Depressive symptoms and cannabis use in a placebo-controlled trial of N-Acetylcysteine for adult cannabis use disorder

Who responds to a multi-component treatment for cannabis use disorder? Using multivariable and machine learning models to classify treatment responders and non-responders

BACKGROUND AND AIMS

Treatments for cannabis use disorder (CUD) have limited efficacy and little is known about who responds to existing treatments. Accurately predicting who will respond to treatment can improve clinical decision-making by allowing clinicians to offer the most appropriate level and type of care. This study aimed to determine whether multivariable/machine learning models can be used to classify CUD treatment responders versus non-responders.

METHODS

This secondary analysis used data from a National Drug Abuse Treatment Clinical Trials Network multi-site outpatient clinical trial in the United States. Adults with CUD (n = 302) received 12 weeks of contingency management, brief cessation counseling and were randomized to receive additionally either (1) N-Acetylcysteine or (2) placebo. Multivariable/machine learning models were used to classify treatment responders (i.e. two consecutive negative urine cannabinoid tests or a 50% reduction in days of use) versus non-responders using baseline demographic, medical, psychiatric and substance use information.

RESULTS

Prediction performance for various machine learning and regression prediction models yielded area under the curves (AUCs) >0.70 for four models (0.72-0.77), with support vector machine models having the highest overall accuracy (73%; 95% CI = 68-78%) and AUC (0.77; 95% CI = 0.72, 0.83). Fourteen variables were retained in at least three of four top models, including demographic (ethnicity, education), medical (diastolic/systolic blood pressure, overall health, neurological diagnosis), psychiatric (depressive symptoms, generalized anxiety disorder, antisocial personality disorder) and substance use (tobacco smoker, baseline cannabinoid level, amphetamine use, age of experimentation with other substances, cannabis withdrawal intensity) characteristics.

CONCLUSIONS

Multivariable/machine learning models can improve on chance prediction of treatment response to outpatient cannabis use disorder treatment, although further improvements in prediction performance are likely necessary for decisions about clinical care.

Feedback-loop between psychotic symptoms and brain volume: A cross-lagged panel model study

Brain structural changes are known to be associated with psychotic symptoms, with worse symptoms consistently associated with brain volume loss in some areas. It is not clear whether volume and symptoms interfere with each other over the course of psychosis. In this paper, we analyse the temporal relationships between psychosis symptom severity and total gray matter volume. We applied a cross-lagged panel model to a public dataset from the NUSDAST cohorts. The subjects were assessed at three-time points: baseline, 24 months, and 48 months. Psychosis symptoms were measured by SANS and SAPS scores. The cohort contained 673 subjects with schizophrenia, healthy subjects and their siblings. There were significant effects of symptom severity on total gray matter volume and vice-versa. The worse the psychotic symptoms, the smaller the total gray volume, and the smaller the volume, the worse the symptomatology. There is a bidirectional temporal relationship between symptoms of psychosis and brain volume.

Assessment of patient perception of treatment assignment and patient-reported outcomes in a cannabis use disorder trial

Background: Blinding is a cornerstone of trial methodology. Prior work indicates participant-perceived assignment may be associated with trial outcomes. Less is known about how perception changes over time and if this is associated with outcomes.Objectives: To evaluate if participants change their perception of assignment over time in a blinded trial, and if perception is associated with different types of patient-reported outcomes (PROs).Methods: This was a secondary analysis of data from the Achieving Cannabis Cessation-Evaluating N-Acetylcysteine Treatment (ACCENT) trial, which evaluated the efficacy of N-acetylcysteine (NAC) relative to placebo for treating cannabis use disorder. Participants (N = 234; 164 men, 70 women) were asked at weeks 5 and 9 what treatment (placebo or NAC) they believed they were receiving. We included PROs proximal (cannabis-associated problems, craving) and distal (anxiety) to the intervention. Analysis was by multiple linear regression and mixed models.Results: Approximately 20% of participants in both arms changed their perception over time. Relative to participants who consistently perceived assignment to placebo, participants who consistently perceived assignment to NAC did not always have comparatively better average scores (coefficient -3.3 [95% CI: -7.0, 0.5]). In some analyses, participants who switched to guessing NAC from placebo had comparatively better average scores (coefficient -3.0 [95% CI: -9.3, 3.4]), but this was inconsistent across outcomes or strata defined by actual assignment or guess accuracy.Conclusion: The study suggests that the proportion of individuals who switch their perception over time is modest. However, this group may influence the estimates of intervention effects on some PROs.

N-acetylcysteine improves impulse control and attenuates relapse-like alcohol intake in long-term drinking rats

Increasing evidence suggests that individuals with alcohol use disorder (AUD) present with a disrupted glutamatergic system that underlies core components of addictive disorders, including drug relapse and low impulse control. N-acetylcysteine (NAC) is a cystine prodrug that has been found to promote glutamate homeostasis and drug abstinence. However, no studies to date have evaluated NAC's effect on impulsivity in substance use disorders. Here we determined whether NAC would decrease alcohol-intake behaviors, in addition to improving impulse control, in long-term alcohol drinking male Wistar-Han rats. Before the start of the experiments, all rats were exposed to long-term intermittent access to 20% ethanol for at least seven weeks. Next, in different groups of rats, the effect of NAC (60 and/or 90mg/kg) was evaluated on (i) voluntary alcohol drinking using a two-bottle free choice paradigm, (ii) the motivation to self-administer alcohol under a progressive ratio schedule of reinforcement, and (iii) relapse-like drinking using the alcohol deprivation effect model. Finally, (iv) NAC's effect on impulse control was evaluated using the five-choice serial reaction time task. Results showed that NAC administration at 90mg/kg significantly reduced relapse-like drinking and improved impulse control. In contrast, NAC had no effect on levels of alcohol drinking or motivation to drink alcohol. In conclusion, our findings continue to support the use of NAC as an adjuvant treatment for the maintenance of abstinence in AUD. Moreover, we provide evidence for NAC's efficacy in improving impulse control following drinking, which warrants further investigation in substance use settings.

N-acetyl cysteine in the treatment of cannabis use disorder: A systematic review of clinical trials

BACKGROUND AND AIM

Cannabis is the most consumed illicit drug globally, with a high risk of developing cannabis use disorder (CUD). No approved pharmacological treatment exists for CUD, but N-Acetyl Cysteine (NAC) has shown promising results in different clinical studies. This study aims to conduct a systematic review of NAC clinical trials for the treatment of CUD.

METHODS

Systematic review of randomized controlled trials (RCTs) was conducted to determine the effect of NAC for the treatment of cannabis dependence/cannabis use disorder (CUD). Articles were electronically searched across different databases using PubMed, Google Scholar, EMBASE, Cochrane Library, Medline and PsycINFO from inception to June 2021. Several study characteristics, including study duration, sample size, study population and age group, intervention, adverse effects, and outcome measure were extracted. A PICO table was used for data extraction.

RESULTS

We included 08 RCTs in the qualitative analysis. The risk of bias (RoB) was assessed according to Cochrane RoB criteria, and a 5 point grading system according to the Oxford Centre for Evidence-Based Medicine was used to rate the methodological quality (level of evidence) of the included articles. Mild and well-tolerated adverse events were reported in the placebo and NAC group.

CONCLUSIONS

The studies collectively offer mixed results, although the strength of the evidence available on which to make a recommendation is strong. NAC has shown to be effective in promoting abstinence, medication adherence and reducing cannabis use and craving among cannabis dependent users. This review also suggests recommendations for future research.

Analysis of female enrollment in clinical trials for alcohol and substance use disorders: Is it time for sex-informed pharmacotherapy?

BACKGROUND

Women represent an increasing number of individuals with alcohol and substance use disorders (ASUDs), and sex-differences might affect results of interventional clinical trials (CTs). We aim at assessing the proportion of women and the reporting of sex-stratified and female-specific data in CTs for ASUDs.

METHODS

We extracted data from ClinicalTrials.gov on Phase 1-3 CTs of investigational drugs for ASUDs conducted from 2000 to 2021 and identified articles related to these trials. We determined the average proportions of women enrolled per trial overall, over time, and by disease area and trial phase. Next, we calculated the proportion of articles reporting sex-stratified and female-specific data.

RESULTS

In the 234 CTs identified, the overall proportion of women was 33.4% [95% CI: 32.7%-33.9%]), with an increasing temporal trend. Women's participation was higher in CTs of investigational drugs for tobacco (43.5% [95% CI: 42.4% -44.5%]) and alcohol use disorder (35.9% [95% CI: 34.54%-37.21%]), and closely mirrored their representation in the disease populations (46% and 37%). Conversely, women were underrepresented in clinical trials of drugs for stimulants and cocaine use disorders (25.8% [95% CI: 24.6%-27.1%]) and opioid use disorders (25.9% [95% CI:24.2%-27.7%]). Nine publications reported sex-stratified data in the method and/or result section, whereas none documented female-specific data.

CONCLUSIONS

Enrollment of women in ASUDs CTs has increased over time but remains low in several disease areas. This, together with the low rates of reporting of sex-stratified data, calls for an adequate inclusion of sex in the design and analysis of CTs for ASUDs.

The Potential of N-Acetyl-L-Cysteine (NAC) in the Treatment of Psychiatric Disorders

N-acetyl-L-cysteine (NAC) is a compound of increasing interest in the treatment of psychiatric disorders. Primarily through its antioxidant, anti-inflammatory, and glutamate modulation activity, NAC has been investigated in the treatment of neurodevelopmental disorders, schizophrenia spectrum disorders, bipolar-related disorders, depressive disorders, anxiety disorders, obsessive compulsive-related disorders, substance-use disorders, neurocognitive disorders, and chronic pain. Whilst there is ample preclinical evidence and theoretical justification for the use of NAC in the treatment of multiple psychiatric disorders, clinical trials in most disorders have yielded mixed results. However, most studies have been underpowered and perhaps too brief, with some evidence of benefit only after months of treatment with NAC. Currently NAC has the most evidence of having a beneficial effect as an adjuvant agent in the negative symptoms of schizophrenia, severe autism, depression, and obsessive compulsive and related disorders. Future research with well-powered studies that are of sufficient length will be critical to better understand the utility of NAC in the treatment of psychiatric disorders.

Clinical Approaches to Cannabis: A Narrative Review

Cannabis use in the United States is growing at an unprecedented pace. Most states in the United States have legalized medical cannabis use, and many have legalized nonmedical cannabis use. In this setting, health care professionals will increasingly see more patients who have questions about cannabis use, its utility for medical conditions, and the risks of its use. This narrative review provides an overview of the background, pharmacology, therapeutic use, and potential complications of cannabis.

Natural and synthetic estrogens specifically alter nicotine demand and cue-induced nicotine seeking in female rats

Women have more difficulty maintaining smoking cessation than men, and experience greater withdrawal symptomatology as well as higher prevalence of relapse. Further, currently available treatments for smoking cessation, such as the nicotine patch and varenicline, have been shown to be less effective in women. Fluctuations in ovarian hormones across the menstrual cycle can affect craving and smoking relapse propensity. In addition, many women who smoke use some form of oral contraceptives, which most often contain ethinyl estradiol (EE), a synthetic, orally bio-available estrogen that is currently prescribed to women chronically and has been shown to alter smoking reward in women. The current study examined the impact of 17β-estradiol (E2), the prominent endogenous form of the steroid hormone estrogen, as well as EE, on nicotine self-administration, demand, and reinstatement following ovariectomy (OVX) or sham surgery. OVX vehicle-treated female rats consumed less nicotine, had lower intensity of demand, and reinstated less compared to sham vehicle-treated female rats. OVX-E2 and OVX-EE treatment groups showed a rebound of nicotine intake later in training, and Q₀ levels of consumption were partially rescued in both groups. Further, E2 but not EE reversed the abolishment of reinstated nicotine seeking induced by OVX. Taken together, these results demonstrate that natural and synthetic estrogens play a critical role in mediating the neurobehavioral effects of nicotine, and future studies are essential for our understanding of how synthetic hormones contained within oral contraceptives interact with smoking.

N-acetylcysteine in substance use disorder: a lesson from preclinical and clinical research

Substance use disorder (SUD) is a chronic brain condition, with compulsive and uncontrollable drug-seeking that leads to long-lasting and harmful consequences. The factors contributing to the development of SUD, as well as its treatment settings, are not fully understood. Alterations in brain glutamate homeostasis in humans and animals implicate a key role of this neurotransmitter in SUD, while the modulation of glutamate transporters has been pointed as a new strategy to diminish the excitatory glutamatergic transmission observed after drugs of abuse. N-acetylcysteine (NAC), known as a safe mucolytic agent, is involved in the regulation of this system and may be taken into account as a novel pharmacotherapy for SUD. In this paper, we summarize the current knowledge on the ability of NAC to reduce drug-seeking behavior induced by psychostimulants, opioids, cannabinoids, nicotine, and alcohol in animals and humans. Preclinical studies showed a beneficial effect in animal models of SUD, while the clinical efficacy of NAC has not been fully established. In summary, NAC will be a small add-on to usual treatment and/or psychotherapy for SUD, however, further studies are required.

Psychosocial and pharmacological treatments for cannabis use disorder and mental health comorbidities: a narrative review

Cannabis is the most widely used illicit drug worldwide, and it is estimated that up to 30% of people who use cannabis will develop a cannabis use disorder (CUD). Demand for treatment of CUD is increasing in almost every region of the world and cannabis use is highly comorbid with mental disorders, where sustained use can reduce treatment compliance and increase risk of relapse. In this narrative review, we outline evidence for psychosocial and pharmacological treatment strategies for CUD, both alone and when comorbid with psychosis, anxiety or depression. Psychosocial treatments such as cognitive behavioural therapy, motivational enhancement therapy and contingency management are currently the most effective strategy for treating CUD but are of limited benefit when comorbid with psychosis. Pharmacological treatments targeting the endocannabinoid system have the potential to reduce cannabis withdrawal and cannabis use in CUD. Mental health comorbidities including anxiety, depression and psychosis hinder effective treatment and should be addressed in treatment provision and clinical decision making to reduce the global burden of CUDs. Antipsychotic medication may decrease cannabis use and cannabis craving as well as psychotic symptoms in patients with CUD and psychosis. Targeted treatments for anxiety and depression when comorbid with CUD are feasible.

Influence of n-acetylcysteine maintenance on the pharmacodynamic effects of oral ethanol

RATIONALE

Glutamate systems play an important role in the abuse related effects of alcohol. n-Acetylcysteine, a drug that promotes glutamate homeostasis, attenuates a range of alcohol effects in preclinical models.

OBJECTIVES

This human laboratory study determined the influence of n-acetylcysteine maintenance on alcohol self-administration using a model predictive of treatment effectiveness, along with the subjective, performance and physiological effects of alcohol. We hypothesized that n-acetylcysteine would attenuate alcohol self-administration, as well as positive subjective effects of alcohol.

METHODS

Nine subjects with alcohol use disorder completed this within-subjects study. Subjects were maintained on placebo, 1.2 and 2.4 g n-acetylcysteine in random order on an outpatient basis. After five days of maintenance on the target dose, subjects completed overnight inpatient experimental sessions in which the pharmacodynamic effects of alcohol were determined.

RESULTS

Alcohol produced prototypic effects (e.g., increased breath alcohol concentration, increased ratings of Feel Drink). n-Acetylcysteine did not alter the effects of alcohol.

CONCLUSIONS

These results indicate that although n-acetylcysteine can safely be combined with alcohol, it does not attenuate the abuse related effects of alcohol and is unlikely to be an effective standalone alcohol use disorder treatment. However, considering study limitations, future work is needed to further understand whether and how n-acetylcysteine might be used as a treatment for alcohol use disorder (e.g., in combination with a behavioral treatment or another pharmacological agent).