Galantamine reduces smoking in alcohol-dependent patients: a randomized, placebo-controlled trial

Integrative Pharmacology in the Treatment of Substance Use Disorders

The detrimental physical, mental, and socioeconomic effects of substance use disorders (SUDs) have been apparent to the medical community for decades. However, it has become increasingly urgent in recent years to develop novel pharmacotherapies to treat SUDs. Currently, practitioners typically rely on monotherapy. Monotherapy has been shown to be superior to no treatment at all for most substance classes. However, many randomized controlled trials (RCTs) have revealed that monotherapy leads to poorer outcomes when compared with combination treatment in all specialties of medicine. The results of RCTs suggest that monotherapy frequently fails since multiple dysregulated pathways, enzymes, neurotransmitters, and receptors are involved in the pathophysiology of SUDs. As such, research is urgently needed to determine how various neurobiological mechanisms can be targeted by novel combination treatments to create increasingly specific yet exceedingly comprehensive approaches to SUD treatment. This article aims to review the neurobiology that integrates many pathophysiologic mechanisms and discuss integrative pharmacology developments that may ultimately improve clinical outcomes for patients with SUDs. Many neurobiological mechanisms are known to be involved in SUDs including dopaminergic, nicotinic, N-methyl-D-aspartate (NMDA), and kynurenic acid (KYNA) mechanisms. Emerging evidence indicates that KYNA, a tryptophan metabolite, modulates all these major pathophysiologic mechanisms. Therefore, achieving KYNA homeostasis by harmonizing integrative pathophysiology and pharmacology could prove to be a better therapeutic approach for SUDs. We propose KYNA-NMDA-α7nAChRcentric pathophysiology, the "conductor of the orchestra," as a novel approach to treat many SUDs concurrently. KYNA-NMDA-α7nAChR pathophysiology may be the "command center" of neuropsychiatry. To date, extant RCTs have shown equivocal findings across comparison conditions, possibly because investigators targeted single pathophysiologic mechanisms, hit wrong targets in underlying pathophysiologic mechanisms, and tested inadequate monotherapy treatment. We provide examples of potential combination treatments that simultaneously target multiple pathophysiologic mechanisms in addition to KYNA. Kynurenine pathway metabolism demonstrates the greatest potential as a target for neuropsychiatric diseases. The investigational medications with the most evidence include memantine, galantamine, and N-acetylcysteine. Future RCTs are warranted with novel combination treatments for SUDs. Multicenter RCTs with integrative pharmacology offer a promising, potentially fruitful avenue to develop novel therapeutics for the treatment of SUDs.

Current Pharmacotherapies for Smoking Cessation and Promising Emerging Drugs

OBJECTIVE

Pharmacotherapy is commonly used during quit attempts and has shown an increase in the likelihood of achieving abstinence. However, with established pharmacotherapies, abstinence rates following a quit attempt remain low, and relapse is common. This review aims to investigate the efficacy and harm profiles of current and emerging pharmacotherapies.

METHODS

Literature review of current and emerging pharmacotherapies for smoking cessation and tobacco use disorder.

RESULTS

Emerging pharmacotherapies include new formulations of existing therapies, drug repurposing and some new treatments. New treatments are welcome and may incorporate different mechanisms of action or different safety and tolerability profiles compared to existing treatments. However, emerging pharmacotherapies have yet to demonstrate greater efficacy compared to existing treatments. The emergence of Electronic Nicotine Delivery Systems (ENDS) or 'vaping' is a feature of the current debate around tobacco use disorder. ENDS appear to facilitate switching but not quitting and are controversial as a harm minimisation strategy.

LIMITATIONS

Studies included a broad range of therapies and trial designs that should be compared with their differences taken into consideration.

CONCLUSION

Strategies to successfully quit smoking vary between individuals and may extend beyond pharmacotherapy and involve complex psychosocial factors and pathways.

Galantamine beyond Alzheimer's disease-a fact or artefact?

Galantamine is US-Food and Drug Administration FDA-approved for mild-to-moderate Alzheimer's disease. However, its unique pharmacological portfolio speaks to the idea of a pluripotent agent with a broad therapeutic potential. Here, authors briefly discuss these off-label clinical indications synthesizing the extant evidence.

Galantamine as a Treatment Option for Nicotine Addiction

The pharmacological therapy for smoking cessation recommended by National Institute for Health and care Excellence (NICE) guidelines is nicotine replacement therapy such as gum, inhalator, lozenge, nasal spray, oral spray, sublingual tablet, and transdermal patch. Medications such as bupropion and varenicline are also used. Varenicline is the only established drug used to alleviate symptoms of craving as it acts as a partial nicotine agonist. Galantamine has a similar mechanism of action where it is an acetylcholinesterase inhibitor and nicotinic receptor agonist. However, varenicline is the only recommended drug. There are not many studies to illustrate the effectiveness of galantamine for smoking cessation. This article explores the possibility of potential use of galantamine in alleviating the symptoms of nicotine withdrawal.

More than Smoke and Patches: The Quest for Pharmacotherapies to Treat Tobacco Use Disorder

Tobacco use is a persistent public health issue. It kills up to half its users and is the cause of nearly 90% of all lung cancers. The main psychoactive component of tobacco is nicotine, primarily responsible for its abuse-related effects. Accordingly, most pharmacotherapies for smoking cessation target nicotinic acetylcholine receptors (nAChRs), nicotine's major site of action in the brain. The goal of the current review is twofold: first, to provide a brief overview of the most commonly used behavioral procedures for evaluating smoking cessation pharmacotherapies and an introduction to pharmacokinetic and pharmacodynamic properties of nicotine important for consideration in the development of new pharmacotherapies; and second, to discuss current and potential future pharmacological interventions aimed at decreasing tobacco use. Attention will focus on the potential for allosteric modulators of nAChRs to offer an improvement over currently approved pharmacotherapies. Additionally, given increasing public concern for the potential health consequences of using electronic nicotine delivery systems, which allow users to inhale aerosolized solutions as an alternative to smoking tobacco, an effort will be made throughout this review to address the implications of this relatively new form of nicotine delivery, specifically as it relates to smoking cessation. SIGNIFICANCE STATEMENT: Despite decades of research that have vastly improved our understanding of nicotine and its effects on the body, only a handful of pharmacotherapies have been successfully developed for use in smoking cessation. Thus, investigation of alternative pharmacological strategies for treating tobacco use disorder remains active; allosteric modulators of nicotinic acetylcholine receptors represent one class of compounds currently under development for this purpose.

Advances in the In vitro and In vivo pharmacology of Alpha4beta2 nicotinic receptor positive allosteric modulators

Receptors containing α4 and β2 subunits are a major neuronal nicotinic acetylcholine receptor (nAChR) subtype in the brain. This receptor plays a critical role in nicotine addiction, with potential smoking cessation therapeutics producing modulation of α4β2 nAChR. In addition, compounds that act as agonists at α4β2 nAChR may be useful for the treatment of pathological pain. Further, as the α4β2 nAChR has been implicated in cognition, therapeutics that act as α4β2 nAChR agonists are also being examined as treatments for cognitive disorders and neurological diseases that impact cognitive function, such as Alzheimer's disease and schizophrenia. This review will cover the molecular in vitro evidence that allosteric modulators of the α4β2 neuronal nAChR provide several advantages over traditional α4β2 nAChR orthosteric ligands. Specifically, we explore the concept that nAChR allosteric modulators allow for greater pharmacological selectivity, while minimizing potential deleterious off-target effects. Further, here we discuss the development and preclinical in vivo behavioral assessment of allosteric modulators at the α4β2 neuronal nAChR as therapeutics for smoking cessation, pathological pain, as well as cognitive disorders and neurological diseases that impact cognitive function. This article is part of the special issue on 'Contemporary Advances in Nicotine Neuropharmacology'.

Randomized placebo-controlled trial of galantamine in individuals with cocaine use disorder

No pharmacotherapies are approved for the treatment of cocaine use disorder (CUD). Galantamine, a cholinesterase inhibitor, has shown initial promise for cocaine use reduction in methadone-maintained individuals with CUD and cognitive improvement in abstinent individuals with past CUD. However, galantamine has not previously tested in individuals with current CUD and no comorbid opioid use disorder or methadone maintenance. The goal of this 13-week, double-blind, placebo-controlled, randomized controlled trial was to test the efficacy of galantamine (8 mg or 16 mg/day; extended release (ER)) for reducing cocaine use and improving cognitive function in individuals with cocaine use disorder (CUD). Ninety-three treatment-seeking cocaine users were randomized to placebo (n = 32), 8 mg/day galantamine (n = 31) or 16 mg/day galantamine (n = 30). The medication was well-tolerated with minimal reports of side-effects. However, there were no significant treatment group differences in cocaine use outcomes (as measured by self-report or urines). The 16 mg galantamine group had a greater improvement in working memory capacity (Backwards Digit Span), but there were no other significant treatment group differences on key cognitive outcomes. These findings did not provide support for the efficacy of galantamine as a treatment for cocaine use in this sample of individuals with CUD.

Galantamine and Computerized Cognitive Behavioral Therapy for Cocaine Dependence: A Randomized Clinical Trial

OBJECTIVE

To examine whether galantamine, a cognitive-enhancing medication that is both acetylcholinesterase inhibitor and agonist at nicotinic acetylcholine receptors, is effective at improving cocaine use outcomes and cognitive functioning, alone and in combination with computerized cognitive behavioral therapy (CBT).

METHOD

A 12-week, randomized 2 × 2, factorial trial was conducted to evaluate galantamine versus placebo (double-blind) and computerized CBT plus standard methadone treatment versus standard methadone treatment alone in a community-based methadone maintenance program (September 2009-April 2015). One hundred twenty individuals diagnosed with DSM-IV cocaine use disorder were randomly assigned to the following conditions: (1) galantamine (8 mg/d) plus standard methadone maintenance treatment (treatment as usual [TAU]), (2) placebo plus TAU, (3) galantamine plus computerized CBT plus TAU, or (4) placebo plus computerized CBT plus TAU; medication administration was supervised at the time of daily methadone dosing. The primary cocaine use outcome was change in percent days of abstinence over time. Number of cocaine-negative urine toxicology screens submitted and cognitive function were secondary outcomes.

RESULTS

Random effect regression analysis indicated significant reductions in frequency of cocaine use over time, with significant treatment-by-time effects for both galantamine over placebo (F = 5.3, P = .02, d = 0.34) and computerized CBT over standard methadone treatment (F = 4.2, P = .04, d = 0.30) but no evidence of significant benefit of the combination over either treatment alone. Pretreatment to posttreatment comparisons of multiple indices of cognitive functioning, including sustained attention, indicated no benefit of galantamine over placebo.

CONCLUSIONS

Findings suggest benefits of galantamine and computerized CBT for reducing cocaine use in this sample. Although galantamine did not improve measures of cognitive function in this sample, multiple measures of cognitive function were associated with cocaine use outcomes, underlining the significance of cognitive function in cocaine treatment outcomes.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00809835.

Comparative biophysical characterization: A screening tool for acetylcholinesterase inhibitors

Among neurodegenerative diseases, Alzheimer’s disease (AD) is one of the most grievous disease. The oldest cholinergic hypothesis is used to elevate the level of cognitive impairment and acetylcholinesterase (AChE) comprises the major targeted enzyme in AD. Thus, acetylcholinesterase inhibitors (AChEI) constitutes the essential remedy for the treatment of AD. The study aims to evaluate the interactions between natural molecules and AChE by Surface Plasmon Resonance (SPR). The molecules like alkaloids, polyphenols and substrates of AChE have been considered for the study with a major emphasis on affinity and kinetics. To better understand the activity of small molecules, the investigation is supported by both experimental and theoretical approach such as fluorescence, Circular Dichroism (CD) and molecular docking studies. Amongst the screened ones tannic acid showed promising results compared with others. The methodology followed here have highlighted many molecules with a higher affinity towards AChE and these findings may take lead molecules generated in preclinical studies to treat neurodegenerative diseases. Additionally, we suggest a unique signature for the heterogeneous analyte model using competitive experiments for analyzing simultanous interactions of both the analytes.

Association of status of acetylcholinesterase and ACHE gene 3' UTR variants (rs17228602, rs17228616) with drug addiction vulnerability in pakistani population

Substance addiction is a chronic, relapsing mental disorder Characterized by compulsive drug seeking, and loss of control over drug intake and relapse after prolonged abstinence. Genetics has been shown to contribute towards an individual's vulnerability to addiction. Acetylecholine (ACh), a cholinergic neurotransmitter hydrolyzed by acetylcholinesterase (AChE), is an essential neurotransmitter and neuromodulator in central and peripheral nervous system and has regulatory influence on numerous neuronal functions including addiction. The present study was carried out to investigate the role of acetylcholinesterase (AChE) in addiction through measurement of enzyme activity and to find potential association of ACHE gene 3'UTR variants rs17228602 and rs17228616 in heroin, hashish and poly drug addicts. Both SNPs are located within microRNA (miRNA) recognition sites with potential to affect miRNA/transcript interaction. A total of 122 addicts of heroin, hashish and polydrug were recruited from local rehabilitation centers to participate in this study. AChE activity was measured in blood by Ellman's method. SNP genotyping was performed by restriction fragment length polymorphism (PCR-RFLP) and Sanger sequencing. The AChE activity was found significantly higher (p ≤ 0.005) in addicted cohort (mean ± standard error of mean 0.020 ± 0.001 μmol/L/min; 95% confidence interval (CI) 0.018-0.022) in comparison to non-addicted healthy subjects (0.011 ± 0.001 μmol/L/min; 95% confidence interval CI 0.010-0.013). A statistically significant association of ACHE rs17228602 SNP with addiction vulnerability in dominant (DM: Odd's ratio OR = 2.095, 95% CI = 1.157-3.807 p = 0.009) and allelic genetic models (OR = 1.854 95% CI = 1.082-3.187, p = 0.016) was observed. However, no statistically significant association of rs17228616 SNP with substance abuse disorder was found. The data presented here shows that AChE could play significant role in substance addiction. Further studies with larger sample size and other variants of AChE are recommended to identify novel therapeutic approaches for cholinergic based treatment of addiction.

Nicotine-like discriminative stimulus effects of acetylcholinesterase inhibitors and a muscarinic receptor agonist in Rhesus monkeys

Acetylcholinesterase (AChE) inhibitors and positive allosteric nicotinic acetylcholine receptor (nAChR) modulators are potential pharmacotherapies for nicotine dependence. Because some smoking cessation aids (e.g. varenicline) appear to work by mimicking the effects of nicotine, we used drug discrimination to examine whether AChE inhibitors and nAChR allosteric modulators mimic the effects of nicotine. Rhesus monkeys discriminated 1.78 mg/kg of nicotine s.c. under an FR5 schedule of stimulus-shock termination. Nicotine and the AChE inhibitors donepezil and galantamine dose-dependently increased responding on the nicotine-appropriate lever with ED₅₀ values of 0.35, 0.22, and 0.77 mg/kg, respectively. Donepezil (0.56 mg/kg) produced nicotine-like effects for at least 6 h, whereas the duration of action of galantamine (1.78 mg/kg) was less than 3 h. The positive allosteric nAChR modulator PNU-120596 (up to 10 mg/kg) and midazolam (up to 1.0 mg/kg) produced no more than 22% nicotine-lever responding. Oxotremorine, a muscarinic acetylcholine receptor agonist that was used to explore the extent to which muscarinic receptor agonism might contribute to the effects of AChE inhibitors, produced 94% nicotine-lever responding (ED₅₀ value 0.013 mg/kg). The muscarinic antagonist atropine significantly antagonized the effects of both oxotremorine and nicotine; however, the dose of atropine antagonizing oxotremorine was smaller than the dose required to antagonize nicotine. Collectively, these results suggest that AChE inhibitors can mimic the effects of nicotine by indirectly stimulating both nicotinic and muscarinic receptors. Inasmuch as some smoking cessation aids work by exerting nicotine-like effects, the current results are consistent with the potential use of AChE inhibitors as novel smoking cessation aids.

Mechanisms and Clinical Features of Co-occurring Opioid and Nicotine Use

Purpose of review

To review the literature addressing shared pathophysiological and clinical features of opioid and nicotine use to inform etiology and treatment, and highlight areas for future research.

Recent findings

Opioid and nicotine use co-occur at an alarmingly high rate, and this may be driven in part by interactions between the opioid and cholinergic systems underlying drug reward and the transition to dependence. Pain, among other shared risk factors, is strongly implicated in both opioid and nicotine use and appears to play an important role in their co-occurrence. Additionally, there are important sex/gender considerations that require further study. Regarding treatment, smoking cessation can improve treatment outcomes in opioid use disorder, and pharmacological approaches that target the opioid and cholinergic systems may be effective for treating both classes of substance use disorders.

Summary

Understanding overlapping etiological and pathophysiological mechanisms of opioid and nicotine use can aid in understanding their co-occurrence and guiding their treatment.

The Cholinergic System as a Treatment Target for Opioid Use Disorder

Opioid overdoses recently became the leading cause of accidental death in the US, marking an increase in the severity of the opioid use disorder (OUD) epidemic that is impacting global health. Current treatment protocols for OUD are limited to opioid medications, including methadone, buprenorphine, and naltrexone. While these medications are effective in many cases, new treatments are required to more effectively address the rising societal and interpersonal costs associated with OUD. In this article, we review the opioid and cholinergic systems, and examine the potential of acetylcholine (ACh) as a treatment target for OUD. The cholinergic system includes enzymes that synthesize and degrade ACh and receptors that mediate the effects of ACh. ACh is involved in many central nervous system functions that are critical to the development and maintenance of OUD, such as reward and cognition. Medications that target the cholinergic system have been approved for the treatment of Alzheimer's disease, tobacco use disorder, and nausea. Clinical and preclinical studies suggest that medications such as cholinesterase inhibitors and scopolamine, which target components of the cholinergic system, show promise for the treatment of OUD and further investigations are warranted.

Effects of galantamine on smoking behavior and cognitive performance in treatment-seeking smokers prior to a quit attempt

OBJECTIVE

Drugs that enhance cholinergic transmission have demonstrated promise treating addictive disorders. Galantamine, an acetylcholinesterase inhibitor, may reduce cigarette smoking in otherwise healthy treatment-seeking smokers.

METHODS

The current study is a double-blind, placebo-controlled, study that randomized daily smokers (n = 60) to receive one of two doses of galantamine extended release (8 or 16 mg/day), or a placebo treatment. Participants completed a smoking choice task as well as study measures and cognitive tasks in the laboratory and daily life using ecological momentary assessment. Analysis focused on smoking behavior and satisfaction, cognitive performance, and decision to smoke prior to a quit attempt.

RESULTS

Linear mixed models demonstrated that, compared with placebo, both doses of galantamine reduced smoking in a laboratory choice task (p = 0.006) and decreased urine cotinine levels, but not self-reported cigarettes, during the pre-quit period (p = 0.007). Treatment had minimal effect on smoking satisfaction or cognitive performance.

CONCLUSIONS

The results suggest that galantamine reduces nicotine intake but it is unlikely that galantamine improves cognitive performance in otherwise healthy, treatment-seeking smokers. Larger randomized clinical trials can determine if galantamine adjunctive to addiction treatment can improve smoking treatment outcomes.

Interventions for tobacco use cessation in people in treatment for or recovery from substance use disorders

BACKGROUND

Smoking rates in people with alcohol and other drug dependencies are two to four times those of the general population. Concurrent treatment of tobacco dependence has been limited due to concern that these interventions are not successful in this population or that recovery from other addictions could be compromised if tobacco cessation was combined with other drug dependency treatment.

OBJECTIVES

To evaluate whether interventions for tobacco cessation are associated with tobacco abstinence for people in concurrent treatment for or in recovery from alcohol and other drug dependence.

SEARCH METHODS

We searched the Cochrane Tobacco Addiction Group Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, and clinicaltrials.gov databases, with the most recent search completed in August 2016. A grey literature search of conference abstracts from the Society on Nicotine Research and Treatment and the ProQuest database of digital dissertations yielded one additional study, which was excluded.

SELECTION CRITERIA

We included randomised controlled trials assessing tobacco cessation interventions among people in concurrent treatment for alcohol or other drug dependence or in outpatient recovery programmes.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed study risk of bias and extracted data. We resolved disagreements by consensus. The primary outcome was abstinence from tobacco use at the longest period of follow-up, and the secondary outcome was abstinence from alcohol or other drugs, or both. We reported the strictest definition of abstinence. We summarised effects as risk ratios and 95% confidence intervals (CI). Two clustered studies did not provide intraclass correlation coefficients, and were excluded from the sensitivity analysis. We used the I² statistic to assess heterogeneity.

MAIN RESULTS

Thirty-five randomised controlled trials, one ongoing, involving 5796 participants met the criteria for inclusion in this review. Included studies assessed the efficacy of tobacco cessation interventions, including counselling, and pharmacotherapy consisting of nicotine replacement therapy (NRT) or non-NRT, or the two combined, in both inpatient and outpatient settings for participants in treatment and in recovery. Most studies did not report information to assess the risk of allocation, selection, and attrition bias, and were classified as unclear.Analyses considered the nature of the intervention, whether participants were in treatment or recovery and the type of dependency. Of the 34 studies included in the meta-analysis, 11 assessed counselling, 11 assessed pharmacotherapy, and 12 assessed counselling in combination with pharmacotherapy, compared to usual care or no intervention. Tobacco cessation interventions were significantly associated with tobacco abstinence for two types of interventions. Pharmacotherapy appeared to increase tobacco abstinence (RR 1.60, 95% CI 1.22 to 2.12, 11 studies, 1808 participants, low quality evidence), as did combined counselling and pharmacotherapy (RR 1.74, 95% CI 1.39 to 2.18, 12 studies, 2229 participants, low quality evidence) at the period of longest follow-up, which ranged from six weeks to 18 months. There was moderate evidence of heterogeneity (I² = 56% with pharmacotherapy and 43% with counselling plus pharmacotherapy). Counselling interventions did not significantly increase tobacco abstinence (RR 1.33, 95% CI 0.90 to 1.95).Interventions were significantly associated with tobacco abstinence for both people in treatment (RR 1.99, 95% CI 1.59 to 2.50) and people in recovery (RR 1.33, 95% CI 1.06 to 1.67), and for people with alcohol dependence (RR 1.47, 95% CI 1.20 to 1.81) and people with other drug dependencies (RR 1.85, 95% CI 1.43 to 2.40).Offering tobacco cessation therapy to people in treatment or recovery for other drug dependence was not associated with a difference in abstinence rates from alcohol and other drugs (RR 0.97, 95% CI 0.91 to 1.03, 11 studies, 2231 participants, moderate evidence of heterogeneity (I² = 66%)).Data on adverse effect of the interventions were limited.

AUTHORS' CONCLUSIONS

The studies included in this review suggest that providing tobacco cessation interventions targeted to smokers in treatment and recovery for alcohol and other drug dependencies increases tobacco abstinence. There was no evidence that providing interventions for tobacco cessation affected abstinence from alcohol and other drugs. The association between tobacco cessation interventions and tobacco abstinence was consistent for both pharmacotherapy and combined counselling and pharmacotherapy, for participants both in treatment and in recovery, and for people with alcohol dependency or other drug dependency. The evidence for the interventions was low quality due primarily to incomplete reporting of the risks of bias and clinical heterogeneity in the nature of treatment. Certain results were sensitive to the length of follow-up or the type of pharmacotherapy, suggesting that further research is warranted regarding whether tobacco cessation interventions are associated with tobacco abstinence for people in recovery, and the outcomes associated with NRT versus non-NRT or combined pharmacotherapy. Overall, the results suggest that tobacco cessation interventions incorporating pharmacotherapy should be incorporated into clinical practice to reduce tobacco addiction among people in treatment for or recovery from alcohol and other drug dependence.

A threshold model for opposing actions of acetylcholine on reward behavior: Molecular mechanisms and implications for treatment of substance abuse disorders

The cholinergic system plays important roles in both learning and addiction. Medications that modify cholinergic tone can have pronounced effects on behaviors reinforced by natural and drug reinforcers. Importantly, enhancing the action of acetylcholine (ACh) in the nucleus accumbens and ventral tegmental area (VTA) dopamine system can either augment or diminish these behaviors. A threshold model is presented that can explain these seemingly contradictory results. Relatively low levels of ACh rise above a lower threshold, facilitating behaviors supported by drugs or natural reinforcers. Further increases in cholinergic tone that rise above a second upper threshold oppose the same behaviors. Accordingly, cholinesterase inhibitors, or agonists for nicotinic or muscarinic receptors, each have the potential to produce biphasic effects on reward behaviors. Pretreatment with either nicotinic or muscarinic antagonists can block drug- or food- reinforced behavior by maintaining cholinergic tone below its lower threshold. Potential threshold mediators include desensitization of nicotinic receptors and biphasic effects of ACh on the firing of medium spiny neurons. Nicotinic receptors with high- and low- affinity appear to play greater roles in reward enhancement and inhibition, respectively. Cholinergic inhibition of natural and drug rewards may serve as mediators of previously described opponent processes. Future studies should evaluate cholinergic agents across a broader range of doses, and include a variety of reinforced behaviors.

Repeated administration of an acetylcholinesterase inhibitor attenuates nicotine taking in rats and smoking behavior in human smokers

Tobacco smoking remains the leading cause of preventable death worldwide and current smoking cessation medications have limited efficacy. Thus, there is a clear need for translational research focused on identifying novel pharmacotherapies for nicotine addiction. Our previous studies demonstrated that acute administration of an acetylcholinesterase inhibitor (AChEI) attenuates nicotine taking and seeking in rats and suggest that AChEIs could be repurposed for smoking cessation. Here, we expand upon these findings with experiments designed to determine the effects of repeated AChEI administration on voluntary nicotine taking in rats as well as smoking behavior in human smokers. Rats were trained to self-administer intravenous infusions of nicotine (0.03 mg kg(-1) per 0.59 ml) on a fixed-ratio-5 schedule of reinforcement. Once rats maintained stable nicotine taking, galantamine or donepezil was administered before 10 consecutive daily nicotine self-administration sessions. Repeated administration of 5.0 mg kg(-1) galantamine and 3.0 mg kg(-1) donepezil attenuated nicotine self-administration in rats. These effects were reinforcer-specific and not due to adverse malaise-like effects of drug treatment as repeated galantamine and donepezil administration had no effects on sucrose self-administration, ad libitum food intake and pica. The effects of repeated galantamine (versus placebo) on cigarette smoking were also tested in human treatment-seeking smokers. Two weeks of daily galantamine treatment (8.0 mg (week 1) and 16.0 mg (week 2)) significantly reduced smoking rate as well as smoking satisfaction and reward compared with placebo. This translational study indicates that repeated AChEI administration reduces nicotine reinforcement in rats and smoking behavior in humans at doses not associated with tolerance and/or adverse effects.

The case of galantamine: repurposing and late blooming of a cholinergic drug

Galantamine is a reversible inhibitor of cholinesterases and an allosteric modulator of neuronal nicotinic acetylcholine receptors which restores reduced cholinergic tone in the central and peripheral nervous system. Characterized in the early 1950s in Bulgaria, it saw limited use for paralytic and neuropathic conditions until the cholinergic hypothesis of Alzheimer’s disease opened totally new perspectives for its utility. Although constricted supplies at extremely high prices and a fragmented patent situation made its repurposing challenging, galantamine was globally launched as an Alzheimer’s disease drug in 2000. Many other possible uses have been clinically investigated, and might yet develop into another drug career. This case study is presented as an example for classical on-target drug repurposing and the challenges that such a project can face.

Acetylcholine is a key neurotransmitter that regulates many functions in the CNS, as well as in other body organs, through the cholinergic system. Galantamine is a well-known alkaloid drug that modulates this system toward a higher cholinergic tone, and has been put to several therapeutic uses during the past decades, most recently, for Alzheimer’s disease. However, its known actions might allow repurposing toward even more applications not only in psychiatry and neurology but also in eye medicine and even in immunology. This article summarizes the claims, the evidence and the potential of galantamine beyond its currently approved uses.

Donepezil, an acetylcholinesterase inhibitor, attenuates nicotine self-administration and reinstatement of nicotine seeking in rats

Nicotine craving and cognitive impairments represent core symptoms of nicotine withdrawal and predict relapse in abstinent smokers. Current smoking cessation pharmacotherapies have limited efficacy in preventing relapse and maintaining abstinence during withdrawal. Donepezil is an acetylcholinesterase inhibitor that has been shown previously to improve cognition in healthy non-treatment-seeking smokers. However, there are no studies examining the effects of donepezil on nicotine self-administration and/or the reinstatement of nicotine-seeking behavior in rodents. The present experiments were designed to determine the effects of acute donepezil administration on nicotine taking and the reinstatement of nicotine-seeking behavior, an animal model of relapse in abstinent human smokers. Moreover, the effects of acute donepezil administration on sucrose self-administration and sucrose seeking were also investigated in order to determine whether donepezil's effects generalized to other reinforced behaviors. Acute donepezil administration (1.0 or 3.0 mg/kg, i.p.) attenuated nicotine, but not sucrose self-administration maintained on a fixed-ratio 5 schedule of reinforcement. Donepezil administration also dose-dependently attenuated the reinstatement of both nicotine- and sucrose-seeking behaviors. Commonly reported adverse effects of donepezil treatment in humans are nausea and vomiting. However, at doses required to attenuate nicotine self-administration in rodents, no effects of donepezil on nausea/malaise as measured by pica were observed. Collectively, these results indicate that increased extracellular acetylcholine levels are sufficient to attenuate nicotine taking and seeking in rats and that these effects are not due to adverse malaise symptoms such as nausea.

Optimizing treatments for nicotine dependence by increasing cognitive performance during withdrawal

INTRODUCTION

Current FDA-approved smoking cessation pharmacotherapies have limited efficacy and are associated with high rates of relapse. Therefore, there is a clear need to develop novel antismoking medications. Nicotine withdrawal is associated with cognitive impairments that predict smoking relapse. It has been proposed that these cognitive deficits are a hallmark of nicotine withdrawal that could be targeted in order to prevent smoking relapse. Thus, pharmacotherapies that increase cognitive performance during nicotine withdrawal may represent potential smoking cessation agents.

AREAS COVERED

The authors review the clinical literature demonstrating that nicotine withdrawal is associated with deficits in working memory, attention and response inhibition. They then briefly summarize different classes of compounds and strategies to increase cognitive performance during nicotine withdrawal. Particular emphasis has been placed on translational research in order to highlight areas for which there is strong rationale for pilot clinical trials of potential smoking cessation medications.

EXPERT OPINION

There is emerging evidence that supports deficits in cognitive function as a plausible nicotine withdrawal phenotype. The authors furthermore believe that the translational paradigms presented here may represent efficient and valid means for the evaluation of cognitive-enhancing medications as possible treatments for nicotine dependence.

EPA Guidance on Tobacco Dependence and Strategies for Smoking Cessation in People with Mental Illness

Tobacco dependence is the most common substance use disorder in adults with mental illness. The prevalence rates for tobacco dependence are two to four times higher in these patients than in the general population. Smoking has a strong, negative influence on the life expectancy and quality of life of mental health patients, and remains the leading preventable cause of death in this group. Despite these statistics, in some countries smokers with mental illness are disadvantaged in receiving intervention and support for their tobacco dependence, which is often overlooked or even tolerated. This statement from the European Psychiatric Association (EPA) systematically reviews the current evidence on tobacco dependence and withdrawal in patients with mental illness and their treatment. It provides seven recommendations for the core components of diagnostics and treatment in this patient group. These recommendations concern: (1) the recording process, (2) the timing of the intervention, (3) counselling specificities, (4) proposed treatments, (5) frequency of contact after stopping, (6) follow-up visits and (7) relapse prevention. They aim to help clinicians improve the care, health and well-being of patients suffering from mental illness.

Nicotine aversion: Neurobiological mechanisms and relevance to tobacco dependence vulnerability

Nicotine stimulates brain reward circuitries, most prominently the mesocorticolimbic dopamine system, and this action plays a critical in establishing and maintaining the tobacco smoking habit. Compounds that attenuate nicotine reward are considered promising therapeutic candidates for tobacco dependence, but many of these agents have other actions that limit their potential utility. Nicotine is also highly noxious, particularly at higher doses, and aversive reactions to nicotine after initial exposure can decrease the likelihood of developing a tobacco habit in many first time smokers. Nevertheless, relatively little is known about the mechanisms of nicotine aversion. The purpose of this review is to present recent new insights into the neurobiological mechanisms that regulate avoidance of nicotine. First, the role of the mesocorticolimbic system, so often associated with nicotine reward, in regulating nicotine aversion is highlighted. Second, genetic variation that modifies noxious responses to nicotine and thereby influences vulnerability to tobacco dependence, in particular variation in the CHRNA5-CHRNA3-CHRNB4 nicotinic acetylcholine receptor (nAChR) subunit gene cluster, will be discussed. Third, the role of the habenular complex in nicotine aversion, primarily medial habenular projections to the interpeduncular nucleus (IPN) but also lateral habenular projections to rostromedial tegmental nucleus (RMTg) and ventral tegmental area (VTA) are reviewed. Forth, brain circuits that are enriched in nAChRs, but whose role in nicotine avoidance has not yet been assessed, will be identified. Finally, the feasibility of developing novel therapeutic agents for tobacco dependence that act not by blocking nicotine reward but by enhancing nicotine avoidance will be considered. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

Smoking behaviour and mental health disorders--mutual influences and implications for therapy

Tobacco use is strongly associated with a variety of psychiatric disorders. Smokers are more likely than non-smokers to meet current criteria for mental health conditions, such as mood disorders, anxiety disorders and psychosis. Evidence also suggest that smokers with psychiatric disorders may have more difficulty quitting, offering at least a partial explanation for why smoking rates are higher in this population. The mechanisms linking mental health conditions and cigarette smoking are complex and likely differ across each of the various disorders. The most commonly held view is that patients with mental health conditions smoke in an effort to regulate the symptoms associated with their disorder. However some recent evidence suggests that quitting smoking may actually improve mental health symptoms. This is particularly true if the tobacco cessation intervention is integrated into the context of ongoing mental health treatment. In this paper we reviewed and summarized the most relevant knowledge about the relationship between tobacco use and dependence and psychiatric disorders. We also reviewed the most effective smoking cessation strategies available for patients with psychiatric comorbidity and the impact of smoking behavior on psychiatric medication.

Cognitive function during nicotine withdrawal: Implications for nicotine dependence treatment

Nicotine withdrawal is associated with deficits in neurocognitive function including sustained attention, working memory, and response inhibition. Several convergent lines of evidence suggest that these deficits may represent a core dependence phenotype and a target for treatment development efforts. A better understanding of the mechanisms underlying withdrawal-related cognitive deficits may lead to improve nicotine dependence treatment. We begin with an overview of the neurocognitive effects of withdrawal in rodent and human models, followed by discussion of the neurobehavioral mechanisms that are thought to underlie these effects. We then review individual differences in withdrawal-related neurocognitive effects including genetics, gender, and psychiatric comorbidity. We conclude with a discussion of the implications of this research for developing improved therapies, both pharmacotherapy and behavioral treatments, that target cognitive symptoms of nicotine withdrawal. This article is part of a Special Issue entitled 'NIDA 40th Anniversary Issue'.

Translational research in nicotine dependence

Nicotine addiction accounts for 4.9 million deaths each year. Furthermore, although smoking represents a significant health burden in the United States, at present there are only three FDA-approved pharmacotherapies currently on the market: (1) nicotine replacement therapy, (2) bupropion, and (3) varenicline. Despite this obvious gap in the market, the complexity of nicotine addiction in addition to the increasing cost of drug development makes targeted drug development prohibitive. Furthermore, using combinations of mouse and human studies, additional treatments could be developed from off-the-shelf, currently approved medication lists. This article reviews translational studies targeting manipulations of the cholinergic system as a viable therapeutic target for nicotine addiction.

APOE ɛ4, an Alzheimer's disease susceptibility allele, and smoking cessation

Possessing an apolipoprotein E (APOE) ɛ4 allele, advanced age and smoking are risk factors for Alzheimer's disease and cognitive decline. Deficits in cognitive function also increase risk for smoking relapse. Data from 917 adult smokers of European ancestry were pooled across three randomized trials of smoking cessation. We examined whether smokers who carry at least one ɛ4 allele (n=252) have more difficulty quitting smoking compared with noncarriers (n=665), and whether age moderated this association. The genotype by age interaction was significant for 7-day point-prevalence abstinence rates (P=0.04) and time to 7-day failure (P=0.03). Among smokers over age 60, ɛ4 carriers were less likely to quit (odds ratio=0.27, P=0.018) and relapsed more quickly (hazard ratio=3.38, P=0.001) compared with noncarriers. The genotype association with relapse was nonsignificant among younger smokers. An increased understanding of the underlying pathophysiological mechanisms of this association could facilitate the development of targeted therapies for smokers with increased risk for cognitive decline.

Galantamine attenuates some of the subjective effects of intravenous nicotine and improves performance on a Go No-Go task in abstinent cigarette smokers: a preliminary report

RATIONALE

Galantamine (GAL), a reversible and competitive inhibitor of acetylcholinesterase, is used clinically in the treatment of Alzheimer's dementia. Some preclinical and clinical studies support the potential efficacy of cholinesterase inhibitors for smoking cessation, although their effects on the behavioral and physiological responses to nicotine have not been examined. The goal of this study was to characterize GAL's actions on multiple outcomes, including withdrawal severity and cognitive performance, as well as subjective and physiological responses to nicotine administered intravenously.

METHODS

A total of 12 smokers participated in a double-blind, placebo-controlled, crossover study. Smokers had two 4-day treatment periods, assigned in random sequence, to GAL (8 mg/day) or placebo treatment. On day 4 of each treatment phase, smokers had an experimental session in which they received an intravenous (IV) dose of saline or 1 mg/70 kg nicotine, 1 h apart, in a random order.

RESULTS

GAL attenuated the self-reported rating of "craving for cigarettes" and prevented decrements in performance in a Go/No-Go task. In response to IV nicotine, GAL treatment attenuated the self-report ratings of "like the drug effects," "good drug effects," "bad drug effects," and "stimulated."

CONCLUSIONS

These findings support the potential utility of GAL as a treatment for smoking cessation.

Cognitive effects of the acetylcholinesterase inhibitor, donepezil, in healthy, non-treatment seeking smokers: a pilot feasibility study

BACKGROUND

There is a need to identify medications to aid in smoking cessation. Reducing withdrawal-related cognitive deficits represents a pharmacological target for new pharmacotherapies. Endogenous acetylcholine levels, which are modulated by acetylcholinesterase inhibitors (AChEIs), play an important role in smoking behavior and cognition. This pilot feasibility study tested whether an AChEI, donepezil, enhanced cognitive performance among healthy smokers.

METHODS

Eighteen non-treatment seeking daily smokers (6 female) received either donepezil (5 mg q.d) or placebo (double-blind; 2:1 allocation ratio) for 4 weeks. Smoking rate, side effects, and neurocognitive measures of working memory (Letter-N-back) and sustained attention (Penn Continuous Performance Task) were assessed weekly.

RESULTS

For the working memory task, there was a significant group×load×time interaction (p=0.03) indicating that the donepezil group demonstrated an increase in true positives from baseline to week 4 at the highest working memory load (3-back). The placebo group showed no change in accuracy. For the sustained attention task, there was a marginal effect in the same direction for discriminability, or d', p=0.08. There were no significant effects on reaction time during either task. There was also a reduction in cigarettes per day in the placebo group, but not the donepezil group.

CONCLUSIONS

AChEIs, such as donepezil, may have pro-cognitive effects among healthy smokers while they continue to smoke as usual. Given the association between cognitive deficits and relapse, AChEIs should be explored as potential therapeutics for smoking cessation.

Development of novel pharmacotherapeutics for tobacco dependence: progress and future directions

INTRODUCTION

The vast majority of tobacco smokers seeking to quit will relapse within the first month of abstinence. Currently available smoking cessation agents have limited utility in increasing rates of smoking cessation and in some cases there are notable safety concerns related to their use. Hence, there is a pressing need to develop safer and more efficacious smoking cessation medications.

METHODS

Here, we provide an overview of current efforts to develop new pharmacotherapeutic agents to facilitate smoking cessation, identified from ongoing clinical trials and published reports.

RESULTS

Nicotine is considered the major addictive agent in tobacco smoke, and the vast majority of currently available smoking cessation agents act by modulating nicotinic acetylcholine receptor (nAChR) signaling. Accordingly, there is much effort directed toward developing novel small molecule therapeutics and biological agents such as nicotine vaccines for smoking cessation that act by modulating nAChR activity. Our increasing knowledge of the neurobiology of nicotine addiction has revealed new targets for novel smoking cessation therapeutics. Indeed, we highlight many examples of novel small molecule drug development around non-nAChR targets. Finally, there is a growing appreciation that medications already approved for other disease indications could show promise as smoking cessation agents, and we consider examples of such repurposing efforts.

CONCLUSION

Ongoing clinical assessment of potential smoking cessation agents offers the promise of new effective medications. Nevertheless, much of our current knowledge of molecular mechanisms of nicotine addiction derived from preclinical studies has not yet been leveraged for medications development.

Acetylcholine, drug reward and substance use disorder treatment: intra- and interindividual striatal and accumbal neuron ensemble heterogeneity may explain apparent discrepant findings

Converging evidence from different independent laboratories suggests that acetylcholine may play an important role in drug reward and that modulation of the cholinergic system may be useful for the treatment of substance use disorders. In this commentary, we try to reconcile apparently discrepant animal behavioral, human behavioral and clinical data with a unifying hypothesis positing that the modulation of drug-versus natural stimuli-mediated reward by cholinergic interneurons in the nucleus accumbens (and the dorsal striatum) is restricted to distinct neuron ensembles that show considerable intra- and interindividual variation with respect to their spatial distribution. The precise targeting of these interindividually variable neuron ensembles would be a prerequisite for a successful pharmacotherapy based on the modulation of the cholinergic system. We also provide experimental data to support our unifying hypothesis.

Galantamine, an acetylcholinesterase inhibitor and positive allosteric modulator of nicotinic acetylcholine receptors, attenuates nicotine taking and seeking in rats

Current smoking cessation pharmacotherapies have limited efficacy in preventing relapse and maintaining abstinence during withdrawal. Galantamine is an acetylcholinesterase inhibitor that also acts as a positive allosteric modulator of nicotinic acetylcholine receptors. Galantamine has recently been shown to reverse nicotine withdrawal-induced cognitive impairments in mice, which suggests that galantamine may function to prevent relapse in human smokers. However, there are no studies examining whether galantamine administration modulates nicotine self-administration and/or reinstatement of nicotine seeking in rodents. The present experiments were designed to determine the effects of galantamine administration on nicotine taking and reinstatement of nicotine-seeking behavior, an animal model of relapse. Moreover, the effects of galantamine on sucrose-maintained responding and sucrose seeking were also examined to determine whether galantamine's effects generalized to other reinforced behaviors. An inverted U-shaped dose-response curve was obtained when animals self-administered different unit doses of nicotine with the highest responding for 0.03 mg/kg per infusion of nicotine. Acute galantamine administration (5.0 mg/kg, i.p.) attenuated nicotine self-administration when animals were maintained on either a fixed-ratio 5 (FR5) or progressive ratio (PR) schedule of reinforcement. Galantamine administration also attenuated the reinstatement of nicotine-seeking behavior. No significant effects of galantamine on sucrose self-administration or sucrose reinstatement were noted. Acetylcholinesterase inhibitors have also been shown to produce nausea and vomiting in humans. However, at doses required to attenuate nicotine self-administration, no effects of galantamine on nausea/malaise as measured by pica were noted. These results indicate that increased extracellular acetylcholine levels and/or nicotinic acetylcholine receptor stimulation is sufficient to attenuate nicotine taking and seeking in rats and that these effects are reinforcer selective and not due to adverse malaise symptoms such as nausea.

Pharmacogenetics of smoking cessation: role of nicotine target and metabolism genes

Many smokers attempt to quit smoking but few are successful in the long term. The heritability of nicotine addiction and smoking relapse have been documented, and research is focused on identifying specific genetic influences on the ability to quit smoking and response to specific medications. Research in genetically modified cell lines and mice has identified nicotine acetylcholine receptor subtypes that mediate the pharmacological and behavioral effects of nicotine sensitivity and withdrawal. Human genetic association studies have identified single nucleotide polymorphisms (SNPs) in genes encoding nicotine acetylcholine receptor subunits and nicotine metabolizing enzymes that influence smoking cessation phenotypes. There is initial promising evidence for a role in smoking cessation for SNPs in the β2 and α5/α3/β4 nAChR subunit genes; however, effects are small and not consistently replicated. There are reproducible and clinically significant associations of genotypic and phenotypic measures of CYP2A6 enzyme activity and nicotine metabolic rate with smoking cessation as well as response to nicotine replacement therapies and bupropion. Prospective clinical trials to identify associations of genetic variants and gene-gene interactions on smoking cessation are needed to generate the evidence base for both medication development and targeted therapy approaches based on genotype.

Evaluation of the effects of rivastigmine on cigarette smoking by methamphetamine-dependent volunteers

Compared to smokers alone, smokers with co-morbid substance use disorders are at greater risk of suffering from smoking-related death. Despite this, relatively few studies have examined smoking cessation treatments for those with stimulant dependence. In the current study, we sought to evaluate the effects produced by short-term exposure to the cholinesterase inhibitor rivastigmine (0, 3 or 6 mg) on cigarette smoking in non-treatment-seeking, methamphetamine-dependent volunteers. This was a double-blind, placebo-controlled, crossover study that took place over 9 days. The data indicate that rivastigmine treatment did not alter Fagerström Test for Nicotine Dependence scores, carbon monoxide readings, or cigarettes smoked per day, but a trend toward reduced urges to smoke (p<0.09) was detected during treatment with rivastigmine 3mg. These data, while preliminary, indicate that cholinesterase inhibitors warrant consideration as treatments for nicotine dependence, including use in stimulant-dependent individuals who exhibit significantly higher rates of smoking than the general population.

Cognitive enhancers in the treatment of substance use disorders: clinical evidence

Attenuation of drug reward has been the major focus of medication development in the addiction area to date. With the growth of research in the area of cognitive neuroscience, the importance of executive function and inhibitory cognitive control in addictive disorders is becoming increasingly apparent. An emerging strategy in the pharmacotherapy of addictions and other psychiatric disorders involves the use of medications that improve cognitive function. In particular, agents that facilitate inhibitory and attentional control, improve abstraction, planning and mental flexibility could be beneficial in the treatment of substance use disorders. Because there are multiple neurotransmitter systems involved in the regulation of cognitive function, agents from a number of drug classes have been tested. In particular, agents acting through the cholinergic, adrenergic and glutamatergic systems have shown potential for improving cognitive function in a number of psychiatric and neurologic disorders, but most of these agents have not been tested in the treatment of individuals with substance use disorders. This manuscript provides a review of clinical data supporting the use of the major classes of cognitive enhancing agents in substance use disorders. Agents that have shown promise in cognitive enhancement in other disorders, and have a theoretical or mechanistic rationale for application to substance use disorders are also highlighted.

The effects of galantamine on nicotine withdrawal-induced deficits in contextual fear conditioning in C57BL/6 mice

Current smoking cessation aids are relatively ineffective at maintaining abstinence during withdrawal. Nicotine withdrawal is associated with a variety of symptoms including cognitive deficits and targeting these deficits may be a useful strategy for maintaining abstinence. Galantamine is an acetylcholinesterase inhibitor and allosteric modulator of nicotinic acetylcholine receptors (nAChRs) with cognitive enhancing effects that may alleviate cognitive deficits associated with nicotine withdrawal. The effects of galantamine on nicotine withdrawal-induced deficits in contextual fear conditioning in C57BL/6 mice were examined. An initial acute dose-response experiment revealed that 0.5 and 1mg/kg galantamine had no effect on fear conditioning. To determine if galantamine would reverse nicotine withdrawal-related deficits in contextual fear conditioning, mice were implanted with osmotic mini-pumps that delivered chronic saline or 6.3mg/kg/d nicotine for 12 days and then pumps were removed. Training and testing of fear conditioning occurred 24 and 48 h later, respectively. Nicotine withdrawal disrupted contextual fear conditioning, which was reversed with 1 but not 0.5mg/kg galantamine. Across all conditions in both studies 2mg/kg galantamine led to high levels of freezing that were likely due to nonspecific effects. The ability of galantamine to reverse nicotine withdrawal-deficits in contextual conditioning is likely mediated through enhanced levels of acetylcholine via inhibition of acetylcholinesterase, potentiation of hippocampal α4β2* nAChRs, or both. The present study suggests that acetylcholinesterase inhibitors and/or drugs that act as allosteric modulators of nAChRs might be targets for smoking cessation aids because they may alleviate withdrawal symptoms such as cognitive deficits that can lead to relapse.

Addiction research centres and the nurturing of creativity department of addictive behaviour and addiction medicine, central institute of Mental Health, Mannheim, University of Heidelberg

Addictive behaviour is as prevalent in Germany as in other western countries, but in contrast to some European countries and the United States, very little money was given to this research field. Change came in the early 1990s, when the German government started to launch specific grants for addiction research. The first chair in addiction research was created in 1999 (Karl Mann) at the Central Institute of Mental Health Mannheim (CIMH; University of Heidelberg). The recruitment of a pre-clinical alcohol researcher as head of the department of psychopharmacology followed (Rainer Spanagel). This 'addiction research cluster' collaborates with several research groups at the CIMH (such as genetics). We inaugurated a clinical trial network which now comprises up to 20 treatment centres throughout Germany. Like most authors, we found effect sizes of different treatment modalities more in the low to moderate range, perhaps because of the heterogeneity of large patient samples. Therefore, we concentrated upon the biological basis of addiction in order to define more homogeneous 'subtypes' of patients for a better match with existing treatments. Results concerning genetics and neuroimaging (both animal and human) are promising, and could move our field towards a more personalized treatment approach. Our funding has been extended over the years, including involvement in several large European grants. We are studying substance-related problems as well as so-called 'behavioural addictions'. As a natural consequence of this development, we are deeply involved both in informing the general public on addiction issues as well as in counselling policy makers in Germany.

Convergent evidence that choline acetyltransferase gene variation is associated with prospective smoking cessation and nicotine dependence

The ability to quit smoking is heritable, yet few genetic studies have investigated prospective smoking cessation. We conducted a systems-based genetic association analysis in a sample of 472 treatment-seeking smokers of European ancestry after 8 weeks of transdermal nicotine therapy for smoking cessation. The genotyping panel included 169 single-nucleotide polymorphisms (SNPs) in 7 nicotinic acetylcholine receptor subunit genes and 4 genes in the endogenous cholinergic system. The primary outcome was smoking cessation (biochemically confirmed) at the end of treatment. SNPs clustered in the choline acetyltransferase (ChAT) gene were individually identified as nominally significant, and a 5-SNP haplotype (block 6) in ChAT was found to be significantly associated with quitting success. Single SNPs in ChAT haplotype block 2 were also associated with pretreatment levels of nicotine dependence in this cohort. To replicate associations of SNPs in haplotype blocks 2 and 6 of ChAT with nicotine dependence in a non-treatment-seeking cohort, we used data from an independent community-based sample of 629 smokers representing 200 families of European ancestry. Significant SNP and haplotype associations were identified for multiple measures of nicotine dependence. Although the effect sizes in both cohorts are modest, converging data across cohorts and phenotypes suggest that ChAT may be involved in nicotine dependence and ability to quit smoking. Additional sequencing and characterization of ChAT may reveal functional variants that contribute to nicotine dependence and smoking cessation.

Cholinergic functioning in stimulant addiction: implications for medications development

Acetylcholine, the first neurotransmitter discovered, participates in many CNS functions, including sensory and motor processing, sleep, nociception, mood, stress response, attention, arousal, memory, motivation and reward. These diverse cholinergic effects are mediated by nicotinic- and muscarinic-type cholinergic receptors (nAChR and mAChR, respectively). The goal of this review is to synthesize a growing literature that supports the potential role of acetylcholine as a treatment target for stimulant addiction. Acetylcholine interacts with the dopaminergic reward system in the ventral tegmental area, nucleus accumbens and prefrontal cortex. In the ventral tegmental area, both nAChR and mAChR stimulate the dopaminergic system. In the nucleus accumbens, cholinergic interneurons integrate cortical and subcortical information related to reward. In the prefrontal cortex, the cholinergic system contributes to the cognitive aspects of addiction. Preclinical studies support a facilitative role of nicotinic receptor agonists in the development of stimulant addiction. In contrast, nonselective muscarinic receptor agonists seem to have an inhibitory role. In human studies, acetylcholinesterase inhibitors, which increase synaptic acetylcholine levels, have shown promise for the treatment of stimulant addiction. Further studies testing the efficacy of cholinergic medications for stimulant addiction are warranted.

Alcoholism: A Systems Approach From Molecular Physiology to Addictive Behavior

Alcohol consumption is an integral part of daily life in many societies. The benefits associated with the production, sale, and use of alcoholic beverages come at an enormous cost to these societies. The World Health Organization ranks alcohol as one of the primary causes of the global burden of disease in industrialized countries. Alcohol-related diseases, especially alcoholism, are the result of cumulative responses to alcohol exposure, the genetic make-up of an individual, and the environmental perturbations over time. This complex gene × environment interaction, which has to be seen in a life-span perspective, leads to a large heterogeneity among alcohol-dependent patients, in terms of both the symptom dimensions and the severity of this disorder. Therefore, a reductionistic approach is not very practical if a better understanding of the pathological processes leading to an addictive behavior is to be achieved. Instead, a systems-oriented perspective in which the interactions and dynamics of all endogenous and environmental factors involved are centrally integrated, will lead to further progress in alcohol research. This review adheres to a systems biology perspective such that the interaction of alcohol with primary and secondary targets within the brain is described in relation to the behavioral consequences. As a result of the interaction of alcohol with these targets, alterations in gene expression and synaptic plasticity take place that lead to long-lasting alteration in neuronal network activity. As a subsequent consequence, alcohol-seeking responses ensue that can finally lead via complex environmental interactions to an addictive behavior.

Lack of beneficial galantamine effect for smoking behavior: a double-blind randomized trial in people with schizophrenia

Cigarette smoking is in schizophrenia is prevalent and may be due to self-medicating attempts to improve cognitive deficits related to alpha7 and alpha4beta2 nicotinic receptor dysregulation. Galantamine is an acetylcholinesterase inhibitor that acts as a positive allosteric modulator of nicotine acetylcholine receptors including both the alpha4beta2 and alpha7 subunits. In a double-blind randomized clinical trial galantamine was compared to placebo for its effects on cognitive functioning in people with schizophrenia. This manuscript reports findings for galantamine's effect on smoking behavior in people from this 12-week trial who were smokers (18 galantamine, 25 placebo). Expired CO was measured every 2 weeks and the Fagerström Test for Nicotine Dependence (FTND) was administered at baseline and endpoint. Expired CO measures in galantamine subjects were 23.0+/-9.7 ppm and 21.1+/-10.3 ppm at baseline and Week 12, respectively, compared to 20.1+/-8.5 ppm and 21.0+/-10.3 ppm at baseline and Week 12 in placebo subjects. The mean tau-b correlation between expired CO level and visit was -0.05+/-0.41 in the galantamine group and 0.13+/-0.42 in the placebo group (F=0.73, df=1,38, p=0.40), suggesting that there were no trends toward increased or decreased smoking in either group. Mean FTND scores in the galantamine group were 4.9+/-2.5 at baseline and 5.2+/-2.2 at Week 12, compared to 4.1+/-2.6 at baseline and 3.7+/-2.6 at Week 12 in the placebo group (Mantel-Haenszel chi2=5.53, df=1, p=0.019), for an effect size of 0.4. These results suggest that galantamine has no effect on cigarette smoking and that during galantamine treatment nicotine dependency scores worsen.