Meta-analysis of the acute effects of nicotine and smoking on human performance

Inter-Individual Differences in Executive Functions Predict Multitasking Performance - Implications for the Central Attentional Bottleneck

Human multitasking suffers from a central attentional bottleneck preventing parallel performance of central mental operations, leading to profound deferments in task performance. While previous research assumed that the deferment is caused by a mere waiting time (refractory period), we show that the bottleneck requires executive functions (EF; active scheduling account) accounting for a profound part of the deferment. Three participant groups with EF impairments (dyslexics, highly neurotics, deprived smokers) showed worse multitasking performance than respective control groups. Three further groups with EF improvements (video-gamers, bilinguals, coffee consumers) showed improved multitasking. Finally, three groups performed a dual-task and different measures of EF (reading span, rotation span, symmetry span) and showed significant correlations between multitasking performance and working memory capacity. Demands on EF during multitasking may cause more errors, mental fatigue and stress, with parts of the population being considerably more prone to this.

Association Between Various Types or Statuses of Smoking and Subjective Cognitive Decline Based on a Community Health Survey of Korean Adults

Objectives

The relationship between smoking and subjective cognitive decline (SCD), which is defined as the subjective perception of cognitive decline, is not well known. This study aimed to investigate the relationship of various types of smoking, including E-cigarette smoking and the use of E-liquid, with the incidence of SCD among Korean adults.

Methods

We evaluated the 2018 Korean Community Health Survey data collected from community-dwelling people in Korea. A total of 104,453 non-smokers, 38,607 past smokers, and 26,776 current smokers with eligible data were included in the study. SCD was assessed using the Behavioral Risk Factor Surveillance System. The past or current smoking pack-years throughout each participant's entire life were calculated. Multiple regression analyses were carried out to estimate the adjusted odds ratios (ORs) as measures of the association between each type of smoking and SCD after adjustment for potential confounders.

Results

Compared to no exposure, passive smoking was associated with higher odds of SCD. Compared to non-smokers, past smokers had a higher OR for SCD; however, current smokers did not. There were no significant associations between passive smoking and SCD in the non-smoker and past smoker groups, but there was a significant relationship between them in the current smoker group. While the cumulative dose of smoking was correlated with an increased OR of SCD in each group of current smokers and past smokers, E-cigarette smoking and the use of E-liquid were not associated with higher ORs in the current smoker group.

Conclusion

Our findings support that passive smoking and past smoking are significantly associated with SCD and that more cumulative exposure to smoking is correlated with a higher OR of SCD.

Chronic Nicotine Exposure Increases Hematoma Expansion Following Collagenase-Induced Intracerebral Hemorrhage in Rats

Spontaneous intracerebral hemorrhage (sICH) is a deadly stroke subtype, and tobacco use increases sICH risk. However epidemiological studies show that, there are no confirmatory studies showing the effect of tobacco use on sICH outcome. Therefore, we evaluated the effect of chronic nicotine exposure (as a surrogate for tobacco use) on outcomes following sICH. Young male and female rats were randomly assigned to either nicotine (4.5 mg/kg b.w. per day) or vehicle (saline) treatment (2–3 weeks) groups. sICH was induced by injecting collagenase into the right striatum. Neurological score and hematoma volume were determined 24 h post-sICH. The hematoma volumes in nicotine-treated male and female rats were significantly higher by 42% and 48% when compared to vehicle-treated male and female rats, respectively. Neurological deficits measured in terms of neurological score for the nicotine-treated male and female groups were significantly higher when compared to the respective vehicle-treated male and female groups. Our results show that chronic nicotine exposure increases hematoma volume post-sICH in rats of both sexes. Identifying the mechanism of nicotine-dependent increase in hematoma growth post-sICH will be crucial to understanding the detrimental effect of tobacco use on the severity of bleeding following intracerebral hemorrhage.

Impact of Nicotine on Cognition in Patients With Schizophrenia: A Narrative Review

Nicotine is the psychoactive component given tobacco has several main components and acts as an agonist for nicotinic acetylcholine receptors (nAChRs) in the nervous system. Although the ligand-gated cation channels known as nAChRs are found throughout the nervous system and body, this review focuses on neuronal nAChRs. Individuals with psychiatric diseases such as schizophrenia, comorbid substance use disorders, attention-deficit hyperactivity disorder, major depression, and bipolar disorder have increased rates of smoking. These psychiatric disorders are associated with various cognitive deficits, including working memory, deficits in attention, and response inhibition functions. The cognitive-enhancing effects of nicotine may be particularly relevant predictors of smoking initiation and continuation in this comorbid population. Individuals with schizophrenia make up a significant proportion of smokers. Literature suggests that patients smoke to alleviate cognitive deficiencies due to the stimulating effects of nicotine. This narrative review examines the role of nicotine on cognition in schizophrenia.

Impact of delivery rate on the acute response to intravenous nicotine: A human laboratory study with implications for regulatory science

Faster delivery rate enhances the abuse potential of drugs of abuse, yet systematic studies on the impact of delivery rate on the acute effects of nicotine in humans are lacking. Using an intravenous (IV) nicotine infusion procedure that allows precise control of rate of delivery, we examined the impact of nicotine delivery rate on the positive subjective drug effects, smoking urges, withdrawal, heart rate, blood pressure and attention function in smokers. Twenty-four male and female (ages 21-35) dependent smokers attended five experimental sessions, following overnight abstinence from smoking. Using a crossover design, participants attended five sessions, where they were assigned to a random sequence of saline infusion or 1 mg nicotine delivered over 1, 2.5, 5 or 10 min at rates of 1, 0.4, 0.2 or 0.1 mg/min, respectively. The positive subjective effects of nicotine were most robust under the two faster delivery rate conditions, 1- and 0.4-mg nicotine/min. In contrast, all nicotine delivery rates were equally more effective than saline in alleviating urges to smoke. Likewise, nicotine-induced heart rate increases did not vary with the rate of nicotine delivery. Lastly, the cognitive enhancing effects of nicotine were observed only under the two slowest delivery rate conditions-0.1- and 0.2-mg nicotine/min. Collectively, these findings support the critical role of delivery rate in optimizing nicotine's abuse potential versus potential therapeutic effects and have timely implications for developing novel therapeutics for nicotine dependence, as well as for tobacco regulatory science.

Nicotine depresses facial stimulation-evoked molecular layer interneuron-Purkinje cell synaptic transmission via α7 nicotinic acetylcholine receptors in mouse cerebellar cortex

Nicotine modulates cerebellar physiology function by interacting with nicotinic acetylcholine receptors (nAChRs) and is involved in modulation of cerebellar cortical circuitry functions. Here, we investigated the effect of nicotine on sensory stimulation-evoked molecular layer interneuron-Purkinje cell (MLI-PC) synaptic transmission mouse cerebellar cortex using in vivo cell-attached recording technique and pharmacological methods. The results show that micro-application of nicotine to the cerebellar molecular layer significantly decreased sensory stimulation-evoked MLI-PC synaptic transmission in mouse cerebellar cortex. Nicotine-induced depression in sensory stimulation-evoked MLI-PC synaptic transmission was abolished by either a non-selective nAChR blocker, hexamethonium, or the α7-nAChR antagonist methyllycaconitine (MLA), but not the selective α4β2-nAChR antagonist dihydro-β-erythroidine. Notably, molecular layer micro-application of nicotine did not significantly affect the number of spontaneous or facial stimulation-evoked action potentials of MLIs. Moreover, nicotine produced significant increases in the amplitude and frequency of miniature inhibitory postsynaptic currents of PCs, which were abolished by MLA in cerebellar slices. These results indicate that micro-application of nicotine to the cerebellar molecular layer depresses facial stimulation-induced MLI-PC synaptic transmission by activating α7 nAChRs, suggesting that cholinergic inputs modulate MLI-PC synapses to process sensory information in the cerebellar cortex of mice in vivo.

Deprivation Has Inconsistent Effects on Delay Discounting: A Review

Delay discounting, the tendency for outcomes to be devalued as they are more temporally remote, has implications as a target for behavioral interventions. Because of these implications, it is important to understand how different states individuals may face, such as deprivation, influence the degree of delay discounting. Both dual systems models and state-trait views of delay discounting assume that deprivation may result in steeper delay discounting. Despite early inconsistencies and mixed results, researchers have sometimes asserted that deprivation increases delay discounting, with few qualifications. The aim of this review was to determine what empirical effect, if any, deprivation has on delay discounting. We considered many kinds of deprivation, such as deprivation from sleep, drugs, and food in humans and non-human animals. For 23 studies, we analyzed the effect of deprivation on delay discounting by computing effect sizes for the difference between delay discounting in a control, or baseline, condition and delay discounting in a deprived state. We discuss these 23 studies and other relevant studies found in our search in a narrative review. Overall, we found mixed effects of deprivation on delay discounting. The effect may depend on what type of deprivation participants faced. Effect sizes for deprivation types ranged from small for sleep deprivation (Hedge's gs between −0.21 and 0.07) to large for opiate deprivation (Hedge's gs between 0.42 and 1.72). We discuss possible reasons why the effect of deprivation on delay discounting may depend on deprivation type, including the use of imagined manipulations and deprivation intensity. The inconsistency in results across studies, even when comparing within the same type of deprivation, indicates that more experiments are needed to reach a consensus on the effects of deprivation on delay discounting. A basic understanding of how states affect delay discounting may inform translational efforts.

The role of the SLC6A3 3' UTR VNTR in nicotine effects on cognitive, affective, and motor function

RATIONALE

Nicotine has been widely studied for its pro-dopaminergic effects. However, at the behavioural level, past investigations have yielded heterogeneous results concerning effects on cognitive, affective, and motor outcomes, possibly linked to individual differences at the level of genetics. A candidate polymorphism is the 40-base-pair variable number of tandem repeats polymorphism (rs28363170) in the SLC6A3 gene coding for the dopamine transporter (DAT). The polymorphism has been associated with striatal DAT availability (9R-carriers > 10R-homozygotes), and 9R-carriers have been shown to react more strongly to dopamine agonistic pharmacological challenges than 10R-homozygotes.

OBJECTIVES

In this preregistered study, we hypothesized that 9R-carriers would be more responsive to nicotine due to genotype-related differences in DAT availability and resulting dopamine activity.

METHODS

N=194 non-smokers were grouped according to their genotype (9R-carriers, 10R-homozygotes) and received either 2-mg nicotine or placebo gum in a between-subject design. Spontaneous blink rate (SBR) was obtained as an indirect measure of striatal dopamine activity and smooth pursuit, stop signal, simple choice and affective processing tasks were carried out in randomized order.

RESULTS

Reaction times were decreased under nicotine compared to placebo in the simple choice and stop signal tasks, but nicotine and genotype had no effects on any of the other task outcomes. Conditional process analyses testing the mediating effect of SBR on performance and how this is affected by genotype yielded no significant results.

CONCLUSIONS

Overall, we could not confirm our main hypothesis. Individual differences in nicotine response could not be explained by rs28363170 genotype.

Risky decision-making as an antecedent or consequence of adolescent cannabis use: findings from a 2-year longitudinal study

BACKGROUND AND AIMS

Although poor decision-making (DM) has been correlated with problematic cannabis use (CU), cross-sectional designs make it difficult to determine whether poor DM represents an antecedent and/or consequence of CU. The current study measured bidirectional associations between CU and DM among adolescents over 2 years and compared these findings to those observed with episodic memory, which is consistently reported as a consequence of CU. We also measured the role of DM as a risk factor for cannabis use disorder (CUD) onset.

DESIGN

Two-year longitudinal study with five bi-annual assessments.

PARTICIPANTS

Participants were 401 adolescents aged 14-17 years at baseline.

SETTING

Miami, Florida, USA.

MEASUREMENTS

CU frequency and CUDs were assessed at each time-point through the Drug Use History Questionnaire and Structured Clinical Interview for DSM-IV, respectively. Neurocognition was assessed at odd time-points throughout the Iowa Gambling Task, Game of Dice Task and Cups Task [decision-making (DM)] and the Wechsler Memory Scale IV and California Verbal Learning Test II (episodic memory). We used latent growth curve modeling to examine bidirectional influences between CU and neurocognition over time. We applied discrete time survival analyses to determine whether baseline DM predicted CUD onset.

FINDINGS

Greater lifetime CU frequency was associated with poorer episodic memory at baseline (bs = -14.84, -16.44, Ps = 0.038, 0.021). Greater CU escalation predicted lesser gains in immediate episodic memory (b = -0.05, P = 0.020). Baseline DM did not predict CU escalation (b = 0.07, P = 0.421), nor did escalation in CU predict changes in DM (b = 0.02, P = 0.352). Baseline DM also did not predict CUD onset (adjusted OR = 1.01, 95% confidence interval = 0.98-1.06).

CONCLUSIONS

This study replicates findings that poorer episodic memory in adolescents appears to be a consequence of cannabis use, even among adolescents at earlier stages of use. Poor decision-making does not appear to be either a consequence of or a risk factor for escalating cannabis use or onset of cannabis use disorder among adolescents.

Acute Effects of Nicotine on Physiological Responses and Sport Performance in Healthy Baseball Players

There is interest in whether nicotine could enhance attention in sporting performance, but evidence on the acute effect of nicotine on physical response and sports performance in baseball players remains scant. This was an observational study to examine whether nicotine gum chewed before exercise could provide acute effects on physiological responses and sport performance. Accordingly, heart rate variability (HRV), saliva cotinine concentration and α-amylase activity, cognitive function, muscle strength, and baseball-hitting performance were measured. Thirteen healthy male non-smoker baseball players were recruited. Conducting two sequences with 7-day intervals, they chewed nicotine gum (nicotine group) or flavor-matched placebo gum (placebo group) for 30 min. HRV and saliva analyses were conducted before gum consumption (S1), after gum consumption (S2), and after test completion (S3). Cognitive, muscle strength, and baseball-hitting performance tests were performed after nicotine or placebo gum chewing. The outcomes of all assessed variables were compared within and between the groups. Significant changes in HRV, α-amylase, testosterone, and cortisol were observed in the nicotine group at S2 and S3 (p < 0.05). Compared with the placebo group, the nicotine group exhibited enhanced motor reaction times, grooved pegboard test (GPT) results on cognitive function, and baseball-hitting performance, and small effect sizes were noted (d = 0.47, 0.46 and 0.41, respectively). Nicotine could induce changes in endocrine and sympathetic nerve activity and enhance cognitive function and baseball-hitting performance. However, no increase in muscle strength was observed after nicotine intake.

Betel Quid Dependence Effects on Working Memory and Remote Memory in Chewers with Concurrent Use of Cigarette and Alcohol

OBJECTIVE

The current study asked whether BQ dependence level could affect working memory (WM) and remote memory for the chewers with concurrent use of cigarettes and alcohol, a common phenomenon in Taiwan.

METHODS

The standardized neuropsychological tests (Wechsler Memory Scale III (WMS-III) and Remote Memory Test) were adopted to address the BQ chewers' verbal WM, spatial WM and remote memory. The Spatial Span Test and the Digit Span Test from WMS-III and the Remote Memory Test were adopted. The Betel Nut Dependency Scale (BNDS), the Fagerstrom Test for Nicotine Dependence (FTND), and the Alcohol Use Disorders Identification Test (AUDIT) were adopted to measure the dependence levels.

RESULTS

The BQ dependence level and Last BQ did not affect spatial WM, verbal WM, and remote memory. Last Cigarette is critical in affecting WM; namely, longer interval led to worse performance. Finally, higher alcohol dependence level could lead to better remote memory.

CONCLUSIONS

To our knowledge, there are no BQ studies addressing the effects of concurrent use of cigarettes and alcohol on memory. The current results suggest that cigarette smoking and alcohol drinking, rather than BQ chewing, are critical for memory performance.

O Papel Bidirecional da Nicotina na Tarefa Go/No-Go: Um Ensaio Clínico Piloto

Resumo Estudos mostram que o tabagismo é responsável por afetar algumas funções cognitivas. No entanto, a nicotina é apenas um dos componentes existentes no cigarro e existem evidências de que pode servir como agente neuroprotetivo e causar melhoras em algumas funções cognitivas. O objetivo desta pesquisa foi investigar como a nicotina interage com algumas funções cognitivas. Um ensaio clínico piloto com administração de gomas de nicotina contendo 2-mg ou 4-mg, ou gomas placebo contendo a mesma textura, sabor e aparência, foi realizado. Quarenta e dois participantes participaram da pesquisa e os resultados indicaram que a relação entre nicotina e o desempenho na tarefa Go/No-Go podem ser bidirecionais. Os resultados indicaram que participantes do grupo que utilizaram 4-mg de nicotina apresentaram menor desempenho, enquanto os participantes que fizeram uso de 2-mg de nicotina tiveram melhor desempenho do que os demais. Esta pesquisa tem aplicações biopsicossociais e podem ajudar na compreensão da relação entre tabagismo e nicotina, além de contribuir para estratégias que possam ajudar no abandono do cigarro ou na melhora de condições que afetem a cognição.

Anhedonia in Nicotine Dependence

Prior findings indicate that trait anhedonia enhances the likelihood of becoming a tobacco smoker, and preliminary evidence suggests that smoking abstinence leads to anhedonic states in some individuals and situations, and nicotine administration reduces anhedonic states. Nevertheless, many vital questions exist concerning relationships between anhedonia and nicotine dependence, including situational and individual difference factors that may moderate the strength of these associations. This chapter provides a critical review of the literature assessing relationships of anhedonia to nicotine dependence and the effects of acute nicotine through the lenses of the Research Domain Criteria's (RDoC) Positive Valence Systems (NIMH, RDoC changes to the matrix (CMAT) workgroup update: proposed positive valence domain revisions. A report by the national advisory mental health council workgroup on changes to the research domain criteria matrix, 2018) and the Situation x Trait Affective Response (STAR) model of nicotine's effects and nicotine dependence (Gilbert, Smoking individual differences, psychopathology, and emotion. Taylor and Francis, Washington, DC, 1995; Gilbert, Hum Psychopharmacol Clin Exp 12:S89-S102, 1997). The effects of nicotine and nicotine withdrawal on subjective, behavioral, and brain indices vary across the three RDoC Positive Valences Systems (Reward Responsiveness, Reward Learning, and Reward Valuation) in a manner that supports the research and potential clinical utility of using RDoC criteria and the STAR model to guide research and clinical innovation. We provide a revision of the STAR model that incorporates the three RDoC Positive Valence Systems with evidence that nicotine's effects on hedonic and affective processes vary as a function of the dominance/salience of (1) situational hedonic and affective cues and task/active coping cues, and (2) state executive functioning level/capacity and state reward sensitivity such that these effects of nicotine are maximal during states of suboptimal cognitive functioning and reward sensitivity, combined with low situational stimulus salience and low task-related cues/demands.

Sex differences in P50 inhibition defects with psychopathology and cognition in patients with first-episode schizophrenia

BACKGROUND

A large number of studies have shown that the pathophysiology of schizophrenia may be involved in sensory gating that appears to be P50 inhibition. However, few studies have investigated the relationship between clinical symptoms, cognitive impairment and sensory gating disorders in patients with first-episode schizophrenia. The purpose of this study was to explore the sex differences in the relationship between clinical symptoms, cognitive impairment and P50 inhibition defects in patients with first-episode schizophrenia, which has not been reported.

METHODS

130 patients with first-episode schizophrenia (53 males and 77 females) and 189 healthy controls (87 males and 102 females) participated in the study. Positive and Negative Syndrome Scale (PANSS) was used to evaluate the patients' psychopathological symptoms, and the 64-channel electroencephalogram (EEG) system was used to record the P50 inhibition.

RESULTS

Male patients had higher PANSS negative symptom, general psychopathology, cognitive factor and total scores than female patients (all p < 0.01). The S1 amplitude was smaller in male than female patients (all p < 0.05). Multiple regression analysis showed that in male patients, S1 latency was contributor to negative symptoms, while S1 latency, S2 latency, age, and smoking status were contributors to cognitive factor (all p < 0.05). In female patients, no P50 component was found to be an independent contributor to PANSS scores (all p > 0.05).

CONCLUSIONS

Our results indicate that there is a sex difference in the relationship between clinical symptoms, cognitive impairment and P50 inhibition defects in Chinese Han patients with first-episode schizophrenia.

Nicotine Use Disorder in Older Adults

Nicotine is one of the most abused substances worldwide. Just as in adolescence and adulthood, tobacco use is also problematic in the elderly. Older people are more vulnerable to smoking consequences because of the additive effects of smoke. Cardiovascular diseases are the most common health problems associated with smoking; however, other systems are also affected, including the respiratory, nervous, integumentary, and many other systems. Smoking cessation is a difficult task especially in the elderly; therefore, physicians should encourage older patients to quit with every patient-physician encounter by offering counseling and replacement therapy.

Acute effects of inhaled menthol on cognitive effects of intravenous nicotine among young adult cigarette smokers

Basic science studies indicate that menthol can enhance the cognitive effects of nicotine to increase nicotine dependence; however, the effect of menthol and nicotine on cognitive functioning among humans has been understudied. This double-blind, placebo-controlled study examined the dose-dependent effects of inhaled menthol flavoring and intravenous nicotine on cognitive task performance. Twenty menthol (MS) and 18 non-menthol (NMS) cigarette preferring, young-adult smokers (21% female; 7.9% Hispanic, 44.7% Non-Hispanic/White, 47.4% Non-Hispanic/Black) completed three sessions with randomized order of menthol flavoring (between-sessions: 0.0%/tobacco control, 0.5%/low, 3.2%/high) and intravenous nicotine (within-session: 0.0 mg/saline control, 0.25 mg/low, 0.5 mg/high). After each administration, participants completed three cognitive tasks: Continuous Performance Task (CPT), Mathematical Processing Task (MPT), and Stroop Task. Mixed effects models were used to examine interactive effects of cigarette type preference and menthol and nicotine doses. MS vs. NMS had decreased accuracy on CPT and MPT and efficiency during Stroop. No significant effects of cigarette type preference by menthol or nicotine were found for any task. Significant effects of nicotine by menthol were found during Stroop, where participants had greater accuracy for high nicotine compared to saline during the low menthol session. Significant effects of menthol by timepoint were seen during Stroop, where participants improved across timepoints during the low menthol session. Findings did not support significant effects of inhaled menthol, alone or with nicotine, on cognitive performance. Further research clarifying the impact of varying menthol and nicotine levels in nicotine products may help to elucidate menthol's role in smoking sustainment.

Magnetic resonance imaging for smoking abstinence: symptoms, mechanisms, and interventions

Tobacco smoking is the leading preventable cause of morbidity and mortality worldwide. Although a number of smokers are aware of the adverse outcomes of smoking and express a strong desire to stop smoking, most smoking quit attempts end in relapse within the first few days of abstinence, primarily resulting from the aversive aspects of the nicotine withdrawal syndrome. Therefore, studying the neural mechanisms of smoking abstinence, identifying smokers with heightened relapse vulnerability prior to quit attempts, and developing effective smoking cessation treatments appear to be promising strategies for improving the success of quit attempts. In recent years, with the development of magnetic resonance imaging, the neural substrates of smoking abstinence have become extensively studied. In this review, we first introduce the psychophysiological changes induced by smoking abstinence, including affective, cognitive, and somatic signs. We then provide an overview of the magnetic resonance imaging-based evidence regarding abstinence-related functional changes accompanied by these psychophysiological changes. We conclude with a discussion of the neural markers that could predict relapse during quit attempts and a summary of the psychophysiological interventions that are currently often used to help with smoking cessation. This review extends our understanding of the role of the central nervous system in smoking abstinence.

Body Mass Index Predicts Decline in Executive Function in Bipolar Disorder: Preliminary Data of a 12-Month Follow-up Study

INTRODUCTION

Obesity and associated risk factors have been linked to cognitive decline before.

OBJECTIVES

In the present study, we evaluated potential cumulative negative effects of overweight and obesity on cognitive performance in euthymic patients with bipolar disorder (BD) in a longitudinal design.

METHODS

Neurocognitive measures (California Verbal Learning Test, Trail Making Test [TMT] A/B, Digit-Symbol-Test, Digit-Span, d2 Test), anthropometrics (e.g., body mass index [BMI]), and clinical ratings (Hamilton Depression Scale, Young Mania Rating Scale) were collected over a 12-month observation period. Follow-up data of 38 patients with BD (mean age 40 years; 15 males, 23 females) were available.

RESULTS

High baseline BMI predicted a decrease in the patient's performance in the Digit-Span backwards task measuring working memory performance. In contrast, cognitive performance was not predicted by increases in BMI at follow-up. Normal weight bipolar patients (n = 19) improved their performance on the TMT B, measuring cognitive flexibility and executive functioning, within 1 year, while overweight bipolar patients (n = 19) showed no change in this task.

CONCLUSIONS

The results suggest that overweight can predict cognitive performance changes over 12 months.

Impact of smoking Behavior on cognitive functioning in persons at risk for psychosis and healthy controls: A longitudinal study

Background

The high prevalence of smoking in individuals who are at ultra-high risk (UHR) for psychosis is well known and moderate cognitive deficits have also been found in UHR. However, the association between smoking and cognition in UHR is unknown and longitudinal studies are lacking.

Method

A cohort study with 330 UHR individuals and 66 controls was conducted, as part of the European network of national schizophrenia networks studying gene–environment interactions (EU-GEI). At baseline and after 6, 12, and 24 months, smoking behavior was assessed with the Composite International Diagnostic Interview and cognitive functioning with a comprehensive test battery. Linear mixed-effects analyses were used to examine the multicross-sectional and prospective associations between (change in) smoking behavior and cognitive functioning, accounting for confounding variables.

Results

At baseline, 53% of UHR and 27% of controls smoked tobacco. Smoking UHR and controls did not significantly differ from nonsmoking counterparts on the tested cognitive domains (speed of processing, attention/vigilance, working memory, verbal learning, or reasoning/problem solving) across different assessment times. Neither smoking cessation nor initiation was associated with a significant change in cognitive functioning in UHR.

Conclusions

No associations were found between smoking and cognitive impairment in UHR nor in controls. However, the fact that one in every two UHR individuals report daily use of tobacco is alarming. Our data suggest that UHR have fewer cognitive impairments and higher smoking cessation rates compared to patients with first-episode psychosis found in literature. Implications to promote smoking cessation in the UHR stage need further investigation.

A 28-Day Challenge to Help Quit Smoking Using Telephone Follow-Ups Combined With the WeChat App: The Impact of the Humanistic Approach on Smoking Cessation

The study aims to assess the effectiveness of telephone follow-ups combined with a smartphone app (e.g., WeChat [Tencent], which is one of the most widely used communication apps in China), as a smoking cessation intervention. Social volunteers were recruited on March 1, 2017, and randomized to supervision groups with five participants in each group. Every day, the specialists shared some information related to smoking cessation including the videos, songs, and scientific knowledge in WeChat groups and conducted telephone follow-ups on the third, fifth, seventh, ninth, 12th, 17th, 22nd, 27th, and 30th day in March and on April 1. Ultimately, a comparison was made of the self-reported smoking abstinence and self-reported average number of cigarettes smoked between the participants. One hundred ten volunteers participated in the study, with 105 who completed follow-up. Self-reported smoking abstinence in the past 7 days occurred in 65.7% of the participants (n = 69) compared with 34.3% (n = 36) in whom smoking abstinence did not occur. The mean age of those who failed was 40.15 years (range: 22–70 years), and 55.5% (n = 20) attributed their failure to personal reasons. However, the self-reported average number of cigarettes smoked every day was less than that before the study (on average, 10.34 ± 8.17 per day), and this difference was statistically significant (95% CI [8.312, 12.364], p < .01). It was effective to deliver a telephone follow-up combined with a smartphone app follow-up as an intervention for smoking cessation.

Ameliorating Effect of Combined Cinnamon and Ginger Oils against the Neurotoxicity of Nicotine Administration on the Prefrontal Cortex of Adult Albino Rats: Immunohistochemical and Ultrastructural Study

Background: Nicotine is the active alkaloid in cigarettes. It was reported that tobacco smoking has many hazards; one of these hazards is the effect on the cognitive function of the prefrontal cortex. The aim of our study is to investigate the antioxidant effects of ginger, cinnamon oils, and their combination on morphological changes in the prefrontal cortex that were induced by nicotine. Materials and methods: Fifty adult male albino rats were divided into five groups: group I (control group), group II (nicotine), group III (nicotine + cinnamon), group IV (nicotine + ginger), and group V (nicotine + cinnamon + ginger). The coronal sections from the anterior part of the rat brain at the site of prefrontal cortex were examined by light microscope for (H&E and immunohistochemical staining with TNF-α and GFAP), while the ultrastructure morphology was examined by transmission electron microscopy. Levels of the oxidative stress markers (MDA, GSH) in the rats’ brain tissue homogenate were biochemically assessed. Results: Compared to the control group, the rats that were treated with nicotine (group II) showed a significant oxidative stress in the form of marked elevation of MDA and decrease in GSH, apoptotic changes especially in the pyramidal cells in the form of neuronal cell degeneration and pyknosis, and an elevation in the inflammatory marker TNF-α and GFAP expressions. These changes were observed to a lesser degree in rat group (III) and group (IV), while there was a marked improvement achieved by the combined usage of cinnamon and ginger oils, together compared to the nicotine group. Conclusions: Ginger and cinnamon are powerful antioxidants which ameliorate the degenerative and oxidative effects produced by nicotine on a rat’s prefrontal cortex.

An Open Trial of Metacognitive Remediation Therapy and Pharmacotherapy to Promote Smoking Cessation among Individuals with Psychotic-Spectrum Disorders

Introduction

Individuals with psychotic-spectrum disorders may smoke due to the ameliorating effect of nicotine on the cognitive deficits that accompany these illnesses. Metacognitive remediation therapy (MCR) has been shown to produce improvements in cognitive functioning among individuals with psychotic-spectrum disorders and provides a foundation for a novel smoking cessation intervention for this population.

Aims

To complete an open investigation of pharmacotherapy and a modified version of MCR [MCR to Quit (MCR-Q)] in promoting smoking cessation among individuals with psychotic-spectrum disorders.

Methods

Forty-nine individuals with a psychotic-spectrum disorder and who currently smoke cigarettes participated in MCR-Q while also receiving evidence-based smoking cessation pharmacotherapy. Tobacco use was assessed as follows: (i) prior to MCR-Q, (ii) immediately after completing MCR-Q, and (iii) six weeks after completion of MCR-Q.

Results

/Findings. During participation in MCR-Q, nearly 80% of participants made a 24-hour quit attempt. Following the completion of MCR-Q, participants experienced reductions in level of nicotine dependency and exhaled carbon monoxide, with reductions in nicotine dependency sustained six weeks after completion of MCR-Q. Over the course of their participation in MCR-Q, participants reported strong therapeutic alliance with their MCR-Q therapist and high levels of intrinsic motivation with regard to completing MCR-Q exercises.

Conclusions

The results from the current study suggest cautious optimism with regard to the use of MCR-Q in combination with medication for individuals with psychotic-spectrum disorders who want to quit smoking.

Effects of transdermal nicotine delivery on cognitive outcomes: A meta-analysis

OBJECTIVE

By the association of nicotinic acetylcholine receptors in the brain, nicotine in the therapeutic window lowers neuronal damage and raises protective factors. These data, however, are contradicted by other findings. Here, we assessed the effects of transdermal nicotine administration on cognitive functions in healthy non-smoker adults by systematic review and meta-analysis of clinical trials.

METHODS

We included reports of clinical trials comparing the effects of nicotine patches with placebo in healthy non-smoking adults. The main outcome was the impact of nicotine patches on overall cognitive function with a focus on attention and memory. Standard meta-analytic and statistical methods measured the effect of transdermal nicotine compared with placebo patches.

RESULTS

We included 31 publications involving 978 subjects. Nicotine patches boosted cognitive function in healthy adults (0.233 SMD, 95%CI, 0.111-0.355, p < .001). Overall heterogeneity of the studies was found to be modest (ϰ²  = 68.24, T²  = 0.07, I²  = 50.17%, p < .001). Also, nicotine patches improved attention (0.231 SMD, 95%CI, 0.106-0.356, p < .001). We found the inter-study heterogeneity to be low (ϰ²  = 40.95, T²  = 0.03, I²  = 34.07%, p = .042). Further, the enhancement of memory by transdermal nicotine did not reach statistical significance in normal subjects (0.270 SMD, 95% CI, -0.293-0.833, p = .347). Also, high inter-study heterogeneity was found among studies (ϰ²  = 27.25, T²  = 0.43, I²  = 77.98%, p < .001).

CONCLUSION

The meta-analysis showed that transdermal nicotine had statistically significant positive effects on attention, and non-significant effects on memory, in healthy non-smoking adults. The results encourage further studies of the therapeutic potential of nicotine patches in disorders of cognition.

The negative impact of chronic tobacco smoking on adult neuropsychological function: a cross-sectional study

Background

The evidence on the effects of chronic tobacco smoking on neuropsychological functions is conflicting. The literature remains limited by inconsistent accounting for potentially confounding biomedical and psychiatric conditions. This study aimed to assess the neuropsychological functions of adult chronic tobacco smokers in comparison to group-matched non-smokers.

Method

The study included 73 smokers and 84 group-matched non-smokers. The data was collected during the year 2019. After an initial interview to collect demographics and smoking profile, the subjects undertook neuropsychological assessments that targeted a wide range of cognitive domains.

Results

The performance of smokers was poorer on almost all neuropsychological domains, namely selective attention (p ≤ .001, p = .044), alternating attention (p = .002) working memory (p ≤ .001), Short-term memory (p = .006 and .003), Long-term memory (p ≤ .001), processing accuracy (p ≤ .001), and executive function (p = .011 and .026). Smokers were intact on processing speed. Smoking accumulation and lower age onset of regular smoking were correlated with lower neuropsychological function.

Conclusion

Our findings add to the growing body of evidence suggesting that chronic tobacco smoking impacts cognition negatively.

Vitamin D3 reduces hippocampal NR2A and anxiety in nicotine withdrawal mice

Nicotine withdrawal symptoms, mainly anxiety, cause high level of relapse rate after quitting smoking. Vitamin D supplementation has shown its potential for the prevention and treatment of anxiety disorders; however, neurobiological studies about the effect of vitamin D on nicotine withdrawal-induced anxiety are limited. To investigate the effect and molecular mechanism of vitamin D3 supplement by dietary on anxiety-like behavior during nicotine withdrawal, male C57/BL6 mice were divided into four groups: vehicle, nicotine only, vitamin D3 only, and nicotine plus vitamin D3. Mice were administrated with nicotine in drinking water (200 µg/mL), and vitamin D3 in feed for 6 weeks. During nicotine withdrawal, vitamin D3-treated mice showed significantly less anxiety-like behavior by an open-field test and marble buried test that performed an increase in the duration of the central zone and a decrease buried marble, respectively. Moreover, vitamin D3 supplementation attenuated the hippocampal NR2A expression on both protein and mRNA levels in nicotine and vitamin D3-treated mice. Our data showed that dietary supplementation with vitamin D3 ameliorated nicotine withdrawal-induced anxiety, which may be related to downregulation of NR2A expression in hippocampus. Vitamin D3 may provide a new dietary intervention with the easy access for smoking cessation.

Differences in Cognitive Task Performance, Reinforcement Enhancement, and Nicotine Dependence Between Menthol and Nonmenthol Cigarette Smokers

INTRODUCTION

Menthol has been shown to target similar brain regions and neural receptors as nicotine, yet the association between menthol cigarette use and cognitive performance remains unknown.

AIMS AND METHODS

This study examined differences in cognitive task performance between menthol (MS) and nonmenthol (NMS) cigarette smokers after acute cigarette consumption. Sixty white and black and/or African American, nonabstinent, MS (n = 30) and NMS (n = 30) were assessed presmoking and postsmoking their preferred cigarette on four computerized tasks: Continuous Performance Task (CPT; alerting attention), N-Back Task (working memory), Finger Tapping Task (motor control), and Apple Picker Task (reinforcement enhancement). Self-reported nicotine dependence and objective smoking topography measures were also compared between groups.

RESULTS

Initial unadjusted analyses showed a significant effect of cigarette type × time on CPT speed (p = .042), where MS improved while NMS group worsened in CPT speed after smoking. After controlling for baseline cigarette craving and cigarette nicotine levels, the effect of cigarette type × time for all cognitive outcomes was statistically nonsignificant (ps > .05). However, there remained a significant effect of cigarette type, where MS versus NMS had poorer CPT (p = .046) and N-Back Task accuracy (p = .006) but faster N-Back speed (p = .039). There were no statistically significant differences between groups on reinforcement enhancement, nicotine dependence, or smoking behavior outcomes (ps > .05).

CONCLUSIONS

Contrary to our hypotheses, results did not find a significant effect of cigarette type on the change in cognitive performance after acute smoking in nonabstinent smokers. Further studies are needed to clarify the specific pharmacological effects of nicotine and menthol on cognitive functioning.

IMPLICATIONS

The current study is the first to compare the potential enhancement of cognitive task performance after acute cigarette smoking between satiated menthol and nonmenthol cigarette smokers. Study results suggest that acute menthol cigarette use may not enhance cognitive function above and beyond nonmenthol cigarettes to increase dependence among menthol smokers. However, the contribution of other psychological factors (eg, craving, mood) and cigarette characteristics (eg, nicotine content) may be involved in cognitive function enhancement to perpetuate dependence and smoking persistence for menthol smokers.

Nicotine smoking is associated with impaired cognitive performance in Pakistani young people

Nicotine smoking is the most common mode of tobacco smoking among young people. It affects the areas of the brain associated with memory, attention, and learning. This study has investigated the effect of nicotine smoking on cognitive performance. One hundred male volunteers (50 nicotine smokers and 50 nonsmokers) aged 18–30 years with similar socioeconomic backgrounds were recruited for this study. Clinical history of participants was obtained using a questionnaire. Their brain health and handedness were determined using the Mini Mental State Examination (MMSE) and the Edinburgh Handedness Inventory (EHI), respectively. The dependent variables examined in the study were attention-switching tasks (AST), pattern recognition memory (PRM), and choice reaction time (CRT). These parameters were assessed using the Cambridge Neuropsychological Automated Battery (CANTAB). The average ages of participating smokers and nonsmokers were 24.02 ± 3.41 years (mean ± standard deviation) and 22.68 ± 1.87 years, respectively. MMSE and EHI scores of smokers were 28.42 ± 1.09 and 99.75 ± 1.77, respectively; for nonsmokers, these scores were 28.54 ± 1.34 and 98 ± 1.91, respectively. The mean score for AST correct latency/delay was significantly higher (p = 0.050) in smokers (620.26 ± 142.03) than in nonsmokers (570.11 ± 108.39). The percentage of correct AST trials was significantly higher (p = 0.000) in nonsmokers (96.95 ± 2.18) than in smokers (83.75 ± 11.22). The PRM percent correct were significantly higher (p = 0.000) of nonsmokers (93.42 ± 8.34) than of smokers (79.75 ± 13.44). The mean correct latency for CRT was significantly higher (p = 0.009) in smokers (509.87 ± 129.83) than in nonsmokers (455.20 ± 65.73). From this data, it can be concluded that nicotine smoking is linked with impaired cognitive functions in smokers.

The effects of psychological stress on approach tendencies for smoking-related cues in smokers

Stress may potentiate the chronification of nicotine addiction, but the exact mechanisms remain elusive. We performed an explorative pilot study examining the effects of psychological stress, administered via the socially evaluated cold pressor task (SECPT), on implicit approach bias for smoking-related cues in smokers in the approach-avoidance task (AAT). Smokers (N = 24) were subjected to the stress or control condition of the SECPT by using a within-subject design. Consistent with previous findings, a strong approach bias for smoking-related cues in the AAT was found in smokers. Exposure to stress did not affect the general bias for smoking-related cues in the AAT relative to the control condition of the SECPT. In additional explorative analyses, an interaction among carbon monoxide (CO) levels in expired air, cortisol levels, and stress on approach bias for smoking-related cues was found. Higher CO levels, possibly due to recent smoking, prior to stress exposure were associated with an approach bias for smoking-related cues. Our results suggest that CO levels in interaction with stress can modulate implicit, automatic processing in the context of nicotine addiction. Our findings might provide novel cues to how stress influences cigarette craving and smoking behavior.

Neurochemistry of Visual Attention

Visual attention is the cognitive process that mediates the selection of important information from the environment. This selection is usually controlled by bottom-up and top-down attentional biasing. Since for most humans vision is the dominant sense, visual attention is critically important for higher-order cognitive functions and related deficits are a core symptom of many neuropsychiatric and neurological disorders. Here, we summarize the importance and relative contributions of different neuromodulators and neurotransmitters to the neural mechanisms of top-down and bottom-up attentional control. We will not only review the roles of widely accepted neuromodulators, such as acetylcholine, dopamine and noradrenaline, but also the contributions of other modulatory substances. In doing so, we hope to shed some light on the current understanding of the role of neurochemistry in shaping neuron properties contributing to the allocation of attention in the visual field.

Nicotine and Cognition in Cognitively Normal Older Adults

The cholinergic system has been shown to be the primary neurotransmitter system which is responsible for the cognitive symptoms associated with dementia; its role in healthy non-demented older adults remains a gap in the literature. Understanding the effects of age-related functional changes on the nicotinic system will address this knowledge gap. As the older adult population grows and hence the importance of understanding cognitive changes that impact functional abilities and everyday life. In this article we examine the benefits of using nicotine as a method for improving cognition in non-demented healthy older adults which may have the potential for slowing neurodegeneration in aging. Furthermore, we discuss how nicotine can play a crucial role in maintaining cognitive abilities throughout normal cognitive aging.

Moderating Effects of BDNF Genetic Variants and Smoking on Cognition in PTSD Veterans

Posttraumatic stress disorder (PTSD) is frequently associated with cognitive disturbances and high prevalence of smoking. This study evaluated cognition in war veterans with PTSD and control subjects, controlled for the effect of smoking and brain derived neurotrophic factor (BDNF) rs6265 and rs56164415 genotypes/alleles. Study included 643 male war veterans with combat related PTSD and 120 healthy controls. Genotyping was done by real time PCR. Cognitive disturbances were evaluated using the Positive and Negative Syndrome Scale (PANSS) cognition subscale and the Rey-Osterrieth Complex Figure (ROCF) test scores. Diagnosis (p < 0.001), BDNF rs56164415 (p = 0.011) and smoking (p = 0.028) were significant predictors of the cognitive decline in subjects with PTSD. BDNF rs56164415 T alleles were more frequently found in subjects with PTSD, smokers and non-smokers, with impaired cognition, i.e., with the higher PANSS cognition subscale scores and with the lower ROCF immediate recall test scores. Presence of one or two BDNF rs56164415 T alleles was related to cognitive decline in PTSD. The T allele carriers with PTSD had advanced cognitive deterioration in smokers and nonsmokers with PTSD, and worse short-term visual memory function. Our findings emphasize the role of the BDNF rs56164415 T allele and smoking in cognitive dysfunction in war veterans with PTSD.

Evidence for a Causal Relationship Between Academic Achievement and Cigarette Smoking

INTRODUCTION

Academic achievement (AA) is associated with smoking rates. Can we determine the degree to which this relationship is likely a causal one?

METHODS

We predict smoking in male conscripts (mean age 18.2) assessed from 1984 to 1991 (N = 233 248) and pregnant females (mean age 27.7) receiving prenatal care 1972-1990 (N = 494 995) from AA assessed in all students at 16. Instrumental variable (IV) analyses used the instrument month-of-birth as in each school year, older children have high AA. Co-relative analyses used AA-smoking associations in the population, cousins and siblings to predict the AA-smoking relationship in MZ twins, thereby controlling for familial confounding.

RESULTS

In males, higher AA was associated with a substantial decrease in risk for smoking (odds ratio [OR] [95% confidence intervals [CIs]] per standard deviation [SD] = 0.41 [0.40-0.41]) while the parallel figures obtain from our IV and co-relative analyses were 0.47 (0.39-0.57) and 0.51 (0.43-0.60), respectively. In females, these figures for pre-pregnancy smoking were, respectively, 0.39 (0.39-0.39), 0.50 (0.46-0.54) and 0.54 (0.51-0.58). Results for heavy versus light smoking suggested a causal effect but were inconsistent across methods. However, among females smoking prior to pregnancy, AA predicted a reduced risk for continued smoking with ORs for uncontrolled, IV, and co-relative analyses equaling, respectively, were 0.54 (0.53-0.55) 0.68 (0.56-0.82) and 0.78 (0.66-0.91), respectively.

CONCLUSIONS

Two different methods produced consistent evidence that higher AA has a causal effect on reducing smoking rates and increasing cessation rates in smoking pregnant females. Improving AA may result in meaningful gains in population health through reduced smoking.

IMPLICATIONS

This study provides consistent evidence across two different methods that high AA is causally related to reduced rates of smoking and increasing rates of smoking cessation among pregnant women. Our results suggest that interventions that improve educational achievement in adolescence would reduce tobacco consumption, thereby improving public health.

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.

APOE genotype influences P3b amplitude and response to smoking abstinence in young adults

RATIONALE

There is strong evidence that nicotine can enhance cognitive functions and growing evidence that this effect may be larger in young healthy APOE ε4 carriers. However, the moderating effects of the APOE ε4 allele on cognitive impairments caused by nicotine deprivation in chronic smokers have not yet been studied with brain indices.

OBJECTIVE

We sought to determine whether young female carriers of the APOE ε4 allele, relative to noncarriers, would exhibit larger abstinence-induced decreases in P3b amplitude during a two-stimulus auditory oddball task.

METHODS

We compared parietal P3bs in female chronic smokers with either APOE ε3/ε3 (n = 54) or ε3/ε4 (n = 20) genotype under nicotine-sated conditions and after 12-17-h nicotine deprivation.

RESULTS

Nicotine deprivation significantly reduced P3b amplitudes in APOE ε4 carriers, but not in APOE-ε3/ε3 individuals, such that the difference seen prior to nicotine deprivation was eliminated.

CONCLUSIONS

The results suggest that subjects with the APOE ε4 allele are more sensitive to nicotine, which could influence smoking patterns, the risk for nicotine dependence, and the cognitive effects of nicotine use in these individuals.

Nicotine supplementation enhances simulated game performance of archery athletes

Background

Nicotine is beneficial to mood, arousal and cognition in humans. Due to the importance of cognitive functioning for archery athletes, we investigated the effects of nicotine supplementation on the cognitive abilities, heart rate variability (HRV), and sport performance of professional archers.

Methods

Eleven college archers were recruited and given 2 mg of nicotine supplementation (NIC group) and placebo (PLA group) in a crossover design.

Results

The results showed that at 30 min after the intake of nicotine gum, the “correct rejection” time in the NIC group was significantly lower than that of the PLA group (7.29 ± 0.87 vs. 8.23 ± 0.98 msec, p < 0.05). In addition, the NIC group completed the grooved pegboard test in a shorter time than the PLA group (48.76 ± 3.18 vs. 53.41 ± 4.05 s, p < 0.05), whereas motor reaction times were not different between the two groups. Saliva α-amylase activity was significantly lower after nicotine supplementation (p < 0.01) but increased immediately after the archery test in the NIC group (p < 0.05). In addition, nicotine supplementation significantly decreased HRV and increased the archery score (290.58 ± 10.09 vs. 298.05 ± 8.56, p < 0.01).

Conclusions

Nicotine enhances the performance of archery athletes by increasing cognitive function and stimulating the sympathetic adrenergic system.

Nicotinic receptor modulation of the default mode network

RATIONALE

Previous neuroimaging studies of cognition involving nicotinic acetylcholine receptor (nAChR) agonist administration have repeatedly found enhanced task-induced deactivation of regions of the default mode network (DMN), a group of brain systems that is more active at rest and mediates task-independent thought processes. This effect may be related to pro-cognitive nAChR agonist effects OBJECTIVES: The present study sought to test whether nAChR modulation of the DMN is bi-directional, i.e., whether a nAChR antagonist would reduce task-induced deactivation.

METHODS

Eighteen healthy non-smokers underwent functional magnetic resonance imaging while performing a letter N-back task. Scans were performed after nicotine administration (7 mg/24 h, transdermally), after administration of the nAChR antagonist mecamylamine (7.5 mg, p.o.), and after double placebo, in counterbalanced sequence. Blood-oxygen-level-dependent (BOLD) signal was analyzed within ventromedial prefrontal cortex (vmPFC) and posterior cingulate cortex (PCC) regions of interest-central hubs of the DMN in which consistent nAChR agonist-induced changes had previously been identified.

RESULTS

Nicotine enhanced hit rate in both the 0-back and 2-back condition, while mecamylamine slowed reaction time in the 2-back condition. Mecamylamine reduced task-induced deactivation of vmPFC and PCC. Nicotine had no significant effects on the BOLD signal.

CONCLUSIONS

The finding that nAChR tone reduction by mecamylamine weakened task-induced DMN deactivation indicates that a constant tone of nAChR activation helps regulate DMN activity in healthy individuals. This suggests that low nAChR tone may play a causal role in DMN dysregulation seen in conditions such as mild cognitive impairment or Alzheimer's disease.

The two-way relationship between nicotine and cortical activity: a systematic review of neurobiological and treatment aspects

Nicotine intake and cortical activity are closely related, as they can influence each other. Nicotine is implicated in the induction and modification of cortical plasticity and excitability, whereas a change on cortical plasticity and excitability can also lead to a modification of the smoking behaviour of an individual. The aim of this systematic review was, on the one hand, to evaluate the effects of nicotinergic modulation on cortical excitability and plasticity, and, on the other hand, to assess if modifying the brain's excitability and plasticity could influence one's smoking behaviour. Two systematic literature searches in the PubMed/MEDLINE and PsycINFO databases were conducted. Studies focusing either on the impact of nicotinergic modulation on cortical activity or the treatment effect of non-invasive brain stimulation techniques (NIBS) on smoking behaviour were included. A total of 22 studies for the first systematic search and 35 studies for the second one were included after full-text screening. Nicotine's effect on cortical activity appeared to depend on smoking status of the individual. While deprived smokers seem to generally profit from nicotine consumption in terms of cortical excitability and plasticity, the contrary was true for non-smokers. Regarding the questions of how changes in cortical excitability can influence smoking behaviour, a trend points towards NIBS being a potential intervention technique for smoking cessation.

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.

Age at illness onset and physical activity are associated with cognitive impairment in patients with current diagnosis of major depressive disorder

BACKGROUND

Cognitive impairment has been reported in patients with Major Depressive Disorder (MDD). This study aims to explore the association between lifestyle habits and health-related factors and the presence of cognitive symptoms in MDD patients.

METHODS

Demographic, clinical, health-related variables and cognitive scores measured with the Cambridge Neuropsychological Test Automated Battery (CANTAB) were compared between 74 patients with current MDD and 68 healthy controls (HC). To test the hypothesis of associated factors to cognitive symptoms, multivariate backward stepwise linear regression models were run.

RESULTS

Significant neuropsychological deficits were evident in MDD compared with HC in the global cognitive index (F=8.29; df=1, 140; p=0.005). In the regression analysis performed on MDD and HC, years of schooling (β=-0.11; p=<0.001), job status (β=-0.50; p=0.016), physical activity (β=-0.25; p=0.04) and age at illness onset (β=0.17; p=0.017) were statistically significant factors associated to cognitive impairment. The regression model ran in HC showed that only years of schooling were significant (β=-0.07; p=<0.001) in this group.

LIMITATIONS

Sample size was relatively small. Everyday cognitive skills were not evaluated.

CONCLUSIONS

MDD patients have cognitive deficits. These deficits are linked with the years of education, job status, age of onset of the disease and the performance of physical activity. These results support the importance of the implementation of interventions targeting the cognitive reserve and lifestyle habits of MDD patients, in addition to the conventional therapeutic approach focused on symptoms control.

Assessing attention orienting in mice: a novel touchscreen adaptation of the Posner-style cueing task

Atypical attention orienting has been found to be impaired in many neuropsychological disorders, but the underlying neural mechanism remains unclear. Attention can be oriented exogenously (i.e., driven by salient stimuli) or endogenously (i.e., driven by one's goals or intentions). Genetic mouse models are useful tools to investigate the neurobiology of cognition, but a well-established assessment of attention orienting in mice is missing. This study aimed to adapt the Posner task, a widely used attention orienting task in humans, for use in mice using touchscreen technology and to test the effects of two attention-modulating drugs, methylphenidate (MPH) and atomoxetine (ATX), on the performance of mice during this task. In accordance with human performance, mice responded more quickly and more accurately to validly cued targets compared to invalidly cued targets, thus supporting mice as a valid animal model to study the neural mechanisms of attention orienting. This is the first evidence that mice can be trained to voluntarily maintain their nose-poke on a touchscreen and to complete attention orienting tasks using exogenous peripheral cues and endogenous symbolic cues. The results also showed no significant effects of MPH and ATX on attention orienting, although MPH improved overall response times in mice during the exogenous orienting task. In summary, the current study provides a critical translational task for assessing attention orienting in mice and to investigate the effects of attention-modulating drugs on attention orienting.

The cognitive and behavioral effects of D-amphetamine and nicotine sensitization in adult zebrafish

BACKGROUND

Zebrafish are growing in use as a model for understanding drug dependence and addiction. Sensitization paradigms have been a useful tool in identifying mechanisms involved in drug-induced behavioral and neurological changes, but in zebrafish have tended to focus on locomotor, rather than cognitive, endpoints.

METHODS

Here, we used a novel method, the FMP Y-maze, which measures continuous performance through a series of repeated binary choices (L vs R), to establish a model for assessing parameters associated with psychostimulant-induced behavioral and cognitive sensitization in adult zebrafish.

RESULTS

Repeat, intermittent exposure to d-amphetamine (AMPH) for 14 days increased alternations (LRLR) in the maze, suggesting improved working memory, which was enhanced further following drug challenge after a short withdrawal period, suggesting behavioral sensitization. However, this cognitive enhancement coincided with a reduction in the use of other exploration strategies, hypolocomotion, and inhibition of cognitive flexibility. Like AMPH, exposure to nicotine (NIC) increased alternations following drug challenge after chronic treatment. Repeat NIC exposure appeared to induce both cognitive and psychomotor sensitization, as evidenced by increased working memory performance (alternations) and locomotor activity, without negatively impacting other search strategies or cognitive flexibility.

CONCLUSION

Chronic treatment with AMPH or NIC boosts cognitive performance in adult zebrafish. Cognitive sensitization occurred with both drugs, resulting in enhanced working memory; however, repeat AMPH exposure, following a withdrawal period, resulted in inhibited cognitive flexibility, an effect not evident with repeat NIC exposure. Cognitive and behavioral sensitization paradigms in zebrafish could serve as a useful tool for assessing cognitive states which result in cognitive enhancing or impairing effects of drugs.

Cigarette Smoking and Schizophrenia: Etiology, Clinical, Pharmacological, and Treatment Implications

Recent data suggests that the prevalence of smoking in schizophrenia remains high. While reports suggest that smoking increases the risk of developing schizophrenia, the potential causative role of smoking in this relationship needs further investigation. Smokers with schizophrenia are more likely to have more intense positive symptoms and lower cognitive function, but diminished intensity of extrapyramidal side effects than nonsmoking patients with schizophrenia. They were also more likely to exhibit aggressive behaviour compared to nonsmokers, which could suggest higher levels of baseline aggression. The significant cost associated with regular tobacco expenditure can detract from investment in key domains. Large-scale trials have shown that pharmacotherapy for smoking cessation is effective and does not worsen the risk of developing neuropsychiatric symptoms compared to placebo. Electronic cigarette use among schizophrenia patients is high, and there is emerging evidence supportive of its efficacy. Future improvements include large-scale trials assessing the utility, efficacy, and safety of electronic cigarettes in schizophrenia patients.

Cognitive function in women with major mental illnesses who use tobacco

Cognitive effects of tobacco use among women with schizophrenia, bipolar disorder or depression have not been studied extensively as most studies focussed on men smokers. As part of a study on prevalence and cognitive effects of tobacco use, women with schizophrenia, bipolar disorder and depression were assessed for cognitive functioning using an information questionnaire derived from the Indian Post Graduate Institute Battery of Brain Dysfunction (PGIBBD) and the Trail Making Tests (TMT) A and B. The community dwelling women were clinically diagnosed and recruited from the outpatient department of a free tertiary care teaching hospital in India. The sample consisted of 321 women, 141 with schizophrenia (SZ), 80 with Bipolar Disorder (BD) and 100 with Recurrent Depressive Disorder (RDD). Tobacco users answered statistically significantly fewer questions on the PGIBBD Information Questionnaire. Users also took significantly more time to complete both TMT-A and TMT-B. Age, years of schooling and tobacco use were all significant co-variates for performance on cognitive tests. Tobacco users had lower motor speed and lesser visual scanning, poorer flexibility of thinking and working memory. Women with schizophrenia performed the worst. Tobacco use may exacerbate the cognitive dysfunction associated with major mental illnesses among women.

Food Addiction and Tobacco Use Disorder: Common Liability and Shared Mechanisms

As food addiction is being more commonly recognized within the scientific community, parallels can be drawn between it and other addictive substance use disorders, including tobacco use disorder. Given that both unhealthy diets and smoking are leading risk factors for disability and death, a greater understanding of how food addiction and tobacco use disorder overlap with one another is necessary. This narrative review aimed to highlight literature that investigated prevalence, biology, psychology, and treatment options of food addiction and tobacco use disorder. Published studies up to August 2020 and written in English were included. Using a biopsychosocial lens, each disorder was assessed together and separately, as there is emerging evidence that the two disorders can develop concurrently or sequentially within individuals. Commonalities include but are not limited to the dopaminergic neurocircuitry, gut microbiota, childhood adversity, and attachment insecurity. In addition, the authors conducted a feasibility study with the purpose of examining the association between food addiction symptoms and tobacco use disorder among individuals seeking tobacco use disorder treatment. To inform future treatment approaches, more research is necessary to identify and understand the overlap between the two disorders.

The retrotrapezoid nucleus and the neuromodulation of breathing

Breathing is regulated by a host of arousal and sleep-wake state-dependent neuromodulators to maintain respiratory homeostasis. Modulators such as acetylcholine, norepinephrine, histamine, serotonin (5-HT), adenosine triphosphate (ATP), substance P, somatostatin, bombesin, orexin, and leptin can serve complementary or off-setting functions depending on the target cell type and signaling mechanisms engaged. Abnormalities in any of these modulatory mechanisms can destabilize breathing, suggesting that modulatory mechanisms are not overly redundant but rather work in concert to maintain stable respiratory output. The present review focuses on the modulation of a specific cluster of neurons located in the ventral medullary surface, named retrotrapezoid nucleus, that are activated by changes in tissue CO₂/H⁺ and regulate several aspects of breathing, including inspiration and active expiration.

Cognitive Impairment among People Who Use Heroin and Fentanyl: Findings from the Miami Adult Studies on HIV (MASH) Cohort

Background: Cognitive impairment is common in people living with HIV (PLWH). Opioid drugs exert direct and indirect effects on cognitive processes, which may contribute to cognitive dysfunction among PLWH. This study was designed to determine if opioid use is associated with cognitive impairment and whether the effect differs between PLWH and HIV-uninfected adults. Other neuropsychiatric symptoms, such as depression and apathy, were also examined. We conducted a cross-sectional analysis of 265 PLWH and 284 HIV-uninfected participants from the Miami Adult Studies on HIV (MASH) cohort. The Mini-Mental State Examination (MMSE) was used to assess cognitive impairment. Substance use was self-reported. Overall, 26.8% of PLWH and 15.1% of HIV-uninfected used opioids. Cognitive impairment was more frequent among people who used heroin and/or fentanyl than those who misused prescription opioids (31.6% vs. 10.5%, p = .005). The use of heroin/fentanyl was associated with increased odds for cognitive impairment (adjusted OR: 2.21, 95% CI 1.05-4.64, p = .036). Among PLWH only, the misuse of opioids was associated with a higher frequency of neuropsychiatric symptoms such as depression and apathy. A higher risk for cognitive impairment was seen among people who used heroin and fentanyl. PLWH who misuse opioids may be at an increased risk for neuropathology, but elucidation of mechanisms for opioid-induced cognitive deficits is needed.

Opposite effects of smoking and nicotine intake on cognition

Our main purpose was to investigate how smoking and nicotine interacted with specific aspects of cognitive functioning. The research was conducted in two parts: (i) an investigation of cognition in heavy smokers and healthy nonsmokers, and (ii) an investigation of cognition in healthy nonsmokers enrolled in a clinical trial involving administration of nicotine gum. Results indicated that the relationship between smoking and nicotine was characterized by an inverted U-shaped effect. On the one hand, cognitive test performance of the heavy smokers group was reduced on all of the cognitive tasks used here. On the other hand, healthy nonsmokers who used 2-mg of nicotine gum performed better, whilst the 4-mg group performed worse than the 2-mg and the placebo group. Demographic data were not related to the cognitive tasks. These data suggest that small doses of nicotine can have an activating function that leads to improved cognition, while heavy smoking on a chronic (and possibly acute) basis leads to cognitive impairment.