a greater breadth of experimental designs, with more research needed on processing of primary appetitive cues, aversive processing, and in vulnerable/at-risk groups.

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We outline the current psychological theories of addiction and their predictions.

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We review recent fMRI literature of substance addictions and appetitive processing.

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Reasons for opposing results (hyper- vs hypo-active reward regions) are discussed.

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Recent fMRI findings of appetitive processing in pathological gambling are reviewed.

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Pathological gambling is suggested as a prototypical addiction for imaging research.

Reduced genual corpus callosal white matter integrity in pathological gambling and its relationship to alcohol abuse or dependence

OBJECTIVE

Magnetic resonance imaging (MRI) studies have demonstrated functional prefrontal cortical (PFC) abnormalities in pathological gambling (PG) and other psychiatric disorders characterized by impaired impulse control; e.g., cocaine dependence and bipolar disorder. These abnormalities are accompanied by impairments in white matter microstructures in the anterior (genual) corpus callosum (CC) in cocaine dependence and bipolar disorder. Prior studies have not examined white matter integrity in PG. We predicted impairments in genual CC white matter in PG.

METHODS

Nineteen participants with PG and 19 matched control participants underwent diffusion tensor imaging (DTI) to compare white matter integrity in the CC, as assessed using fractional anisotropy (FA).

RESULTS

In PG subjects as compared to control subjects, reduced FA values in the left and right genu of the CC were observed. Multiple regression analyses confirmed that PG status - in addition to age and past alcohol abuse/dependence (AA/AD) - was a significant predictor of genual FA values. Among PG participants, left and right genu FA values were negatively correlated with scores on the Behavioral Activation System Fun-Seeking (BAS-FS) subscale. Limitations. Limitations include a reliance on self-report measures of impulsivity and related constructs and a relatively small sample of PG subjects with past AA/AD.

CONCLUSION

Findings of decreased FA values in the genu of the CC in PG subjects suggest that, like with other disorders of behavioral dyscontrol, white matter microstructural abnormalities contribute to the pathophysiology of PG. These differences appear particularly relevant to individuals with remitted AA/AD, highlighting the importance of considering co-occurring substance use disorders when investigating PG.

Biological contributions to addictions in adolescents and adults: prevention, treatment, and policy implications

PURPOSE

Despite significant advances in our understanding of the biological bases of addictions, these disorders continue to represent a huge public health burden that is associated with substantial personal suffering. Efforts to target addictions require consideration of how the improved biological understanding of addictions may lead to improved prevention, treatment, and policy initiatives.

METHOD

In this article, we provide a narrative review of current biological models for addictions with a goal of placing existing data and theories within a translational and developmental framework targeting the advancement of prevention, treatment, and policy strategies.

RESULTS

Data regarding individual differences, intermediary phenotypes, and main and interactive influences of genetic and environmental contributions in the setting of developmental trajectories that may be influenced by addictive drugs or behavior indicate complex underpinnings of addictions.

CONCLUSIONS

Consideration and further elucidation of the biological etiologies of addictions hold significant potential for making important gains and reducing the public health impact of addictions.

The association between pathological internet use and comorbid psychopathology: a systematic review

BACKGROUND

Pathological Internet use (PIU) has been conceptualized as an impulse-control disorder that shares characteristics with behavioral addiction. Research has indicated a potential link between PIU and psychopathology; however, the significance of the correlation remains ambiguous. The primary objective of this systematic review was to identify and evaluate studies performed on the correlation between PIU and comorbid psychopathology; the secondary aims were to map the geographical distribution of studies, present a current synthesis of the evidence, and assess the quality of available research.

SAMPLING AND METHODS

An electronic literature search was conducted using the following databases: MEDLINE, PsycARTICLES, PsychINFO, Global Health, and Web of Science. PIU and known synonyms were included in the search. Data were extracted based on PIU and psychopathology, including depression, anxiety, symptoms of attention deficit and hyperactivity disorder (ADHD), obsessive-compulsive symptoms, social phobia and hostility/aggression. Effect sizes for the correlations observed were identified from either the respective publication or calculated using Cohen's d or R(2). The potential effect of publication bias was assessed using a funnel plot model and evaluated by Egger's test based on a linear regression.

RESULTS

The majority of research was conducted in Asia and comprised cross-sectional designs. Only one prospective study was identified. Twenty articles met the preset inclusion and exclusion criteria; 75% reported significant correlations of PIU with depression, 57% with anxiety, 100% with symptoms of ADHD, 60% with obsessive-compulsive symptoms, and 66% with hostility/aggression. No study reported associations between PIU and social phobia. The majority of studies reported a higher rate of PIU among males than females. The relative risks ranged from an OR of 1.02 to an OR of 11.66. The strongest correlations were observed between PIU and depression; the weakest was hostility/aggression.

CONCLUSIONS

Depression and symptoms of ADHD appeared to have the most significant and consistent correlation with PIU. Associations were reported to be higher among males in all age groups. Limitations included heterogeneity in the definition and diagnosis of PIU. More studies with prospective designs in Western countries are critically needed.

Problematic Internet Use, Mental Health and Impulse Control in an Online Survey of Adults

BACKGROUND AND AIMS

Internet use has become a popular entertainment source and has become highly integrated into daily life. However, some people display problematic or addictive usage of the Internet. The present study attempts to fill current knowledge gaps regarding at-risk/problematic Internet use (ARPIU) and its relation to various health and functioning measures.

METHODS

Online survey data from 755 adults in the United States were analyzed using chi-square and ANOVAs.

RESULTS

The ARPIU group did not differ from the non-ARPIU group with respect to substance use. Individuals with ARPIU were, however, more likely to report at-risk/problematic engagement in video-game playing and gambling. Compared to the non-ARPIU group, the ARPIU group reported poorer self-control and higher levels of impulsivity and depression.

CONCLUSIONS

ARPIU appears associated with other risk behaviors, particularly those that might be performed on the Internet. Future studies should examine the extent to which the Internet may promote engagement in these risk behaviors and the extent to which preventative interventions targeting better self-control or negative mood states might help a range of non-substance-related addictive behaviors.

Neuropsychologie der pathologischen Internetnutzung

Zielsetzung: Ziel dieses Übersichtsartikels ist es, aktuelle Forschungsarbeiten zur Neuropsychologie der pathologischen Internetnutzung zusammenzufassen. Methodik: Kriteriengeleitete Literaturauswahl. Ergebnisse: Neuropsychologische Studien berichten, dass Personen mit pathologischer Internetnutzung unvorteilhafte Entscheidungen treffen, da sie kurzfristig belohnende Handlungsalternativen bevorzugen und dabei mögliche längerfristige, negative Konsequenzen, weniger beachten. Auch scheint die Verarbeitung von internetbezogenen Reizen mit kognitiven Funktionen, beispielsweise Arbeitsgedächtnisleistungen, zu interferieren. Bildgebungs- und neuropsychologische Befunde veranschaulichen, dass Cue-Reactivity, Craving und Entscheidungsverhalten wichtige Konzepte für das Verständnis des Phänomens der pathologischen Internetnutzung sind. Schlussfolgerungen: Befunde zu neurokognitiven Funktionen und zu Hirnkorrelaten der Verarbeitung internetbezogener Reize bei Personen mit spezifischer pathologischer Internetnutzung (z. B. von Onlinespielen) sind vergleichbar mit denen zu Personen mit Substanzabhängigkeit oder pathologischem Glücksspiel und sprechen für die Klassifikation einer pathologischen Internetnutzung als Verhaltenssucht.

Prevalence of pathological internet use among adolescents in Europe: demographic and social factors

AIMS

To investigate the prevalence of pathological internet use (PIU) and maladaptive internet use (MIU) among adolescents in 11 European countries in relation to demographic, social factors and internet accessibility.

DESIGN

Cross-sectional survey.

SETTING

The 7th Framework European Union (EU) funded project, Saving and Empowering Young Lives in Europe (SEYLE), is a randomized controlled trial (RCT) evaluating interventions for risk behaviours among adolescents in Austria, Estonia, France, Germany, Hungary, Ireland, Israel, Italy, Romania, Slovenia and Spain, with Sweden serving as the coordinating centre.

PARTICIPANTS

A total of 11 956 adolescents (female/male: 6731/5225; mean age: 14.9 ± 0.89) recruited from randomly selected schools within the 11 study sites.

MEASUREMENTS

Internet users were classified by gender into three categories: adaptive, maladaptive and pathological, based on their score in the Young Diagnostic Questionnaire for Internet Addiction (YDQ).

FINDINGS

The overall prevalence of PIU was 4.4%; it was higher among males than females (5.2% versus 3.8%) and differed between countries (χ(2)  = 309.98; d.f. = 20; P < 0.001). PIU correlated significantly with mean hours online and male gender. The highest-ranked online activities were watching videos, frequenting chatrooms and social networking; significantly higher rates of playing single-user games were found in males and social networking in females. Living in metropolitan areas was associated with PIU. Students not living with a biological parent, low parental involvement and parental unemployment showed the highest relative risks of both MIU and PIU.

CONCLUSIONS

Across a range of countries in Europe, using the Young Diagnostic Questionnaire for Internet Addiction yields a prevalence of 'pathological internet use' of 4.4% among adolescents, but varies by country and gender; adolescents lacking emotional and psychological support are at highest risk.

Compulsive features in behavioural addictions: the case of pathological gambling

AIMS

To describe, in the context of DSM-V, how a focus on addiction and compulsion is emerging in the consideration of pathological gambling (PG).

METHODS

A systematic literature review of evidence for the proposed re-classification of PG as an addiction.

RESULTS

Findings include: (i) phenomenological models of addiction highlighting a motivational shift from impulsivity to compulsivity associated with a protracted withdrawal syndrome and blurring of the ego-syntonic/ego-dystonic dichotomy; (ii) common neurotransmitter (dopamine, serotonin) contributions to PG and substance use disorders (SUDs); (iii) neuroimaging support for shared neurocircuitries between 'behavioural' and substance addictions and differences between obsessive-compulsive disorder (OCD), impulse control disorders (ICDs) and SUDs; (iv) genetic findings more closely related to endophenotypic constructs such as compulsivity and impulsivity than to psychiatric disorders; (v) psychological measures such as harm avoidance identifying a closer association between SUDs and PG than with OCD; (vi) community and pharmacotherapeutic trials data supporting a closer association between SUDs and PG than with OCD. Adapted behavioural therapies, such as exposure therapy, appear applicable to OCD, PG or SUDs, suggesting some commonalities across disorders.

CONCLUSIONS

PG shares more similarities with SUDs than with OCD. Similar to the investigation of impulsivity, studies of compulsivity hold promising insights concerning the course, differential diagnosis and treatment of PG, SUDs, and OCD.

The German version of the internet addiction test: a validation study

Reports about excessive Internet use, possibly amounting to an addiction, have increased. Progress with research and treatment of this phenomenon requires valid standardized assessment instruments. A frequently used questionnaire is the Internet Addiction Test (IAT) by Kimberly Young. The 20-item questionnaire is well established in a number of languages, but a German validation was lacking so far. An online (ON) sample (n=1,041, age 24.2±7.2 years, 46.7 percent men) completed an Internet version of the IAT and a student sample (offline [OF] sample, n=841, age: 23.5±3.0 years, 46.8 percent men) filled in a paper/pencil version. The participants also answered questions regarding their Internet use habits. A further sample of 108 students (21.5±2.0 years, 25.7 percent men) completed the questionnaire twice to determine the 14-day retest reliability. The internal consistencies were α=0.91 (ON) and α=0.89 (OF). Item-whole correlations ranged from r=0.23 to r=0.65 (ON) and from r=0.30 to r=0.64 (OF). Two-week retest reliability was r(tt)=0.83. Factor analyses with Varimax rotation yielded the same two factors in both samples, which explained 46.7 percent (ON) and 42.0 percent (OF) of the variance. The IAT score correlated with the time spent in the Internet in a typical week (ON: r=0.44; OF: r=0.38). The German version of the IAT was shown to have good psychometric properties and a stable two-factorial structure. Correlations with online time were in line with those reported for the IAT in other languages.