Cocaine craving is associated with electrophysiological brain responses to cocaine-related stimuli

Associations of the P300 Event-Related Potentials and Self-Reported Craving in Substance Use Disorders: A Systematic Review

INTRODUCTION

The phenomenon of craving and attention bias towards drug cues is theorized to operate cooperatively, owing to the principles of associative learning. In this context, the conditioned response to drug-related stimuli activates reward mechanisms within the brain, consequently inducing craving and fostering the underlying mechanisms that contribute to relapse in individuals with substance use disorders. Multiple studies have assessed the relationship between attention to substance-related cues and subjective craving through electroencephalography (EEG), but their findings have yet to be synthesized and examined. This review summarizes the association between the amplitude of the P300 event-related potential (ERP) and substance use craving, compares discrepancies in results by type of substance, and discusses gaps in the literature to inform future research.

METHODS

A systematic search was conducted on Embase, Web of Science, CINAHL, and PsychINFO databases. Studies were published in English and included peer-reviewed human research investigating the relationship between EEG P300 ERP and self-reported substance use craving. The included study samples comprised of in treatment or non-treatment-seeking participants who use substances. The primary outcomes of interest were those derived from inferential statistics assessing P300 amplitude and substance use craving.

RESULTS

Ten studies were included in the final search and were organized by substance type: three alcohol, three cocaine, two tobacco, one heroin, and one cannabis. Results were mixed for alcohol and cocaine. Studies on tobacco, heroin, and cannabis use were congruent for associations between the P300 amplitude and craving.

CONCLUSIONS

Overall findings are mixed between studies addressing the association of the EEG P300 amplitude and craving. These results should be considered in the context of the limited sample size, underpowered analyses, and methodological differences that potentially contribute to discrepancies in outcomes. Further research is required to assess the role of craving assessment, EEG methodology, and substance-related factors on the association between P300 amplitude and self-reported craving.

Preventing incubation of drug craving to treat drug relapse: from bench to bedside

In 1986, Gawin and Kleber reported a progressive increase in cue-induced drug craving in individuals with cocaine use disorders during prolonged abstinence. After years of controversy, as of 2001, this phenomenon was confirmed in rodent studies using self-administration model, and defined as the incubation of drug craving. The intensification of cue-induced drug craving after withdrawal exposes abstinent individuals to a high risk of relapse, which urged us to develop effective interventions to prevent incubated craving. Substantial achievements have been made in deciphering the neural mechanisms, with potential implications for reducing drug craving and preventing the relapse. The present review discusses promising drug targets that have been well investigated in animal studies, including some neurotransmitters, neuropeptides, neurotrophic factors, and epigenetic markers. We also discuss translational exploitation and challenges in the field of the incubation of drug craving, providing insights into future investigations and highlighting the potential of pharmacological interventions, environment-based interventions, and neuromodulation techniques.

Reducing short- and long-term cocaine craving with voluntary exercise in male rats

BACKGROUND

In a previous study in female rats, voluntary wheel running attenuated incubation of cocaine craving after 30 but not 3 days (Zlebnik and Carroll Zlebnik and Carroll, Psychopharmacology 232:3507-3413, 2015). The present study in male rats, using the same procedure, showed that wheel running reduced incubated craving after both 30 and 3 days of abstinence.

METHODS

Male rats self-administered i.v. cocaine (0.4 mg/kg) during 6-h sessions for 10 days. They were then moved from the operant chamber to a home cage with an attached running wheel or stationary wheel, for 6 h daily for a 3- or 30-day period when cocaine craving was hypothesized to incubate. Rats were then returned to the operant chamber for a 30-min test of cocaine seeking, or "craving," indicated by responses on the former "drug" lever was formerly associated with drug stimulus lights and responses (vs. no drug stimuli), and lever responding was compared to responses on the "inactive" that was illuminated and counted lever pressing.

RESULTS

Mean wheel revolutions were similar across the 3- and 30-day incubation groups, when both groups of rats were given access to wheel running vs. access to a stationary wheel in controls. Subsequently, when rats were tested in the operant chamber for "relapse" responding (drug-lever responding) on the lever formerly associated with drug access, cocaine craving was reduced by recent running wheel access (vs. stationary wheel access) in both the 3- and 30-day wheel exposure groups.

CONCLUSION

Voluntary, self-initiated, and self-sustained physical exercise reduced cocaine craving after short- (3 days) and long-term (30 days) abstinence periods in male rats that previously self-administered cocaine. This was contrasted with reduction of cocaine seeking in females after 30-day, but not 3-day, incubation periods under the wheel running vs. stationary wheel conditions in a previous study (Zlebnik and Carroll Zlebnik and Carroll, Psychopharmacology 232:3507-3413, 2015). These initial findings suggest males may be more sensitive to incubated craving for cocaine than females.

Late positive potential as a candidate biomarker of motivational relevance in substance use: Evidence from a meta-analysis

The objective of the current meta-analysis was to assess the effect size of the Late Positive Potential (LPP) to drug and emotional cues in substance users compared to controls. The secondary objective was to test for moderation by: age, gender, years of use, use status, and substance type. Search was performed in August 2021 using PubMed. Inclusion criteria were: substance use disorder/dependence or validated self-report, LPP means, healthy control comparison, non-acute drug study, data available, peer-reviewed journal, English, and human participants. Selection bias was tested through modified Egger's regression and exploratory 3-parameter selection model tests. Results (k = 11) indicated LPP to drug cues was larger in substance use compared to control group, with a large effect size (Hedges' g=1.66, 95%CI [0.64,2.67], p = 0.005). There were no overall differences for emotional cues. Though threats of selection bias were not severe, inclusion of more studies with larger sample sizes in future meta-analyses will allow more robust tests of publication bias and more accurate measures of effect size.

Neurophysiological correlate of incubation of craving in individuals with methamphetamine use disorder

Previous studies both in laboratory animals and humans have reported that abstinence induces incubation of cue-induced drug craving for nicotine, alcohol, cocaine, and methamphetamine. However, current experimental procedures utilized to study incubation of methamphetamine craving do not incorporate the temporal dynamics of neuropsychological measures and electrophysiological activities associated with this incubation process. This study utilized the high-density electroencephalogram (EEG) signals as a rapid, inexpensive, and noninvasive measure of cue-induced craving potential. A total of 156 male individuals with methamphetamine use disorder (MUD) enrolled in this multisite, cross-sectional study. Structured clinical interview data, self-report questionnaires (cued craving, quality of sleep, impulsivity, anxiety, and depression) and resting-state, eye-closed 128 high-density channel EEG signals were collected at 5 abstinence duration time points (<1, 1-3, 3-6, 6-12, and 12-24 months) to track the neuropsychological and neurophysiological signatures. Cue-induced craving was higher after 1-3 months than after the other time points. This incubation effect was also observed for sleep quality but not for anxiety, depression, and impulsivity symptoms, along with exhibited decreased power spectrum for theta (5.5-8 Hz) and alpha (8-13 Hz), and increased in beta (16.5-26.5 Hz) frequency band. Source reconstructed resting-state EEG analysis showed increased synchronization of medial prefrontal cortex (MPFC) for the beta frequency band in 1-3 months abstinent MUD group, and associated with the incubation of craving. Remarkably, the robust incubation-related abnormalities may be driven by beta-band source space connectivity between MPFC and bilateral orbital gyrus (ORB). Our findings suggest the enhancement of beta activity in the incubation period most likely originates from a dysfunction involving frontal brain regions. This neurophysiological signature of incubation of craving can be used to identify individuals who might be most susceptible to relapse, providing a potential insight into future therapeutic interventions for MUD via neuromodulation of beta activity.

Electrophysiological indexes for impaired response inhibition and salience attribution in substance (stimulants and depressants) use disorders: A meta-analysis

The impairment of inhibitory control and reward system is the core feature underlying substance use disorder (SUD). Previous studies suggested that it can be regarded as impaired response inhibition and salience attribution syndrome (iRISA). The neural substrates of the two deficit functions were widely investigated in neuroimaging studies, and the impaired prefrontal cortex, limbic-orbitofrontal network, and fronto-insular-parietal network were observed. Previous Event-related potential (ERP) studies were also conducted to explore EEG indexes related to abnormal brain function. In the current meta-analysis, we aimed to explore the consistency of ERP indexes that can reflect the two aberrant processes: P300/slow potential (SP) for salience attribution and Error-related negativity (ERN)/Nogo-N200/Nogo-P300 for inhibitory control and conflict monitoring. Subgroup analyses for drug type and drug use conditions were also conducted. According to the 60 research studies, we found significantly enhanced drug-cue-induced P300 amplitude and attenuated Nogo-N200 amplitude in SUD individuals relative to Healthy control (HC), which supports the dual model. Moreover, the drug-cue-induced P300 displayed time-dependence recovery, suggesting a potential index for treatment evaluation. In conclusion, drug-cue-induced P300 and Nogo-N200 demonstrated high consistency, and the drug-cue-induced P300 can be used to track the changes of functional recovery for SUD. The integration of the two ERP components could be regarded as a potential biomarker for SUD, which may provide a new insight for clinical treatment and investigation.

Roles of P300 and Late Positive Potential in Initial Romantic Attraction

Initial romantic attraction (IRA) refers to a series of positive reactions to potential romantic partners at the initial encounter; it evolved to promote mate selection, allowing individuals to focus their mating efforts on their preferred potential mates. After decades of effort, we now have a deeper understanding of the evolutionary value and dominant factors of IRA; however, little is known regarding the brain mechanisms related to its generation and evaluation. In this study, we combined classic event-related potential analysis with dipole-source analysis to examine electroencephalogram (EEG) signals generated while participants assessed their romantic interest in potential partners. The EEG signals were categorized into IRA-engendered and unengendered conditions based on behavioral indicators. We found that the faces elicited multiple late positivities, including P300 over the occipital-parietal regions and late positive potentials (LPPs) over the anterior regions. When compared to faces that did not engender IRA, faces that did engender IRA elicited (1) enhanced P300 over the parietal regions and heightened neural activity in the insula and cingulate cortex and (2) larger LPPs over the anterior regions and heightened neural activity in the orbitofrontal cortex, dorsolateral prefrontal cortex, cingulate cortex, frontal eye field, visual cortex, and insula. These results suggest IRA is generated and evaluated by an extensive brain network involved in emotion processing, attention control, and social evaluations. Furthermore, these findings indicate that P300 and LPP may represent different cognitive processes during IRA.

Posttraumatic stress symptom clusters differentially predict late positive potential to cocaine imagery cues in trauma-exposed adults with cocaine use disorder

BACKGROUND

While studies have investigated the effects of posttraumatic stress disorder (PTSD) symptoms on substance use, information on these associations in the context of drug cue reactivity is lacking, which can provide meaningful information about risk for relapse. The current study assessed the associations between PTSD symptom clusters and reactivity to cues in trauma-exposed adults with cocaine use disorder.

METHODS

We recorded electroencephalogram on 52 trauma-exposed participants (M_age = 51.3; SD = 7.0; 15.4 % women) diagnosed with cocaine use disorder while they viewed pleasant (i.e., erotic, romantic, sweet foods), unpleasant (i.e., mutilations, violence, accidents), neutral, and cocaine-related images. Reactivity was measured with the late positive potential (LPP), an indicator of motivational relevance. It was hypothesized that individuals with greater PTSD avoidance and negative alterations in cognition and mood (NACM) symptoms, as determined by the PTSD Checklist for DSM-5 (PCL-5), would have higher LPPs to cocaine-related images, indicating greater cue reactivity.

RESULTS

Linear mixed modeling indicated that higher NACM symptomatology was associated with higher LPPs to cocaine cues and higher arousal/reactivity was associated with lower LPPs to cocaine cues.

CONCLUSIONS

These results highlight the potential clinical utility of the LPP in assessing drug cue reactivity in trauma-exposed adults with substance use disorder.

Attention bias modification in drug addiction: Enhancing control of subsequent habits

A relapse in addiction is often precipitated by heightened attention bias to drug-related cues, underpinned by a subcortically mediated transition to habitual/automatized responding and reduced prefrontal control. Modification of such automatized attention bias is a fundamental, albeit elusive, target for relapse reduction. Here, on a trial-by-trial basis, we used electroencephalography and eye tracking with a task that assessed, in this order, drug cue reactivity, its instructed self-regulation via reappraisal, and the immediate aftereffects on spontaneous (i.e., not instructed and automatized) attention bias. The results show that cognitive reappraisal, a facet of prefrontal control, decreased spontaneous attention bias to drug-related cues in cocaine-addicted individuals, more so in those with less frequent recent use. The results point to the mechanisms underlying the disruption of automatized maladaptive drug-related attention bias in cocaine addiction. These results pave the way for future studies to examine the role of such habit disruption in reducing compulsive drug seeking outside the controlled laboratory environment, with the ultimate goal of developing a readily deployable cognitive-behavioral and personalized intervention for drug addiction.

Biomarkers and neuromodulation techniques in substance use disorders

Addictive disorders are a severe health concern. Conventional therapies have just moderate success and the probability of relapse after treatment remains high. Brain stimulation techniques, such as transcranial Direct Current Stimulation (tDCS) and Deep Brain Stimulation (DBS), have been shown to be effective in reducing subjectively rated substance craving. However, there are few objective and measurable parameters that reflect neural mechanisms of addictive disorders and relapse. Key electrophysiological features that characterize substance related changes in neural processing are Event-Related Potentials (ERP). These high temporal resolution measurements of brain activity are able to identify neurocognitive correlates of addictive behaviours. Moreover, ERP have shown utility as biomarkers to predict treatment outcome and relapse probability. A future direction for the treatment of addiction might include neural interfaces able to detect addiction-related neurophysiological parameters and deploy neuromodulation adapted to the identified pathological features in a closed-loop fashion. Such systems may go beyond electrical recording and stimulation to employ sensing and neuromodulation in the pharmacological domain as well as advanced signal analysis and machine learning algorithms. In this review, we describe the state-of-the-art in the treatment of addictive disorders with electrical brain stimulation and its effect on addiction-related neurophysiological markers. We discuss advanced signal processing approaches and multi-modal neural interfaces as building blocks in future bioelectronics systems for treatment of addictive disorders.

Decreases in the Late Positive Potential to Alcohol Images Among Alcohol Treatment Seekers Following Mindfulness-Based Relapse Prevention

Aim

Heightened craving among individuals with alcohol use disorder (AUD) has been attributed to a hypersensitivity to alcohol cues in attentional brain networks. Active mindfulness training has been shown to help improve attentional control. Here, we examined alcohol cue-related hypersensitivity among individuals with AUD who received rolling group mindfulness-based relapse prevention (MBRP) in combination with transcranial direct current stimulation (tDCS), over right inferior frontal gyrus.

Methods

Participants (n = 68) viewed a series of emotionally negative, emotionally neutral and alcohol-related images. Following image presentation, participants were asked to rate their level of craving for the alcohol cues, and their level of negative affect evoked by neutral and negative cues. During the task, electroencephalogram (EEG) was recorded to capture an event-related component shown to relate to emotionally salient stimuli: the late positive potential (LPP). Participants who completed a follow-up EEG (n = 37) performed the task a second time after up to eight sessions of MBRP coupled with active or sham tDCS.

Results

We found that both craving ratings and the LPP significantly decreased in response to alcohol cues from pre- to post-treatment, but not for other image cues. The magnitude of alcohol image craving reductions was associated with the number of MBRP group sessions attended. Active tDCS was not associated with craving ratings, but it was associated with greater LPP amplitudes across image types.

Conclusions

Taken together, these results suggest that disruption of alcohol-cue hypersensitivity in people with AUD may be a target mechanism of MBRP.

Mindfulness-Oriented Recovery Enhancement remediates hedonic dysregulation in opioid users: Neural and affective evidence of target engagement

Addiction neuroscience models posit that recurrent drug use increases reactivity to drug-related cues and blunts responsiveness to natural rewards, propelling a cycle of hedonic dysregulation that drives addictive behavior. Here, we assessed whether a cognitive intervention for addiction, Mindfulness-Oriented Recovery Enhancement (MORE), could restructure reward responsiveness from valuation of drug-related reward back to valuation of natural reward. Before and after 8 weeks of MORE or a support group control, prescription opioid users (N = 135) viewed opioid and natural reward cues while an electroencephalogram biomarker of target engagement was assessed. MORE was associated with decreased opioid cue-reactivity and enhanced capacity to regulate responses to opioid and natural reward cues. Increased positive affective responses to natural reward cues were associated with decreased craving and mediated MORE's therapeutic effects on opioid misuse. This series of randomized experiments provide the first neurophysiological evidence that an integrative behavioral treatment can remediate hedonic dysregulation among chronic opioid users.

Cue reactivity towards bodies in anorexia nervosa - common and differential effects in adolescents and adults

BACKGROUND

Aberrant reward mechanisms with regard to slim body shapes are discussed in patients with anorexia nervosa (AN). The aim of the present study was to examine of cue reactivity toward body shapes in AN via the late positive potential (LPP), an event-related electroencephalography (EEG) component. By including adolescents and adults, aspects of development and chronification could be studied (2 × 2 design).

METHODS

Thirty-two female AN patients (19 adolescents and 13 adults) and 37 control participants (16 adolescents and 21 adults) were included. Standardized photographic stimuli showing women's bodies in underwear from five body mass index (BMI) categories (extremely underweight to extremely overweight) were presented. During picture evaluation, EEG activity was recorded (10-20 system). The LPP was measured in two time windows characterized by different topographies (450-700 ms: posterior; 1000-1300 ms: central).

RESULTS

Regarding the posterior component, LPP amplitudes were clearly reduced in adult but not in adolescent patients; for both time windows the LPP showed differential patterns over BMI categories for patients and controls. Regarding the central component, a highly significant linear decrease from extremely underweight to extremely overweight body shapes was revealed in patients and no significant modulation in control participants.

CONCLUSIONS

Adolescent and adult patients show increased sustained attention toward extremely underweight bodies. In chronically ill patients, this bias appears to be accompanied by generally reduced automatic attention. The LPP findings provide a differentiated picture of aberrant cue reactivity which could be interpreted as motivated attention toward body shapes in AN.

Toward biomarkers of the addicted human brain: Using neuroimaging to predict relapse and sustained abstinence in substance use disorder

The ability to predict relapse is a major goal of drug addiction research. Clinical and diagnostic measures are useful in this regard, but these measures do not fully and consistently identify who will relapse and who will remain abstinent. Neuroimaging approaches have the potential to complement these standard clinical measures to optimize relapse prediction. The goal of this review was to survey the existing drug addiction literature that either used a baseline functional or structural neuroimaging phenotype to longitudinally predict a clinical outcome, or that examined test-retest of a neuroimaging phenotype during a course of abstinence or treatment. Results broadly suggested that, relative to individuals who sustained abstinence, individuals who relapsed had (1) enhanced activation to drug-related cues and rewards, but reduced activation to non-drug-related cues and rewards, in multiple corticolimbic and corticostriatal brain regions; (2) weakened functional connectivity of these same corticolimbic and corticostriatal regions; and (3) reduced gray and white matter volume and connectivity in prefrontal regions. Thus, beyond these regions showing baseline group differences, reviewed evidence indicates that function and structure of these regions can prospectively predict - and normalization of these regions can longitudinally track - important clinical outcomes including relapse and adherence to treatment. Future clinical studies can leverage this information to develop novel treatment strategies, and to tailor scarce therapeutic resources toward individuals most susceptible to relapse.

The sound and the fury: Late positive potential is sensitive to sound affect

Emotion is an emergent construct of multiple distinct neural processes. EEG is uniquely sensitive to real-time neural computations, and thus is a promising tool to study the construction of emotion. This series of studies aimed to probe the mechanistic contribution of the late positive potential (LPP) to multimodal emotion perception. Experiment 1 revealed that LPP amplitudes for visual images, sounds, and visual images paired with sounds were larger for negatively rated stimuli than for neutrally rated stimuli. Experiment 2 manipulated this audiovisual enhancement by altering the valence pairings with congruent (e.g., positive audio + positive visual) or conflicting emotional pairs (e.g., positive audio + negative visual). Negative visual stimuli evoked larger early LPP amplitudes than positive visual stimuli, regardless of sound pairing. However, time frequency analyses revealed significant midfrontal theta-band power differences for conflicting over congruent stimuli pairs, suggesting very early (∼500 ms) realization of thematic fidelity violations. Interestingly, late LPP modulations were reflective of the opposite pattern of congruency, whereby congruent over conflicting pairs had larger LPP amplitudes. Together, these findings suggest that enhanced parietal activity for affective valence is modality independent and sensitive to complex affective processes. Furthermore, these findings suggest that altered neural activities for affective visual stimuli are enhanced by concurrent affective sounds, paving the way toward an understanding of the construction of multimodal affective experience.

Incubation of Cue-Induced Craving in Adults Addicted to Cocaine Measured by Electroencephalography

IMPORTANCE

A common trigger for relapse in drug addiction is the experience of craving via exposure to cues previously associated with drug use. Preclinical studies have consistently demonstrated incubation of cue-induced drug-seeking during the initial phase of abstinence, followed by a decline over time. In humans, the incubation effect has been shown for alcohol, nicotine, and methamphetamine addictions, but not for heroin or cocaine addiction. Understanding the trajectory of cue-induced craving during abstinence in humans is of importance for addiction medicine.

OBJECTIVE

To assess cue-induced craving for cocaine in humans using both subjective and objective indices of cue-elicited responses.

DESIGN, SETTING, AND PARTICIPANTS

Seventy-six individuals addicted to cocaine with varying durations of abstinence (ie, 2 days, 1 week, 1 month, 6 months, and 1 year) participated in this laboratory-based cross-sectional study from June 19, 2007, to November 26, 2012. The late positive potential component of electroencephalography, a recognized marker of incentive salience, was used to track motivated attention to drug cues across these self-selected groups. Participants also completed subjective ratings of craving for cocaine before presentation of a cue, and ratings of cocaine "liking" (hedonic feelings toward cocaine) and "wanting" (craving for cocaine) after presentation of cocaine-related pictures. Data analysis was conducted from June 5, 2015, to March 30, 2016.

MAIN OUTCOMES AND MEASURES

The late positive potential amplitudes and ratings of liking and wanting cocaine in response to cocaine-related pictures were quantified and compared across groups.

RESULTS

Among the 76 individuals addicted to cocaine, 19 (25%) were abstinent for 2 days, 20 (26%) were abstinent for 1 week, 15 (20%) were abstinent for 1 month, 12 (16%) were abstinent for 6 months, and 10 (13%) were abstinent for 1 year. In response to drug cues, the mean (SD) late positive potential amplitudes showed a parabolic trajectory that was higher at 1 (1.26 [1.36] µV) and 6 (1.17 [1.19] µV) months of abstinence and lower at 2 days (0.17 [1.09] µV), 1 week (0.36 [1.26] µV), and 1 year (-0.27 [1.74] µV) of abstinence (P = .02, partial η2 = 0.16). In contrast, the subjective assessment of baseline craving (mean [SD] rating: 2 days, 26.05 [9.85]; 1 week, 18.70 [11.01]; 1 month, 10.87 [10.70]; 6 months, 6.92 [8.47]; and 1 year, 3.00 [3.77]) and cue-induced liking (mean [SD] rating: 2 days, 3.06 [2.34]; 1 week, 2.33 [2.87]; 1 month, 1.15 [2.03]; 6 months, 1.00 [2.24]; and 1 year, 1.00 [1.26]) and wanting (mean [SD] rating: 2 days, 3.44 [2.62]; 1 week, 2.72 [2.87]; 1 month, 1.46 [2.33]; 6 months, 1.00 [2.16]; and 1 year, 1.00 [1.55]) of cocaine showed a linear decline from 2 days to 1 year of abstinence (P ≤ .001, partial η2 > 0.26).

CONCLUSIONS AND RELEVANCE

The late positive potential responses to drug cues, indicative of motivated attention, showed a trajectory similar to that reported in animal models. In contrast, we did not detect incubation of subjective cue-induced craving. Thus, the objective electroencephalographic measure may possibly be a better indicator of vulnerability to cue-induced relapse than subjective reports of craving, although this hypothesis must be empirically tested. These results suggest the importance of deploying intervention between 1 month and 6 months of abstinence, when addicted individuals may be most vulnerable to, and perhaps least cognizant of, risk of relapse.

Deconstructing the Emotion Regulatory Properties of Mindfulness: An Electrophysiological Investigation

The present study sought to uncover the emotion regulatory properties of mindfulness by examining its effects—differentiated as a meditative practice, state of mind and dispositional trait—on the late positive potential (LPP), an event-related potentials (ERPs) indexing emotional processing. Results revealed that mindfulness as a meditative practice produced a reduction in the difference between the LPP response to negative high arousing and neutral stimuli across time. In contrast, a state mindfulness induction (i.e., instructions to attend to the stimuli mindfully) failed to modulate the LPP. Dispositional mindfulness, however, was related to modulation of the LPP as a function of meditation practice. Dispositional mindfulness was associated with a reduction of the LPP response to negative high arousal stimuli and the difference between negative high arousal and neutral stimuli in participants who listened to a control audio recording but not for those who engaged in the guided meditation practice. Together, these findings provide experimental evidence demonstrating that brief mindfulness meditation, but not deliberate engagement in state mindfulness, produces demonstrable changes in emotional processing indicative of reduced emotional reactivity. Importantly, these effects are akin to those observed in individuals with naturally high dispositional mindfulness, suggesting that the benefits of mindfulness can be cultivated through practice.

Electrophysiological mechanisms of biased response to smoking-related cues in young smokers

Cigarette smoking during young adult may result in serious health issues in later life. Hence, it is extremely necessary to study the smoking neurophysiological mechanisms in this critical transitional period. However, few studies revealed the electrophysiological mechanisms of cognitive processing biases in young adult smokers. In present study, nineteen young smokers with 12h abstinent and 19 matched nonsmokers were recruited. By employing event-related potentials (ERP) measurements during a smoking cue induced craving task, electrophysiological brain responses were compared between the young adult smokers and nonsmokers. The Slow Positive Wave (SPW) amplitude of smoking-related cues was enhanced in young adult smokers compared with nonsmokers. In addition, increased P300/SPW component of smoking-related cues relative to neutral cues were found in young adult smokers. Meanwhile, a positive correlation between Cigarette Per Day (CPD) and the amplitude of ERPs wave (P300/SPW) at anterior (Fz), central (Cz) were observed in young adult smokers. Our findings provided direct electrophysiological evidence for the cognitive processing bias of smoking cue and may shed new insights into the smoking behavior in young adult smokers.

Abstinence reverses EEG-indexed attention bias between drug-related and pleasant stimuli in cocaine-addicted individuals

BACKGROUND

Increased attention bias toward drug-related cues over non-drug-related intrinsically pleasant reinforcers is a hallmark of drug addiction. In this study we used the late positive potential (LPP) to investigate whether such increased attention bias toward drug-related relative to non-drug-related cues changes over a protracted period of reduced drug use in treatment-seeking individuals with a cocaine use disorder (CUD).

METHODS

Treatment-seeking individuals with CUD and matched healthy controls passively viewed a series of pleasant, neutral and drug-related pictures while their event-related potentials were recorded at baseline (≤ 3 weeks after treatment initiation) and at 6-month follow-up (only CUD).

RESULTS

We included 19 treatment-seeking individuals with CUD and 18 matched controls in our analyses. The results showed a reversal in attention bias (i.e., LPP amplitude) from baseline (i.e., drug > pleasant) to follow-up (i.e., pleasant > drug) driven by an increased attentional engagement with pleasant pictures; this LPP reversal was paralleled by a concomitant reduction in self-reported wanting and craving for cocaine in the CUD group. Furthermore, reduced attention bias toward drug-related cues (relative to pleasant cues) was correlated with longer duration of abstinence at baseline, and the extent of its longitudinal reversal was correlated with decreased craving at follow-up, providing support for abstinence as a putative mechanism of this bottom-up attentional change.

LIMITATIONS

A limited sample size and the use of the same set of pictures at baseline and follow-up were the major limitations of this study.

CONCLUSION

Results collectively indicate that, by tracking with drug abstinence, LPP in response to drug-related relative to pleasant cues may serve as an indicator of clinical progress in treatment-seeking individuals with CUD.

Validation of the cocaine versions of the Obsessive Compulsive Drug Use Scale and the Desires for Drug Questionnaire

BACKGROUND

The Obsessive Compulsive Drug Use Scale (OCDUS) and the Desires for Drug Questionnaire (DDQ) are two frequently used drug craving questionnaires. Although both heroin and cocaine versions of the questionnaires exist, only the heroin versions have been psychometrically evaluated. The present study was conducted to evaluate the psychometric qualities of the cocaine versions of the OCDUS (OCDUS-C) and DDQ (DDQ-C).

METHODS

Cocaine-dependent inpatients (n = 101) completed both scales as well as a Visual Analogue Craving Scale (VACS), an alternative, one-item index for assessing momentary craving. We examined the reliability (internal consistency), construct validity (factor structure), and concurrent validity (correlations among both questionnaires, the VACS, and indicators of severity of dependence). A subsample also completed the OCDUS-C and DDQ-C for a second time, one week after the initial administration to obtain a preliminary investigation of the test-retest reliability.

RESULTS

In general, both questionnaires displayed good internal consistency, test-retest reliability, and concurrent validity. Further, the construct validity of both the DDQ and OCDUS was demonstrated by means of confirmatory factor analyses showing the expected three-factor models.

CONCLUSION

Our results indicate that the OCDUS and DDQ for cocaine are both easy to administer and reliable instruments to assist the clinical practitioner or researcher to measure craving in cocaine dependent subjects. Moreover, the factor structure for the cocaine versions were similar to the heroin versions, indicating the OCDUS and the DDQ can be reliably used to measure craving for both substances, enabling a direct comparison between heroin and cocaine craving.

Emotional graphic cigarette warning labels reduce the electrophysiological brain response to smoking cues

There is an ongoing public debate about the new graphic warning labels (GWLs) that the Food and Drug Administration (FDA) proposes to place on cigarette packs. Tobacco companies argued that the strongly emotional images FDA proposed to include in the GWLs encroached on their constitutional rights. The court ruled that FDA did not provide sufficient scientific evidence of compelling public interest in such encroachment. This study's objectives were to examine the effects of the GWLs on the electrophysiological and behavioral correlates of smoking addiction and to determine whether labels rated higher on the emotional reaction (ER) scale are associated with greater effects. We studied 25 non-treatment-seeking smokers. Event-related potentials (ERPs) were recorded while participants viewed a random sequence of paired images, in which visual smoking (Cues) or non-smoking (non-Cues) images were preceded by GWLs or neutral images. Participants reported their cigarette craving after viewing each pair. Dependent variables were magnitude of P300 ERPs and self-reported cigarette craving in response to Cues. We found that subjective craving response to Cues was significantly reduced by preceding GWLs, whereas the P300 amplitude response to Cues was reduced only by preceding GWLs rated high on the ER scale. In conclusion, our study provides experimental neuroscience evidence that weighs in on the ongoing public and legal debate about how to balance the constitutional and public health aspects of the FDA-proposed GWLs. The high toll of smoking-related illness and death adds urgency to the debate and prompts consideration of our findings while longitudinal studies of GWLs are underway.

Cannabis cue reactivity and craving among never, infrequent and heavy cannabis users

Substance cue reactivity is theorized as having a significant role in addiction processes, promoting compulsive patterns of drug-seeking and drug-taking behavior. However, research extending this phenomenon to cannabis has been limited. To that end, the goal of the current work was to examine the relationship between cannabis cue reactivity and craving in a sample of 353 participants varying in self-reported cannabis use. Participants completed a visual oddball task whereby neutral, exercise, and cannabis cue images were presented, and a neutral auditory oddball task while event-related brain potentials (ERPs) were recorded. Consistent with past research, greater cannabis use was associated with greater reactivity to cannabis images, as reflected in the P300 component of the ERP, but not to neutral auditory oddball cues. The latter indicates the specificity of cue reactivity differences as a function of substance-related cues and not generalized cue reactivity. Additionally, cannabis cue reactivity was significantly related to self-reported cannabis craving as well as problems associated with cannabis use. Implications for cannabis use and addiction more generally are discussed.

Electrophysiological evidence of early attentional bias to drug-related pictures in chronic cannabis users

Behavioral and electrophysiological correlates of attentional bias to cannabis-related cues were investigated in a marijuana dependent group and a non-user group employing a drug Stroop task in which cannabis-related, negative and neutral images were presented. Behaviorally, cannabis users were less accurate during drug-containing blocks than non-users. Electrophysiologically, in chronic marijuana-users, an early positive ERP enhancement over left frontal scalp (EAP, 200-350ms) was present in response to drug-containing blocks relative to negative blocks. This effect was absent in the non-user group. Furthermore, drug-containing blocks gave rise to enhanced voltage of a posterior P300 (300-400ms), and a posterior sustained slow wave (LPP, 400-700ms) relative to negative blocks. However, such effects were similar between cannabis users and non-users. Brain source imaging in cannabis users revealed a generator for the EAP effect to drug stimuli in left ventromedial prefrontal cortex/medial orbitofrontal cortex, a region active in fMRI studies of drug cue-reactivity and a target of the core dopaminergic mesolimbic pathway involved in the processing of substances of abuse. This study identifies the timing and brain localization of an ERP correlate of early attentional capture to drug-related pictures in chronic marijuana users. The EAP to drug cues may identify a new electrophysiological marker with clinical implications for predicting abstinence versus relapse or to evaluate treatment interventions.

Effects of non-invasive neurostimulation on craving: a meta-analysis

This meta-analysis was conducted to evaluate the available evidence regarding the effects of non-invasive neurostimulation of the dorsolateral prefrontal cortex (DLPFC), on craving in substance dependence and craving for high palatable food. Non-invasive neurostimulation techniques were restricted to repetitive Transcranial Magnetic Stimulation (rTMS) and transcranial Direct Current Stimulation (tDCS). A total of 17 eligible studies were identified. Random effects analysis revealed a pooled standardized effect size (Hedge's g) of 0.476 (CI: 0.316-0.636), indicating a medium effect size favouring active non-invasive neurostimulation over sham stimulation in the reduction of craving (z=5.832, p<0.001). No significant differences were found between rTMS and tDCS, between the various substances of abuse and between substances of abuse and food, or between left and right DLPFC stimulation. In conclusion, this meta-analysis provides the first clear evidence that non-invasive neurostimulation of the DLPFC decreases craving levels in substance dependence.

Reprint of "Affective picture processing as a function of preceding picture valence: an ERP analysis"

Event-related brain potential (ERP) studies consistently revealed that a relatively early (early posterior negativity; EPN) and a late (late positive potential; LPP) ERP component differentiate between emotional and neutral picture stimuli. Two studies examined the processing of emotional stimuli when preceded either by pleasant, neutral, or unpleasant context images. In both studies, distinct streams of six pictures were shown. In Study 1, hedonic context was alternated randomly across the 180 picture streams. In Study 2, hedonic context sequences were blocked, resulting in 60 preceding sequences of pleasant, neutral, and unpleasant context valence, respectively. The main finding was that the valence of the preceding picture sequence had no significant effect on the emotional modulation of the EPN and LPP components. However, previous results were replicated in that emotional stimulus processing was associated with larger EPN and LPP components as compared to neutral pictures. These findings suggest that the prioritized processing of emotional stimuli is primarily driven by the valence of the current picture.

The late positive potential as a marker of motivated attention to underweight bodies in girls with anorexia nervosa

OBJECTIVE

In anorexia nervosa (AN), aspects of motivational salience and reward are increasingly discussed. Event related potentials, particularly the late positive potential (LPP), have been investigated as a marker for motivational salience of stimuli, for example in addictive disorders. The aim of this study was to assess the LPP as a possible indicator of motivated attention towards disease-specific pictures of underweight female bodies in adolescents with AN in comparison to typically developing (TD) adolescent girls.

METHOD

13 girls with AN and 18 TD adolescent girls (aged 12 to 18 years) viewed pictures of underweight, normal-weight and overweight women while EEG activity was recorded. An earlier (450-680 ms after stimulus onset) as well as a later time window (850-1250 ms after stimulus onset) of the LPP were examined for the different picture categories. Participants were also asked to rate subjective emotions (fear, disgust, happiness) elicited by the pictures.

RESULTS

Subjective ratings showed no differential experience of emotions for the two groups. For AN patients, highest LPP amplitudes were found for underweight women in the earlier as well as in the later time window. In TD girls, highest amplitudes for pictures of overweight women were observed in the earlier time window.

CONCLUSION

A differential LPP pattern for girls with AN and TD girls when viewing pictures of women's bodies of different weight categories was obtained. Highest amplitudes in AN patients for pictures of underweight women may reflect motivational significance of strongly underweight body shapes.

Psychophysiological prediction of choice: relevance to insight and drug addiction

An important goal of addiction research and treatment is to predict behavioural responses to drug-related stimuli. This goal is especially important for patients with impaired insight, which can interfere with therapeutic interventions and potentially invalidate self-report questionnaires. This research tested (i) whether event-related potentials, specifically the late positive potential, predict choice to view cocaine images in cocaine addiction; and (ii) whether such behaviour prediction differs by insight (operationalized in this study as self-awareness of image choice). Fifty-nine cocaine abusers and 32 healthy controls provided data for the following laboratory components that were completed in a fixed-sequence (to establish prediction): (i) event-related potential recordings while passively viewing pleasant, unpleasant, neutral and cocaine images, during which early (400-1000 ms) and late (1000-2000 ms) window late positive potentials were collected; (ii) self-reported arousal ratings for each picture; and (iii) two previously validated tasks: one to assess choice for viewing these same images, and the other to group cocaine abusers by insight. Results showed that pleasant-related late positive potentials and arousal ratings predicted pleasant choice (the choice to view pleasant pictures) in all subjects, validating the method. In the cocaine abusers, the predictive ability of the late positive potentials and arousal ratings depended on insight. Cocaine-related late positive potentials better predicted cocaine image choice in cocaine abusers with impaired insight. Another emotion-relevant event-related potential component (the early posterior negativity) did not show these results, indicating specificity of the late positive potential. In contrast, arousal ratings better predicted respective cocaine image choice (and actual cocaine use severity) in cocaine abusers with intact insight. Taken together, the late positive potential could serve as a biomarker to help predict drug-related choice--and possibly associated behaviours (e.g. drug seeking in natural settings, relapse after treatment)--when insight (and self-report) is compromised.

Electrophysiological indices of biased cognitive processing of substance-related cues: a meta-analysis

Several studies indicate that individuals with substance use disorders (SUD) exhibit biases in the cognitive processing of substance-related stimuli. These biases facilitate the detection of substance cues and have been argued to play a causal or perpetuating role in addiction. Two electrophysiological indices of cognitive processing, the P300 and Slow Potential (SP) components of the event-related potential (ERP), are associated with the deployment of attentional resources to motivationally relevant stimuli. In the present meta-analysis P300 (300-800ms) and SP (>800ms) amplitudes are used to investigate whether SUD persons show enhanced cognitive processing of substance cues relative to neutral cues as opposed to control participants. Results indicated the P300 and SP amplitude effect sizes were significantly larger in SUD participants than controls. This result is explained by substance users' motivated attention. Additional stratified moderator analyses revealed that both P300 and SP amplitudes were not moderated by electrode site (Fz vs. Pz), type of substance used (stimulants vs. depressants), substance use status (abstinent vs. non-abstinent), age, gender and task requirements (active vs. passive paradigms).

Intentional modulation of the late positive potential in response to smoking cues by cognitive strategies in smokers

Attentional bias is considered an important concept in addiction since it has been found to correlate with subjective craving and is strongly associated with relapse after periods of abstinence. Hence, investigating in ways to regulate attention for drug cues would be of major clinical relevance. The present study examined deliberate, cognitive modulation of motivated attention for smoking cues in smokers. The effects of three different reappraisal strategies on an electrophysiological measure of attentive processing were investigated. Early and late LPP components in response to passively viewed neutral and smoking pictures were compared with LPPs in response to smoking pictures that were reappraised with three different reappraisal strategies. Results show that when smokers actively imagine how pleasant it would be to smoke (pleasant condition), their early LPP in response to smoking cues increases, but when smokers actively focus on an alternative stimulus (distraction condition) or think of a rational, uninvolved interpretation of the situation (rational condition), smoking-related late LPP amplitude decreases to the processing level of neutral stimuli. Present results are the first to indicate that smoking cue-elicited LPP amplitudes can be modulated by cognitive strategies, suggesting that attentive processing of smoking cues can be intentionally regulated by smokers with various levels of dependence. Although cognitive strategies can lead to enhanced processing of smoking cues, it is not completely clear whether cognitive strategies are also successful in reducing smoking-related motivated attention. Although findings do point in this direction, present study is best considered preliminary and a starting point for other research on this topic. A focus on the distraction strategy is proposed, as there are indications that this strategy is more successful than the rational strategy in decreasing LPP amplitude.

Cue reactivity in cannabis-dependent adolescents

The authors measured event-related potentials with a craving manipulation to investigate the neural correlates of drug cue reactivity in 13 adolescents who are cannabis dependent (CD; ages 14-17). The P300 responses to marijuana (MJ) pictures (MJ-P300) and control pictures (C-P300) were assessed after handling neutral objects and again after handling MJ paraphernalia (MJP). Self-reported drug craving and heart rates also were measured. MJ-P300 were larger than C-P300 (p < .001), and both the MJ-P300 and craving increased significantly after handling MJP (p = .002 and p = .003, respectively), with no association between the magnitude of craving and MJ-P300. Heart rates were not affected by handling MJP. The results showed that adolescents who are CD have an attentional bias to MJ stimuli that increases after handling marijuana paraphernalia. Generally, the results are consistent with what has been reported for adult heavy chronic cannabis smokers, although there were some differences that require further investigation.

Implicit and explicit selective attention to smoking cues in smokers indexed by brain potentials

Substance use disorders are characterized by cognitive processing biases, such as automatically detecting and orienting attention towards drug-related stimuli. However, it is unclear how, when and what kind of attention (i.e. implicit, explicit) interacts with the processing of these stimuli. In addition, it is unclear whether smokers are hypersensitive to emotionally significant cues in general or to smoking-related cues in particular. The present event-related potential study aimed to enhance insight in drug-related processing biases by manipulating attention for smoking and other motivationally relevant (emotional) cues in smokers and non-smokers using a visual oddball task. Each of the stimulus categories served as a target (explicit attention; counting) or as a non-target (implicit attention; oddball) category. Compared with non-smokers, smokers' P300 (350-600 ms) was enhanced to smoking pictures under both attentional conditions. P300 amplitude did not differ between groups in response to positive, negative, and neutral cues. It can be concluded from this study that attention manipulation affects the P300 differently in smokers and non-smokers. Smokers display a specific bias to smoking-related cues, and this bias is present during both explicit and implicit attentional processing. Overall, it can be concluded that both explicit and implicit attentional processes appear to play an important role in drug-related processing bias.

Motivated attention to cocaine and emotional cues in abstinent and current cocaine users--an ERP study

Event-related potentials (ERPs) are a direct measure of neural activity and are ideally suited to study the time-course of attentional engagement with emotional and drug-related stimuli in addiction. In particular, the late positive potential (LPP) appears to be enhanced following cocaine-related compared with neutral stimuli in human participants with cocaine use disorders (CUD). However, previous studies have not directly compared cocaine-related with emotional stimuli while examining potential differences between abstinent and current cocaine users. The present study examined ERPs in 55 CUD (27 abstinent and 28 current users) and 29 matched healthy controls while they passively viewed pleasant, unpleasant, neutral and cocaine-related pictures. To examine the time-course of attention to these stimuli, we analysed both an early and later window in the LPP as well as the early posterior negativity (EPN), established in assessing motivated attention. Cocaine pictures elicited increased electrocortical measures of motivated attention in ways similar to affectively pleasant and unpleasant pictures in all CUD, an effect that was no longer discernible during the late LPP window for the current users. This group also exhibited deficient processing of the other emotional stimuli (early LPP window - pleasant pictures; late LPP window - pleasant and unpleasant pictures). Results were unique to the LPP and not EPN. Taken together, results support a relatively early attention bias to cocaine stimuli in cocaine-addicted individuals, further suggesting that recent cocaine use decreases such attention bias during later stages of processing but at the expense of deficient processing of other emotional stimuli.

The P3 Event-Related Potential as an Index of Motivational Relevance

Watching motivationally relevant pictures modulates two types of event-related brain potentials (ERPs), the early posterior negativity (EPN) and the P3. Several studies show that the EPN and P3 to emotional stimuli are enhanced as compared to neutral stimuli. The goal of the present study was to investigate whether experimentally conditioned abstract stimuli (Gabor patches) that predict the occurrence of a subsequent emotional event are able to elicit an enhanced EPN and P3. This would confirm that these ERP components indeed reflect the motivational relevance of a stimulus, rather than other stimulus properties such as complexity. In a conditioning paradigm, abstract patches (conditioned stimuli; CS) were contingently paired with emotional or neutral pictures (unconditioned stimuli; UCS). Both EPN and P3 to these CS were measured in 80 healthy participants. The results demonstrate an enhanced P3 to CS predicting emotional stimuli as compared to CS predicting neutral stimuli. The EPN was not modulated by the CS. These results show that the P3 is a suitable index of acquired motivational relevance and is not, at least not completely, dependent on task-irrelevant stimulus properties such as complexity and contrast. The EPN seems less suitable as an index of recently acquired motivational relevance because, although the CS acquired emotional significance, this did not result in the typical EPN modulation.

A meta-analytic investigation of the relationship between attentional bias and subjective craving in substance abuse

Theoretical models of addiction suggest that attentional bias for substance-related cues should be associated with self-reported craving. The authors evaluated the strength of the association by performing a meta-analysis on 68 independent data sets from which correlation coefficients between subjective craving and attentional bias indices were derived. Additional stratified analyses were conducted to identify any variables that might moderate the association between craving and attentional bias. The primary meta-analysis indicated a significant, albeit weak (r=.19), association between attentional bias and craving. Stratified analyses revealed that the association was larger for illicit drug and caffeine craving than for alcohol and tobacco craving, larger for direct measures of attention (eye movement measures and event-related potential measures) than for indirect behavioral measures of attentional bias, and larger when craving strength was high than when it was low (all ps<.05). The size of the correlation did not differ among patients in treatment and individuals who were not seeking treatment. These results suggest that attentional bias and craving are related phenomena, although the relationship is generally modest and appears to be moderated by various factors. Theoretical implications are discussed.