Aviv Weinstein

Introduction to Behavioral Addictions

Background: Several behaviors, besides psychoactive substance ingestion, produce short-term reward that may engender persistent behavior, despite knowledge of adverse consequences, i.e., diminished control over the behavior. These disorders have historically been conceptualized in several ways. One view posits these disorders as lying along an impulsive-compulsive spectrum, with some classified as impulse control disorders. An alternate, but not mutually exclusive, conceptualization considers the disorders as non-substance or “behavioral” addictions. Objectives: Inform the discussion on the relationship between psychoactive substance and behavioral addictions. Methods: We review data illustrating similarities and differences between impulse control disorders or behavioral addictions and substance addictions. This topic is particularly relevant to the optimal classification of these disorders in the forthcoming fifth edition of the American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders (DSM-V). Results: Growing evidence suggests that behavioral addictions resemble substance addictions in many domains, including natural history, phenomenology, tolerance, comorbidity, overlapping genetic contribution, neurobiological mechanisms, and response to treatment, supporting the DSM-V Task Force proposed new category of Addiction and Related Disorders encompassing both substance use disorders and non-substance addictions. Current data suggest that this combined category may be appropriate for pathological gambling and a few other better studied behavioral addictions, e.g., Internet addiction. There is currently insufficient data to justify any classification of other proposed behavioral addictions. Conclusions and Scientific Significance: Proper categorization of behavioral addictions or impulse control disorders has substantial implications for the development of improved prevention and treatment strategies.

Internet Addiction or Excessive Internet Use

Background: Problematic Internet addiction or excessive Internet use is characterized by excessive or poorly controlled preoccupations, urges, or behaviors regarding computer use and Internet access that lead to impairment or distress. Currently, there is no recognition of internet addiction within the spectrum of addictive disorders and, therefore, no corresponding diagnosis. It has, however, been proposed for inclusion in the next version of the Diagnostic and Statistical Manual of Mental Disorder (DSM). Objective: To review the literature on Internet addiction over the topics of diagnosis, phenomenology, epidemiology, and treatment. Methods: Review of published literature between 2000–2009 in Medline and PubMed using the term “internet addiction. Results: Surveys in the United States and Europe have indicated prevalence rate between 1.5% and 8.2%, although the diagnostic criteria and assessment questionnaires used for diagnosis vary between countries. Cross-sectional studies on samples of patients report high comorbidity of Internet addiction with psychiatric disorders, especially affective disorders (including depression), anxiety disorders (generalized anxiety disorder, social anxiety disorder), and attention deficit hyperactivity disorder (ADHD). Several factors are predictive of problematic Internet use, including personality traits, parenting and familial factors, alcohol use, and social anxiety. Conclusions and Scientific Significance: Although Internet-addicted individuals have difficulty suppressing their excessive online behaviors in real life, little is known about the patho-physiological and cognitive mechanisms responsible for Internet addiction. Due to the lack of methodologically adequate research, it is currently impossible to recommend any evidence-based treatment of Internet addiction.

New treatments for cocaine dependence: a focused review.

Cocaine, already a significant drug problem in North and South America, has become a more prominent part of the European drug scene. Cocaine dependence has major somatic, psychological, psychiatric, socio-economic, and legal implications. No specific effective pharmacological treatment exists for cocaine dependence. Recent advances in neurobiology have identified various neuronal mechanisms implicated in cocaine addiction and suggested several promising pharmacological approaches. Data were obtained from Medline, EMBASE, and PsycINFO searches of English-language articles published between 1985 and June 2007 using the key words: cocaine, addiction, cocaine dependence, clinical trials, pharmacotherapy(ies) singly and in combination. Large well-controlled studies with appropriate statistical methods were preferred. Pharmacological agents such as GABA agents (topiramate, tiagabine, baclofen and vigabatrin) and agonist replacement agents (modafinil, disulfiram, methylphenidate) seem to be the most promising in treatment of cocaine dependence. The results from trials of first- and second-generation neuroleptics are largely negative. Aripiprazole, a partial dopaminergic agonist that may modulate the serotonergic system, shows some promise. Preliminary results of human studies with anti-cocaine vaccine, N-acetylcysteine, and ondansetron, are promising, as are several compounds in preclinical development. While no medication has received regulatory approval for the treatment of cocaine dependence, several medications marketed for other indications have shown efficacy in clinical trials. An anti-cocaine vaccine and several compounds in preclinical development have also shown promise. Findings from early clinical trials must be confirmed in larger, less selective patient populations.

Pharmacological approaches to methamphetamine dependence: a focused review

Methamphetamine dependence is a serious worldwide public health problem with major medical, psychiatric, socioeconomic and legal consequences. Various neuronal mechanisms implicated in methamphetamine dependence have suggested several pharmacological approaches. A literature search from a range of electronic databases (PubMed, EMBASE, PsycInfo, the NIDA research monograph index and the reference list of clinicaltrials.gov) was conducted for the period from January 1985 to October 2009. There were no restrictions on the identification or inclusion of studies in terms of publication status, language and design type. A variety of medications have failed to show efficacy in clinical trials, including a dopamine partial agonist (aripiprazole), GABAergic agents (gabapentin) and serotonergic agents (SSRI, ondansetron, mirtazapine). Three double-blind placebo-controlled trials using modafinil, bupropion and naltrexone have shown positive results in reducing amphetamine or methamphetamine use. Two studies employing agonist replacement medications, one with d-amphetamine and the other with methylphenidate, have also shown promise. Despite the lack of success in most studies to date, increasing efforts are being made to develop medications for the treatment of methamphetamine dependence and several promising agents are targets of further research.

Computer and Video Game Addiction—A Comparison between Game Users and Non-Game Users

Background: Computer game addiction is excessive or compulsive use of computer and video games that may interfere with daily life. It is not clear whether video game playing meets diagnostic criteria for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV). Objectives: First objective is to review the literature on computer and video game addiction over the topics of diagnosis, phenomenology, epidemiology, and treatment. Second objective is to describe a brain imaging study measuring dopamine release during computer game playing. Methods: Article search of 15 published articles between 2000 and 2009 in Medline and PubMed on computer and video game addiction. Nine abstinent “ecstasy” users and 8 control subjects were scanned at baseline and after performing on a motorbike riding computer game while imaging dopamine release in vivo with [123I] IBZM and single photon emission computed tomography (SPECT). Results: Psycho-physiological mechanisms underlying computer game addiction are mainly stress coping mechanisms, emotional reactions, sensitization, and reward. Computer game playing may lead to long-term changes in the reward circuitry that resemble the effects of substance dependence. The brain imaging study showed that healthy control subjects had reduced dopamine D2 receptor occupancy of 10.5% in the caudate after playing a motorbike riding computer game compared with baseline levels of binding consistent with increased release and binding to its receptors. Ex-chronic “ecstasy” users showed no change in levels of dopamine D2 receptor occupancy after playing this game. Conclusion: This evidence supports the notion that psycho-stimulant users have decreased sensitivity to natural reward. Significance: Computer game addicts or gamblers may show reduced dopamine response to stimuli associated with their addiction presumably due to sensitization.

Visual ERPs evidence for enhanced processing of threatening information in anxious university students

There is accumulating evidence that highly anxious individuals selectively attend to threatening information; however, contrary to expectations, there is no evidence of enhanced processing of threat stimuli in those individuals. We investigated this question by using a sample of 20 University students who were split into two groups consisting of 10 high-anxious and 10 low-anxious subjects according to Spielberger Trait Anxiety Inventory score (median STAI = 40). Without emphasizing speed, subjects were required to decide whether visually presented words (positive, neutral, or threat) matched semantically with previous priming sentences (threat or positive) displayed on a computer screen (altogether, two types of priming sentences and three types of probe words). There was a fixed interval of 1.1 seconds between priming sentences (SI) and probe words (S2) as well as between each priming sentence word. Response time and visual event-related potentials (ERPs) were recorded in both conditions. The results showed that, compared to the Low-Anxious group, the amplitude of N100 and P400 were enhanced for the High-Anxious group in the threat priming conditions. Low-anxious individuals showed almost identical processing of threat-related situations and positive situations. Furthermore, the P400 peak latency was shorter for emotional incongruous probes in high-anxious individuals. ERPs results of the experiment suggest that highly anxious individuals deploy more processing resources to threatening information. This bias in information processing occurs in the absence of any behavioral changes (indicated by reaction times). Attentional bias in anxiety therefore implies that threatening information is given a priority over other information and is more persistently activated in anxiety states.

Cognitive processing of drug-related stimuli: the role of memory and attention.

Recent studies have investigated the role of attentional biases and memory in alcohol and other drugs of dependence and the relationship between the motivation to use alcohol or other drugs and vigilance for relevant stimuli in alcohol and drug dependence. Based on this research, we describe relationships among motivation, memory, and attentional biases in order to enable better understanding of their multiple and interacting roles in the maintenance and development of alcohol and other drug dependence. We argue that memory and attentional processes are critical in the development and maintenance of addiction processes. Furthermore, we assume that attentional bias is not simply a by-product of an addiction disorder but plays a vital role in its development and maintenance, and it serves to enhance actual drug use. Finally, we predict that the motivation to use alcohol or other drugs will increase vigilance for substance-related stimuli, which in turn can lead to actual use. Future research is needed to ll gaps in our knowledge and lead to a more dened and articulated cognitive-behavioural model of drug dependence.

Pharmacological treatment of cannabis dependence.

Cannabis is the most frequently used illegal psychoactive substance in the world. There is a significant increase in the number of treatment admissions for cannabis use disorders in the past few years, and the majority of cannabis-dependent individuals who enter treatment have difficulty in achieving and maintaining abstinence. Thus, there is increased need for medications that can be used to treat this population. So far, no medication has been shown broadly and consistently effective; none has been approved by any national regulatory authority. Medications studied have included those that alleviate symptoms of cannabis withdrawal (e.g., dysphoric mood, irritability),those that directly affect endogenous cannabinoid receptor function, and those that have shown efficacy in treatment of other drugs of abuse or psychiatric conditions. Buspirone is the only medication to date that has shown efficacy for cannabis dependence in a controlled clinical trial. Results from controlled human laboratory studies and small open-label clinical trials suggest that dronabinol, the COMT inhibitor entacapone, and lithium may warrant further study. Recent pre-clinical studies suggest the potential of fatty acid amide hydrolase (FAAH) inhibitors such as URB597, endocannabinoid-metabolizing enzymes, and nicotinic alpha 7 receptor antagonists such as methyllycaconitine (MLA).Controlled clinical trials are needed to evaluate the clinical efficacy of these medications and to validate the laboratory models being used to study candidate medications.

New developments in brain research of internet and gaming disorder

There is evidence that the neural mechanisms underlying Internet Gaming Disorder (IGD) resemble those of drug addiction. Functional Magnetic Resonance Imaging (fMRI) studies of the resting state and measures of gray matter volume have shown that Internet game playing was associated with changes to brain regions responsible for attention and control, impulse control, motor function, emotional regulation, sensory-motor coordination. Furthermore, Internet game playing was associated with lower white matter density in brain regions that are involved in decision-making, behavioral inhibition and emotional regulation. Videogame playing involved changes in reward inhibitory mechanisms and loss of control. Structural brain imaging studies showed alterations in the volume of the ventral striatum that is an important part of the brains reward mechanisms. Finally, videogame playing was associated with dopamine release similar in magnitude to those of drugs of abuse and lower dopamine transporter and dopamine receptor D2 occupancy indicating sub-sensitivity of dopamine reward mechanisms.

Imagery of craving in opiate addicts undergoing detoxification

Craving is a significant factor in opiate addiction that is associated with drug-dependence and in relapse to drug use after treatment. In order to better understand the psychological and physiological mechanisms of craving for opiates, we have developed an imagery-based procedure using personal verbal descriptions of craving in abstinent opiate addicts. Thirteen opiate addicts in detoxification were required to imagine and describe their craving experiences while autonomic measures of heart rate and arterial pressure were taken. Subjects displayed a significant increase in systolic blood pressure and heart rate while describing drug craving compared with neutral descriptions. Furthermore, an increase in systolic blood pressure during imagery of craving descriptions compared with neutral descriptions was observed. These results provide preliminary evidence that imagery is powerful in eliciting craving for opiates, as indicated by subjective ratings and autonomic measures. The implications of the results of this paper for the cue-exposure paradigm and contemporary models of addiction are being discussed.