Electrophysiological responses to emotional and cocaine cues reveal individual neuroaffective profiles in cocaine users

Exenatide as an adjunct to nicotine patch for smoking cessation and prevention of postcessation weight gain among treatment-seeking smokers with pre-diabetes and/or overweight: study protocol for a randomised, placebo-controlled clinical trial

INTRODUCTION

Obesity and smoking are the two leading causes of preventable death in the USA. Unfortunately, most smokers gain weight after quitting. Postcessation weight gain (PCWG) is frequently cited as one of the primary barriers to a quit attempt and a common cause of relapse. Further, excessive PCWG may contribute to the onset or progression of metabolic conditions, such as hyperglycaemia and obesity. The efficacy of the current treatments for smoking cessation is modest, and these treatments have no clinically meaningful impact on mitigating PCWG. Here, we outline a novel approach using glucagon-like peptide 1 receptor agonists (GLP-1RA), which have demonstrated efficacy in reducing both food and nicotine intake. This report describes the design of a double-blind, placebo-controlled, randomised clinical trial that evaluates the effects of the GLP-1RA exenatide as an adjunct to nicotine patches on smoking abstinence and PCWG.

METHODS AND ANALYSIS

The study will be conducted at two university-affiliated research sites in Houston, Texas, the UTHealth Center for Neurobehavioral Research on Addiction and Baylor College of Medicine Michael E. DeBakey VA Medical Centre. The sample will consist of 216 treatment-seeking smokers with pre-diabetes (haemoglobin A1c of 5.7%-6.4%) and/or overweight (body mass index of 25 kg/m² or above). Participants will be randomised (1:1) to receive subcutaneous injections of placebo or 2 mg exenatide, once weekly for 14 weeks. All participants will receive transdermal nicotine replacement therapy and brief smoking cessation counselling for 14 weeks. The primary outcomes are 4-week continuous abstinence and changes in body weight at the end of treatment. The secondary outcomes are (1) abstinence and changes in body weight at 12 weeks post end of treatment and (2) changes in neuroaffective responses to cigarette-related and food-related cues as measured by electroencephalogram.

ETHICS AND DISSEMINATION

The study has been approved by the UTHealth Committee for the Protection of Human Subjects (HSC-MS-21-0639) and Baylor College of Medicine Institutional Review Board (H-50543). All participants will sign informed consent. The study results will be disseminated via peer-reviewed publications and conference presentations.

TRIAL REGISTRATION NUMBER

NCT05610800.

Towards neuromarkers for tailored smoking cessation treatments

Vulnerability to compulsive drug use stems from dysregulated activity within the neural networks that underlie reward and executive functions. Empirical evidence suggests that a) attributing high motivational salience to drug-related stimuli leads to compulsive drug seeking and b) cognitive control deficits lead to compulsive drug taking. Noninvasive neuroimaging techniques enable brain activity monitoring during affective and cognitive processing and are paving the way to precision medicine for substance use disorders. Identifying robust neuromarkers of affective and cognitive dysregulation would allow clinicians to personalize treatments by targeting individual psychophysiological vulnerabilities. However, methodological choices have biased the field toward experimental paradigms that cannot optimally assess individual differences in the motivational salience of drug-related cues and in the ability to control drug-related decisions, choices which have hindered the identification of clinically relevant neuromarkers. Here, we show that once these shortcomings are amended, replicable neuromarkers of the tendency to attribute motivational salience to drug-related cues and the ability to control drug-related decisions emerge. While we use tobacco use disorder as a model, we also show that the methodological issues highlighted here are relevant to other disorders characterized by maladaptive appetitive behaviors.

Neuroaffective reactivity profiles are associated with vulnerability to e-cigarette use

BACKGROUND

We tested whether neuroaffective responses to motivationally salient stimuli are associated with vulnerability to cue-induced e-cigarette use in e-cigarette naïve adults who smoke daily. We hypothesized that individuals with stronger neuroaffective responses to nicotine-related cues than to pleasant stimuli (the C>P reactivity profile) would be more vulnerable to cue-induced nicotine self-administration than individuals with stronger neuroaffective responses to pleasant stimuli than to nicotine-related cues (the P>C reactivity profile).

METHODS

We used event-related potentials (ERPs, a direct measure of cortical activity) to measure neuroaffective reactivity to pleasant, unpleasant, neutral, and nicotine-related cues indicating the opportunity to use an e-cigarette in 36 participants. For each picture category, we computed the amplitude of the late positive potential (LPP), a robust index of motivational salience. To identify each individual's neuroaffective reactivity profile we applied k-means cluster analysis on the LPP responses. We compared the e-cigarette use frequency across profiles using quantile regression for counts.

RESULTS

K-means cluster analysis assigned 18 participants to the C>P profile and 18 participants to the P>C profile. Individuals with the C>P neuroaffective profile used the e-cigarette significantly more often than those with the P>C profile. Significant differences in the number of puffs persisted across different quantiles.

CONCLUSIONS

These results support the hypothesis that individual differences in the tendency to attribute motivational salience to drug-related cues underlie vulnerability to cue-induced drug self-administration. Targeting the neuroaffective profiles that we identified with tailored treatments could improve clinical outcomes.

Associations between the late positive potential and PTSD, anxiety, and depressive symptoms among trauma-exposed undergraduates

BACKGROUND

The late positive potential (LPP) is a neural marker of attention to emotional stimuli; dysregulations in those attentional processes might contribute to trauma-related psychopathology. Although higher LPP amplitudes to negative images have been found to be associated with anxiety symptoms, results have been mixed regarding depressive and PTSD symptoms, especially among trauma-exposed populations. Further, the relationships between the LPP to positive and neutral images and psychopathology symptoms have been underexamined. The purpose of the current study was to test the effects of image valence, and PTSD, anxiety, and depressive symptoms on LPP amplitude among trauma-exposed undergraduates.

METHOD

Seventy-three trauma-exposed undergraduates viewed a series of negative, positive, and neutral images while LPPs were recorded. Self-report measures were used to assess recent PTSD, anxiety, and depressive symptoms. Hierarchical linear modeling tested valence and symptom main effects, as well as Valence by Symptom interactions on LPP amplitude.

RESULTS

We found a main effect of valence such that individuals exhibited higher LPP amplitudes to negative images compared to neutral images. We also found a Valence by Depressive Symptoms interaction such that there was an inverse relationship between depressive symptoms and the LPP to neutral images but no associations between depressive symptoms and the LPP for positive or negative images. We found no main effects or interactions for anxiety and PTSD symptoms.

CONCLUSION

Depressive symptoms might be related to diminished attention to neutral stimuli among trauma-exposed undergraduates. Further investigation of the relationship between the LPP and psychopathology is needed.

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.

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.