Working memory in cigarette smokers: comparison to non-smokers and effects of abstinence

Chronic effects of tobacco smoking on electrical brain activity: A systematic review on electroencephalography studies

Despite significant strides in reducing smoking prevalence globally, tobacco use remains a leading contributor to ill health and premature death worldwide. While the detrimental impacts of smoking on various organs are well-established, its specific effects on nervous system function remain an area of ongoing investigation. This systematic review delves into the neurobiological effects of smoking, particularly through the lens of resting-state electroencephalography (EEG). A systematic search was conducted in May 2024 in PubMed, Embase, and Web of Science databases, and all available evidence comparing resting-state EEG findings between smokers and non-smokers was assessed. The 13 included studies investigated a total of 684 participants, with a median female percentage of of 25 % (range: 0-100), and the age of participants ranged from 18 to approximately 73 years. Alterations in the alpha band were the most prevalent findings observed in the EEG of smokers compared to non-smokers, observed in 8 studies, suggesting changes in the attention and cognitive functions of smokers. However, findings regarding the specific direction and location of changes were not consistent. Additionally, changes in delta, theta, and beta bands were identified on a less frequent basis. There was evidence suggesting that the observed neural oscillation changes are influenced by various factors, including the number of cigarettes used, pack years of smoking, age of smoking initiation, and smoking cessation status. These findings underscore the multifaceted nature of the impact of smoking on brain activity, especially on cognition and the attentional system.

The impact of electronic cigarette aerosol exposure on spatial memory formation: Modulation by orally administered vitamin E

The use of electronic cigarettes (ECIGs) has grown exponentially among young adolescents. Tobacco smoking, in general and ECIG use in particular, has been linked to disruption of the oxidative system, resulting in organ damage. The current investigation intends to evaluate if orally administered Vitamin E (VitE) can protect from learning and cognitive impairment induced by ECIG aerosol exposure in a rat model. This effect was determined by studying behavioral and molecular targets for potential learning and memory impairment. Adult Wistar rats were assigned to the following groups (N= 12/group): Control, ECIG, VitE, and VitE+ECIG. The animals in the groups ECIG and VitE+ECIG were exposed to ECIG aerosol (1 hr/day, 6 days/week) for four weeks. The control group and VitE group were exposed to fresh air. At the same time, the VitE group and VitE+ECIG group were given Vitamin E 100 mg/kg/ day via gavage for the same period as the exposure. The control group and ECIG group were given the vehicle via gavage. Behavioral assessment was performed using the Radial Arm Water Maze. In addition, molecular measures (BDNF, SOD, GPx, GSH, and GSSG), were measured in rats' hippocampal tissues. The results showed that VitE prevented ECIG aerosol exposure-induced impairment of spatial short-term and long-term memory formation (p<0.05), decreased BDNF, and activities/levels of GPx, SOD, and GSH (p<0.05). Moreover, VitE protected against GSSG levels increases (p<0.05) associated with ECIG aerosol exposure. In summary, exposure to ECIGs resulted in spatial memory impairments, which could be mitigated by orally administered vitamin E.

The role of CART peptide in learning and memory: A potential therapeutic target in memory-related disorders

Cocaine and amphetamine-regulated transcript (CART) mRNA and peptide are vastly expressed in both cortical and subcortical brain areas and are involved in critical cognitive functions. CART peptide (CARTp), described in reward-related brain structures, regulates drug-induced learning and memory, and its role appears specific to psychostimulants. However, many other drugs of abuse, such as alcohol, opiates, nicotine, and caffeine, have been shown to alter the expression levels of CART mRNA and peptides in brain structures directly or indirectly associated with learning and memory processes. However, the number of studies demonstrating the contribution of CARTp in learning and memory is still minimal. Notably, the exact cellular and molecular mechanisms underlying CARTp effects are still unknown. The discoveries that CARTp effects are mediated through a putative G-protein coupled receptor and activation of cellular signaling cascades via NMDA receptor-coupled ERK have enhanced our knowledge about the action of this neuropeptide and allowed us to comprehend better CARTp exact cellular/molecular mechanisms that could mediate drug-induced changes in learning and memory functions. Unfortunately, these efforts have been impeded by the lack of suitable and specific CARTp receptor antagonists. In this review, following a short introduction about CARTp, we report on current knowledge about CART's roles in learning and memory processes and its recently described role in memory-related neurological disorders. We will also discuss the importance of further investigating how CARTp interacts with its receptor(s) and other neurotransmitter systems to influence learning and memory functions. This topic is sure to intrigue and motivate further exploration in the field of neuroscience.

Lower Dorsal Putamen D2/3 Receptor Availability and Amphetamine-Induced Dopamine Release are Related to Poorer Cognitive Function in Recently Abstinent People Who Smoke and Healthy Controls

INTRODUCTION

In the dopamine system, the mesolimbic pathway, including the dorsal striatum, underlies the reinforcing properties of tobacco smoking, and the mesocortical pathway, including the dorsolateral prefrontal cortex (dlPFC), is critical for cognitive functioning. Dysregulated dopamine signaling has been linked to drug-seeking behaviors and cognitive deficits. The dorsal striatum and dlPFC are structurally and functionally connected and are key regions for cognitive functioning. We recently showed that people who smoke have lower dlPFC dopamine (D2/3R) receptor availability than people who do not, which is related to poorer cognitive function.

AIMS AND METHODS

The goal of this study was to examine the same brain-behavior relationship in the dorsal striatum. Twenty-nine (18 males) recently abstinent people who smoke and 29 sex-matched healthy controls participated in 2 same-day [11C]-(+)-PHNO positron emission tomography scans before and after amphetamine administration to provoke dopamine release. D2/3R availability (binding potential; BPND) and amphetamine-induced dopamine release (%ΔBPND) were calculated. Cognition (verbal learning and memory) was assessed with the CogState computerized battery.

RESULTS

There were no group differences in baseline BPND. People who smoke have a smaller magnitude %ΔBPND in dorsal putamen than healthy controls (p = .022). People who smoke perform worse on immediate (p = .035) and delayed (p = .011) recall than healthy controls. In all people, lower dorsal putamen BPND was associated with worse immediate (p = .006) and delayed recall (p = .049), and lower %ΔBPND was related to worse delayed recall (p = .022).

CONCLUSIONS

Lower dorsal putamen D2/3R availability and function are associated with disruptions in cognitive function that may underlie difficulty with resisting smoking.

IMPLICATIONS

This study directly relates dopamine imaging outcomes in the dorsal striatum to cognitive function in recently abstinent people who smoke cigarettes and healthy controls. The current work included a well-characterized subject sample in terms of demographics, smoking characteristics, and a validated neurocognitive test of verbal learning and memory. The findings of this study extend previous literature relating dopamine imaging outcomes to cognition in recently abstinent people who smoke and people who do not smoke, expanding our understanding of brain-behavior relationships.

Is impulsivity related to attentional bias in cigarette smokers? An exploration across levels of nicotine dependency and deprivation

Research has largely focused on how attentional bias to smoking-related cues and impulsivity independently influence the development and maintenance of cigarette smoking, with limited exploration of the relationship between these mechanisms. The current experiments systematically assessed relationships between multiple dimensions of impulsivity and attentional bias, at different stages of attention, in smokers varying in nicotine dependency and deprivation. Nonsmokers (NS; n  = 26), light-satiated smokers (LS; n  = 25), heavy-satiated smokers (HS; n  = 23) and heavy 12-hour nicotine-deprived smokers (HD; n  = 30) completed the Barratt Impulsivity Scale, delayed discounting task, stop-signal task, information sampling task and a visual dot-probe assessing initial orientation (200 ms) and sustained attention (2000 ms) toward smoking-related cues. Sustained attention to smoking-related cues was present in both HS and LS, while initial orientation bias was only evident in HS. HS and LS also had greater levels of trait motor and nonplanning impulsivity and heightened impulsive choice on the delay discounting task compared with NS, while heightened trait attentional impulsivity was only found in HS. In contrast, in HD, nicotine withdrawal was associated with no attentional bias but heightened reflection impulsivity, poorer inhibitory control and significantly lower levels of impulsive choice relative to satiated smokers. Trait and behavioral impulsivity were not related to the extent of attentional bias to smoking-related cues at any stage of attention, level of nicotine dependency or state of deprivation. Findings have both clinical and theoretical implications, highlighting the unique and independent roles impulsivity and attentional bias may play at different stages of the nicotine addiction cycle.

Two-Hour Nicotine Withdrawal Improves Inhibitory Control Dysfunction in Male Smokers: Evidence from a Smoking-Cued Go/No-Go Task ERP Study

Purpose

Nicotine withdrawal is a multifaceted physiological and psychological process that can induce a spectrum of mood disturbances. Gaining a more nuanced understanding of how pure nicotine withdrawal influences cognitive control functions may provide valuable insights for the enhancement of smoking cessation programs. This study investigated changes in inhibitory control function in smokers after 2-hour nicotine withdrawal using the event-related potential (ERP) technique.

Participants and Methods

28 nicotine dependence (ND) patients and 28 health controls (HCs) completed a smoking-cued Go/No-go task containing two different types of picture stimuli, smoking-cued and neutral picture stimuli. We analyzed the behavioral and ERP data using a mixed model Repeated Measure Analysis of Variance (ANOVA).

Results

No-go trials accuracy rate (ACC) at baseline (time 1) was lower in the ND group compared to HCs with smoking-cued stimuli, and No-go trials ACC after 2-hour nicotine withdrawal (time 2) was not lower in the ND group compared to HCs. When confronted with smoking-cued stimuli, the No-go trials ACC was higher in time 2 than in time 1 in the ND group. For the ERP component, the No-go N2 amplitudes in the ND group with smoking-cued stimuli were lower than that of HCs, whereas after 2-hour nicotine withdrawal, the ND group's No-go N2 amplitudes higher than that at time 1, and did not differ from that of HCs. No-go P3 amplitudes were not significantly different between the two groups.

Conclusion

Evidenced from ERP data, ND patients have an inhibitory control dysfunction in the face of smoking cues, which is mainly manifested in the early stage of response inhibition rather than in the late stage. Two-hour nicotine withdrawal improves inhibitory control dysfunction in ND patients. The No-go N2 component is an important and sensitive neuroelectrophysiological indicator of inhibitory control function in ND patients.

Lower Dopamine D2/3 Receptor Availability is Associated With Worse Verbal Learning and Memory in People Who Smoke Cigarettes

INTRODUCTION

Tobacco smoking is a major public health burden. The mesocortical dopamine system-including the dorsolateral prefrontal cortex (dlPFC)-plays an important role in cognitive function. Dysregulated dopamine signaling in dlPFC is associated with cognitive deficits such as impairments in attention, learning, working memory, and inhibitory control. We recently showed that dlPFC dopamine D2/3-type receptor (D2R) availability was significantly lower in people who smoke than in healthy-controls and that dlPFC amphetamine-induced dopamine release was lower in females who smoke relative to males who smoke and female healthy-controls. However, we did not examine whether the smoking-related dopamine deficits were related to cognitive deficits.

AIMS AND METHODS

The goal of this study was to relate dopamine metrics to cognitive performance in people who smoke and healthy-controls. In total 24 (12 female) people who smoke cigarettes and 25 sex- and age-matched healthy-controls participated in two same-day [11C]FLB457 positron emission tomography (PET) scans before and after amphetamine administration. Two outcome measures were calculated-D2R availability (non-displaceable binding potential; BPND) and amphetamine-induced dopamine release (%ΔBPND). Cognition (verbal learning and memory) was assessed with a computerized test from the CogState battery (International Shopping List).

RESULTS

People who smoke had significantly worse immediate (p = .04) and delayed (p = .03) recall than healthy-controls. Multiple linear regression revealed that for people who smoke only, lower D2R availability was associated with worse immediate (p = .04) and delayed (p < .001) recall. %ΔBPND was not significantly related to task performance.

CONCLUSION

This study demonstrated that lower dlPFC D2R availability in people who smoke is associated with disruptions in cognitive function that may underlie difficulty with resisting smoking.

IMPLICATIONS

This is the first study to directly relate dopamine metrics in the prefrontal cortex to cognitive function in people who smoke cigarettes compared to healthy-controls. The current work included a well-characterized subject sample with regards to demographic and smoking variables, as well as a validated neurocognitive test of verbal learning and memory. The findings of this study extend previous literature by relating dopamine metrics to cognition in people who smoke, providing a better understanding of brain-behavior relationships.

Not all smokers are alike: the hidden cost of sustained attention during nicotine abstinence

Nicotine Withdrawal Syndrome (NWS)-associated cognitive deficits are notably heterogeneous, suggesting underlying endophenotypic variance. However, parsing this variance in smokers has remained challenging. In this study, we identified smoker subgroups based on response accuracy during a Parametric Flanker Task (PFT) and then characterized distinct neuroimaging endophenotypes using a nicotine state manipulation. Smokers completed the PFT in two fMRI sessions (nicotine sated, abstinent). Based on response accuracy in the stressful, high cognitive demand PFT condition, smokers split into high (HTP, n = 21) and low task performer (LTP, n = 24) subgroups. Behaviorally, HTPs showed greater response accuracy (88.68% ± 5.19 SD) vs. LTPs (51.04% ± 4.72 SD), independent of nicotine state, and greater vulnerability to abstinence-induced errors of omission (EOm, p = 0.01). Neurobiologically, HTPs showed greater BOLD responses in attentional control brain regions, including bilateral insula, dorsal ACC, and frontoparietal Cx for the [correct responses (-) errors of commission] PFT contrast in both states. A whole-brain functional connectivity (FC) analysis with these subgroup-derived regions as seeds identified two circuits: Precentral Cx↔Insula and Insula↔Occipital Cx, with abstinence-induced FC strength increases seen only in HTPs. Finally, abstinence-induced FC and behavior (EOm) differences were positively correlated for HTPs in a Precentral Cx↔Orbitofrontal cortical circuit. In sum, only the HTP subgroup demonstrated sustained attention deficits following 48-hr nicotine abstinence, a stressor in dependent smokers. Unpacking underlying smoker heterogeneity with this 'dual (task and abstinence) stressor' approach revealed discrete smoker subgroups with differential attentional deficits to withdrawal that could be novel pharmacological/behavioral targets for therapeutic interventions to improve cessation outcomes.

Working Memory Training Reduces Cigarette Smoking Among Low-Income Individuals With Elevated Delay Discounting

INTRODUCTION

The competing neurobehavioral decision systems theory conceptualizes addictive behavior, such as cigarette smoking, as arising from the imbalance between stronger impulsive relative to weaker executive decision processes. Working memory trainings may enhance executive decision processes, yet few studies have evaluated its efficacy on substance misuse, with mixed evidence. The current study is the first to evaluate the efficacy of a working memory training on cigarette smoking. We consider the moderating role of delay discounting (DD), or the preference for smaller, immediately available rewards relative to larger, delayed rewards, which has been associated with smoking onset, progression, and resumption. The investigation focuses on individuals living in high-poverty, low-resource environments due high burden of tobacco-related disease they experience.

AIMS AND METHODS

The study utilized a subset of data (N = 177 individuals who smoke) generated from a randomized clinical trial that is evaluating the efficacy of working memory training for improving health-related outcomes. Participants were randomized to complete up to 15 sessions of the active, working memory training or a control training.

RESULTS

Findings showed that among participants who were randomized to the working memory condition, those with higher rates of baseline DD demonstrated decreases in cigarette smoking (p = .05). Conversely, individuals randomized to the control condition, who had higher rates of baseline DD exhibited increases in cigarette smoking (p = .025).

CONCLUSIONS

Results suggest that DD may be an important indicator of working memory training outcomes and a possible approach for effectively targeting treatments in the future.

IMPLICATIONS

DD is important indicator of working memory training outcomes on cigarette smoking. The findings suggest the possibility to effectively target treatments considering the impact of DD. Given that rates of DD tend to be higher among individuals from low-resource communities, and that computer-based working memory training programs are relatively low-cost and scalable, these findings suggest this approach may have specific utility for adults at heightened risk for cigarette use.This study was registered with ClinicalTrials.gov (Identifier NCT03501706).

Electronic Cigarette Vaping Did Not Enhance the Neural Process of Working Memory for Regular Cigarette Smokers

Background

Electronic cigarettes (e-cigs) as substitute devices for regular tobacco cigarettes (r-cigs) have been increasing in recent times. We investigated neuronal substrates of vaping e-cigs and smoking r-cigs from r-cig smokers.

Methods

Twenty-two r-cig smokers made two visits following overnight smoking cessation. Functional magnetic resonance imaging (fMRI) data were acquired while participants watched smoking images. Participants were then allowed to smoke either an e-cig or r-cig until satiated and fMRI data were acquired. Their craving levels and performance on the Montreal Imaging Stress Task and a 3-back alphabet/digit recognition task were obtained and analyzed using two-way repeated-measures analysis of variance. Regions-of-interest (ROIs) were identified by comparing the abstained and satiated conditions. Neuronal activation within ROIs was regressed on the craving and behavioral data separately.

Results

Craving was more substantially reduced by smoking r-cigs than by vaping e-cigs. The response time (RT) for the 3-back task was significantly shorter following smoking r-cigs than following vaping e-cigs (interaction: F (1, 17) = 5.3, p = 0.035). Neuronal activations of the right vermis (r = 0.43, p = 0.037, CI = [-0.05, 0.74]), right caudate (r = 0.51, p = 0.015, CI = [0.05, 0.79]), and right superior frontal gyrus (r = −0.70, p = 0.001, CI = [−0.88, −0.34]) were significantly correlated with the RT for the 3-back task only for smoking r-cigs.

Conclusion

Our findings suggest that insufficient satiety from vaping e-cigs for r-cigs smokers may be insignificant effect on working memory function.

Time-Varying Functional Connectivity Decreases as a Function of Acute Nicotine Abstinence

BACKGROUND

The nicotine withdrawal syndrome (NWS) includes affective and cognitive disruptions whose incidence and severity vary across time during acute abstinence. However, most network-level neuroimaging uses static measures of resting-state functional connectivity and assumes time-invariance and is thus unable to capture dynamic brain-behavior relationships. Recent advances in resting-state functional connectivity signal processing allow characterization of time-varying functional connectivity (TVFC), which characterizes network communication between networks that reconfigure over the course of data collection. Therefore, TVFC may more fully describe network dysfunction related to the NWS.

METHODS

To isolate alterations in the frequency and diversity of communication across network boundaries during acute nicotine abstinence, we scanned 25 cigarette smokers in the nicotine-sated and abstinent states and applied a previously validated method to characterize TVFC at a network and a nodal level within the brain.

RESULTS

During abstinence, we found brain-wide decreases in the frequency of interactions between network nodes in different modular communities (i.e., temporal flexibility). In addition, within a subset of the networks examined, the variability of these interactions across community boundaries (i.e., spatiotemporal diversity) also decreased. Finally, within 2 of these networks, the decrease in spatiotemporal diversity was significantly related to NWS clinical symptoms.

CONCLUSIONS

Using multiple measures of TVFC in a within-subjects design, we characterized a novel set of changes in network communication and linked these changes to specific behavioral symptoms of the NWS. These reductions in TVFC provide a meso-scale network description of the relative inflexibility of specific large-scale brain networks during acute abstinence.

Testing the association between tobacco and cannabis use and cognitive functioning: Findings from an observational and Mendelian randomization study

BACKGROUND

Although studies have examined the association between tobacco and cannabis use in adolescence with subsequent cognitive functioning, study designs are usually not able to distinguish correlation from causation.

METHODS

Separate patterns of tobacco and cannabis use were derived using longitudinal latent class analysis based on measures assessed on five occasions from age 13-18 in a large UK population cohort (Avon Longitudinal Study of Parents and Children). Cognitive functioning measures comprised of working memory, response inhibition, and emotion recognition assessed at 24 years of age. Mendelian randomization was used to examine the possible causal relationship between smoking initiation, lifetime cannabis use and cognitive functioning.

RESULTS

We found evidence of a relationship between tobacco and cannabis use and diminished cognitive functioning for each of the outcomes in the observational analyses. There was evidence to suggest that late-onset regular tobacco smokers (b=-0.29, 95 %CI=-0.45 to -0.13), early-onset regular tobacco smokers (b=-0.45, 95 %CI=-0.84 to -0.05), and early-onset regular cannabis users (b=-0.62, 95 %CI=-0.93 to -0.31) showed poorer working memory. Early-onset regular tobacco smokers (b = 0.18, 95 %CI = 0.07 to 0.28), and early-onset regular cannabis users (b = 0.30, 95 %CI = 0.08 to 0.52) displayed poorer ability to inhibit responses. Late-onset regular (b=-0.02, 95 %CI=-0.03 to - 0.00), and early-onset regular tobacco smokers (b=-0.04, 95 %CI=-0.08 to -0.01) showed poorer ability to recognise emotions. Mendelian randomization analyses were imprecise and did not provide additional support for the observational results.

CONCLUSION

There was some evidence to suggest that adolescent tobacco and cannabis use were associated with deficits in working memory, response inhibition and emotion recognition. Better powered genetic studies are required to determine whether these associations are causal.

Systematic Review of Nicotine Exposure's Effects on Neural Stem and Progenitor Cells

While various modalities of chronic nicotine use have been associated with numerous negative consequences to human health, one possible benefit of nicotine exposure has been uncovered. The discovery of an inverse correlation between smoking and Parkinson's disease, and later Alzheimer's disease as well, motivated investigation of nicotine as a neuroprotective agent. Some studies have demonstrated that nicotine elicits improvements in cognitive function. The hippocampus, along with the subventricular zone (SVZ), is a distinct brain region that allow for ongoing postnatal neurogenesis throughout adulthood and plays a major role in certain cognitive behaviors like learning and memory. Therefore, one hypothesis underlying nicotine-induced neuroprotection is possible effects on neural stem cells and neural precursor cells. On the other hand, nicotine withdrawal frequently leads to cognitive impairments, particularly in hippocampal-dependent behaviors, possibly suggesting an impairment of hippocampal neurogenesis with nicotine exposure. This review discusses the current body of evidence on nicotine's effects on neural stem cells and neural progenitors. Changes in neural stem cell proliferation, survival, intracellular dynamics, and differentiation following acute and chronic nicotine exposure are examined.

Associations Between Smoking Abstinence, Inhibitory Control, and Smoking Behavior: An fMRI Study

Nicotine addiction is associated with dysregulated inhibitory control (IC), mediated by corticothalamic circuitry including the right inferior frontal gyrus (rIFG). Among sated smokers, worse IC task performance and greater IC-related rIFG activity have been shown to be associated with greater relapse vulnerability. The present study investigated the effects of smoking abstinence on associations between IC task performance, rIFG activation, and smoking behavior. Smokers (N = 26, 15 female) completed an IC task (Go/Go/No-go) during fMRI scanning followed by a laboratory-based smoking relapse analog task (SRT) on two visits: once when sated and once following 24 h of smoking abstinence. During the SRT, smokers were provided with monetary rewards for incrementally delaying smoking. A significant main effect of No-go accuracy on latency to smoke during the SRT was observed when collapsing across smoking states (abstinent vs. sated). Similarly, a significant main effect of IC-related activation in rIFG on SRT performance was observed across states. The main effect of state, however, was non-significant in both of these models. Furthermore, the interaction between smoking state and No-go accuracy on SRT performance was non-significant, indicating a similar relationship between IC and lapse vulnerability under both sated and abstinent conditions. The state X rIFG activation interaction on SRT performance was likewise non-significant. Post-hoc whole brain analyses indicated that abstinence resulted in greater IC-related activity in the right middle frontal gyrus (MFG) and insula. Activation during IC in these regions was significantly associated with decreased No-go accuracy. Moreover, greater abstinence induced activity in right MFG during IC was associated with smoking sooner on the SRT. These findings are bolstered by the extant literature on the effects of nicotine on executive function and also contribute novel insights on how individual differences in behavioral and neuroimaging measures of IC may influence relapse propensity independent of smoking state.

Cigarette smoking and cognitive function among older adults living in the community

Background. The present study aimed to examine the long-term impact of CS on Executive Function (EF) and memory among older adults living in the community. Methods. Clock Drawing Test (CDT) and Delayed Word Recall Test (DWRT) were used to examine EF and memory, respectively, using four waves of National Health and Aging Trend Study. The respondents were asked whether they have ever smoked, length of smoking, and age of start and quit smoking. Results. CS can have a long-term impact on both EF and memory. However, current smoking can increase the risk of EF impairment compared to former smokers. Lung disease and current smoking can have a synergic effect of impairment in EF. Conclusion. In the long-term, smoking can negatively affect cognitive. Lung diseases and smoking can synergize their impacts on EF. The impact of smoking on cognition varies across ethnic groups; hence, educational programs targeting minorities can reduce discrepancies.

Digital failure: An emerging reason of anger expression among adolescents

Network connectivity can often lead to positive as well as negative mood states among regular Internet users. Recently, studies have mainly focused on the impact of Internet abuse/addiction on the various aspects of the individual, in terms of cognitive, emotional, behavioral, and interpersonal domains. However, one of the issues that is not much reported are the issues about what happens to the children who are not able to access the internet due to connectivity issues. Given this, the current article discusses two cases with negative emotional and behavioral manifestations of increased anger and frustration due to reduced Internet connectivity. This can help draw more research and attention to the need for increased cyber-literacy and incorporation of anger management programs into psychological interventions that address Internet Addiction.

Short-term E-cigarette toxicity effects on brain cognitive memory functions and inflammatory responses in mice

Exposure to cigarette smoke (CS) is associated with an increased risk of several neurological diseases such as stroke, Alzheimer's disease, and dementia. At present, commercialization of E-cigarettes (ECs) is increasing, and they are advertised as a less harmful nicotine-delivery system. There are, however, limited studies regarding the neurotoxicity effects of ECs on the brain, which remains a subject of debate. In the present study, we aimed to evaluate the in vivo effects of short-term EC vapor exposure on the brain and compare them with the effects of cigarette smoke (CS). BALB/c mice were exposed to air, CS, and EC for 14 days. We then assessed the inflammatory responses, oxidative stress, and cognitive functions of the mice by using maze tests. Cognitive spatial tests showed that the mice exposed to CS and ECs had delayed time in finding food rewards. EC exposure demonstrated no improvement in spatial memory learning to find the food reward on the next day. This implies that CS and EC exposure possibly causes damage to the olfactory system. Notably, EC exposure potentially causes abnormalities in mice memory functions. Histological staining of the cerebral cortex of mice brain in the EC-exposed group demonstrated inflammatory responses such as necrosis and cytoplasm vacuolization. Immunohistochemical staining revealed high expression of proinflammatory cytokine TNF-α in both the EC- and CS-exposed groups. Hence, we conclude that ECs share similar toxicity profiles as CS, which potentially negatively impact brain function.

Sleep as a Target for Optimized Response to Smoking Cessation Treatment

Declining national rates of current tobacco use to an all-time low of 15.1% represents a public health victory. Undermining this progress, however, are smoking rates of up to 50% among high-risk, low-income populations. Current FDA-approved treatments for nicotine dependence are ineffective with between 70-95% of treatment-seekers relapsing within the first year of attempted abstinence. Thus, identification of novel intervention targets to optimize response to currently available treatments for nicotine dependence is a critical next step. One such target may be sleep insomnia. Insomnia is a clinically verified nicotine withdrawal symptom but, to date, addressing insomnia or other sleep disturbance symptoms as an adjunctive smoking cessation therapy has yet to be fully considered. To this end, this manuscript presents a narrative review of: (1) sleep continuity and architecture in smokers versus nonsmokers; (2) effects of nicotine abstinence on sleep; (3) possible mechanisms linking sleep with smoking cessation outcomes; (4) plausible adjunctive sleep therapies to promote smoking cessation; (5) possible treatments for unhealthy sleep in smokers; and (6) directions for future research. Taken together, this will provide conceptual support for sleep therapy as an adjunctive treatment for smoking cessation.

Implications

This narrative literature review presents a comprehensive discussion of the relationship between habitual sleep and cigarette smoking. The extent to which unhealthy sleep in smokers may be a viable intervention target for promoting response to smoking cessation treatment is considered. Ultimately, this review provides conceptual support for sleep therapy as an adjunctive treatment for smoking cessation.

Two-Hour Tobacco Abstinence Has No Effect on Cognitive Control in Male Patients With Nicotine Dependence: An ERP Study

The average nicotine half-life in body tissues is 2 h. Understanding the influence of pure nicotine abstinence on cognitive control may be helpful in eliminating nicotine dependence (ND) and preventing smoking relapse. This study was to investigate the effects of 2-h tobacco abstinence on cognitive control in patients with ND. Twenty-five patients with ND completed event-related potential (ERP) P300 measurements at the normality state and the abstinence state. Twenty-five healthy controls (HCs) were measured with P300 twice with a 2-h time interval. HAMD and HAMA were used to assess the emotional state. Results showed that there were significant differences in Carbon monoxide (CO) levels between the abstinence state and the normality state in the ND group. There were no significant differences in HAMD and HAMA scores for the abstinence state in the ND group or the normality state in the ND group and the HC group. For P3a, P3b amplitude, and P3a latency, the main effect for ND group was significant. For P3a, P3b amplitude, and latency, the interaction effect for group × time point was not significant, and the main effect for time point was not significant. It concluded that patients with ND present cognitive control deficits, and 2-h tobacco abstinence has no effect on cognitive control deficits in male patients with ND. Our findings may be helpful in eliminating nicotine dependence and preventing smoking relapse.

The influence of nicotine metabolic rate on working memory over 6 hours of abstinence from nicotine

BACKGROUND

A faster rate of nicotine metabolism has been associated with smoking more cigarettes, greater nicotine withdrawal symptoms, and lower smoking quit rates. However, the association between nicotine metabolic rate (NMR) and cognitive functioning during withdrawal has not been determined.

METHODS

We compared cognitive function in 121 fast or slow nicotine metabolizers after smoking, and at 3 and 6 h of nicotine abstinence. Cognitive functioning was assessed using N-back working memory tests with outcomes of accuracy and processing speed. Participants smoked two cigarettes and then abstained from smoking for 6 h. N-back tests were administered after smoking (0 h) and at 3 and 6 h of nicotine abstinence.

RESULTS

An effect of processing speed was found over time on the 2-back, in that participants had significantly longer average reaction times when the stimuli presented did not match the target letter. NMR was not significantly associated with the processing speed change over time. Within-race differences in working memory were evident in that Caucasian fast metabolizers had significantly poorer accuracy and processing speed.

CONCLUSIONS

Minimal change in working memory over 6 h of nicotine abstinence was observed. Overall, NMR was not significantly associated with the change in processing speed, however Caucasian fast metabolizers displayed poorer accuracy and processing speed at discrete time points.

Neuropeptide CART prevents memory loss attributed to withdrawal of nicotine following chronic treatment in mice

Although chronic nicotine administration does not affect memory, its withdrawal causes massive cognitive deficits. The underlying mechanisms, however, have not been understood. We test the role of cocaine- and amphetamine-regulated transcript peptide (CART), a neuropeptide known for its procognitive properties, in this process. The mice on chronic nicotine treatment/withdrawal were subjected to novel object recognition task. The capability of the animal to discriminate between the novel and familiar objects was tested and represented as discrimination index (DI); reduction in the index suggested amnesia. Nicotine for 49 days had no effect on DI, but 8-hour withdrawal caused a significant reduction, followed by full recovery at 24-hour withdrawal timepoint. Bilateral CART infusion in dorsal hippocampus rescued deficits in DI at 8-hours, whereas CART-antibody infusion into the dorsal hippocampus attenuated the recovery at 24-hours. Commensurate changes were observed in the CART as well as CART mRNA profiles in the hippocampus. CART mRNA expression and the peptide immunoreactivity did not change significantly following chronic nicotine treatment. However, there was a significant reduction at 8-hour withdrawal, followed by a drastic increase in CART immunoreactivity as well as CART mRNA at 24-hour withdrawal, compared with 8-hour withdrawal. Distinct α7-nicotinic receptor immunoreactivity was detected on the hippocampal CART neurons, suggesting cholinergic inputs. An increase in the synaptophysin immunoreactive elements around CART cells in the dentate gyrus, cornu ammonis 3 and subiculum at 24-hour post-withdrawal timepoint suggested neuronal plasticity. CART circuit dynamics in the hippocampus seems to modulate short-term memory associated with nicotine withdrawal.

Changes in brain metabolites related to stress resilience: Metabolomic analysis of the hippocampus in a rat model of depression

The ability to cope successfully with stress is known as 'resilience', and those with resilience are not prone to developing depression. One preclinical animal model for depression is the chronic mild stress (CMS) model. There are CMS-resilient (do not manifest anhedonia) and CMS-susceptible (manifest anhedonia) rats. This study aimed to investigate the differences in the profiles of hippocampal metabolites between susceptible and resilient rats, and to identify a biomarker that can distinguish the two. We divided stress-loaded rats into susceptible and resilient types based on their sucrose preference values. We then conducted brain-derived neurotrophic factor (BDNF) quantification and metabolomic analysis in the hippocampus. Compared to the controls, no significant differences were observed in the hippocampal BDNF levels of susceptible and resilient rats. However, the control rats were clearly distinguishable from the susceptible rats in terms of their brain metabolite profiles; the control rats were difficult to distinguish from the resilient rats. CMS model rats showed an increase in the levels of N-acetylaspartate and glutamate, and a decrease in the levels of aspartate and γ-aminobutyric acid in the hippocampus. Of the 12 metabolites measured in the present study, N-acetylaspartate was the only one that could differentiate the three types (control, susceptible, and resilient) of rats. Thus, brain metabolomic analyses can not only distinguish CMS model rats from control rats, but also indicate stress susceptibility. The variation in the levels of N-acetylaspartate in the hippocampus of control, resilient, and susceptible rats demonstrated that it could be a biomarker for stress susceptibility.

Tea consumption is associated with cognitive impairment in older Chinese adults

OBJECTIVE

To explore the association between tea consumption and cognitive impairment (CoI).

METHODS

4579 adults (≥60 years) from the Weitang Geratric Diseases Study were assessed for characteristics of tea consumption and cognitive function by administering questionnaires and the Abbreviated Mental Test (AMT), respectively. We divided the subjects into normal cognitive function group (AMT score ≥8) and CoI group (AMT score ≤7).   The association between tea consumption and risk of CoI was determined by logistic regression models.

RESULTS

The least-squared means of the AMT scores for the subjects who seldom consumed tea were less favorable than those who habitually consumed tea. An inverse association was found between tea consumption (of any type) and prevalence of CoI (odds ratio = 0.74, 95% confidence interval = 0.57-0.98, P = 0.032). Interestingly, the protective correlation of tea was more obvious in never smokers (odds ratio = 0.63), but vanished in current/former smokers (odds ratio = 1.10). In never smokers, frequency of tea consumption was significantly associated with CoI (P for trend = 0.010).

CONCLUSION

Habitual tea consumption is suggested to be associated with a decreased risk of CoI among elders in Suzhou, and a higher frequency of tea consumption was associated with a lower prevalence of CoI among never smokers.

Adolescent Nicotine Exposure Induces Dysregulation of Mesocorticolimbic Activity States and Depressive and Anxiety-like Prefrontal Cortical Molecular Phenotypes Persisting into Adulthood

Considerable evidence demonstrates strong comorbidity between nicotine dependence and mood and anxiety disorders. Nevertheless, the neurobiological mechanisms linking adolescent nicotine exposure to mood and anxiety disorders are not known. Disturbances in the mesocorticolimbic dopamine (DA) system, comprising the prefrontal cortex (PFC), ventral tegmental area (VTA), and nucleus accumbens (NAc), are correlates of mood and anxiety-related symptoms and this circuitry is strongly influenced by acute or chronic nicotine exposure. Using a combination of behavioral pharmacology, in vivo neuronal electrophysiology and molecular analyses, we examined and compared the effects of chronic nicotine exposure in rats during adolescence versus adulthood to characterize the mechanisms by which adolescent nicotine may selectively confer increased risk of developing mood and anxiety-related symptoms in later life. We report that exposure to nicotine, selectively during adolescence, induces profound and long-lasting neuronal, molecular and behavioral disturbances involving PFC DA D1R and downstream extracellular-signal-related kinase 1-2 (ERK 1-2) signaling. Remarkably, adolescent nicotine induced a persistent state of hyperactive DA activity in the ventral tegmental area (VTA) concomitant with hyperactive neuronal activity states in the PFC. Our findings identify several unique neuronal and molecular biomarkers that may serve as functional risk mechanisms for the long-lasting neuropsychiatric effects of adolescent smoking behaviors.

Phase IIb Trial of an α7 Nicotinic Receptor Partial Agonist With and Without Nicotine Patch for Withdrawal-Associated Cognitive Deficits and Tobacco Abstinence

PURPOSE/BACKGROUND

The objective of this study was to determine whether a novel α7 nicotinic acetylcholine receptor partial agonist improves cognition during nicotine withdrawal and improves abstinence rates. To do so, the effect of the α7 nicotinic acetylcholine receptor partial agonist, encenicline, on cognition and abstinence was evaluated when given as monotherapy and when combined with transdermal nicotine patch (nicotine replacement therapy [NRT]).

METHODS

Adult daily smokers, n = 160, who were motivated to quit smoking completed cognitive testing at satiated baseline and after overnight abstinence and then were randomized to receive a 12-week trial of encenicline 1 mg twice daily or identical placebo the day of the overnight abstinent cognitive testing. In the first 6 weeks of the 12-week encenicline administration, participants were also randomized to 6 weeks of NRT patch or placebo patch. Primary outcomes were cognition during abstinence and 7-day point-prevalence abstinence at week 12.

RESULTS

No beneficial effects of encenicline were observed on cognition or abstinence when compared with placebo or when combined with NRT compared with placebo capsule + NRT. Of the 4 conditions, abstinence rates were lowest among those assigned to encenicline alone.

CONCLUSIONS

Beneficial effects of NRT were observed on cognitive and abstinence outcomes when combined with encenicline compared with encenicline plus placebo patch. Addition of NRT to encenicline improved odds of abstinence approximately 3-fold compared with encenicline plus placebo patch. We conclude that encenicline, 1 mg/d, did not improve abstinence-associated cognitive impairment or abstinence rates as monotherapy or adjunctive therapy to NRT patch.

Cognitive profile of ketamine-dependent patients compared with methamphetamine-dependent patients and healthy controls

BACKGROUND

Ketamine has emerged as a major substance of abuse worldwide and has been listed with methamphetamine (METH) as two of the most widely available illicit substances in Taiwan. Only a few studies have examined the long-term consequences of chronic and heavy ketamine abuse. We compared the cognitive function of ketamine-dependent patients with that of METH-dependent patients and healthy controls.

METHODS

We recruited 165 participants (58 ketamine-dependent and 49 METH-dependent patients who sought treatment and 58 healthy controls) and evaluated them by using a cognitive test battery, the Brief Assessment of Cognition in Schizophrenia, with scores being estimated in reference to normative data in general population.

RESULTS

The ketamine-dependent patients had significantly poorer performance than did the controls in many cognitive tests, including verbal memory, motor speed, verbal fluency, and attention and processing speed, and the battery as a whole. METH-dependent patients exhibited poorer function in motor speed, verbal fluency, and attention and processing speed. The ketamine group performed poorer than did METH group in the domains of verbal memory, working memory, and attention and processing speed and the composite battery scores. A previous experience of ketamine-induced psychotomimetic symptoms, using higher doses of ketamine, and longer abstinence appeared to be associated with performance in some tests; however, the significance disappeared after multiple comparison correction.

CONCLUSIONS

The ketamine-dependent patients had impaired cognitive function, and METH-dependent patients exhibited intermediate performance between ketamine-dependent patients and healthy controls. Given the growing population of ketamine abusers, public education on the cognitive consequences should be provided.

Effects of Negative Affect, Urge to Smoke, and Working Memory Performance (n-back) on Nicotine Dependence

BACKGROUND

Three key domains including negative emotionality, incentive salience, and executive function form the core functional elements of addictive behaviors. Variables related to these broader domains have been studied extensively in relation to one another; however, no studies to date, have examined models including variables from all three domains, in relation to nicotine dependence.

METHOD

Smokers (N = 117), 65.8% female, 78% white, mean age of 44.4 (SD = 10.8), enrolled in a smoking cessation program completed measures of negative affect (a component of negative emotionality), urge to smoke (incentive salience), and working memory (WM; a core executive function), during a baseline assessment period prior to initiating treatment.

RESULTS

Negative affect was associated with greater urge to smoke, and this elevated urge to smoke was associated with higher levels of nicotine dependence. Further, a significant moderated mediation indicated that WM moderated the relationship between increased urge to smoke and nicotine dependence. For those with low to average WM, urge to smoke was significantly related to nicotine dependence; however, for those with higher WM (+1 SD), urge to smoke stemming from negative affect was not associated with nicotine dependence.

CONCLUSIONS

To our knowledge, this is the first reported relationship between negative affect, urge to smoke, WM, and nicotine dependence. Although preliminary, results indicate that WM may moderate the relationship between urge to smoke associated with negative affect and nicotine dependence. Treatments targeting WM may be particularly useful for individuals with average to low WM who experience urge to smoke related to negative affect.

The effects of cannabidiol on impulsivity and memory during abstinence in cigarette dependent smokers

Acute nicotine abstinence in cigarette smokers results in deficits in performance on specific cognitive processes, including working memory and impulsivity which are important in relapse. Cannabidiol (CBD), the non-intoxicating cannabinoid found in cannabis, has shown pro-cognitive effects and preliminary evidence has indicated it can reduce the number of cigarettes smoked in dependent smokers. However, the effects of CBD on cognition have never been tested during acute nicotine withdrawal. The present study therefore aimed to investigate if CBD can improve memory and reduce impulsivity during acute tobacco abstinence. Thirty, non-treatment seeking, dependent, cigarette smokers attended two laboratory-based sessions after overnight abstinence, in which they received either 800 mg oral CBD or placebo (PBO), in a randomised order. Abstinence was biologically verified. Participants were assessed on go/no-go, delay discounting, prose recall and N-back (0-back, 1-back, 2-back) tasks. The effects of CBD on delay discounting, prose recall and the N-back (correct responses, maintenance or manipulation) were null, confirmed by a Bayesian analysis, which found evidence for the null hypothesis. Contrary to our predictions, CBD increased commission errors on the go/no-go task. In conclusion, a single 800 mg dose of CBD does not improve verbal or spatial working memory, or impulsivity during tobacco abstinence.

Changes in resting state functional brain connectivity and withdrawal symptoms are associated with acute electronic cigarette use

Resting state functional brain connectivity (rsFC) may be an important neuromarker of smoking behavior. Prior research has shown, among cigarette smokers, that nicotine administration alters rsFC within frontal and parietal cortices involved in executive control, as well as striatal regions that drive reward processing. These changes in rsFC have been associated with reductions in withdrawal symptom severity. We currently have a limited understanding of how rsFC is affected by the use of electronic cigarettes (ecigs), an increasingly popular class of products, the members of which deliver nicotine with varying effectiveness. The current study used fMRI to determine the effects of ecig use on rsFC and withdrawal symptoms. Independent component, dual regression, and permutation analyses were conducted on rsFC collected from ecig users before and after an ecig use episode (n=9) that occurred after 14h of nicotine abstinence. Similar to the known effects of nicotine administration, ecig use decreased rsFC of two clusters in the right frontal pole and frontal medial cortex with an attentional control salience network, and decreased rsFC of five clusters in the left thalamus, insula, and brain stem with a reward network encompassing the striatum. Ecig use increased inverse coupling between the prefrontal reward network and the right frontoparietal executive control network. Reductions in craving and difficulty with concentration were correlated with decreases in coupling strength between reward and executive control networks. These preliminary results suggest that the effects of ecig use on rsFC are similar to those seen with nicotine administration in other forms. In order to gain insight into the addictive potential of ecigs, further research is needed to understand the neural influence of ecigs across the range of nicotine delivery within this class of products.

Minimal effects of prolonged smoking abstinence or resumption on cognitive performance challenge the "self-medication" hypothesis in schizophrenia

One prominent, long-standing view is that individuals with schizophrenia smoke cigarettes more than the general population to "self-medicate" cognitive deficits and other symptoms. This study tested the self-medication hypothesis by examining the effects of smoking abstinence and resumption on cognition in patients with schizophrenia. Nicotine-dependent smokers with schizophrenia (n=26) were trained on a cognitive battery and then hospitalized to achieve and maintain confirmed abstinence from smoking for ~1 week. Cognition was tested while smoking as usual (baseline), one day after smoking cessation (early abstinence), ~1 week later (extended abstinence), and within ~3 weeks of resuming smoking (resumption). The test battery included measures of processing speed, attention, conflict resolution, verbal memory, working memory, verbal fluency, and executive function to evaluate multiple cognitive domains affected by schizophrenia. Positive and negative symptoms of schizophrenia, depressive symptoms, and dyskinesia were also measured at baseline and after prolonged abstinence. There were no significant changes in global cognitive test performance with smoking cessation, abstinence, or resumption. There were small decreases in a measure of processing speed and delayed verbal recall with abstinence, but these findings failed to survive adjustments for multiple comparisons. Surprisingly, in this within subject "On-Off-Off-On" design, there were no significant effects of early or prolonged abstinence from smoking on cognitive and behavioral measures in smokers with schizophrenia. The results of this study challenge the widely held "self-medication" hypothesis of smoking and schizophrenia, question the extent of pro-cognitive effects of smoking and nicotine in schizophrenia, and support encouraging smoking cessation in schizophrenia.

The Effects of Smoking Abstinence on Incentivized Spatial Working Memory

BACKGROUND AND OBJECTIVE

Reward processing and working memory (WM) underlie value-based decision-making; consequently, joint examination of these systems may further our understanding of why smokers choose to smoke again following a quit attempt (relapse). While previous studies have demonstrated altered reward and WM function associated with nicotine exposure, little is known about the effects of abstinence on the joint function of these systems. The current study aims to address this gap.

METHOD

Eighteen daily smokers were tested on a monetarily incentivized memory guided saccade (MGS) task on two separate, counterbalanced occasions, an abstinent and a non-abstinent session. The MGS task is a widely used metric of spatial working memory and enables precise quantification of the effects of rewards and nicotine exposure on behavior.

RESULTS

During the non-abstinent session, participants showed increased accuracy of the initial saccade towards the remembered target location on reward vs. neutral trials. Participants also showed increased accuracy of the final saccade towards the target, across incentive types, only during the non-abstinent condition.

DISCUSSION AND CONCLUSIONS

Our observation that rewards improve the accuracy of the initial memory guided saccade during the non-abstinent but not abstinent condition extends a growing literature indicating reduced motivation towards monetary rewards during abstinence. Further, differences in the accuracy of the final corrective saccade during the non-abstinent but not the abstinent condition suggests smoking abstinence-related effects on WM precision beyond those related to incentive motivation (e.g., sustained attention).

SIGNIFICANCE

This work extends our fundamental understanding of smoking's effects on core affective and cognitive processes.

Varenicline, the clinically effective smoking cessation agent, restores probabilistic response reversal performance during withdrawal from nicotine

There is recognition that cognitive problems can contribute to renewed drug taking in former addicts. Our previous work has indicated that current smokers show reduced performance on a probabilistic reversal learning (PRL) task, relative to former smokers. To further explore PRL performance and its relevance to smoking, in addition to the role of nicotine, we developed a model of nicotine withdrawal-induced deficits in rodents. A second goal was to test varenicline, an α4β2 partial agonist, for its ability to restore any cognitive impairment. Acute effects of nicotine and varenicline on PRL performance in non-dependent animals were minimal and confined to speed of responding. When rats were made dependent on nicotine via osmotic minipumps implanted for 7 days (3.16 mg/kg/day), repeated tests at specified withdrawal time points revealed PRL disruption peaking at 12 and 24 hours following surgical removal of minipumps. Withdrawal was characterized by significant deficits in the number of reversals (P < 0.05), speed of responding (P < 0.01) and increases in omissions (P < 0.05). Nicotine (0.2 mg/kg SC) or varenicline (0.3 and 1.0 mg/kg SC) administered 10-minute prior to PRL test sessions during withdrawal, relieved the performance deficits. At 24-hour withdrawal, nicotine and varenicline (1 mg/kg) prevented decrements in reversals, in addition to ameliorating slower speed of responding. The high dose of varenicline only reduced omissions. These results confirm the role of nicotine in withdrawal-induced disruption of PRL performance and suggest that the model may be useful for investigating efficacy of potential new treatments for smoking cessation.

12h abstinence-induced right anterior insula network pattern changes in young smokers

BACKGROUND

The strong craving to smoke is a core factor of smoking abstinence that precipitates relapse. Insula plays critical roles in maintaining nicotine dependence, especially in the interoceptive awareness of craving. Despite evidence indicating a link between insula and abstinence-induced craving, less is known about the neural basis of abstinence-induced craving from the circuit level of insula.

METHODS

The present study examined the effects of 12h of abstinence from smoking on the resting state functional connectivity (RSFC) of anterior (AI) and posterior insula in young smokers using a within-subject design. Thirty-three young male smokers underwent functional magnetic resonance imaging scanning on two separate sessions: (1) smoking satiety and (2) abstinence (after ≥12h of smoking deprivation), in counterbalanced order. Multiple regression analysis was applied to investigate the possible relationships between the RSFC changes of insula (abstinence minus satiety) and the abstinence-induced craving changes.

RESULTS

Smoking abstinence state (versus satiety) was associated with increased RSFC between right AI and right medial orbitofrontal cortex (OFC), ventromedial prefrontal cortex as well as anterior cingulate cortex. The abstinence-induced RSFC changes between right AI and right lateral OFC was significantly correlated with the craving changes.

CONCLUSIONS

These findings improve the understanding of the effects of short-term smoking abstinence on insula circuit connectivity and may contribute new insights into the neural basis of abstinence-induced craving to smoke.

Decreased Central Nervous System Grey Matter Volume (GMV) in Smokers Affects Cognitive Abilities: A Systematic Review

Although cigarette smoking is a leading cause of preventable mortality, tobacco is consumed by approximately 22% of the adult population worldwide. Smoking is also a risk factor for cardiovascular disease, affects brain processing, and is a recognized risk factor for Alzheimer disease (AD). Tobacco toxins (e.g., nicotine at high levels) inhaled in smoke may cause disorders resulting in preclinical brain changes. Researchers suggest that there are differences in brain volume between smokers and non-smokers. This review examines these differences in brain grey matter volume (GMV). In March/April 2015, MedLine, Embase, and PsycINFO were searched using the terms: "grey matter" AND "voxel-based" AND "smoking" AND "cigarette". The 4 studies analyzed found brain GMV decreases in smokers compared to non-smokers. Furthermore, sex-specific differences were found; while the thalamus and cerebellum were affected in both sexes, decreased GMV in the olfactory gyrus was found only in male smokers. Age-group differences were also found, and these may suggest pre-existing abnormalities that lead to nicotine dependence in younger individuals. Only 1 study found a positive correlation between number of pack-years smoked and GMV. Smoking decreases GMV in most brain areas. This decrease may be responsible for the cognitive impairment and difficulties with emotional regulation found in smokers compared with non-smokers.

Cigarette smoking and depression comorbidity: systematic review and proposed theoretical model

BACKGROUND AND AIMS

Despite decades of research on co-occurring smoking and depression, cessation rates remain consistently lower for depressed smokers than for smokers in the general population, highlighting the need for theory-driven models of smoking and depression. This paper provides a systematic review with a particular focus upon psychological states that disproportionately motivate smoking in depression, and frame an incentive learning theory account of smoking-depression co-occurrence.

METHODS

We searched PubMed, Scopus, PsychINFO and CINAHL to December 2014, which yielded 852 papers. Using pre-established eligibility criteria, we identified papers focused on clinical issues and motivational mechanisms underlying smoking in established, adult smokers (i.e. maintenance, quit attempts and cessation/relapse) with elevated symptoms of depression. Two reviewers determined independently whether papers met review criteria. We included 297 papers in qualitative synthesis.

RESULTS

Our review identified three primary mechanisms that underlie persistent smoking among depressed smokers: low positive affect, high negative affect and cognitive impairment. We propose a novel application of incentive learning theory which posits that depressed smokers experience greater increases in the expected value of smoking in the face of these three motivational states, which promotes goal-directed choice of smoking behavior over alternative actions.

CONCLUSIONS

The incentive learning theory accounts for current evidence on how depression primes smoking behavior and provides a unique framework for conceptualizing psychological mechanisms of smoking maintenance among depressed smokers. Treatment should focus upon correcting adverse internal states and beliefs about the high value of smoking in those states to improve cessation outcomes for depressed smokers.

Effects of drugs of abuse on hippocampal plasticity and hippocampus-dependent learning and memory: contributions to development and maintenance of addiction

It has long been hypothesized that conditioning mechanisms play major roles in addiction. Specifically, the associations between rewarding properties of drugs of abuse and the drug context can contribute to future use and facilitate the transition from initial drug use into drug dependency. On the other hand, the self-medication hypothesis of drug abuse suggests that negative consequences of drug withdrawal result in relapse to drug use as an attempt to alleviate the negative symptoms. In this review, we explored these hypotheses and the involvement of the hippocampus in the development and maintenance of addiction to widely abused drugs such as cocaine, amphetamine, nicotine, alcohol, opiates, and cannabis. Studies suggest that initial exposure to stimulants (i.e., cocaine, nicotine, and amphetamine) and alcohol may enhance hippocampal function and, therefore, the formation of augmented drug-context associations that contribute to the development of addiction. In line with the self-medication hypothesis, withdrawal from stimulants, ethanol, and cannabis results in hippocampus-dependent learning and memory deficits, which suggest that an attempt to alleviate these deficits may contribute to relapse to drug use and maintenance of addiction. Interestingly, opiate withdrawal leads to enhancement of hippocampus-dependent learning and memory. Given that a conditioned aversion to drug context develops during opiate withdrawal, the cognitive enhancement in this case may result in the formation of an augmented association between withdrawal-induced aversion and withdrawal context. Therefore, individuals with opiate addiction may return to opiate use to avoid aversive symptoms triggered by the withdrawal context. Overall, the systematic examination of the role of the hippocampus in drug addiction may help to formulate a better understanding of addiction and underlying neural substrates.

Novel Therapeutics for Addiction: Behavioral and Neuroeconomic Approaches

The maturing fields of behavioral- and neuro-economics provides conceptual understanding of the Competing Neurobehavioral Decision Systems theory (CNDS) and reinforcer pathology (i.e. high valuation of and excessive preference for drug reinforcers) allowing us to coherently categorize treatments into a theoretically comprehensive framework of addiction. In this chapter, we identify and clarify how existing and novel interventions can ameliorate reinforcer pathology in light of the CNDS and be leveraged to treat addiction.

The effects of nicotine and non-nicotine smoking factors on working memory and associated brain function

Smoking abstinence impairs executive function, which may promote continued smoking behavior and relapse. The differential influence of nicotine and non-nicotine (i.e. sensory, motor) smoking factors and related neural substrates is not known. In a fully factorial, within-subjects design, 33 smokers underwent fMRI scanning following 24 hours of wearing a nicotine or placebo patch while smoking very low nicotine content cigarettes or remaining abstinent from smoking. During scanning, blood oxygenation level-dependent (BOLD) signal was acquired while participants performed a verbal N-back task. Following 24-hour placebo (versus nicotine) administration, accuracy on the N-back task was significantly worse and task-related BOLD signal lower in dorsomedial frontal cortex. These effects were observed irrespective of smoking. Our data provide novel evidence that abstinence-induced deficits in working memory and changes in underlying brain function are due in large part to abstinence from nicotine compared with non-nicotine factors. This work has implications both for designing interventions that target abstinence-induced cognitive deficits and for nicotine-reduction policy.

Smoke and mirrors: The overnight abstinence paradigm as an index of disrupted cognitive function

RATIONALE

Smoking abstinence is known to cause decrements in cognition, but the effects are small and variable. One way to reduce variance may be to aggregate measures or visits. Although trait-like individual differences in smoking abstinence effects on cognition are theorized to predict relapse, the test-retest reliability (TRR) assumed in trait models has not been evaluated.

OBJECTIVES

The objectives of this study were to assess the value of aggregating measures to determine effect sizes (ESs) of smoking versus abstinence on measures of cognition and to assess the short-term TRR of abstinence effects on cognition.

METHODS

Thirty adult smokers completed the typical overnight abstinence paradigm twice; each visit pair consisted of one smoking visit and one abstinent visit. Measures of attention, working memory, and inhibitory control were obtained in each visit.

RESULTS

There were small to medium ESs for smoking abstinence on individual cognitive measures during the first abstinence experience ("visit pair"). Aggregating the measures within the visit pair and across visit pairs additively increased the ES of smoking versus abstinence. Although TRRs were acceptable between smoking visits and between abstinent visits, TRRs for abstinence effects (smoking vs. abstinent visit differences) on cognition were consistently weak.

DISCUSSION

The ability of the typical overnight abstinence paradigm to reflect disrupted cognition at the group level can be substantially improved by aggregating across cognitive outcomes and/or multiple study visits. However, the patterns of poor TRR of smoking-abstinence differences in cognition caution against their use as trait-like markers in studies of relapse or treatment response.

Executive Functions in Tobacco Dependence: Importance of Inhibitory Capacities

BACKGROUND

Executive functions are linked to tobacco dependence and craving. In this cross-sectional study, we assessed the impact of three executive functions: updating, inhibition and shifting processes on tobacco craving and dependence.

METHOD

134 tobacco consumers were included in this study: 81 moderately (Fagerström score <7) and 53 heavily dependent (Fagerström score >7). Dependence was assessed with the Fagerström test and craving with the tobacco craving questionnaire (TCQ 12). We used the Stroop test and the Hayling test to measure inhibition, the Trail Making Test to measure shifting processes and the n-back test to measure updating processes. A multivariate logistic model was used to assess which variables explained best the level of nicotine dependence.

RESULTS

Inhibition (p = 0.002) and updating (p = 0.014) processes, but not shifting processes, were associated with higher tobacco dependence. Inhibition capacity had a significant effect on the nicotine dependence level independently of age, education, time since last cigarette, intellectual quotient, craving, updating and shifting process.

CONCLUSIONS

Nicotine dependence level seems better explained by inhibition capacities than by craving and updating effects. The capacity to inhibit our behaviours is a good predictor of the severity of tobacco dependence. Our results suggest a prefrontal cortex dysfunction affecting the inhibitory capacities of heavy tobacco dependent smokers. Further studies are needed to investigate the application of these findings in the treatment of tobacco dependence.

ABT-089, but not ABT-107, ameliorates nicotine withdrawal-induced cognitive deficits in C57BL6/J mice

Nicotine withdrawal produces cognitive deficits that can predict relapse. Amelioration of these cognitive deficits emerges as a target in current smoking cessation therapies. In rodents, withdrawal from chronic nicotine disrupts contextual fear conditioning (CFC), whereas acute nicotine enhances this hippocampus-specific learning and memory. These modifications are mediated by β2-subunit-containing (β2*) nicotinic acetylcholine receptors in the hippocampus. We aimed to test ABT-089, a partial agonist of α4β2*, and ABT-107, an α7 nicotinic acetylcholine receptor agonist, for amelioration of cognitive deficits induced by withdrawal from chronic nicotine in mice. Mice underwent chronic nicotine administration (12.6 mg/kg/day or saline for 12 days), followed by 24 h of withdrawal. At the end of withdrawal, mice received 0.3 or 0.6 mg/kg ABT-089 or 0.3 mg/kg ABT-107 (doses were determined through initial dose-response experiments and prior studies) and were trained and tested for CFC. Nicotine withdrawal produced deficits in CFC that were reversed by acute ABT-089, but not ABT-107. Cued conditioning was not affected. Taken together, our results suggest that modulation of hippocampal learning and memory using ABT-089 may be an effective component of novel therapeutic strategies for nicotine addiction.

Nicotine Addiction and Psychiatric Disorders

Even though smoking rates have long been on the decline, nicotine addiction still affects 20% of the US population today. Moreover, nicotine dependence shows high comorbidity with many mental illnesses including, but are not limited to, attention deficit hyperactivity disorder, anxiety disorders, and depression. The reason for the high rates of smoking in patients with mental illnesses may relate to attempts to self-medicate with nicotine. While nicotine may alleviate the symptoms of mental disorders, nicotine abstinence has been shown to worsen the symptoms of these disorders. In this chapter, we review the studies from animal and human research examining the bidirectional relationship between nicotine and attention deficit hyperactivity disorder, anxiety disorders, and depression as well as studies examining the roles of specific subunits of nicotinic acetylcholine receptors (nAChRs) in the interaction between nicotine and these mental illnesses. The results of these studies suggest that activation, desensitization, and upregulation of nAChRs modulate the effects of nicotine on mental illnesses.

Working memory-related neural activity predicts future smoking relapse

Brief abstinence from smoking impairs cognition, particularly executive function, and this has a role in relapse to smoking. This study examined whether working memory-related brain activity predicts subsequent smoking relapse above and beyond standard clinical and behavioral measures. Eighty treatment-seeking smokers completed two functional magnetic resonance imaging sessions (smoking satiety vs 24 h abstinence challenge) during performance of a visual N-back task. Brief counseling and a short-term quit attempt followed. Relapse during the first 7 days was biochemically confirmed by the presence of the nicotine metabolite cotinine. Mean percent blood oxygen level-dependent (BOLD) signal change was extracted from a priori regions of interest: bilateral dorsolateral prefrontal cortex (DLPFC), medial frontal/cingulate gyrus, posterior cingulate cortex (PCC), and ventromedial prefrontal cortex. Signal from these brain regions and additional clinical measures were used to model outcome status, which was then validated with resampling techniques. Relapse to smoking was predicted by increased withdrawal symptoms, decreased left DLPFC and increased PCC BOLD percent signal change (abstinence vs smoking satiety). Receiver operating characteristic analysis demonstrated 81% area under the curve using these predictors, a significant improvement over the model with clinical variables only. The combination of abstinence-induced decreases in left DLPFC activation and reduced suppression of PCC may be a prognostic marker for poor outcome, specifically early smoking relapse.

Inhibition of monoacylglycerol lipase reduces nicotine withdrawal

BACKGROUND AND PURPOSE

Abrupt discontinuation of nicotine, the main psychoactive component in tobacco, induces a withdrawal syndrome in nicotine-dependent animals, consisting of somatic and affective signs, avoidance of which contributes to drug maintenance. While blockade of fatty acid amide hydrolase, the primary catabolic enzyme of the endocannabinoid arachidonoylethanolamine (anandamide), exacerbates withdrawal responses in nicotine-dependent mice, the role of monoacylglycerol lipase (MAGL), the main hydrolytic enzyme of a second endocannabinoid 2-arachidonylglycerol (2-AG), in nicotine withdrawal remains unexplored.

EXPERIMENTAL APPROACH

To evaluate the role of MAGL enzyme inhibition in nicotine withdrawal, we initially performed a genetic correlation approach using the BXD recombinant inbred mouse panel. We then assessed nicotine withdrawal intensity in the mouse after treatment with the selective MAGL inhibitor, JZL184, and after genetic deletion of the enzyme. Lastly, we assessed the association between genotypes and smoking withdrawal phenotypes in two human data sets.

KEY RESULTS

BXD mice displayed significant positive correlations between basal MAGL mRNA expression and nicotine withdrawal responses, consistent with the idea that increased 2-AG brain levels may attenuate withdrawal responses. Strikingly, the MAGL inhibitor, JZL184, dose-dependently reduced somatic and aversive withdrawal signs, which was blocked by rimonabant, indicating a CB1 receptor-dependent mechanism. MAGL-knockout mice also showed attenuated nicotine withdrawal. Lastly, genetic analyses in humans revealed associations of the MAGL gene with smoking withdrawal in humans.

CONCLUSIONS AND IMPLICATIONS

Overall, our findings suggest that MAGL inhibition maybe a promising target for treatment of nicotine dependence.

Smoking history, and not depression, is related to deficits in detection of happy and sad faces

INTRODUCTION

Previous research has demonstrated that chronic cigarette smoking and major depressive disorder (MDD) are each associated with cognitive decrements. Further, these conditions co-occur commonly, though mechanisms in the comorbid condition are poorly understood. There may be distinct, additive, or overlapping factors underlying comorbid cigarette smoking and MDD. The present study investigated the impact of smoking and MDD on executive function and emotion processing.

METHODS

Participants (N=198) were grouped by diagnostic category (MDD and healthy controls, HC) and smoking status (ever-smokers, ES and never-smokers, NS). Participants completed the Facial Emotion Perception Test (FEPT), a measure of emotional processing, and the parametric Go/No-go task (PGNG), a measure of executive function.

RESULTS

FEPT performance was analyzed using ANCOVA with accuracy and reaction time as separate dependent variables. Repeated measures MANCOVA was conducted for PGNG with performance measure and task level as dependent variables. Analyses for each task included diagnostic and smoking group as independent variables, and gender was controlled for. Results for FEPT reveal that lower overall accuracy was found for ES relative to NS, though MDD did not differ from HC. Post-hoc analyses revealed that ES were poorer at identifying happy and sad, but not fearful or angry, faces. For PGNG, poorer performance was observed in MDD relative to HC in response time to Go targets, but there were no differences for ES and NS. Interaction of diagnosis and smoking group was not observed for performance on either task.

CONCLUSIONS

The results of this study provide preliminary evidence for distinctive cognitive decrements in smokers and individuals with depression.

Extended access nicotine self-administration with periodic deprivation increases immature neurons in the hippocampus

RATIONALE

Limited access nicotine self-administration decreases hippocampal neurogenesis, providing a mechanism for the deleterious effects of nicotine on hippocampal neuronal plasticity. However, recent studies have shown that limited access nicotine self-administration does not exhibit key features of nicotine dependence such as motivational withdrawal and increased motivation for nicotine after deprivation.

OBJECTIVES

The present study used extended access nicotine self-administration (0.03 mg/kg/infusion, 21 h/day, 4 days) with intermittent periods of deprivation (3 days) for 14 weeks, to test the hypothesis that this model enhances nicotine seeking and produces distinct responses in hippocampal neurogenesis when compared with limited access (1 h/day, 4 days) intake. Animals in the extended access group were either perfused prior to or following their final deprivation period, whereas animals in the limited access group were perfused after their last session.

RESULTS

Limited- and extended access nicotine self-administration with periodic deprivation did not affect proliferation and differentiation of oligodendrocyte progenitors in the medial prefrontal cortex (mPFC). Conversely, extended access nicotine self-administration with periodic deprivation enhanced proliferation and differentiation of hippocampal neural progenitors. Furthermore, in the hippocampus, the number of differentiating NeuroD-labeled cells strongly and positively correlated with enhanced nicotine seeking in rats that experienced extended access nicotine self-administration.

CONCLUSIONS

These findings demonstrate that extended versus limited access to nicotine self-administration differentially affects the generation of new oligodendroglia and new neurons during adulthood. The increases in the number of differentiating cells in extended access nicotine self-administering rats may consequently contribute to aberrant hippocampal neurogenesis and may contribute to maladaptive addiction-like behaviors dependent on the hippocampus.

Nicotinic receptors, memory, and hippocampus

Nicotinic acetylcholine receptors (nAChRs) modulate the neurobiological processes underlying hippocampal learning and memory. In addition, nicotine's ability to desensitize and upregulate certain nAChRs may alter hippocampus-dependent memory processes. Numerous studies have examined the effects of nicotine on hippocampus-dependent learning, as well as the roles of low- and high-affinity nAChRs in mediating nicotine's effects on hippocampus-dependent learning and memory. These studies suggested that while acute nicotine generally acts as a cognitive enhancer for hippocampus-dependent learning, withdrawal from chronic nicotine results in deficits in hippocampus-dependent memory. Furthermore, these studies demonstrated that low- and high-affinity nAChRs functionally differ in their involvement in nicotine's effects on hippocampus-dependent learning. In the present chapter, we reviewed studies using systemic or local injections of acute or chronic nicotine, nAChR subunit agonists or antagonists; genetically modified mice; and molecular biological techniques to characterize the effects of nicotine on hippocampus-dependent learning.

Smoking abstinence and neurocognition: implications for cessation and relapse

In this chapter, we review the last decade of research on the effects of smoking abstinence on various forms of neurocognition, including executive function (working memory, sustained attention, response inhibition), reward processing, and cue-reactivity. In our review we identify smoking abstinence-induced deficits in executive function mediated by effects on frontal circuitry, which in turn is known to be affected by modulation of cholinergic, dopaminergic, and other neurotransmitter systems. We also review evidence that smoking abstinence blunts reactivity to non-drug reinforcers-a finding that is consistent with results in the animal literature. Finally, our review of cue-reactivity indicates that smoking abstinence does not appear to amplify cue-provoked craving, although it may increase attentional bias to smoking-related cues. Inconsistencies across findings and potential contributing factors are discussed. In addition, we review the literature on the effects of nicotine and non-nicotine factors in neurocognition. Finally, we provide a multi-factor model and an agenda for future research on the effects of smoking abstinence on neurocognition. The model includes four distinct yet interacting factors, including: Negative Reinforcement, Drug-Reward Bias, Goal and Skill Interference, and Non-Cognitive Factors. Additional research is needed to further evaluate the scope and time-course of abstinence-induced changes in neurocognition, the mechanisms that underlie these changes and the specific role of these processes in drug reinforcement, lapse, and relapse.