Reactivity to cannabis cues in virtual reality environments

Attentional Bias, Pupillometry, and Spontaneous Blink Rate: Eye Characteristic Assessment Within a Translatable Nicotine Cue Virtual Reality Paradigm

Background

Incentive salience processes are important for the development and maintenance of addiction. Eye characteristics such as gaze fixation time, pupil diameter, and spontaneous eyeblink rate (EBR) are theorized to reflect incentive salience and may serve as useful biomarkers. However, conventional cue exposure paradigms have limitations that may impede accurate assessment of these markers.

Objective

This study sought to evaluate the validity of these eye-tracking metrics as indicators of incentive salience within a virtual reality (VR) environment replicating real-world situations of nicotine and tobacco product (NTP) use.

Methods

NTP users from the community were recruited and grouped by NTP use patterns: nondaily (n=33) and daily (n=75) use. Participants underwent the NTP cue VR paradigm and completed measures of nicotine craving, NTP use history, and VR-related assessments. Eye-gaze fixation time (attentional bias) and pupillometry in response to NTP versus control cues and EBR during the active and neutral VR scenes were recorded and analyzed using ANOVA and analysis of covariance models.

Results

Greater subjective craving, as measured by the Tobacco Craving Questionnaire-Short Form, following active versus neutral scenes was observed (F1,106=47.95; P<.001). Greater mean eye-gaze fixation time (F1,106=48.34; P<.001) and pupil diameter (F1,102=5.99; P=.02) in response to NTP versus control cues were also detected. Evidence of NTP use group effects was observed in fixation time and pupillometry analyses, as well as correlations between these metrics, NTP use history, and nicotine craving. No significant associations were observed with EBR.

Conclusions

This study provides additional evidence for attentional bias, as measured via eye-gaze fixation time, and pupillometry as useful biomarkers of incentive salience, and partially supports theories suggesting that incentive salience diminishes as nicotine dependence severity increases.

VR for Studying the Neuroscience of Emotional Responses

Emotions are frequently considered as the driving force of behavior, and psychopathology is often characterized by aberrant emotional responding. Emotional states are reflected on a cognitive-verbal, physiological-humoral, and motor-behavioral level but to date, human research lacks an experimental protocol for a comprehensive and ecologically valid characterization of such emotional states. Virtual reality (VR) might help to overcome this situation by allowing researchers to study mental processes and behavior in highly controlled but reality-like laboratory settings. In this chapter, we first elucidate the role of presence and immersion as requirements for eliciting emotional states in a virtual environment and discuss different VR methods for emotion induction. We then consider the organization of emotional states on a valence continuum (i.e., from negative to positive) and on this basis discuss the use of VR to study threat processing and avoidance as well as reward processing and approach behavior. Although the potential of VR has not been fully realized in laboratory and clinical settings yet, this technological tool can open up new avenues to better understand the neurobiological mechanisms of emotional responding in healthy and pathological conditions.

The relationship between sleep and appetitive conditioning: A systematic review and meta-analysis

This systematic review and meta-analysis (PROSPERO registration animal/human studies: CRD42021234793/CRD42021234790) examined the relationship between sleep and appetitive conditioning. Inclusion criteria included: a) appetitive conditioning paradigm; b) measure of conditioning; c) sleep measurement and/or sleep loss; d) human and/etor non-human animal samples; and e) written in English. Searches of seven databases returned 3777 publications. The final sample consisted of 42 studies using primarily animal samples and involving food- and drug-related conditioning tasks. We found sleep loss disrupted appetitive conditioning of food rewards (p < 0.001) but potentiated appetitive conditioning of drug rewards (p < 0.001). Furthermore, sleep loss negatively impacted extinction learning irrespective of the reward type. Post-learning sleep was associated with increases in REM sleep (p = 0.02). Findings suggest sleep loss potentiates the impact of psychoactive substances in a manner likely to produce an increased risk of problematic substance use. In obese/overweight populations, sleep loss may be associated with deficits in the conditioning and extinction of reward-related behaviours. Further research should assess the relationship between sleep and appetitive conditioning in humans.

Virtual reality in the diagnostic and therapy for mental disorders: A systematic review

BACKGROUND

Virtual reality (VR) technologies are playing an increasingly important role in the diagnostics and treatment of mental disorders.

OBJECTIVE

To systematically review the current evidence regarding the use of VR in the diagnostics and treatment of mental disorders.

DATA SOURCE

Systematic literature searches via PubMed (last literature update: 9^th of May 2022) were conducted for the following areas of psychopathology: Specific phobias, panic disorder and agoraphobia, social anxiety disorder, generalized anxiety disorder, posttraumatic stress disorder (PTSD), obsessive-compulsive disorder, eating disorders, dementia disorders, attention-deficit/hyperactivity disorder, depression, autism spectrum disorder, schizophrenia spectrum disorders, and addiction disorders.

ELIGIBILITY CRITERIA

To be eligible, studies had to be published in English, to be peer-reviewed, to report original research data, to be VR-related, and to deal with one of the above-mentioned areas of psychopathology.

STUDY EVALUATION

For each study included, various study characteristics (including interventions and conditions, comparators, major outcomes and study designs) were retrieved and a risk of bias score was calculated based on predefined study quality criteria.

RESULTS

Across all areas of psychopathology, k = 9315 studies were inspected, of which k = 721 studies met the eligibility criteria. From these studies, 43.97% were considered assessment-related, 55.48% therapy-related, and 0.55% were mixed. The highest research activity was found for VR exposure therapy in anxiety disorders, PTSD and addiction disorders, where the most convincing evidence was found, as well as for cognitive trainings in dementia and social skill trainings in autism spectrum disorder.

CONCLUSION

While VR exposure therapy will likely find its way successively into regular patient care, there are also many other promising approaches, but most are not yet mature enough for clinical application.

REVIEW REGISTRATION

PROSPERO register CRD42020188436.

FUNDING

The review was funded by budgets from the University of Bonn. No third party funding was involved.

Impaired Brain-Heart Relation in Patients With Methamphetamine Use Disorder During VR Induction of Drug Cue Reactivity

Methamphetamine use disorder (MUD) is an illness associated with severe health consequences. Virtual reality (VR) is used to induce the drug-cue reactivity and significant EEG and ECG abnormalities were found in MUD patients. However, whether a link exists between EEG and ECG abnormalities in patients with MUD during exposure to drug cues remains unknown. This is important from the therapeutic viewpoint because different treatment strategies may be applied when EEG abnormalities and ECG irregularities are complications of MUD. We designed a VR system with drug cues and EEG and ECG were recorded during VR exposure. Sixteen patients with MUD and sixteen healthy subjects were recruited. Statistical tests and Pearson correlation were employed to analyze the EEG and ECG. The results showed that, during VR induction, the patients with MUD but not healthy controls showed significant [Formula: see text] and [Formula: see text] power increases when the stimulus materials were most intense. This finding indicated that the stimuli are indiscriminate to healthy controls but meaningful to patients with MUD. Five heart rate variability (HRV) indexes significantly differed between patients and controls, suggesting abnormalities in the reaction of patient's autonomic nervous system. Importantly, significant relations between EEG and HRV indexes changes were only identified in the controls, but not in MUD patients, signifying a disruption of brain-heart relations in patients. Our findings of stimulus-specific EEG changes and the impaired brain-heart relations in patients with MUD shed light on the understanding of drug-cue reactivity and may be used to design diagnostic and/or therapeutic strategies for MUD.

Neuronal Abnormalities Induced by an Intelligent Virtual Reality System for Methamphetamine Use Disorder

Methamphetamine use disorder (MUD) is a brain disease that leads to altered regional neuronal activity. Virtual reality (VR) is used to induce the drug cue reactivity. Previous studies reported significant frequency-specific abnormalities in patients with MUD during VR induction of drug craving. However, whether those patients exhibit neuronal abnormalities after VR induction that could serve as the treatment target remains unclear. Here, we developed an integrated VR system for inducing drug related changes and investigated the neuronal abnormalities after VR exposure in patients. Fifteen patients with MUD and ten healthy subjects were recruited and exposed to drug-related VR environments. Resting-state EEG were recorded for 5 minutes twice-before and after VR and transformed to obtain the frequency-specific data. Three self-reported scales for measurement of the anxiety levels and impulsivity of participants were obtained after VR task. Statistical tests and machine learning methods were employed to reveal the differences between patients and healthy subjects. The result showed that patients with MUD and healthy subjects significantly differed in, and power changes after VR. These neuronal abnormalities in patients were associated with the self-reported behavioral scales, indicating impaired impulse control. Our findings of resting-state EEG abnormalities in patients with MUD after VR exposure have the translation value and can be used to develop the treatment strategies for methamphetamine use disorder.

Using Virtual Reality to Induce and Assess Objective Correlates of Nicotine Craving: Paradigm Development Study

BACKGROUND

Craving is a clinically important phenotype for the development and maintenance of nicotine addiction. Virtual reality (VR) paradigms are successful in eliciting cue-induced subjective craving and may even elicit stronger craving than traditional picture-cue methods. However, few studies have leveraged the advances of this technology to improve the assessment of craving.

OBJECTIVE

This report details the development of a novel, translatable VR paradigm designed to both elicit nicotine craving and assess multiple eye-related characteristics as potential objective correlates of craving.

METHODS

A VR paradigm was developed, which includes three Active scenes with nicotine and tobacco product (NTP) cues present, and three Neutral scenes devoid of NTP cues. A pilot sample (N=31) of NTP users underwent the paradigm and completed subjective measures of nicotine craving, sense of presence in the VR paradigm, and VR-related sickness. Eye-gaze fixation time ("attentional bias") and pupil diameter toward Active versus Neutral cues, as well as spontaneous blink rate during the Active and Neutral scenes, were recorded.

RESULTS

The NTP Cue VR paradigm was found to elicit a moderate sense of presence (mean Igroup Presence Questionnaire score 60.05, SD 9.66) and low VR-related sickness (mean Virtual Reality Sickness Questionnaire score 16.25, SD 13.94). Scene-specific effects on attentional bias and pupil diameter were observed, with two of the three Active scenes eliciting greater NTP versus control cue attentional bias and pupil diameter (Cohen d=0.30-0.92). The spontaneous blink rate metrics did not differ across Active and Neutral scenes.

CONCLUSIONS

This report outlines the development of the NTP Cue VR paradigm. Our results support the potential of this paradigm as an effective laboratory-based cue-exposure task and provide early evidence of the utility of attentional bias and pupillometry, as measured during VR, as useful markers for nicotine addiction.

Virtual reality: a powerful technology to provide novel insight into treatment mechanisms of addiction

Due to its high ecological validity, virtual reality (VR) technology has emerged as a powerful tool for mental health research. Despite the wide use of VR simulations in research on mental illnesses, the study of addictive processes through the use of VR environments is still at its dawn. In a systematic literature search, we identified 38 reports of research projects using highly immersive head-mounted displays, goggles, or CAVE technologies to provide insight into treatment mechanisms of addictive behaviors. So far, VR research has mainly addressed the roles of craving, psychophysiology, affective states, cognition, and brain activity in addiction. The computer-generated VR environments offer very realistic, dynamic, interactive, and complex real-life simulations requesting active participation. They create a high sense of immersion in users by combining stereoscopic three-dimensional visual, auditory, olfactory, and tactile perceptions, tracking systems responding to user movements, and social interactions. VR is an emerging tool to study how proximal multi-sensorial cues, contextual environmental cues, as well as their interaction (complex cues) modulate addictive behaviors. VR allows for experimental designs under highly standardized, strictly controlled, predictable, and repeatable conditions. Moreover, VR simulations can be personalized. They are currently refined for psychotherapeutic interventions. Embodiment, eye-tracking, and neurobiological factors represent novel future directions. The progress of VR applications has bred auspicious ways to advance the understanding of treatment mechanisms underlying addictions, which researchers have only recently begun to exploit. VR methods promise to yield significant achievements to the addiction field. These are necessary to develop more efficacious and efficient preventive and therapeutic strategies.

Provider experiences of virtual reality in clinical treatment

Background

Virtual reality (VR) has proven effective in the treatment of specific phobias and trauma particularly when in-vivo exposure therapy might be costly (e.g. fear of flying, combat scenes). Similarly, VR has been associated with improvement of chronic pain and of acute pain during medical procedures. Despite its effectiveness as a healthcare tool, VR technology is not well-integrated into common practice. This qualitative study aims to explore the provider perception of the value of VR and identify barriers to VR implementation among healthcare providers.

Methods

A 66-item self-report survey was created to examine application of VR to clinical practice, perceived value of this treatment, ease of learning the technology, billing considerations, and other obstacles. 128 providers (MDs and PhDs) who were located in the United States and had used VR as a therapeutic tool in the past year were identified through research papers, as well as user lists and news articles from VR application websites. Of the 128 providers contacted, 17% (22) completed our online self-report measure. Of these, 13% of respondents (N = 17) completed greater than 75% of the questionnaire and were considered completers. Provider responses were collected over a one-month period and qualitatively analyzed.

Results

The majority of providers were from an academic institution (n = 12, 70.6%), and all providers practiced in the outpatient setting. Providers most commonly reported using VR for the treatment of acute pain and/or anxiety related to medical procedures (n = 11, 64.7%), followed by specific phobia (n = 6, 35.3%) and social phobia (n = 6, 35.3%). All providers agreed VR is a valuable tool they would recommend to colleagues. The majority (n = 15, 93.8%) believed VR helped their patients progress in treatment, compared with other methods. Providers cited the ability to individualize treatment (n = 14, 87.5%) and increase patient engagement (n = 15, 93.8%) as main benefits of VR. A minority reported negative feedback from patients about content (n = 4, 25%) or about the technology in general (n = 6, 37.5%), whereas all reported some form of positive feedback. The slight majority (n = 10, 58.8%) of providers did not find transitioning to VR difficult. Of those who did, cost was the most commonly cited barrier (n = 6). Regarding reimbursement, only 17.6% (n = 3) of providers reported the ability to bill for VR sessions. Most providers (n = 15, 88.2%) received training on their VR platform which they found beneficial. Comparing the trained and untrained groups found no significant difference in VR comfort level (p = 0.5058), the value of VR in practice (p = 0.551) or whether providers would recommend VR to others (p = 0.551), though sample sizes were small.

Conclusions

In corroboration with previous research, this study demonstrates that VR is well-received by patients and providers, allowing increased patient engagement and treatment individualization. However, associated costs, including an inability to bill for this service, can present a barrier to further implementation. These findings will guide further development of virtual reality as a standardized tool in psychiatry and pain management.

Virtual Reality-Based Treatment Approaches in the Field of Substance Use Disorders

Purpose

Substance use disorders (SUD) are burdening chronic conditions characterized by high relapse rates despite severe negative consequences. Substance-related cues that elicit craving by means of automatic physiological and behavioural responses have long been suggested to predict relapse. One major mechanism contributing to relapse behaviour are cue-induced behavioural approach tendencies towards the addictive agent. Recently, there has been an emerging interest in virtual reality (VR)-based approaches to assess and modify craving and its related responses. This review aims at elucidating (1) VR techniques applied in the field of SUD, (2) VR as an induction/assessment tool for biopsychological correlates of craving and (3) VR-based therapeutic approaches.

Findings

There is an emerging number of studies focusing on different substances of abuse incorporating VR in craving induction/assessment as well as therapy. Despite some limitations as missing of randomized controlled clinical trials with large samples and missing data on the long-term effects of VR treatment, the VR approach showed consistent results in eliciting and reducing craving across different substances.

Summary

This review suggests virtual reality as a promising tool for the assessment and treatment of craving among individuals with substance use disorders. Because of its ecological validity, VR unifies the benefits of a laboratory setting with the advantages of a realistic environment. Further studies with large samples and randomized controlled clinical trials using more homogenous VR techniques as well as assessment of objective biophysiological craving markers are required.

Virtual Reality (VR) Applications in Cardiology: A Review

Virtual reality (VR) has applications in cardiology to create enhancement, thereby improving the quality of associated planning, treatment and surgery. The need is to study different applications of this technology in the field of cardiology. We have studied research papers on VR and its applications in cardiology through a detailed bibliometric analysis. The study identified five significant steps for proper implementation of this technology in cardiology. Some challenges are to be undertaken by using this technology, and they can provide some benefits; thus, authors contemplate extensive research and development. This study also identifies 10 major VR technology applications in cardiology and provided a brief description. This innovative technology helps a heart surgeon to perform complex heart surgery effectively. Thus, VR applications have the potential for improving decision-making, which helps save human life. VR plays a significant role in the development of a surgical procedure. This technology undertakes 3D heart model information in full colour, which helps to analyze the overall heart vane, blockage and blood flow. With the help of this digital technology, a surgeon can improve the accuracy of heart surgery, and he can simulate the surgery. A surgeon can undertake surgery in a virtual environment on a virtual patient. The unique purpose of this technology is to practice pre-operatively on the specific circumstance. A cardiologist can also check the proper status of inner and outer heart wall layer. Thus, by using this 3D information, the surgeon can now interact with heart data/information without any physical touch. This technology opens a new opportunity to improve the heart surgery and development in cardiovascular treatment to improve patient outcome.

FMRI activation to cannabis odor cues is altered in individuals at risk for a cannabis use disorder

INTRODUCTION

The smell of cannabis is a cue with universal relevance to cannabis users. However, most cue reactivity imaging studies have solely utilized visual images, auditory imagery scripts, or tactile cues in their experiments. This study introduces a multimodal cue reactivity paradigm that includes picture, odor, and bimodal picture + odor cues.

METHODS

Twenty-eight adults at risk for cannabis use disorder (CUD; defined as at least weekly use and Substance Involvement Score of ≥4 on the Cannabis sub-test of the Alcohol, Smoking and Substance Involvement Screening Test) and 26 cannabis-naive controls were exposed to cannabis and floral cues during event-related fMRI. Between-group differences in fMRI activation and correlations were tested using FMRIB's Local Analyses of Mixed Effects and corrected for multiple comparisons using a voxelwise threshold of z > 2.3 and a corrected cluster threshold of p < .05.

RESULTS

Both visual and olfactory modalities resulted in significant activation of craving and reward systems, with cannabis odor cues eliciting a significantly greater response in regions mediating anticipation and reward (nucleus accumbens, pallidum, putamen, and anterior insular cortex, supplementary motor area, angular gyrus and superior frontal gyrus) and cannabis picture cues eliciting a significantly greater response in the occipital cortex and amygdala. Furthermore, the CUD group showed significantly increased activation in the ventral tegmental area (VTA), the insula, and the pallidum compared to controls. Within the CUD group, activation in the insula, anterior cingulate, and occipital cortex to bimodal cannabis cues was significantly correlated with self-reported craving.

CONCLUSION

Our multimodal cue reactivity paradigm is sensitive to neural adaptations associated with problematic cannabis use.

Virtual Reality (VR) in Assessment and Treatment of Addictive Disorders: A Systematic Review

Background: Substance Use Disorder (SUD) and behavioral addictions are common and require a multidisciplinary approach. New technologies like Virtual Reality could have the potential to improve assessment and treatment of these disorders.

Objective: In the present paper, we therefore present an overview of Virtual Reality (Head Mounted Devices) in the field of addiction medicine for craving assessment and treatment.

Method: We conducted a systematic review by querying PubMed database for the titles of articles published up to March 2019 with the terms [virtual] AND [addictive] OR [addiction] OR [substance] OR [alcohol] OR [cocaine] OR [cannabis] OR [opioid] OR [tobacco] OR [nicotine] OR [methamphetamine] OR [gaming] OR [gambling].

Results: We screened 319 abstracts and analyzed 37 articles, dividing them into two categories, the first for assessment of cue reactivity (craving, psychophysiological response and attention to cue) and the second for intervention, each drug (nicotine, cocaine, alcohol, cannabis, gambling) being detailed within each category.

Conclusions: This overview suggest that VR provide benefits in the assessment and treatment of substance use disorders and behavior addictions and achieve high levels of ecological validity. While, craving provocation in VR is effective across addiction disorders, treatments based exclusively on virtual exposure to drug related cues as shown heterogenous results.

Investigating a novel fMRI cannabis cue reactivity task in youth

OBJECTIVE

Adult and adolescent studies suggest increased motivational responses to cannabis cues among regular cannabis users. However, functional magnetic resonance imaging (fMRI) studies have not explored neural activation in response to visual cannabis cues among adolescents in the United States. Gaining a better understanding of the neural circuits related to cue-elicited craving during adolescence may shed light on the neural basis for the development of problematic cannabis use that could ultimately be targeted for interventions.

METHODS

41 non-treatment-seeking youth (ages 17-21; mean age = 18.83; 46.3% female) who reported regular cannabis use underwent fMRI scanning involving a visual cannabis cue task and completed self-report and biological measures. Whole-brain activation was examined for cannabis cues compared to non-cannabis cues, and for active versus passive cannabis cues. Associations between self-reported substance use and task activation were examined.

RESULTS

Cannabis images were identifiable to adolescents and were rated as more rewarding than matched non-cannabis images (p < .05). Greater activation was found for the cannabis cues compared to non-cannabis cues in bilateral posterior cingulate, cuneus, fusiform, precuneus, inferior temporal and parahippocampal gyri, as well as left thalamus, medial frontal and superior frontal gyri. Cue-elicited activation was not significantly associated with self-reported cannabis use (ps > 0.05). No differences were observed for the active versus passive cue contrast.

CONCLUSIONS

Cannabis-using youth show more activation to cannabis cues than non-cannabis cues in brain regions underlying incentive salience, reward, and visual attention. This task could be useful for future studies examining neural underpinnings of reward processes in adolescent cannabis users.

Detection of patients with methamphetamine dependence with cue-elicited heart rate variability in a virtual social environment

In the present study, we developed a methamphetamine (METH)-related virtual social environment to elicit subjective craving and physiological reactivity. Sixty-one male patients who were abstinent from METH use and 45 age-matched healthy males (i.e., normal controls) were recruited. The physiological electrocardiogram (ECG) signals were recorded before (resting-state condition) and during viewing of a METH-cue video in the virtual environment (cue-induced condition). The cue-induced subjective craving was measured with a visual analogue scale (VAS) for patients with METH dependence. The results indicated that the cue-induced condition elicited significant differences in heart rate variability (HRV) between patients with METH dependence and normal controls. The changes of HRV indexes on time domain and non-linear domain from the resting-state condition to the cue-induced condition were positively correlated with the score on VAS of METH craving. Using a supervised machine learning algorithm with the features extracted from HRV changes, our results showed that the discriminant model provided a high predictive power for distinguishing patients with METH dependence from normal controls. Our findings support that immersing subjects with METH dependence in a METH-related virtual social environment can successfully induce physiological reactivity, and cue-induced physiological signal changes may have a potential implication in clinical practice.

Computer tool to evaluate the cue reactivity of chemically dependent individuals

BACKGROUND AND OBJECTIVE

Anxiety is one of the major influences on the dropout of relapse and treatment of substance abuse treatment. Chemically dependent individuals need (CDI) to be aware of their emotional state in situations of risk during their treatment. Many patients do not agree with the diagnosis of the therapist when considering them vulnerable to environmental stimuli related to drugs. This research presents a cue reactivity detection tool based on a device acquiring physiological signals connected to personal computer. Depending on the variations of the emotional state of the drug addict, alteration of the physiological signals will be detected by the computer tool (CT) which will modify the displayed virtual sets without intervention of the therapist.

METHODS

Developed in 3ds Max® software, the CT is composed of scenarios and objects that are in the habit of marijuana and cocaine dependent individual's daily life. The interaction with the environment is accomplished using a Human-Computer Interface (HCI) that converts incoming physiological signals indicating anxiety state into commands that change the scenes. Anxiety was characterized by the average variability from cardiac and respiratory rate of 30 volunteers submitted stress environment situations. To evaluate the effectiveness of cue reactivity a total of 50 volunteers who were marijuana, cocaine or both dependent were accompanied.

RESULTS

Prior to CT, the results demonstrated a poor correlation between the therapists' predictions and those of the chemically dependent individuals. After exposure to the CT, there was a significant increase of 73% in awareness of the risks of relapse.

CONCLUSION

We confirmed the hypothesis that the CT, controlled only by physiological signals, increases the perception of vulnerability to risk situations of individuals with dependence on marijuana, cocaine or both.

Virtual Reality Objectifies the Diagnosis of Psychiatric Disorders: A Literature Review

BACKGROUND

To date, a diagnosis in psychiatry is largely based on a clinical interview and questionnaires. The retrospective and subjective nature of these methods leads to recall and interviewer biases. Therefore, there is a clear need for more objective and standardized assessment methods to support the diagnostic process. The introduction of virtual reality (VR) creates the possibility to simultaneously provoke and measure psychiatric symptoms. Therefore, VR could contribute to the objectivity and reliability in the assessment of psychiatric disorders.

OBJECTIVE

In this literature review, we will evaluate the assessment of psychiatric disorders by means of VR environments. First, we investigate if these VR environments are capable of simultaneously provoking and measuring psychiatric symptoms. Next, we compare these measures with traditional diagnostic measures.

METHODS

We performed a systematic search using PubMed, Embase, and Psycinfo; references of selected articles were checked for eligibility. We identified studies from 1990 to 2016 on VR used in the assessment of psychiatric disorders. Studies were excluded if VR was used for therapeutic purposes, if a different technique was used, or in case of limitation to a non-clinical sample.

RESULTS

A total of 39 studies were included for further analysis. The disorders most frequently studied included schizophrenia (n = 15), developmental disorders (n = 12), eating disorders (n = 3), and anxiety disorders (n = 6). In attention-deficit hyperactivity disorder, the most comprehensive measurement was used including several key symptoms of the disorder. Most of the studies, however, concerned the use of VR to assess a single aspect of a psychiatric disorder.

DISCUSSION

In general, nearly all VR environments studied were able to simultaneously provoke and measure psychiatric symptoms. Furthermore, in 14 studies, significant correlations were found between VR measures and traditional diagnostic measures. Relatively small clinical sample sizes were used, impeding definite conclusions. Based on this review, the innovative technique of VR shows potential to contribute to objectivity and reliability in the psychiatric diagnostic process.

Craving cannabis: a meta-analysis of self-report and psychophysiological cue-reactivity studies

AIMS

To estimate the magnitude of cannabis cue-reactivity responses in people who regularly use cannabis.

METHODS

EMBASE, PUBMED, PsycINFO, PsycEXTRA and Project CORK were searched for within-subject comparison studies published between January 2000 and December 2014. Eligible studies compared regular cannabis users' subjective craving or psychophysiological responding when exposed to cannabis cues to their responses to neutral cues and/or to their responses during a baseline assessment. Eligible studies presented original data and were written in English. Fourteen studies met inclusion criteria, but data were not available for two. The 12 included studies contained 393 participants (12-97 participants per study; mean age range: 16.4-32.6 years). Standardized effects sizes were computed for heart rate, skin conductance, skin temperature, blood pressure, event-related potentials (Pz P300) and self-reported craving (Visual Analogue Scales and Marijuana Craving Questionnaire) and synthesized using a multivariate meta-regression model.

RESULTS

On average, cannabis users experienced moderate cue-reactivity, as determined by comparisons with baseline conditions [d = 0.59, 95% confidence interval (CI) = 0.43, 0.74, P < 0.001] and with neutral cue comparisons (d = 0.47, 95% CI = 0.32, 0.62, P < 0.001). This model, which excluded studies at a greater than low risk of bias and included PzP300 studies as a moderator (due to having larger effect sizes), had a moderately low level of heterogeneity of effect size (I²  = 45.6%, Q = 56.97, P = 0.003) and showed no evidence of publication bias. Cue-reactivity was most noticeable (large effect size) when assessed by Pz P300 waves (d = 1.71, 95% CI = 0.77, 2.64, P = 0.0003; I²  = 86%, Q = 36.30, P < 0.001) and least noticeable (trivial effect size) when examining heart rate (d = 0.14, 95% CI = -0.34, 0.62, P = 0.58; I²  = 80%, Q = 20.0, P < 0.001). These subgroup models demonstrated high heterogeneity of effect size.

CONCLUSIONS

Regular cannabis users experience moderate to extremely intense cue-reactivity, such that their attentional biases towards cannabis cues are much stronger than their perceptions of craving for the drug.

Cue-elicited increases in incentive salience for marijuana: Craving, demand, and attentional bias

BACKGROUND

Incentive salience is a multidimensional construct that includes craving, drug value relative to other reinforcers, and implicit motivation such as attentional bias to drug cues. Laboratory cue reactivity (CR) paradigms have been used to evaluate marijuana incentive salience with measures of craving, but not with behavioral economic measures of marijuana demand or implicit attentional processing tasks.

METHODS

This within-subjects study used a new CR paradigm to examine multiple dimensions of marijuana's incentive salience and to compare CR-induced increases in craving and demand. Frequent marijuana users (N=93, 34% female) underwent exposure to neutral cues then to lit marijuana cigarettes. Craving, marijuana demand via a marijuana purchase task, and heart rate were assessed after each cue set. A modified Stroop task with cannabis and control words was completed after the marijuana cues as a measure of attentional bias.

RESULTS

Relative to neutral cues, marijuana cues significantly increased subjective craving and demand indices of intensity (i.e., drug consumed at $0) and Omax (i.e., peak drug expenditure). Elasticity significantly decreased following marijuana cues, reflecting sustained purchase despite price increases. Craving was correlated with demand indices (r's: 0.23-0.30). Marijuana users displayed significant attentional bias for cannabis-related words after marijuana cues. Cue-elicited increases in intensity were associated with greater attentional bias for marijuana words.

CONCLUSIONS

Greater incentive salience indexed by subjective, behavioral economic, and implicit measures was observed after marijuana versus neutral cues, supporting multidimensional assessment. The study highlights the utility of a behavioral economic approach in detecting cue-elicited changes in marijuana incentive salience.

Cue-induced craving to paraphernalia and drug images in opioid dependence

BACKGROUND AND OBJECTIVES

Stimuli that are repeatedly paired with substance use, such as drug paraphernalia, can themselves elicit drug craving. The aim of this study was to examine whether particular cue types elicit greater craving responses than others among individuals with opioid dependence.

METHODS

Participants seeking inpatient treatment for opioid dependence were recruited for a study of cue-induced craving. This sample (N = 50), included 25 primary heroin users, 20 primary prescription opioid users, and 5 users of heroin and prescription opioids equally. Participants completed a cue reactivity task, in which images of drug-related stimuli were presented on a computer screen, each followed by a question assessing state drug craving.

RESULTS

Overall, participants reported higher craving following paraphernalia stimuli relative to drug stimuli. However, this was moderated by opioid type; there was significantly higher craving in response to images of paraphernalia cues in the heroin group, and higher craving in response to drug cues in the prescription opioid group.

DISCUSSION AND CONCLUSIONS

These findings highlight potential differences in cue reactivity to opioid paraphernalia and drug cues, which appears to be moderated by drug type.

SCIENTIFIC SIGNIFICANCE

Cue-induced craving is an important factor in relapse. This study adds further to the literature on cue-induced craving in opioid dependence, suggesting that craving may vary based on both cue type and opioid type. Future studies designed to discriminate the impact of substance of abuse, route of administration, and cue type will help to further clarify cue-induced craving in this population.

The Use of Virtual Reality in the Production of Cue-Specific Craving for Cigarettes: A Meta-Analysis

INTRODUCTION

The cue-reactivity procedure has demonstrated that smokers respond with increases in subjective craving in the presence of smoking-related cues. Virtual reality is an emerging mode of cue presentation for cue-reactivity research. Despite the successful implementation of virtual reality during the last decade, no systematic review has investigated the magnitude of effects across studies.

METHODS

This research systematically reviewed findings from studies using virtual reality in cigarette craving assessment. Eligible studies assessed subjective craving for cigarettes in smokers exposed to smoking-related and neutral environments. Cohen's d was used to assess differences in craving between smoking-related and nonsmoking-related virtual environments. A random effects approach was used to combine effect sizes.

RESULTS

A total of 18 studies involving 541 smokers was included in the final analyses. Environments with smoking-related cues produced significant increases in craving relative to environments without smoking-related cues. The mean overall effect size (Cohen's d) was 1.041 (SE = 0.12, 95% CI = 0.81 to 1.28, Z = 8.68, P < .001).

CONCLUSIONS

The meta-analysis suggested that presentations of smoking cues through virtual reality can produce strong increases in craving among cigarette smokers. This strong cue-reactivity effect, which was comparable in magnitude to the craving effect sizes found with more conventional modes of cue presentation, supports the use of virtual reality for the generation of robust cue-specific craving in cue-reactivity research.

Effect of oral THC pretreatment on marijuana cue-induced responses in cannabis dependent volunteers

BACKGROUND

The current study tested whether oral Δ(9)-tetrahydrocannabinol (THC: 0-, 10-, and 20-mg) pretreatment would attenuate polysensory cue-induced craving for marijuana.

METHODS

Cannabis dependent participants (7 males and 7 females, who smoked on average 5.4 ± 1.1 blunts daily) completed 3 experimental sessions (oral THC pretreatment dose; counterbalanced order) using a placebo-controlled within-subject crossover design. During each session, participants completed a baseline evaluation and were first exposed to neutral cues then marijuana cues while physiological measures and subjective ratings of mood, craving, and drug effect were recorded.

RESULTS

Following placebo oral THC pretreatment, marijuana (vs. neutral) cues significantly increased ratings of marijuana craving (desire and urge to use, Marijuana Craving Questionnaire (MCQ)-Compulsivity scale), anxious mood and feeling hungry. Males also reported feeling more "Down" during marijuana cues relative to females. Pretreatment with oral THC (10-mg and/or 20-mg vs. placebo) significantly attenuated marijuana cue-induced increases in craving and anxiety but not hunger. Oral THC attenuation of the cue-induced increase in MCQ-Compulsivity ratings was observed in females only. Oral THC produced statistically (but not clinically) significant increases in heart rate and decreases in diastolic blood pressure, independent of cues.

CONCLUSIONS

These marijuana-cue findings replicate earlier results and further demonstrate that oral THC can attenuate selected effects during marijuana multi-cue exposure, and that some of these effects may be sex-related. Results of this study suggest oral THC may be effective for reducing marijuana cue-elicited (conditioned) effects. Further study is needed to determine whether females may selectively benefit from oral THC for this purpose.

The effect of repeated exposure to virtual gambling cues on the urge to gamble

INTRODUCTION

This study aimed to investigate the effectiveness of using a virtual reality (VR) casino environment in cue exposure therapy (CET) for gambling. The main objective of this study was to assess the ability of five VR casino cues to elicit subjective reactions and physiological responses that can be used within the CET paradigm. A second objective was to analyze changes in participants' urge to gamble after repeated exposure to a VR casino program and relaxation training.

METHODS

Twelve recreational gamblers were exposed to five virtual environments with casino-related cues that reproduced typical gambling situations. Self-reported subjective urges and psychophysiological responses were recorded during exposure.

RESULTS

All virtual environments with casino-related cues generated craving in recreational gamblers, whereas no increase in the psychophysiological variables was observed. In addition, urges to gamble elicited by VR casino environment reduced through repeated exposure and relaxation training.

CONCLUSION

These findings provide evidence of the effectiveness of VR for simulating casino environments in the treatment of gambling.

The use of virtual reality in craving assessment and cue-exposure therapy in substance use disorders

Craving is recognized as an important diagnosis criterion for substance use disorders (SUDs) and a predictive factor of relapse. Various methods to study craving exist; however, suppressing craving to successfully promote abstinence remains an unmet clinical need in SUDs. One reason is that social and environmental contexts recalling drug and alcohol consumption in the everyday life of patients suffering from SUDs often initiate craving and provoke relapse. Current behavioral therapies for SUDs use the cue-exposure approach to suppress salience of social and environmental contexts that may induce craving. They facilitate learning and cognitive reinforcement of new behavior and entrain craving suppression in the presence of cues related to drug and alcohol consumption. Unfortunately, craving often overweighs behavioral training especially in real social and environmental contexts with peer pressure encouraging the use of substance, such as parties and bars. In this perspective, virtual reality (VR) is gaining interest in the development of cue-reactivity paradigms and practices new skills in treatment. VR enhances ecological validity of traditional craving-induction measurement. In this review, we discuss results from (1) studies using VR and alternative virtual agents in the induction of craving and (2) studies combining cue-exposure therapy with VR in the promotion of abstinence from drugs and alcohol use. They used virtual environments, displaying alcohol and drugs to SUD patients. Moreover, some environments included avatars. Hence, some studies have focused on the social interactions that are associated with drug-seeking behaviors and peer pressure. Findings indicate that VR can successfully increase craving. Studies combining cue–exposure therapy with virtual environment, however, reported mitigated success so far.

Cannabis cue-induced brain activation correlates with drug craving in limbic and visual salience regions: preliminary results

Craving is a major motivator underlying drug use and relapse but the neural correlates of cannabis craving are not well understood. This study sought to determine whether visual cannabis cues increase cannabis craving and whether cue-induced craving is associated with regional brain activation in cannabis-dependent individuals. Cannabis craving was assessed in 16 cannabis-dependent adult volunteers while they viewed cannabis cues during a functional MRI (fMRI) scan. The Marijuana Craving Questionnaire was administered immediately before and after each of three cannabis cue-exposure fMRI runs. FMRI blood-oxygenation-level-dependent (BOLD) signal intensity was determined in regions activated by cannabis cues to examine the relationship of regional brain activation to cannabis craving. Craving scores increased significantly following exposure to visual cannabis cues. Visual cues activated multiple brain regions, including inferior orbital frontal cortex, posterior cingulate gyrus, parahippocampal gyrus, hippocampus, amygdala, superior temporal pole, and occipital cortex. Craving scores at baseline and at the end of all three runs were significantly correlated with brain activation during the first fMRI run only, in the limbic system (including amygdala and hippocampus) and paralimbic system (superior temporal pole), and visual regions (occipital cortex). Cannabis cues increased craving in cannabis-dependent individuals and this increase was associated with activation in the limbic, paralimbic, and visual systems during the first fMRI run, but not subsequent fMRI runs. These results suggest that these regions may mediate visually cued aspects of drug craving. This study provides preliminary evidence for the neural basis of cue-induced cannabis craving and suggests possible neural targets for interventions targeted at treating cannabis dependence.

Using virtual reality to study food cravings

Food cravings (FCs) are associated with overeating and obesity and are triggered by environmental cues. The study of FCs is challenged by difficulty replicating the natural environment in a laboratory. Virtual reality (VR) could be used to deliver naturalistic cues in a laboratory. The purpose of this study was to investigate whether food related cues delivered by VR could induce greater FCs than neutral VR cues, photographic food cues, or real food. Sixty normal weight non-dieting women were recruited; and, to prevent a floor effect, half were primed with a monotonous diet (MD). Experimental procedures involved delivering neutral cues via VR and food related cues via VR, photographs, and real food in counterbalanced order while measuring subjective (self-report) and objective (salivation) FCs. FCs produced by VR were marginally greater than a neutral cue, not significantly different from picture cues, and significantly less than real food. The modest effects may have been due to quality of the VR system and/or measures of FC (i.e., self-report and salivation). FC threshold among non-dieting normal weight women was lowered with the use of a MD condition. Weight loss programs with monotonous diets may inadvertently increase FCs making diet compliance more difficult.

Reward-related brain response and craving correlates of marijuana cue exposure: a preliminary study in treatment-seeking marijuana-dependent subjects

OBJECTIVE

: Determining the brain substrates underlying the motivation to abuse addictive drugs is critical for understanding and treating addictive disorders. Laboratory neuroimaging studies have demonstrated differential activation of limbic and motivational circuitry (eg, amygdala, hippocampus, ventral striatum, insula, and orbitofrontal cortex) triggered by cocaine, heroin, nicotine, and alcohol cues. The literature on neural responses to marijuana cues is sparse. Thus, the goals of this study were to characterize the brain's response to marijuana cues, a major motivator underlying drug use and relapse, and determine whether these responses are linked to self-reported craving in a clinically relevant population of treatment-seeking marijuana-dependent subjects.

METHODS

: Marijuana craving was assessed in 12 marijuana-dependent subjects using the Marijuana Craving Questionnaire-Short Form. Subsequently, blood oxygen level dependent functional magnetic resonance imaging data were acquired during exposure to alternating 20-second blocks of marijuana-related versus matched nondrug visual cues.

RESULTS

: Brain activation during marijuana cue exposure was significantly greater in the bilateral amygdala and the hippocampus. Significant positive correlations between craving scores and brain activation were found in the ventral striatum and the medial and lateral orbitofrontal cortex (P < 0.0001).

CONCLUSIONS

: This study presents direct evidence for a link between reward-relevant brain responses to marijuana cues and craving and extends the current literature on marijuana cue reactivity. Furthermore, the correlative relationship between craving and brain activity in reward-related regions was observed in a clinically relevant sample (treatment-seeking marijuana-dependent subjects). Results are consistent with prior findings in cocaine, heroin, nicotine, and alcohol cue studies, indicating that the brain substrates of cue-triggered drug motivation are shared across abused substances.

Cannabis cue-elicited craving and the reward neurocircuitry

Cue-elicited craving or the intense desire to consume a substance following exposure to a conditioned drug cue is one of the primary behavioral symptoms of substance use disorders (SUDs). While the concept of cue-elicited craving is well characterized in alcohol and other substances of abuse, only recently has it been described in cannabis. A review of the extant literature has established that cue-elicited craving is a powerful reinforcer that contributes to drug-seeking for cannabis. Further, emergent research has begun to identify the neurobiological systems and neural mechanisms associated with this behavior. What research shows is that while theories of THC's effects on the dopaminergic-reward system remain divergent, cannabis cues elicit neural activation in the brain's reward network.

Feasibility of Using Virtual Reality to Assess Nicotine Cue Reactivity During Treatment

Cue reactivity assessments have been widely used to assess craving and attention to cues among cigarette smokers. Cue reactivity has the potential to offer insights into treatment decisions; however, the use of cue reactivity in treatment studies has been limited. This study assessed the feasibility of using a virtual reality-based cue reactivity assessment approach (VR-NCRAS) during treatment. In a clinical smoking cessation treatment study, 46 treatment-seeking nicotine-dependent adult smokers were assessed for cue reactivity at baseline, Week 4, and Week 10 of treatment. Measures of cue reactivity included subjective craving and attention to cues after exposure to two neutral and two smoking cue environments. Overall, feasibility of using VR-NCRAS was demonstrated and these findings support the use of the cue reactivity assessment during treatment, which can inform treatment decisions.

Using virtual reality to investigate complex and contextual cue reactivity in nicotine dependent problem drinkers

Alcohol and cigarette smoking frequently co-occur among adults in the U.S., resulting in a myriad of deleterious health outcomes. Cue reactivity has been posited as one factor that precludes individuals from overcoming alcohol and nicotine dependency. While cue reactivity studies have focused on the impact of proximal cues on cue reactivity, much less is known about the unique impact of complex and contextual cues. This pilot study compares nicotine and alcohol cue reactivity among a sample of nicotine dependent, daily drinkers (N=21) across neutral, party, and office courtyard virtual reality (VR) contexts embedded with proximal smoking cues to: 1) explore and compare the effects of complex nicotine cues on alcohol cross-cue reactivity between nicotine/alcohol dependent drinkers and nicotine dependent/non-alcohol dependent daily drinkers, and 2) assess the effectiveness of VR for eliciting cue-induced nicotine craving responses using complex nicotine cues. Nicotine dependent/non-alcohol dependent drinkers had significantly lower craving for alcohol in the non-alcohol congruent office courtyard VR scene and there was no difference in the alcohol-congruent party scene when compared to the alcohol dependent group, suggesting that the non-alcohol dependent daily drinking group was more likely to react to contextual cues. Consistent with prior cue reactivity studies, dependent smokers experienced significantly higher craving for nicotine in the VR smoking congruent contexts compared to the neutral contexts; however, nicotine/alcohol dependent participants did not return to baseline craving after exposure to smoking cues. These results suggest substantive differences in the ways that nicotine-dependent, daily alcohol drinkers and nicotine/alcohol dependent drinkers experience craving, whether cross-cue or traditional.

The effect of repeated virtual nicotine cue exposure therapy on the psychophysiological responses: a preliminary study

OBJECTIVE

Smoking related cues may elicit smoking urges and psychophysiological responses in subjects with nicotine dependence. This study aimed to investigate the effect of repeated virtual cue exposure therapy using the surround-screen based projection wall system on the psychophysiological responses in nicotine dependence.

METHODS

The authors developed 3-dimensional neutral and smoking-related environments using virtual reality (VR) technology. Smoking-related environment was a virtual bar, which comprised both object-related and social situation cues. Ten subjects with nicotine dependence participated in 4-week (one session per week) virtual cue exposure therapy. Psychophysiological responses [electromyography (EMG), skin conductance (SC), and heart rate] and subjective nicotine craving were acquired during each session.

RESULTS

VR nicotine cue elicited greater psychophysiological responses and subjective craving for smoking than did neutral cue, and exposure to social situation cues showed greater psychophysiological responses in SC and EMG than did object-related cues. This responsiveness decreased during the course of repeated therapy.

CONCLUSION

The present study found that both psychophysiological responses and subjective nicotine craving were greater to nicotine cue exposure via projection wall VR system than to neutral cues and that enhanced cue reactivity decreased gradually over the course of repeated exposure therapy. These results suggest that VR cue exposure therapy combined with psychophysiological response monitoring may be an alternative treatment modality for smoking cessation, although the current findings are preliminary.

Cue-induced craving for marijuana in cannabis-dependent adults

Recent interest in the development of medications for treatment of cannabis-use disorders indicates the need for laboratory models to evaluate potential compounds prior to undertaking clinical trials. To investigate whether a cue-reactivity paradigm could induce marijuana craving in cannabis-dependent adults, 16 (eight female) cannabis-dependent and 16 (eight female) cannabis-naïve participants were exposed to neutral and marijuana-related cues, and subsequent changes in mood, self-reported craving, and physiologic function were assessed. Significant Group X cue interactions were found on all three VAS craving indices as well as on the Compulsivity scale of the Marijuana Craving Questionnaire-Brief Form (MCQ-BF). Cannabis-dependent individuals responded to marijuana-related cues with significantly increased reports of marijuana craving compared to neutral cue exposure, although there were no cue-induced changes in any of the physiological measures. There were no significant gender differences on any of the measures. These results indicate that marijuana craving can be induced and assessed in cannabis-dependent, healthy adults within a laboratory setting, and support the need for further research of the cue reactivity paradigm in the development of medications to treat cannabis-use disorders.

What virtual reality research in addictions can tell us about the future of obesity assessment and treatment

Virtual reality (VR), a system of human-computer interaction that allows researchers and clinicians to immerse people in virtual worlds, is gaining considerable traction as a research, education, and treatment tool. Virtual reality has been used successfully to treat anxiety disorders such as fear of flying and post-traumatic stress disorder, as an aid in stroke rehabilitation, and as a behavior modification aid in the treatment of attention deficit disorder. Virtual reality has also been employed in research on addictive disorders. Given the strong evidence that drug-dependent people are highly prone to use and relapse in the presence of environmental stimuli associated with drug use, VR is an ideal platform from which to study this relationship. Research using VR has shown that drug-dependent people react with strong craving to specific cues (e.g., cigarette packs, liquor bottles) as well as environments or settings (e.g., bar, party) associated with drug use. Virtual reality has also been used to enhance learning and generalization of relapse prevention skills in smokers by reinforcing these skills in lifelike environments. Obesity researchers and treatment professionals, building on the lessons learned from VR research in substance abuse, have the opportunity to adapt these methods for investigating their own research and treatment questions. Virtual reality is ideally suited to investigate the link between food cues and environmental settings with eating behaviors and self-report of hunger. In addition, VR can be used as a treatment tool for enhancing behavior modification goals to support healthy eating habits by reinforcing these goals in life-like situations.

Reactivity to in vivo marijuana cues among cannabis-dependent adolescents

INTRODUCTION

Cannabis dependence is a common but poorly understood condition in adolescents. Marijuana craving has been posited as a potential contributing factor to continued use and relapse, but relatively few studies have focused on the measurement of craving and reactivity to marijuana cues. The present work sought to explore reactivity to marijuana cues within this age group.

METHODS

Thirty treatment-seeking cannabis-dependent adolescents (age 13-20) completed a cue reactivity session, consisting of exposure to and manipulation of in vivo marijuana cues ("joint" and lighter) and matching neutral cues (pencil and eraser), in counterbalanced order. Subjective craving and physiological reactivity were assessed.

RESULTS

Participants demonstrated increased craving and skin conductance reactivity in response to marijuana cues, relative to neutral cues.

CONCLUSION

In vivo marijuana cues appear to elicit significant subjective and physiological reactivity among treatment-seeking cannabis-dependent adolescents. Further work is needed with a larger sample and with a wider variety of cues.

Drug- and cue-induced reinstatement of cannabinoid-seeking behaviour in male and female rats: influence of ovarian hormones

BACKGROUND AND PURPOSE

Animal and human studies have shown that sex and hormones are key factors in modulating addiction. Previously, we have demonstrated that self-administration of the cannabinoid CB(1) receptor agonist WIN55,212-2 (WIN; 12.5 microg.kg(-1) per infusion) is dependent on sex, intact female rats being more sensitive than males to the reinforcing properties of cannabinoids, and on the oestrous cycle, ovariectomized (OVX) females being less responsive than intact females.

EXPERIMENTAL APPROACH

This follow-up study investigated whether sex and ovarian function also affect reinstatement of cannabinoid-seeking in rats after exposure to drug or cue priming.

KEY RESULTS

After priming with 0.15 or 0.3 mg.kg(-1) WIN, intact female rats exhibited stronger reinstatement than males and OVX females. Responses of intact female rats were higher than those of male and OVX rats even after priming with a drug-associated visual (Light) or auditory (Tone) cue, or a WIN + Light combination. However, latency to the first response did not differ between intact and OVX female rats, and males showed the longest latency to initiate lever-pressing activity.

CONCLUSIONS AND IMPLICATIONS

Our study provides compelling evidence for a pivotal role of sex and the oestrous cycle in modulating cannabinoid-seeking, with ovariectomy diminishing drug and cue-induced reinstatement. However, it is possible that sex differences during self-administration training are responsible for sex differences in reinstatement. Finding that not only drug primings but also acute exposure to drug-associated cues can reinstate responding in rats could have significant implications for the development of pharmacological and behavioural treatments of abstinent female and male marijuana smokers.

Methamphetamine craving induced in an online virtual reality environment

The main aim of this study was to assess self-reported craving and physiological reactivity in a methamphetamine virtual reality (METH-VR) cue model created using Second Life, a freely available online gaming platform. Seventeen, non-treatment seeking, individuals that abuse methamphetamine (METH) completed this 1-day, outpatient, within-subjects study. Participants completed four test sessions: 1) METH-VR, 2) neutral-VR, 3) METH-video, and 4) neutral-video in a counterbalanced (Latin square) fashion. The participants provided subjective ratings of urges to use METH, mood, and physical state throughout each cue presentation. Measures of physiological reactivity (heart rate variability) were also collected during each cue presentation and at rest. The METH-VR condition elicited the greatest change in subjective reports of "crave METH", "desire METH", and "want METH" at all time points. The "high craving" participants displayed more high frequency cardiovascular activity while the "low craving" participants displayed more low frequency cardiovascular activity during the cue conditions, with the greatest difference seen during the METH-VR and METH-video cues. These findings reveal a physiological divergence between high and low craving METH abusers using heart rate variability, and demonstrate the usefulness of VR cues for eliciting subjective craving in METH abusers, as well as the effectiveness of a novel VR drug cue model created within an online virtual world.