Pharmacotherapy for smoking cessation in schizophrenia: a systematic review

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.

Tobacco treatment in the setting of lung cancer screening

PURPOSE OF REVIEW

Lung cancer screening by low-dose CT is an increasingly implemented preventive medicine tool. Screening for lung cancer is incomplete without addressing problematic tobacco use, the greatest modifiable risk factor in the development of lung cancer. This review describes recent work related to lung cancer screening and treatment of tobacco use in that context.

RECENT FINDINGS

Implementation of lung cancer screening demonstrates socioeconomic disparities in terms of adherence to screening as well as likelihood of successful tobacco dependence treatment. Active tobacco dependence is a common comorbidity for patients undergoing lung cancer screening. The optimal implementation of tobacco dependence treatment in the context of lung cancer screening is still an area of active investigation.

SUMMARY

Treatment of tobacco dependence at time of lung cancer screening is a major opportunity for clinicians to intervene to reduce the major modifiable risk factor for lung cancer, tobacco use. Providing comprehensive tobacco dependence treatment is most effective using combination pharmacologic and behavioral interventions. Practices providing comprehensive treatment will benefit from accurate documentation for billing and coding and supplementing with external resources such as state Quit Lines.

Dose-dependent effects of Varenicline on tobacco craving and withdrawal in tobacco smokers with and without schizophrenia

BACKGROUND

People with schizophrenia (SCZ) have significantly higher tobacco smoking rates and lower quit rates than the general population. Varenicline, a partial agonist at α4β2 nicotinic acetylcholine receptors (nAChRs) is an effective smoking cessation pharmacotherapy, however, investigation into its effects in SCZ are less well-studied and mechanisms may differ from non-psychiatric controls due to dysregulation in nAChR neurotransmission associated with SCZ. Here, we investigate whether Varenicline attenuates acute abstinence-induced increases in craving and withdrawal in participants with and without SCZ.

METHODS

Following biochemically-verified overnight abstinence and subsequent smoking reinstatement, individuals with nicotine-dependence (n = 13 SCZ or schizoaffective; n = 12 controls) were assessed on the Minnesota Nicotine Withdrawal Scale (MNWS) and Tiffany Questionnaire for Smoking Urges (TQSU). Participants were pretreated in a double-blind, counterbalanced manner with Varenicline (0, 1 or 2 mg/day x 3 days) over three separate weeks. Data were analyzed using linear mixed-effects modelling and estimated marginal means.

RESULTS

Robust effects of smoking abstinence were observed on TQSU and MNWS scores in SCZ and control participants. Relative to 1 mg, 2 mg/day of Varenicline attenuated abstinence-induced increases in craving (TQSU Factor 1 d=-0.47, p = .006; TQSU Factor 2 d=-0.42, p = .008) and withdrawal (MNWS d=-0.35, p = .03) in both groups.

CONCLUSION

Our preliminary findings suggest that subacute Varenicline treatment reduces abstinence-induced craving and withdrawal in participants with and without SCZ. The efficacy of Varenicline on tobacco withdrawal and craving requires further study.

Association Study of Polymorphisms in Neuronal Nicotinic Acetylcholine Receptor Subunit Genes With Schizophrenia in the Han Chinese Population

OBJECTIVE

To investigate the relation between nicotinic acetylcholine receptor subunit (nAChR) genes and schizophrenia, and the relation between tag single nucleotide polymorphism (rs1317286, rs1044396, rs6494212, rs16969968, and rs684513) and schizophrenia in Han Chinese people.

METHODS

The protein-protein interaction (PPI) network among nAChR protein and 350 proteins encoded by schizophrenia-related susceptibility genes was constructed through the String database to explore whether nAChR genes were associated with schizophrenia in these known databases. Then, five single nucleotide polymorphisms (SNPs) of CHRNA3 (rs1317286), CHRNA4 (rs1044396), CHRNA7 (rs6494212), and CHRNA5 (rs16969968, rs684513) were analyzed in a sample of 1,035 schizophrenic patients and 816 healthy controls. The interaction between the markers was analyzed using multifactor dimensionality reduction (MDR) software. Power analysis was performed using the Quanto program.

RESULTS

There are no significant differences in genotype or allele distribution were identified between the patients and controls (p>0.05). The haplotypes constructed by four markers rs1317286, rs6494212, rs16969968, and rs684513 were not associated with schizophrenia either. However, a significant association between models made of rs1317286, rs1044396, rs6494212, and rs684513 and schizophrenia was revealed in interaction analysis (p<0.05).

CONCLUSION

The nAChR protein may have effects on the development of schizophrenia through the interaction with proteins encoded by schizophrenia-related susceptibility genes, but no relation was found between selected polymorphisms and schizophrenia in the collected Han Chinese people. However, interaction analysis suggested four-SNP model has an important effect on schizophrenia.

Non-pharmacological interventions for smoking in persons with schizophrenia spectrum disorders - A systematic review

INTRODUCTION

The rates and intensity of tobacco use are higher in persons with schizophrenia spectrum disorders (PwS) compared to the general population, contributing to increased morbidity and mortality. We aimed to systematically review randomised control trials (RCTs) that used non-pharmacological interventions to reduce or cease tobacco use in PwS.

METHODS

We searched PubMed, EBSCO, ProQuest and PsycINFO for RCTs, published between January 2004 and December 2019, which included adult PwS. Studies providing self-reported or biochemically measured reduction of tobacco use and cessation after a minimum follow-up period of 6 months were included. We used the Cochrane Risk of Bias (ROB) tool for assessing the quality of selected studies.

RESULTS

Of the six included trials, two compared non-pharmacological interventions alone while four compared combinations with pharmacological interventions with routine care. The non-pharmacological interventions varied widely. Continuous abstinence and seven days point-prevalence abstinence (7 PPA) were reported in 2 and 4 studies respectively, with one study assessing both. All six trials measured reduction in the number of cigarettes smoked, but only two trials reported significant reductions in intervention groups. No worsening of psychiatric symptoms was reported.

CONCLUSIONS

Two trials were rated as "low risk", and 4 trials as "some concerns" on the ROB tool. Heterogeneity among trials precluded meta-analysis. Abstinence was significantly higher among groups who were given combination interventions, and intervention groups in studies showed significantly greater or a trend towards reduction in the number of cigarettes smoked than controls. No specific method of non-pharmacological management was conclusively favoured.

IMPLICATIONS

Reduction in cigarettes smoked seemed to significantly favour or show non-significant trends favouring intervention groups over controls, while abstinence was significantly higher among groups in studies that used specific combination interventions. Combinations of pharmacological and non-pharmacological treatment were better than non-pharmacological interventions used in isolation, for facilitating abstinence and reduction in cigarettes smoked. Specific interventions such as home visits and contingent reinforcement merit further study. Trials included in this study were conducted in high-income and upper-middle-income countries. Thus, the application of these interventions to low and middle-income countries (LAMICs) needs to be further studied.

Cardiovascular disease in patients with severe mental illness

Individuals diagnosed with schizophrenia or bipolar disorder have a life expectancy 15-20 years shorter than that in the general population. The rate of unnatural deaths, such as suicide and accidents, is high for these patients. Despite this increased proportion of unnatural deaths, physical conditions account for approximately 70% of deaths in patients with either schizophrenia or bipolar disorder, with cardiovascular disease contributing 17.4% and 22.0% to the reduction in overall life expectancy in men and women, respectively. Risk factors for cardiovascular disease, such as smoking, unhealthy diet and lack of exercise, are common in these patients, and lifestyle interventions have been shown to have small effects. Pharmacological interventions to reduce risk factors for cardiovascular disease have been proven to be effective. Treatment with antipsychotic drugs is associated with reduced mortality but also with an increased risk of weight gain, dyslipidaemia and diabetes mellitus. These patients have higher risks of both myocardial infarction and stroke but a lower risk of undergoing interventional procedures compared with the general population. Data indicate a negative attitude from clinicians working outside the mental health fields towards patients with severe mental illness. Education might be a possible method to decrease the negative attitudes towards these patients, thereby improving their rates of diagnosis and treatment.

Pharmacological interventions for smoking cessation among people with schizophrenia spectrum disorders: a systematic review, meta-analysis, and network meta-analysis

BACKGROUND

People with schizophrenia have higher rates of smoking than the general population, and lower quit rates. Several randomised controlled trials have investigated the effectiveness of pharmacological interventions for smoking cessation over the past 20 years. We did a systematic review and pairwise and network meta-analysis of smoking abstinence to guide decision making in offering pharmacological interventions for smoking cessation for people with schizophrenia spectrum disorders.

METHODS

We systematically reviewed PubMed, Embase, Cochrane Central Register of Controlled Trials, PsycINFO, and China National Knowledge Infrastructure from inception to Sept 30, 2019, for randomised controlled trials of varenicline, bupropion, and nicotine replacement therapy for smoking cessation for people with schizophrenia spectrum disorders or psychotic disorders who were smokers at the time of study recruitment. Data were extracted from published studies on smoking abstinence outcomes and psychotic symptoms. We did pairwise and network meta-analyses for the primary outcome of smoking abstinence. Sensitivity analyses were done on study inclusion criteria, duration, quality, and location. This study is registered with the international prospective register of systematic reviews PROSPERO, CRD42018102343.

FINDINGS

A total of 15 111 records were identified by the database searches, and 163 full-text articles were assessed for eligibility. 145 articles were then excluded for several reasons including insufficient data, or abstracts published in later studies, and 18 studies were included in the meta-analysis. In the pairwise meta-analyses, four studies with 394 participants assessed varenicline (RR 3·75, 95% CI 1·96-7·19, p<0·0001; I²=0%), four studies with bupropion and 292 participants (RR 3·40, 95% CI 1·58-7·34, p=0·0002; I²=0%), and three studies with 561 participants assessed nicotine replacement therapy (RR 4·27, 95% CI 1·71-10·65, p=0·0002; I²=0%). All three treatments were deemed superior to placebo. In the network meta-analysis, varenicline was superior to bupropion (RR 2·02, 95% CI 1·04-3·93; p=0·038) but no significant difference was found between varenicline and nicotine replacement therapy, or bupropion and nicotine replacement therapy. No agents were associated with changes in psychiatric symptoms, but varenicline was associated with higher rates of nausea than was placebo.

INTERPRETATION

We found evidence to support use of pharmacological agents for smoking cessation for people with psychosis. Varenicline might be superior to bupropion; however, additional direct testing and combination trials of pharmacological agents for smoking cessation are required to inform clinical decision making for people with psychosis.

FUNDING

None.