Translational Research on Nicotine Dependence

Impact of nicotine dependence on self-efficacy and readiness to quit among tobacco consumers in rural areas

Aim and Objectives

The aim of the present study was to determine the impact or effect of nicotine dependence on self-efficacy and readiness to quit.

Materials and Method

The current study was performed using a cross-sectional descriptive questionnaire design among tobacco users visiting primary health care facilities in the rural Jaipur district. Jaipur district is divided into four directions: east, west, north, and south. From each direction, two PHCs were selected randomly based on suitable accessibility to patients. Sample size of study is 465. Out of 465 tobacco consumers, 238 were consuming a smoked form of tobacco, and 227 study participants were consuming a smokeless form of tobacco.

Results

It was observed that the majority of study participants (145 (31%)) need smoke/smokeless tobacco within 5 minutes of waking up. With regards to internal stimuli, the majority of study participants (179 (38%)) and (203 (44%)) were not very sure that they would refrain from smoking when they were nervous and depressed. It was determined that quitting tobacco products was not at all important for 159 (34%) study participants. In regards to confidence in tobacco product quitting, only 79 (16%) of tobacco consumers were extremely confident.

Conclusion

It was concluded that nicotine dependence impacts both self-efficacy and readiness to quit. It was determined that the higher the nicotine dependence, the less self-efficacy and the less would be the readiness to quit.

Post-weaning social isolation increases the incentive value of nicotine-related contexts and decreases the accumulation of ΔFosB in nucleus accumbens in adolescent rats

Adolescent social conditions profoundly affect vulnerability to drug abuse. Preclinical studies have shown that preventing social interactions during adolescence increases the rewarding effects of drugs like alcohol, cocaine, or amphetamines, however, little data exist regarding the impact of social isolation on nicotine effects. The current study evaluated the effects of differential rearing conditions during adolescence (isolation or group rearing) on (1) conditioned place preference induced by low nicotine doses (0.1 or 0.3 mg/kg) and (2) sensitization to the locomotor effects of nicotine after sub-chronic administration (3) and accumulation of ΔFosB in nucleus accumbens (NAc). Results showed that nicotine induced place preference in isolated and grouped rats, but the effect was more persistent for the rats reared in isolation. Isolated reared rats also exhibited lower levels of ΔFosB accumulation in NAc. No differences were found in the behavioral sensitization to nicotine effects between rearing conditions. The results suggest that isolation engenders a more robust incentive value of nicotine-related contexts. This effect could be related to the basal expression of ΔFosB: lower levels of this transcription factor seem to impair the motivation of isolated reared rats and increase their vulnerability to the effects of drugs like nicotine.

Connectome-based predictive modelling of smoking severity in smokers

The functional connectivity within and between networks could provide a framework to characterize the neurobiological mechanism of nicotine addiction. This study examined the brain regions that were functionally connected in response to smoking cues and established the brain-behaviour relationships in smokers. Sixty-seven male smokers were enrolled and scanned while performing the cue-reactivity and Stroop task. A whole-brain analysis approach, connectome-based predictive modelling (CPM), was conducted on the data from the cue-reactivity task to identify the networks that could predict the smoking severity with the Shen atlas as templates. Then, the brain-behaviour relationships were verified in a different brain state (Stroop task). CPM identified the smoking severity-related network, as indicated by a significant correlation between predicted and actual smoking severity scores (r = 0.31, p = 0.02). Identified networks mainly involved the canonical networks implicated in the reward process (motor/sensory network and salience network) and executive control (frontoparietal network). Network strength in the Stroop task marginally significantly predicted smoking severity scores (r = 0.23, p = 0.06), partially replicating the brain-behaviour relationship. The CPM results identified the whole-brain neural network related to smoking severity, which was cross-validated by the AAL and Shen atlas. These findings contribute to more profound insights into neural substrates underlying the smoking severity.

A transcriptome-wide association study identifies susceptibility genes for Parkinson's disease

Genome-wide association study (GWAS) has seen great strides in revealing initial insights into the genetic architecture of Parkinson's disease (PD). Since GWAS signals often reside in non-coding regions, relatively few of the associations have implicated specific biological mechanisms. Here, we aimed to integrate the GWAS results with large-scale expression quantitative trait loci (eQTL) in 13 brain tissues to identify candidate causal genes for PD. We conducted a transcriptome-wide association study (TWAS) for PD using the summary statistics of over 480,000 individuals from the most recent PD GWAS. We identified 18 genes significantly associated with PD after Bonferroni corrections. The most significant gene, LRRC37A2, was associated with PD in all 13 brain tissues, such as in the hypothalamus (P = 6.12 × 10-22) and nucleus accumbens basal ganglia (P = 5.62 × 10-21). We also identified eight conditionally independent genes, including four new genes at known PD loci: CD38, LRRC37A2, RNF40, and ZSWIM7. Through conditional analyses, we demonstrated that several of the GWAS significant signals on PD could be driven by genetically regulated gene expression. The most significant TWAS gene LRRC37A2 accounts for 0.855 of the GWAS signal at its loci, and ZSWIM7 accounts for all the GWAS signals at its loci. We further identified several phenotypes previously associated with PD by querying the single nucleotide polymorphisms (SNPs) in the final model of the identified genes in phenome databases. In conclusion, we prioritized genes that are likely to affect PD by using a TWAS approach and identified phenotypes associated with PD.

Comparative assessment of outcomes of smoking cessation therapies and role of free medications in successful long-term abstinence

INTRODUCTION

Long-term outcomes of smoking cessation treatments are crucial to optimize standards of cessation services, which are known to prevent excess morbidity and mortality. This study aimed to evaluate long-term outcomes of a smoking cessation program, to compare the success rates of interventions, to assess relapse rates after quitting, and to determine the duration until relapse.

METHODS

Patients admitted for smoking cessation between 2010–2018 were contacted to evaluate short- and long-term treatment outcomes. The patients were asked whether they were currently smoking, and whether they quit after smoking cessation treatment and the duration of abstinence.

RESULTS

The study included 579 patients (341 males) with a mean age of 50±12 years. The median time from the date of visit to the smoking cessation clinic to analysis was 5 years (range: 2–10). Of the patient, 436 used medications, including varenicline, bupropion, and nicotine replacement therapy (NRT). The overall quit rate was 31.8% by the primary intervention (varenicline: 45.5%, bupropion: 38.2%, NRT: 33%, psychosocial support: 4.2%), and quit rate was similar in the intervention groups (p=0.073). In the long-term, the quit rates were 19.6, 22.5, 25.9, and 21.7%, respectively (p=0.405). About 9% of the patients failed to quit smoking initially but succeeded for a while after the first intervention at the cessation clinic. The relapse rate after initial cessation was 19%. The longest period of abstinence was in patients using NRT (14±17 months), followed by the patients using varenicline (9.5±12.7 months) and bupropion (8.2±14.8 months).

CONCLUSIONS

Both short- and long-term quit rates with varenicline, bupropion, and NRT, were similar. The long-term quit rates among patients who did not use medication and received psychosocial support initially were comparable to those who used a smoking cessation drug.

Intravenous cocaine self-administration in a panel of inbred mouse strains differing in acute locomotor sensitivity to cocaine

RATIONALE

Initial sensitivity to drugs of abuse often predicts subsequent use and abuse, but this relationship is not always observed in human studies. Moreover, studies examining the relationship between initial locomotor sensitivity and the rewarding and reinforcing effects of drugs in animal models have also been equivocal. Understanding the relationship between initial drug effects and propensity to continue use, potentially resulting in the development of a substance use disorder, may help to identify key targets for prevention and treatment.

OBJECTIVES

We examined intravenous cocaine self-administration in a set of mouse strains that were previously identified to be at the phenotypic extremes for cocaine-induced locomotor activation to determine if initial locomotor sensitivity predicted acquisition, extinction, dose response, or progressive ratio (PR) breakpoint.

METHODS

We selected eight inbred mouse strains based on locomotor sensitivity to 20 mg/kg cocaine. These strains, designated as low and high responders, were tested in an intravenous self-administration paradigm that included acquisition of 0.5 mg/(kg*inf) under a FR1 schedule, extinction, re-acquisition, dose response to 0.125, 0.25, 0.5, 1, and 2 mg/(kg*inf), and progressive ratio.

RESULTS

We observed overall differences in self-administration behavior between high and low responders. Low responders self-administered less cocaine and had lower breakpoints under the PR schedule. However, we also observed strain differences within each group. Self-administration in the low responder, LG/J, more closely resembled the behavior of the high-responding group, and the high responder, P/J, had self-administration behavior that more closely resembled the low-responding group.

CONCLUSIONS

We conclude that acute cocaine-induced locomotor activation does predict self-administration behavior, but in a strain-specific manner. These data support the idea that genetic background influences the relationship among addiction-related behaviors.

Association of opioid receptor mu 1 (OPRM1) A118G polymorphism (rs1799971) with nicotine dependence

Background and Object

Whether opioid-receptor mu 1 (OPRM1) A118G polymorphism (rs1799971) is associated with nicotine dependence is controversial. We analyzed the combined results from published studies of this possibility.

Methods

Literature reviews were performed according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Web of Science, Chinese National Science Infrastructure (CNKI), PubMed, Embase and Google Scholar database searches using MeSH terms were conducted to find all relevant researches up to October 2016. Odds ratios (ORs) and their 95% confidence intervals (95% CIs) were calculated in allele, homozygote, heterozygote, dominant and recessive models. Ethnicity-specific subgroup meta-analysis, heterogeneity, sensitivity analysis and publication bias were considered.

Results

Seven eligible studies with 3313 patients were included. The ORs in the five genetic models mentioned above were 1.000 (95% CI: 0.906, 1.104; p = 0.999), 1.032 (95% CI: 0.771, 1.381; p = 0.834), 0.963 (95% CI: 0.799, 1.162; p = 0.696), 1.006 (95% CI: 0.916, 1.104; p = 0.907), 0.967 (95% CI: 0.715, 1.309; p = 0.830), respectively. Only in dominant model is the association significant. Upon ethnicity-specific subgroup analysis, there is no statistical significance.

Conclusion

OPRM1-A118G polymorphism (A>G) is not associated with nicotine dependence.