Effects of acute nicotine administration on behavioral inhibition in adolescents with attention-deficit/hyperactivity disorder

Effects of open-label transdermal nicotine antidepressant augmentation on affective symptoms and executive function in late-life depression

BACKGROUND

Late-life depression (LLD) is characterized by a poor response to antidepressant medications and diminished cognitive performance, particularly in executive functioning. There is currently no accepted pharmacotherapy for LLD that effectively treats both mood and cognitive symptoms. This study investigated whether transdermal nicotine augmentation of standard antidepressant medications benefitted mood and cognitive symptoms in LLD.

METHODS

Nonsmoking participants aged 60 years or older with unremitted LLD on stable SSRI or SNRI medications (N = 29) received transdermal nicotine patches up to a 21 mg daily dose over 12 weeks. Clinical measures assessed depression severity, secondary affective symptoms, and cognitive performance. Nicotine metabolite concentrations were obtained from blood samples.

RESULTS

Depression severity significantly decreased over the trial, with a 76 % response rate and 59 % remission rate. Change in depression severity was positively associated with nicotine exposure. Participants also exhibited improvement in self-reported affective symptoms (apathy, insomnia, rumination, and generalized anxiety symptoms), negativity bias, and disability. Executive function test performance significantly improved, specifically in measures of cognitive control, as did subjective cognitive performance. Adverse events were generally mild, with 75 % of the sample tolerating the maximum dose.

CONCLUSION

The current study extends our previous pilot open-label trial in LLD, supporting feasibility and tolerability of transdermal nicotine patches as antidepressant augmentation. Although preliminary, this open-label study supports the potential benefit of transdermal nicotine patches for both mood and cognitive symptoms of LLD. Further research, including definitive randomized, blinded trials, is warranted to confirm these findings and explore long-term risk and benefit.

TRIAL REGISTRATION

The study was registered with clinicaltrials.gov (NCT04433767).

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.

Catecholaminergic and cholinergic neuromodulation in autism spectrum disorder: A comparison to attention-deficit hyperactivity disorder

Autism spectrum disorder (ASD) is a heterogeneous neurodevelopmental disorder characterized by social impairments and restricted, repetitive behaviors. Treatment of ASD is notoriously difficult and might benefit from identification of underlying mechanisms that overlap with those disturbed in other developmental disorders, for which treatment options are more obvious. One example of the latter is attention-deficit hyperactivity disorder (ADHD), given the efficacy of especially stimulants in treatment of ADHD. Deficiencies in catecholaminergic systems [dopamine (DA), norepinephrine (NE)] in ADHD are obvious targets for stimulant treatment. Recent findings suggest that dysfunction in catecholaminergic systems may also be a factor in at least a subgroup of ASD. In this review we scrutinize the evidence for catecholaminergic mechanisms underlying ASD symptoms, and also include in this analysis a third classic ascending arousing system, the acetylcholinergic (ACh) network. We complement this with a comprehensive review of DA-, NE-, and ACh-targeted interventions in ASD, and an exploratory search for potential treatment-response predictors (biomarkers) in ASD, genetically or otherwise. Based on this review and analysis we propose that (1) stimulant treatment may be a viable option for an ASD subcategory, possibly defined by genetic subtyping; (2) cerebellar dysfunction is pronounced for a relatively small ADHD subgroup but much more common in ASD and in both cases may point toward NE- or ACh-directed intervention; (3) deficiency of the cortical salience network is sizable in subgroups of both disorders, and biomarkers such as eye blink rate and pupillometric data may predict the efficacy of targeting this underlying deficiency via DA, NE, or ACh in both ASD and ADHD.

Dynamic modulation of inhibition ability following repeated exposures to morphine in macaque monkey

BACKGROUND

Deficits in cognitive control, particularly inhibition ability, play crucial roles in susceptibility, progress, and relapse to opioid addiction. However, it is unclear when and how such deficits develop and interact with repeated exposures to prescribed opioids.

AIM

Using macaque monkey (Macaca mulatta), as an animal model with high translational merits in cognitive neuroscience, we tried to delineate alterations of inhibition ability in the course of repeated exposures to morphine.

METHODS

Monkeys were trained to perform stop-signal task and then we closely monitored their inhibition ability before exposure, after initial exposure, and following repeated exposures to morphine when they experienced abstinent periods. We also assessed morphine-induced conditioned place preference (CPP) in these monkeys to monitor the long-lasting effects of morphine on other behaviors.

RESULTS

Compared to the baseline level, monkeys' inhibition ability was significantly enhanced after initial exposure to morphine (early phase); however, it became significantly attenuated after repeated exposures (late phase). These alterations occurred while monkeys consistently expressed the morphine-induced CPP over the course of morphine exposure.

CONCLUSIONS

Our findings indicate that repeated and scheduled exposures to morphine, which is akin to its clinical and recreational use, lead to dynamic alterations in primates' cognitive control depending on the extent of exposure. Enhancement of inhibition after limited exposure might provide opportunities to intervene and prevent the progress and culmination of opioid addiction, which is characterized by disinhibited drug-seeking and consumption.

Tobacco and ADHD: A Role of MAO-Inhibition in Nicotine Dependence and Alleviation of ADHD Symptoms

Attention-deficit/hyperactivity disorder (ADHD) is a relatively commonly occurring neurodevelopmental disorder affecting approximately 5% of children and young people. The neurobiological mechanisms of ADHD are proposed to particularly center around increased dopamine receptor availability related to associated symptoms of reduced attention regulation and impulsivity. ADHD is also persistent across the lifespan and associated with a raft of impulsive and health-risk behaviors including substance abuse and smoking. Research highlighting the potentially significant levels of monoamine oxidase (MAO) inhibitory properties in tobacco smoke and e-cigarettes may provide a mechanism for increased tobacco smoke dependence among those with ADHD, in addition to the role of nicotine.

Aim

This scoping review aimed to establish evidence for the above neurobiological pathway between smoking and ADHD symptom-alleviation or “self-medication” with the inclusion of the mechanism of MAO-inhibitors indirect increasing dopamine in the brain.

Methodology

Scoping review methodologies were employed in this review selected to synthesize multiple sources of empirical research to identify current gaps in the knowledge base and identify key characteristics of research data related to a phenomenon. Databases searched included OVID MEDLINE(R), Embase, Cochrane, PsycINFO and SCOPUS limited to 2000 onward and empirically validated, peer-reviewed research.

Findings

There is support for the role of MAO-inhibition on greater reinforcement of smoking for individuals with ADHD through a greater impact on dopaminergic availability than nicotine; potentially moderating ADHD symptoms.

Conclusion

Greater support for a “self-medication” model of ADHD and smoking includes not only nicotine but also MAO-inhibitors as dopamine agonists contained in cigarettes and e-cigarettes.

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.

Association of Attention-Deficit/Hyperactivity Disorder With E-Cigarette Use

INTRODUCTION

E-cigarette use in young people has emerged as a public health concern in the U.S. Previous studies have shown that individuals with attention-deficit/hyperactivity disorder are more likely to use conventional cigarettes. However, little is known about their use of E-cigarettes. This study examines the association of attention-deficit/hyperactivity disorder with E-cigarette and other tobacco product use among undergraduate and graduate students in the U.S.

METHODS

This study included data from 195,443 U.S. undergraduate and graduate students aged 18-39 years who participated in the National College Health Assessment surveys from spring 2017 to fall 2018. History of attention-deficit/hyperactivity disorder diagnosis and current use of conventional cigarettes, E-cigarettes, and other tobacco products were ascertained by questionnaires. Logistic regression models estimated the ORs and 99% CIs of use of conventional cigarettes, E-cigarettes, and other tobacco products according to attention-deficit/hyperactivity disorder history.

RESULTS

Among the 195,443 students, 16,800 (8.35%) were current conventional cigarette users and 15,863 (7.89%) were current E-cigarette users; 16,283 (8.10%) had a history of attention-deficit/hyperactivity disorder diagnosis. After adjustment for demographics, socioeconomics, lifestyle factors, BMI, anxiety, and depression, the OR of E-cigarette use among participants with attention-deficit/hyperactivity disorder, compared with those without attention-deficit/hyperactivity disorder, was 1.72 (99% CI=1.60, 1.85), which was comparable to the magnitude of associations for other tobacco products.

CONCLUSIONS

Among U.S. undergraduate and graduate students, there is a significant association between attention-deficit/hyperactivity disorder diagnosis and current use of E-cigarettes. Health consequences of E-cigarette use among individuals with an attention-deficit/hyperactivity disorder diagnosis warrant further investigation.

Relationship between impulsivity, comorbid anxiety and neurocognitive functions in bipolar disorder

OBJECTIVE

The aim of the study is to examine the relationship between anxiety and impulsivity and to reveal the correlation of these variables with clinical and sociodemographic features. It is also aimed to investigate the relationship between impulsivity and anxiety with neurocognitive functions in bipolar disorder.

METHODS

The sample of the study comprises of 71 patients with bipolar disorder type I without any comorbidity (BD), 37 patients with anxiety disorder comorbidity with bipolar disorder type I (BDAD), 52 patients with anxiety disorder (AD) and 50 healthy controls (HC). Participants completed Barratt Impulsivity Scale-11, State-Trait Anxiety Inventory 1-2, Panic Disorder Severity Scale (PDSS), brief version of Fear of Negative Evaluation Scale (FNES), Anxiety Sensitivity Index-3 (ASI-3), Trail-Making Test A-B, Digit Span Test, Stroop Test.

RESULTS

PDSS scores, trait anxiety level, hypomanic and mixed episode numbers explain 26% of attention impulsivity. Gender and ASI-3 social dimensions explain 16% of motor impulsivity. Trait anxiety explains non-planning and total impulsivity at 26 and 24%, respectively. When neurocognitive impairment's effect was controlled, it was found AD and BDAD groups had higher impulsivity levels than the BD and HC groups.

CONCLUSION

Anxiety disorder comorbidity increases impulsivity in bipolar disorder.KEYPOINTSIn the presence of anxiety disorder spectrum comorbidity, bipolar disorder patients will have increased impulsivity and the clinical course may be more severe.Trait anxiety levels and anxiety sensitivity may be predictive factors for impulsivity.In the presence of anxiety disorder spectrum comorbidity, it should be taken into consideration that these patients may be more impulsive and should be treated with more care in terms of evaluation of the disorder.

Attention-deficit hyperactivity disorder

Attention-deficit hyperactivity disorder (ADHD), like other psychiatric disorders, represents an evolving construct that has been refined and developed over the past several decades in response to research into its clinical nature and structure. The clinical presentation and course of the disorder have been extensively characterised. Efficacious medication-based treatments are available and widely used, often alongside complementary psychosocial approaches. However, their effectiveness has been questioned because they might not address the broader clinical needs of many individuals with ADHD, especially over the longer term. Non-pharmacological approaches to treatment have proven less effective than previously thought, whereas scientific and clinical studies are starting to fundamentally challenge current conceptions of the causes of ADHD in ways that might have the potential to alter clinical approaches in the future. In view of this, we first provide an account of the diagnosis, epidemiology, and treatment of ADHD from the perspective of both the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders and the eleventh edition of the International Classification of Diseases. Second, we review the progress in our understanding of the causes and pathophysiology of ADHD on the basis of science over the past decade or so. Finally, using these discoveries, we explore some of the key challenges to both the current models and the treatment of ADHD, and the ways in which these findings can promote new perspectives.

Healthy Subjects With Extreme Patterns of Performance Differ in Functional Network Topology and Benefits From Nicotine

Do subjects with atypical patterns in attentional and executive behaviour show different brain network topology and react differently towards nicotine administration? The efficacy of pro-cognitive drugs like nicotine considerably varies between subjects and previous theoretical and empirical evidence suggest stronger behavioural nicotine effects in subjects with low performance. One problem is, however, how to best define low performance, especially if several cognitive functions are assessed for subject characterisation. We here present a method that used a multivariate, robust outlier detection algorithm to identify subjects with suspicious patterns of performance in attentional and executive functioning. In contrast to univariate approaches, this method is sensitive towards extreme positions within the multidimensional space that do not have to be extreme values in the individual behavioural distributions. The method was applied to a dataset of healthy, non-smoking subjects (n = 34) who were behaviorally characterised by an attention and executive function test on which N = 12 volunteers were classified as outliers. All subjects then underwent a resting-state functional magnetic resonance imaging (fMRI) scan to characterise brain network topology and an experimental behavioural paradigm under placebo and nicotine (7 mg patch) that gauged aspects of attention and executive function. Our results indicate that subjects with an atypical multivariate pattern in attention and executive functioning showed significant differences in nodal brain network integration in visual association and pre-motor brain regions during resting state. These differences in brain network topology significantly predicted larger individual nicotine effects on attentional processing. In summary, the current approach successfully identified a subgroup of healthy volunteers with low behavioural performance who differ in brain network topology and attentional benefit from nicotine.

Effects of nicotine and atomoxetine on brain function during response inhibition

The nicotinic acetylcholine receptor (nAChR) agonist nicotine and the noradrenaline transporter inhibitor atomoxetine are widely studied substances due to their propensity to alleviate cognitive deficits in psychiatric and neurological patients and their beneficial effects on some aspects of cognitive functions in healthy individuals. However, despite growing evidence of acetylcholine-noradrenaline interactions, there are only very few direct comparisons of the two substances. Here, we investigated the effects of nicotine and atomoxetine on response inhibition in the stop-signal task and we characterised the neural correlates of these effects using blood oxygen level dependent (BOLD) functional magnetic resonance imaging (fMRI) at 3T. Nicotine (7 mg dermal patch) and atomoxetine (60 mg per os) were applied to N = 26 young, healthy adults in a double-blind, placebo-controlled, cross-over, within-subjects design. BOLD images were collected during a stop-signal task that controlled for infrequency of stop trials. There were no drug effects on behavioural performance or subjective state measures. However, there was a pronounced upregulation of activation in bilateral prefrontal and left parietal cortex following nicotine during successful compared to unsuccessful stop trials. The effect of nicotine on BOLD during failed stop trials was correlated across individuals with a measure of trait impulsivity. Atomoxetine, however, had no discernible effects on BOLD. We conclude that nicotine effects on brain function during inhibitory control are most pronounced in individuals with higher levels of impulsivity. This finding is compatible with previous evidence of nicotine effects on stop-signal task performance in highly impulsive individuals and implicates the nAChR in the neural basis of impulsivity.

NAChR α4β2 Subtype and their Relation with Nicotine Addiction, Cognition, Depression and Hyperactivity Disorder

BACKGROUND

Neuronal α4β2 nAChRs are receptors involved in the role of neurotransmitters regulation and release, and this ionic channel participates in biological process of memory, learning and attention. This work aims to review the structure and functioning of the α4β2 nAChR emphasizing its role in the treatment of associated diseases like nicotine addiction and underlying pathologies such as cognition, depression and attention-deficit hyperactivity disorder.

METHODS

The authors realized extensive bibliographic research using the descriptors "Nicotine Receptor α4β2" and "cognition", "depression", "attention-deficit hyperactivity disorder", besides cross-references of the selected articles and after analysis of references in the specific literature.

RESULTS

As results, it was that found 179 relevant articles presenting the main molecules with affinity to nAChR α4β2 related to the cited diseases. The α4β2 nAChR subtype is a remarkable therapeutic target since this is the most abundant receptor in the central nervous system.

CONCLUSION

In summary, this review presents perspectives on the pharmacology and therapeutic targeting of α4β2 nAChRs for the treatment of cognition and diseases like nicotine dependence, depression and attention-deficit hyperactivity disorder.

Gender Moderates Chronic Nicotine Cigarette Effects on Verbal Memory in Young Adults

Background: Rates of nicotine use remain a prominent public health concern, especially among young adults. Previous findings have demonstrated that chronic exposure to nicotine during adolescence may be linked to various neurocognitive deficits. Nicotine differentially affects the brain by gender. Objectives: The present study investigated the effects of gender and chronic nicotine use on cognition in the developing brain. Methods: From 2008 to 2011, 57 young adult (ages 18-25) participants were recruited as part of a larger cross-sectional neuroimaging study and divided into 21 nicotine users (12 female) and 36 non-using controls (17 female). Participants completed various questionnaires, drug use interview, neuropsychological battery, and MRI scan in a university setting. A series of multiple regressions was conducted with nicotine group and gender*nicotine group interaction as predictors. Results: After controlling for gender, nicotine group status alone was not associated with neuropsychological performance. A gender x nicotine interaction was significantly associated with performance on trial 1, short delay free recall, and long delay free recall of the CVLT-II. Female smokers demonstrated better performance on trial 1 and short and long delay free recall than female controls. Male smokers performed more poorly than male controls on short and long delay free recall. Conclusions: These preliminary findings suggest that cognitive effects of chronic nicotine use are moderated by gender. Further research is needed to determine causality, and identify underlying brain structures and function that may be responsible for differences in verbal memory.

Externalizing behavior problems are related to substance use in adolescents across six samples from Nordic countries

The aim of this study is to investigate associations between use of cigarettes, cannabis, and alcohol (CCA) and psychosocial problems among adolescents with different cultural backgrounds living in Nordic countries. Data from six questionnaire-based surveys conducted in Denmark, Norway, and Greenland, with participants from different cultural and religious backgrounds, were compared. A total of 2212 adolescents between 15 and 18 years of age participated in the study. The surveys were carried out nationally and in school settings. All adolescents answered a 12-item questionnaire (YouthMap12) with six questions identifying externalizing behavior problems and six questions identifying internalizing behavior problems, as well as four questions regarding childhood neglect and physical or sexual abuse, and questions about last month use of CCA. Externalizing behavior problems were strongly associated with all types of CCA use, while childhood history of abuse and neglect was associated with cigarette and cannabis use. The associations did not differ by sample. Despite differences between samples in use of CCA, national, cultural, and socioeconomic background, very similar associations were found between psychosocial problems and use of CCA. Our findings highlight the need to pay special attention to adolescents with externalizing behavior problems and experiences of neglect and assault in CCA prevention programs, across different ethnic and socioeconomic backgrounds.

Investigating possible causal effects of externalizing behaviors on tobacco initiation: A Mendelian randomization analysis

Observational studies suggest childhood externalizing disorders are associated with increased smoking and earlier initiation. However, causality cannot be inferred from observational data alone. The current study uses two-sample MR to examine the causal relationship between externalizing behaviors and tobacco use. Single nucleotide polymorphisms (SNPs) associated with aggression were obtained from the Early Life Epidemiology Consortium (mean age 8), ADHD from the Integrative Psychiatric Research and Psychiatric Genomics Consortiums (age range 6-18), and tobacco initiation and age of onset from the Tobacco and Genetics Consortium. SNPs were combined using the inverse variance weighted approach, weighted median approach, and MR-Egger regression. There was no clear evidence of an effect of aggression on tobacco initiation or age of onset for childhood aggression (initiation: β -0.002, 95% CI -0.005, 0.001, P = 0.286; age: β -0.001 95% CI -0.002, 0.000, P = 0.310) or adolescent aggression (initiation: β -0.001, 95% CI -0.006, 0.003, P = 0.610; age: β 0.000, 95% CI 0.000, 0.001, P = 0.183)]. However, there was some evidence of an association of ADHD on tobacco initiation (OR 1.23, 95% CI 1.10, 1.35, P = 0.016), although no clear evidence of an effect of ADHD on age of onset (OR = 1.022, 95% CI 0.992, 1.052, P = 0.215). Our results provide some evidence that genetic risk of childhood ADHD is causally related to increased risk of tobacco initiation; however, the causal estimate is relatively small. We found no clear evidence that genetic risk of childhood aggression is causally related to the risk of tobacco initiation or age of onset.

How Substance Users With ADHD Perceive the Relationship Between Substance Use and Emotional Functioning

OBJECTIVE

Although substance use (SU) is elevated in ADHD and both are associated with disrupted emotional functioning, little is known about how emotions and SU interact in ADHD. We used a mixed qualitative-quantitative approach to explore this relationship.

METHOD

Narrative comments were coded for 67 persistent (50 ADHD, 17 local normative comparison group [LNCG]) and 25 desistent (20 ADHD, 5 LNCG) substance users from the Multimodal Treatment Study of Children with ADHD (MTA) adult follow-up (21.7-26.7 years-old).

RESULTS

SU persisters perceived SU positively affects emotional states and positive emotional effects outweigh negative effects. No ADHD group effects emerged. Qualitative analysis identified perceptions that cannabis enhanced positive mood for ADHD and LNCG SU persisters, and improved negative mood and ADHD for ADHD SU persisters.

CONCLUSION

Perceptions about SU broadly and mood do not differentiate ADHD and non-ADHD SU persisters. However, perceptions that cannabis is therapeutic may inform ADHD-related risk for cannabis use.

Pharmacological treatment for attention deficit hyperactivity disorder (ADHD) in children with comorbid tic disorders

BACKGROUND

This is an update of the original Cochrane Review published in Issue 4, 2011.Attention deficit hyperactivity disorder (ADHD) is the most prevalent of the comorbid psychiatric disorders that complicate tic disorders. Medications commonly used to treat ADHD symptoms include stimulants such as methylphenidate and amphetamine; non-stimulants, such as atomoxetine; tricyclic antidepressants; and alpha agonists. Alpha agonists are also used as a treatment for tics. Due to the impact of ADHD symptoms on the child with tic disorder, treatment of ADHD is often of greater priority than the medical management of tics. However, for many decades, clinicians have been reluctant to use stimulants to treat children with ADHD and tics for fear of worsening their tics.  OBJECTIVES: To assess the effects of pharmacological treatments for ADHD in children with comorbid tic disorders on symptoms of ADHD and tics.

SEARCH METHODS

In September 2017, we searched CENTRAL, MEDLINE, Embase, and 12 other databases. We also searched two trial registers and contacted experts in the field for any ongoing or unpublished studies.

SELECTION CRITERIA

We included randomized, double-blind, controlled trials of any pharmacological treatment for ADHD used specifically in children with comorbid tic disorders. We included both parallel-group and cross-over study designs.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures of Cochrane, in that two review authors independently selected studies, extracted data using standardized forms, assessed risk of bias, and graded the overall quality of the evidence by using the GRADE approach.

MAIN RESULTS

We included eight randomized controlled trials (four of which were cross-over trials) with 510 participants (443 boys, 67 girls) in this review. Participants in these studies were children with both ADHD and a chronic tic disorder. All studies took place in the USA and ranged from three to 22 weeks in duration. Five of the eight studies were funded by charitable organizations or government agencies, or both. One study was funded by the drug manufacturer. The other two studies did not specify the source of funding. Risk of bias of included studies was low for blinding; low or unclear for random sequence generation, allocation concealment, and attrition bias; and low or high for selective outcome reporting. We were unable to combine any of the studies in a meta-analysis due to important clinical heterogeneity and unit-of-analysis issues.Several of the trials assessed multiple agents. Medications assessed included methylphenidate, clonidine, desipramine, dextroamphetamine, guanfacine, atomoxetine, and deprenyl. There was low-quality evidence for methylphenidate, atomoxetine, and clonidine, and very low-quality evidence for desipramine, dextroamphetamine, guanfacine and deprenyl in the treatment of ADHD in children with tics. All studies, with the exception of a study using deprenyl, reported improvement in symptoms of ADHD. Tic symptoms also improved in children treated with guanfacine, desipramine, methylphenidate, clonidine, and a combination of methylphenidate and clonidine. In one study, tics limited further dosage increases of methylphenidate. High-dose dextroamphetamine appeared to worsen tics in one study, although the length of this study was limited to three weeks. There was appetite suppression or weight loss in association with methylphenidate, dextroamphetamine, atomoxetine, and desipramine. There was insomnia associated with methylphenidate and dextroamphetamine, and sedation associated with clonidine.

AUTHORS' CONCLUSIONS

Following an updated search of potentially relevant studies, we found no new studies that matched our inclusion criteria and thus our conclusions have not changed.Methylphenidate, clonidine, guanfacine, desipramine, and atomoxetine appear to reduce ADHD symptoms in children with tics though the quality of the available evidence was low to very low. Although stimulants have not been shown to worsen tics in most people with tic disorders, they may, nonetheless, exacerbate tics in individual cases. In these instances, treatment with alpha agonists or atomoxetine may be an alternative. Although there is evidence that desipramine may improve tics and ADHD in children, safety concerns will likely continue to limit its use in this population.

Attention-Deficit/Hyperactivity Disorder and Nicotine Dependence in Adults

Introduction

The aim of this study is to assess clinical characteristics and smoking profiles of individuals diagnosed with attention-deficit/hyperactivity disorder (ADHD) and compare their nicotine dependence status with healthy controls for better understanding the mutual and complex relationship between ADHD and smoking.

Methods

We included the following participants in the study: 40 adults with the diagnosis of ADHD, 40 participants who visited the smoking cessation polyclinic without any psychiatric disorders, and 40 healthy controls. A sociodemographic data form, Wender Utah Rating Scale (WURS), Adult ADD/ADHD Diagnosis and Evaluation Inventory, and Fagerstrom Nicotine Dependence Test (FNDT) were administered to the participants.

Results

Mean age of the ADHD, nicotine dependence, and control groups was 28.68±7.22, 34.17±8.60, 33.70±7.45 years, respectively. Percentages of females and males were 27.5% and 72.5% in the ADHD group, 50% and 50% in the nicotine dependence group, 47.5% and 52.5% in the control group. The attention-deficit scores in the ADHD, nicotine dependence, and control groups were 21.18±5.05, 7.23±3.96, 4.75±2.65, respectively (p=0.001), whereas the hyperactivity scores were.73±5.84, 6.43±4.2, and 3.58±2.27, respectively (p=0.001). The related features scores were 56.53±12.96, 24.30±13.93, and 13.13±6.11, respectively (p=0.001), whereas the WURS scores were 61.88±12.69, 23.03±16.07, 11.90±8.15, respectively (p=0.001). FNDT scores in ADHD and nicotine dependence groups were 5.83±2.11 and 6.20±2.74, respectively (p=0.495).

Conclusion

Considering the argument of ADHD being an independent risk factor for nicotine dependence, we think the co-occurrence of the smoking addiction and ADHD symptoms in the context of dopamine dysregulation is important in the clinical setting. Treatment modalities and of preventive strategies should be considered while keeping this in mind.

Abstinence-induced withdrawal severity among adolescent smokers with and without ADHD: disentangling effects of nicotine and smoking reinstatement

RATIONALE

Individuals with attention deficit hyperactivity disorder (ADHD) start smoking earlier, are more likely to progress to nicotine dependence, and have a more difficult time quitting smoking compared to their non-ADHD peers. Little is known about the underlying behavioral mechanisms associated with this increased risk, particularly at the adolescent stage.

OBJECTIVE

This study aimed to assess the effects of overnight nicotine abstinence and smoking reinstatement on subjective withdrawal states in adolescent smokers with and without ADHD.

METHODS

Adolescent daily smokers (27 with ADHD and 17 without ADHD) completed three experimental sessions: (1) a placebo patch followed by smoking a nicotine cigarette, (2) placebo patch followed by smoking a nicotine-free cigarette, and (3) nicotine patch followed by smoking a nicotine-free cigarette. Subjects abstained overnight before each session, and patches were administered 45 min before smoking. The primary outcome measure was a smoking withdrawal symptom questionnaire.

RESULTS

ADHD smokers experienced greater difficulty concentrating and impatience/restlessness during abstinence than non-ADHD smokers. Smoking a cigarette improved abstinence-induced difficulty concentrating and restlessness, regardless of its nicotine content, and regardless of whether transdermal nicotine was received or not.

CONCLUSIONS

Thus, sensorimotor aspects of smoking, rather than nicotine itself, appeared to relieve withdrawal. Although ADHD smokers report greater withdrawal symptoms than non-ADHD smokers, they responded strongly to the sensorimotor aspects of smoking during withdrawal. These findings suggest that even lighter, adolescent smokers with ADHD are vulnerable to smoking progression through altered smoking abstinence and withdrawal relief processes.

Effects of nicotine on response inhibition and interference control

Nicotine is a cholinergic agonist with known pro-cognitive effects in the domains of alerting and orienting attention. However, its effects on attentional top-down functions such as response inhibition and interference control are less well characterised. Here, we investigated the effects of 7 mg transdermal nicotine on performance on a battery of response inhibition and interference control tasks. A sample of N = 44 healthy adult non-smokers performed antisaccade, stop signal, Stroop, go/no-go, flanker, shape matching and Simon tasks, as well as the attentional network test (ANT) and a continuous performance task (CPT). Nicotine was administered in a within-subjects, double-blind, placebo-controlled design, with order of drug administration counterbalanced. Relative to placebo, nicotine led to significantly shorter reaction times on a prosaccade task and on CPT hits but did not significantly improve inhibitory or interference control performance on any task. Instead, nicotine had a negative influence in increasing the interference effect on the Simon task. Nicotine did not alter inter-individual associations between reaction times on congruent trials and error rates on incongruent trials on any task. Finally, there were effects involving order of drug administration, suggesting practice effects but also beneficial nicotine effects when the compound was administered first. Overall, our findings support previous studies showing positive effects of nicotine on basic attentional functions but do not provide direct evidence for an improvement of top-down cognitive control through acute administration of nicotine at this dose in healthy non-smokers.

Cigarette smoking and ADHD: An examination of prognostically relevant smoking behaviors among adolescents and young adults

Attention-deficit/hyperactivity disorder (ADHD) is associated with health risks in adolescence which includes the potential for smoking cigarettes, early smoking initiation, and rapid progression to daily smoking. Much less is known, however, about prognostically relevant smoking behaviors among individuals with childhood ADHD. Further research in this area is important for identifying individuals at pronounced risk for nicotine addiction, and for developing effective interventions for this population. This study examined initiation of cigarette smoking, progression to regular smoking, quantity of use, indicators of tobacco dependence, and quit rates among adolescents and young adults with (n = 364) and without (n = 240) childhood ADHD. Individuals with, versus without, ADHD histories were significantly more likely to become daily smokers independent of conduct disorder (CD). They were also more likely to initiate smoking at younger ages and to progress to regular smoking more quickly. There were no significant group differences in cigarettes smoked per day, Fagerström Test of Nicotine Dependence (FTND), or Nicotine Dependence Syndrome Scale (NDSS) scores or in smoking within 30 min of waking. However, smokers with ADHD reported more intense withdrawal and craving during periods of abstinence than non-ADHD smokers. There were no significant group differences in number of quit attempts. Lastly, there were no significant differences among symptom persisters and desisters in daily smoking and amount. Individuals with ADHD histories are at high risk for persistent smoking given their early onset, rapid course, and abstinence characteristics. Smoking cessation programs may need to be adapted or otherwise intensified for those with ADHD. (PsycINFO Database Record

Negative occasion setting in juvenile rats

Prior findings indicate that adolescent rats exhibit difficulty using negative occasion setters to guide behavior compared to adult rats (Meyer and Bucci, 2014). Here, additional groups of juvenile rats were trained in the same negative occasion setting procedure to further define the development of negative occasion setting. Beginning on either postnatal day (PND) 30, 40, or 50, rats received daily training sessions in which a tone was paired with food reinforcement on some trials, while on other trials a light preceded the tone and no reinforcement was delivered. We found that rats that began training on PND 50 required 10 training sessions to discriminate between the two types of trials, consistent with prior findings with young adult rats. Interestingly, rats in the PND 30 group (pre-adolescents) also required just 10 training sessions, in stark contrast to adolescent rats that began training on PND 35 (adolescents) and required 18 sessions (Meyer and Bucci, 2014). Rats that began training on PND 40 (adolescents) also required more sessions than the PND 30 group. These data indicate that the development of negative occasion setting is non-linear and have direct bearing on understanding the behavioral and neural substrates that underlie suboptimal behavioral control in adolescents.

Cognitive Dysfunction, Affective States, and Vulnerability to Nicotine Addiction: A Multifactorial Perspective

Although smoking prevalence has declined in recent years, certain subpopulations continue to smoke at disproportionately high rates and show resistance to cessation treatments. Individuals showing cognitive and affective impairments, including emotional distress and deficits in attention, memory, and inhibitory control, particularly in the context of psychiatric conditions, such as attention-deficit hyperactivity disorder, schizophrenia, and mood disorders, are at higher risk for tobacco addiction. Nicotine has been shown to improve cognitive and emotional processing in some conditions, including during tobacco abstinence. Self-medication of cognitive deficits or negative affect has been proposed to underlie high rates of tobacco smoking among people with psychiatric disorders. However, pre-existing cognitive and mood disorders may also influence the development and maintenance of nicotine dependence, by biasing nicotine-induced alterations in information processing and associative learning, decision-making, and inhibitory control. Here, we discuss the potential forms of contribution of cognitive and affective deficits to nicotine addiction-related processes, by reviewing major clinical and preclinical studies investigating either the procognitive and therapeutic action of nicotine or the putative primary role of cognitive and emotional impairments in addiction-like features.

High-Affinity Nicotinic Receptors Modulate Spontaneous Cortical Up States In Vitro

Nicotinic acetylcholine receptors (nAChRs) play an important role in the modulation of many cognitive functions but their role in integrated network activity remains unclear. This is at least partly because of the complexity of the cholinergic circuitry and the difficulty in comparing results from in vivo studies obtained under diverse experimental conditions and types of anesthetics. Hence the role of nAChRs in the synchronization of cortical activity during slow-wave sleep is still controversial, with some studies showing they are involved in ACh-dependent EEG desynchronization, and others suggesting that this effect is mediated exclusively by muscarinic receptors. Here we use an in vitro model of endogenous network activity, in the form of recurring self-maintained depolarized states (Up states), which allows us to examine the role of high-affinity nAChRs on network dynamics in a simpler form of the cortical microcircuit. We find that mice lacking nAChRs containing the β2-subunit (β2-nAChRs) have longer and more frequent Up states, and that this difference is eliminated when β2-nAChRs in wild-type mice are blocked. We further show that endogenously released ACh can modulate Up/Down states through the activation of both β2- and α7-containing nAChRs, but through distinct mechanisms: α7-nAChRs affect only the termination of spontaneous Up states, while β2-nAChRs also regulate their generation. Finally we provide evidence that the effects of β2-subunit-containing, but not α7-subunit-containing nAChRs, are mediated through GABAB receptors. To our knowledge this is the first study documenting direct nicotinic modulation of Up/Down state activity.

SIGNIFICANCE STATEMENT

Through our experiments we were able to uncover a clear and previously disputed effect of nicotinic signaling in synchronized activity of neuronal networks of the cortex. We show that both high-affinity receptors (containing the β2-subunit, β2-nAChRs) and low-affinity receptors (containing the α7-subunit, α7-nAChRs) can regulate cortical network function exhibited in the form of Up/Down states. We further show that the effects of β2-nAChRs, but not α7-nAChRs, are mediated through the activation of GABAB receptors. These results suggest a possible synthesis of seemingly contradictory results in the literature and could be valuable for informing computational models of cortical function and for guiding the search for therapeutic interventions.

Inhibitory learning is modulated by nicotinic acetylcholine receptors

Prior research has established that stimulating nicotinic acetylcholine receptors can facilitate learning and memory. However, most studies have focused on learning to emit a particular behavior, while little is known about the effects of nicotine on learning to withhold a behavioral response. The present study consisted of a dose response analysis of the effects of nicotine on negative occasion setting, a form of learned inhibition. In this paradigm, rats received one type of training trial in which presentation of a tone by itself was followed immediately by food reward. During the other type of trials, the tone was preceded by presentation of a light and no food was delivered after the tone. Rats gradually learned to approach the cup in anticipation of receiving food reward during presentations of the tone alone, but withheld that behavior when the tone was preceded by the light. Nicotine (0.35 mg/kg) facilitated negative occasion setting by reducing the number of sessions needed to learn the discrimination between trial types and by reducing the rate of responding on non-reinforced trials. Nicotine also increased the orienting response to the light, suggesting that nicotine may have affected the ability to withhold food cup behavior on non-reinforced trials by increasing attention to the light. In contrast to the effects of nicotine, rats treated with mecamylamine (0.125, 0.5, or 2 mg/kg) needed more training sessions to discriminate between reinforced and non-reinforced trials compared to saline-treated rats. The findings indicate that nicotinic acetylcholine receptors may be active during negative occasion setting and that nicotine can potentiate learned inhibition.

Modulation of nicotine effects on selective attention by DRD2 and CHRNA4 gene polymorphisms

RATIONALE

Pharmacological and genetic modulation of cholinergic nicotinic neurotransmission influence visuospatial attention in humans. Prior studies show that nicotine as well as a single nucleotide polymorphism (SNP) in the gene coding for the alpha 4 subunit of the nicotinic acetylcholine receptor (CHRNA4) modulate visuospatial attention and distractor interference. The CHRNA4 gene synergistically interacts with a polymorphism in the dopaminergic receptor type d2 (DRD2) gene and impacts brain structure and cognition.

OBJECTIVE

We aimed to investigate whether CHRNA4 and DRD2 genotypes alter the effects of nicotine on distractor interference.

METHODS

Fifty-eight young healthy non-smokers were genotyped for CHRNA4 (rs1044396) and DRD2 (rs6277). They received either 7 mg transdermal nicotine or a matched placebo in a double-blind, within-subject design 1 h prior to performing a visual search task with distractors.

RESULTS

In isolation, DRD2 but not CHRNA4 genotype modulated the effects of nicotine on distractor interference with DRD2 CC carriers showing the strongest reduction of distractor interference after nicotine administration. A further analysis provided additional evidence that this effect was driven by those subjects, who carried at least one C allele in the CHRNA4 gene.

CONCLUSION

The effects of nicotine on distractor interference are modulated synergistically by cholinergic and dopaminergic genetic variations. Hence, both genes may contribute to the often reported individual variability in cognitive and neural effects of nicotine.

Diverse inhibition and working memory of word recognition for dyslexic and typically developing children

The present study focuses on (1) comparing dyslexic and typically developing children's cognitive and behavioural inhibitory abilities; (2) examining the relationship between word recognition, inhibition, and working memory in dyslexic and typically developing children by correlation, regression and path analyses. Participants in the present study were sampled from 3rd and 4th graders in Taiwan. Results indicated that dyslexic and typically developing children did not significantly differ in behavioural inhibition. In contrast, dyslexic children showed significantly lower levels of cognitive inhibition compared to typically developing children. Dyslexic children also showed that only cognitive inhibition significantly contributed to their word recognition, and typically developing children showed similar phenomenon. Finally, models of dyslexic and typically developing children's working memory, inhibition and word recognition were similar in that working memory and cognitive inhibition significantly contributed to word recognition for both dyslexic and typically developing children. Moreover, the contribution of the combination of working memory and inhibition was greater than the contribution of only inhibition; both of typically developing and dyslexic children's working memory showed more contributions than inhibition.

Improving response inhibition in Parkinson's disease with atomoxetine

BACKGROUND

Dopaminergic drugs remain the mainstay of Parkinson's disease therapy but often fail to improve cognitive problems such as impulsivity. This may be due to the loss of other neurotransmitters, including noradrenaline, which is linked to impulsivity and response inhibition. We therefore examined the effect of the selective noradrenaline reuptake inhibitor atomoxetine on response inhibition in a stop-signal paradigm.

METHODS

This pharmacological functional magnetic resonance imaging study used a double-blinded randomized crossover design with low-frequency inhibition trials distributed among frequent Go trials. Twenty-one patients received 40 mg atomoxetine or placebo. Control subjects were tested on no-drug. The effects of disease and drug on behavioral performance, regional brain activity, and functional connectivity were analyzed using general linear models. Anatomical connectivity was examined using diffusion-weighted imaging.

RESULTS

Patients with Parkinson's disease had longer stop-signal reaction times, less stop-related activation in the right inferior frontal gyrus (RIFG), and weaker functional connectivity between the RIFG and striatum compared with control subjects. Atomoxetine enhanced stop-related RIFG activation in proportion to disease severity. Although there was no overall behavioral benefit from atomoxetine, analyses of individual differences revealed that enhanced response inhibition by atomoxetine was associated with increased RIFG activation and functional frontostriatal connectivity. Improved performance was more likely in patients with higher structural frontostriatal connectivity.

CONCLUSIONS

This study suggests that enhanced prefrontal cortical activation and frontostriatal connectivity by atomoxetine may improve response inhibition in Parkinson's disease. These results point the way to new stratified clinical trials of atomoxetine to treat impulsivity in selected patients with Parkinson's disease.

Impulsivity in cocaine-dependent individuals with and without attention-deficit/hyperactivity disorder

BACKGROUND

Cocaine-dependent individuals (CDI) display increased impulsivity. However, despite its multifactorial nature most studies in CDI have treated impulsivity monolithically. Moreover, the impact of attention-deficit/hyperactivity disorder (ADHD) has often not been taken into account. This study investigates whether CDI with ADHD (CDI+ADHD) differ from CDI without an ADHD diagnosis and healthy controls (HC) on several impulsivity measures.

METHODS

Thirty-four CDI, 25 CDI+ADHD and 28 HC participated in this study. Trait impulsivity was assessed with the motor, attentional and non-planning subscales of the Barratt Impulsiveness Scale (BIS-11). Neurocognitive dimensions of impulsivity were examined with the stop signal task (SST), delay discounting task (DDT) and information sampling task (IST).

RESULTS

Relative to HC, both CDI and CDI+ADHD scored higher on all BIS-11 subscales, required more time to inhibit their responses (SST) and sampled less information before making a decision (IST). Greater discounting of delayed rewards (DDT) was only found among CDI+ADHD. Compared to CDI without ADHD, CDI+ADHD scored higher on the BIS-11 non-planning and total scale and showed higher discounting rates.

CONCLUSION

CDI score higher on several indices of impulsivity relative to HC, regardless of whether they have concomitant ADHD or not. CDI+ADHD are specifically characterized by a lack of future orientation compared to CDI without ADHD. © 2015 S. Karger AG, Basel.

Targeting the nicotinic cholinergic system to treat attention-deficit/hyperactivity disorder: rationale and progress to date

Attention-deficit/hyperactivity disorder (ADHD) is a common chronic neurobehavioral disorder related to clinically significant levels of inattention, hyperactivity, and/or impulsivity. ADHD begins in childhood and symptoms persist into adulthood for the majority of those with the disorder. Associated features of ADHD include emotion dysregulation and cognitive impairments, which contribute to the considerable functional impairments in this disorder. Current approved treatments are reasonably effective; however, a significant need remains for new pharmacotherapies, both for individuals who do not achieve a full therapeutic response and for symptoms that are under-treated including cognition and emotion regulation. The striking relationship between ADHD and cigarette smoking and the known effects of nicotine on cognition has spurred research into the therapeutic potential of nicotinic agents for ADHD. Although there are no approved medications for ADHD that target nicotinic acetylcholine receptor (nAChR) function, results from many trials of nicotinic drugs are available and reviewed in this article. ADHD symptoms were reduced in the majority of published studies of nicotine and novel α4β2 nicotinic agonists in adult ADHD. The drugs were generally well tolerated, with mild to moderate side effects reported, which were largely consistent with cholinergic stimulation and included nausea, dizziness, and gastrointestinal distress. Within-subject crossover study designs were used in the majority of positive studies. This design may be particularly useful in ADHD trials because it minimizes variability in this notoriously heterogeneous diagnostic group. In addition, many studies found evidence for a beneficial effect of nicotinic stimulation on cognitive and emotional domains. Thus, targeting nAChRs in ADHD appears to have a modest clinical benefit in adult ADHD. Continued refinement of nAChR agonists with greater specificity and fewer side effects may lead to even more effective nAChR agonists for ADHD. Future clinical trials in ADHD should include direct measures of neuropsychological performance and emotion regulation.

Applications of pharmacogenetics in children with attention-deficit/hyperactivity disorder

This review examines molecular genetic studies shown to be of importance in the etiology of attention-deficit/hyperactivity disorder (ADHD) and contrasts prefrontal versus sub-cortical mechanisms. Although these mechanisms are not completely dissociated, an understanding of prefrontal dopaminergic/noradrenergic versus subcortical D1/D2 receptor mechanisms is useful for studies of diagnosis versus potential adverse effects. Dopamine physiology, dopamine receptor studies, alpha-2 agonist studies, and dopamine transporter and potential new therapies are reviewed. Further understandings of molecular mechanisms involved in etiology versus treatment and adverse effects should help personalize the treatment of ADHD.

Inhibitory control dysfunction in nicotine dependence and the influence of short-term abstinence

BACKGROUND

Although the majority of substance use disorders depict reliable deficits in inhibitory control (IC), similar deficits are not consistently found in nicotine dependence. The mixed results of past research may have been due to confounding variables known to independently influence IC function, including age, concurrent drug use and particularly, length of nicotine abstinence.

METHODS

A stop signal task was used to examine stop signal reaction time (SSRT), a typical measure of IC, in nicotine dependence across two studies that attempted to closely control for IC confounds. Study 1 compared the SSRT of 37 dependent cigarette smokers (11 females) to 36 non-smokers (13 females), following 3-h of nicotine abstinence. Study 2 compared 22 dependent cigarette smokers' (11 females) SSRT scores when satiated on nicotine to their performance following 10-h of nicotine abstinence.

RESULTS

Nicotine dependent individuals did not differ from controls in SSRT performance following 3-h abstinence, but showed a significant decline in performance following 10-h abstinence, when compared to nicotine satiation.

CONCLUSIONS

During shorter abstinence periods, the acute benefits of nicotine satiation appear to facilitate inhibitory control; however, IC was poorer during extended periods of nicotine abstinence. In turn, this suggests that the reliability of IC dysfunction in nicotine dependence varies according to abstinence length and needs to be carefully considered for future behavioural and neuroimaging examination of IC within this population.

Shared versus specific features of psychological symptoms and cigarettes per day: structural relations and mediation by negative- and positive-reinforcement smoking

This study examined the extent to which shared versus specific features across multiple manifestations of psychological symptoms (depression, anxiety, ADHD, aggression, alcohol misuse) associated with cigarettes per day. Subsequently, we investigated whether negative- (i.e., withdrawal relief) and positive- (i.e., pleasure enhancement) reinforcement smoking motivations mediated relations. Adult daily smokers (N = 338) completed self-report measures and structural equation modeling was used to construct a 3-factor (low positive affect-negative affect-disinhibition) model of affective and behavioral symptoms and to test relations of each latent factor (shared features) and indicator residual (specific features) to smoking level. Shared dimensions of low positive affect, negative affect, and disinhibition associated with smoking rate. Negative-reinforcement smoking mediated the link between latent negative affect and heavier daily smoking. Specific features of psychological symptoms unique from latent factors were generally not associated with cigarettes per day. Features shared across several forms of psychological symptoms appear to underpin relations between psychological symptoms and smoking rate.

The relationship between Stroop and stop-signal measures of inhibition in adolescents: influences from variations in context and measure estimation

The Stroop and stop-signal tasks are commonly used to index prepotent response inhibition in studies of cognitive development and individual differences. Inhibitory measures from the two tasks have been derived using a variety of methods. Findings of low inter-correlations amongst these measures have been interpreted as evidence for different kinds of inhibitory functions. Our previous study found Stroop and stop-signal accuracy measures to be uncorrelated and they loaded on different inhibitory components in a principal component analysis. The present study examined whether this finding is replicated across different task contexts, derived measures, and methods of derivation. Adolescents (N = 247) were administered a number-quantity Stroop and word and number stop-signal tasks. For each stop-signal task, inhibitory efficiency was estimated using a stop-signal reaction time measure estimated with the central versus the integration methods. For the Stroop interference task, inhibitory efficiency was indexed by reaction time measures (including inverse efficiency scores) generated from difference scores and regression residuals, and delta-plot slopes. The reaction time measures from the two tasks were generally not correlated. The only exception was that Stroop inhibitory ability, indexed by Stroop errors, was related to stop-signal inhibitory efficiency, indexed by stop-signal reaction time. These findings are consistent with previous findings suggesting that measures from the Stroop and stop-signal tasks are influenced by different underlying processes. The impact of variations in dependent measure derivation on the resulting reliabilities of Stroop and stop-signal measures and on observed correlations between them were examined. Variables that may have contributed to the null findings are discussed.

Detrimental effects of acute nicotine on the response-withholding performance of spontaneously hypertensive and Wistar Kyoto rats

RATIONALE

Attention-deficit hyperactivity disorder (ADHD) is associated with a higher prevalence of smoking, which may be related to potential therapeutic effects of nicotine on ADHD symptoms. Whereas nicotine offers robust improvements in sustained attention, the effects of nicotine on impulsivity are unclear.

OBJECTIVES

The present study examined the effects of nicotine on the response inhibition capacity of spontaneously hypertensive rats (SHR), an animal model of ADHD, compared to that of a normotensive control Wistar Kyoto (WKY), using the fixed minimum interval (FMI) schedule of reinforcement.

METHODS

Tests were conducted following acute injections of subcutaneous nicotine (0.1-0.6 mg/kg). On each FMI trial, the first lever press initiated an inter-response time (IRT); a head entry into a food receptacle terminated the IRT. IRTs longer than 6 s were intermittently reinforced with sucrose.

RESULTS

A model that assumes that only a proportion of IRTs are sensitive to the timing contingencies of the FMI provided a close fit to the data, regardless of strain or treatment. No baseline difference in FMI performance was observed between SHR and WKY. Nicotine reduced the duration of timed IRTs and the duration of latencies to the IRT-initiating lever press similarly for both strains. Nicotine dose-dependently increased the proportion of timed IRTs; the dose-response curve was shifted leftwards in SHR relative to WKY.

CONCLUSIONS

These results suggest that nicotine (a) reduces response-inhibition capacity, (b) enhances the reinforcing efficacy of sucrose, and (c) dose-dependently enhances attention-like sensitivity to contingencies of reinforcement, through mechanisms that are yet unknown.

The effect of enhancing cholinergic neurotransmission by nicotine on EEG indices of inhibition in the human brain

The role of the cholinergic system in inhibition remains to be elucidated. Nicotine is a potent tool to augment this system, but most studies investigated its effects solely on behavior. Reference to brain activity is important to specifically identify inhibition-related mechanisms. In the current study the objective was to elucidate the role of the cholinergic system in inhibition. 16 healthy non-smokers performed in a stop task while EEG was recorded. A pre- versus post-treatment, within subjects, placebo controlled, single-blind design was used. It was hypothesized that nicotine would decrease stop-signal reaction time (SSRT) and increase the amplitude of inhibition-related event related potentials, the stop N2 and stop P3. Behavioral measures show nicotine shortened SSRT, but only when pretreatment values were not taken into account. On EEG measures, an enhanced stop P3 under nicotine was found, but only in a subsample sensitive to nicotine based on diastolic blood pressure. The results are indicative of enhanced inhibitory activity possibly reflecting enhanced activation in the superior frontal gyrus.

A randomized, double-blind, placebo-controlled crossover study of α4β 2* nicotinic acetylcholine receptor agonist AZD1446 (TC-6683) in adults with attention-deficit/hyperactivity disorder

RATIONALE

Stimulation of nicotinic cholinergic systems has been shown to alleviate ADHD symptoms and to improve cognitive performance. AZD1446 is a selective α4β2* nicotinic acetylcholine receptor agonist with potential effect on the symptoms of ADHD.

OBJECTIVES

The purpose of this study is to evaluate the efficacy, safety, and pharmacokinetics of AZD1446 in adults with ADHD treated for 2 weeks.

METHOD

This was a randomized, double-blind, placebo-controlled crossover trial. Participants were 79 adults with ADHD, grouped according to their use of nicotine-containing products. Nicotine non-users received placebo and two of three AZD1446 treatment regimens (80 mg tid, 80 mg qd, 10 mg tid). Nicotine users received placebo, AZD1446 80 mg tid and 80 mg qd. Efficacy measures included the Conners' Adult ADHD Rating Scale and cognitive measures of immediate and delayed verbal episodic memory, learning, attention, working memory, executive functioning, and spatial problem solving (CogState computerized test battery).

RESULTS

There was no significant effect of AZD1446 on any of the clinical scores irrespective of dose, schedule, or concomitant use of nicotine products. A statistically significant improvement was seen on the Groton Maze Learning Task, a measure of executive functioning, in nicotine non-users after treatment with AZD1446 80 mg qd.

CONCLUSIONS

AZD1446 was well tolerated, but did not significantly improve ADHD symptoms after 2 weeks of treatment compared to placebo. While the present study does not support the therapeutic utility of AZD1446 in ADHD, its potential pro-cognitive effects remain to be explored in other neuropsychiatric disorders.

Trait differences in response to chronic nicotine and nicotine withdrawal in rats

INTRODUCTION

Understanding an individual's vulnerability to drug addiction has important implications for the development of effective personal treatment plans. Although theories acknowledge impulsive behaviour as a key component of drug addiction, little is known about the influence of trait impulsivity on an individual's susceptibility to the effects of psychostimulants on impulsivity at critical phases of the addiction cycle.

METHODS

This study investigated the short and longer-term effects of chronic nicotine administration on impulsive choice in rats selected for high (HI) and low impulsivity (LI) on a delay discounting task. Rats prepared with subcutaneously osmotic mini-pumps received either nicotine (3.16 mg/kg/day [freebase]) or saline for 7 days. Performance was assessed during chronic treatment, early and late withdrawal, and in response to acute nicotine challenges following prolonged abstinence.

RESULTS

Chronic nicotine increased impulsive choice in LI but not HI animals. Spontaneous withdrawal was associated with a nicotine abstinence syndrome, the early stages of which were characterised by opposing effects on impulsive choice in HI and LI animals. A transient decrease in impulsivity was observed in HI animals whilst the LI group remained more impulsive for up to 1 week following drug termination. Following normalisation of behaviour, acute nicotine challenges (0.125, 0.25, 0.5 mg/kg, SC) markedly increased impulsive choice regardless of trait impulsivity and drug history.

CONCLUSION

The results indicate that only LI individuals are vulnerable to chronic drug- and withdrawal-induced impairments in self-control which may increase the likelihood of the transition to, and maintenance of, nicotine dependence.

AZD3480, a novel nicotinic receptor agonist, for the treatment of attention-deficit/hyperactivity disorder in adults

BACKGROUND

Laboratory studies have found that acute stimulation of nicotinic acetylcholine receptors improves cognition in adult attention-deficit/hyperactivity disorder (ADHD). Clinical trials of nicotinic agonists have been mixed, underscoring the need to understand the mechanisms for individual differences in clinical response. Using cognitive models within a clinical trial framework may provide insight into these differences.

METHODS

This was a within-subjects, randomized, placebo-controlled double-blind trial of the nicotinic agonist AZD3480 (also termed TC-1734) at doses of 5 mg and 50 mg and placebo in adults with ADHD. The order of the 2-week treatment periods was randomized, and a 3-week wash out separated each drug treatment period. Response inhibition (Stop Signal Task [SST]) and clinical efficacy (Investigator Rated Conners Adult ADHD Rating Scale [CAARS-INV]) were the a priori primary outcome measures of cognitive and clinical effects. We hypothesized that AZD3480 treatment would improve SST performance and clinical symptoms (CAARS-INV Total ADHD Symptoms Score).

RESULTS

Thirty subjects were randomized, with 24 included in the intent-to-treat analyses. SST performance and total ADHD symptoms were significantly improved with 50 mg of AZD3480. CAARS-INV ratings of inattention, memory problems, and emotional lability/impulsivity were significantly improved with 50 mg of AZD3480.

CONCLUSIONS

These results support previous work suggesting that nicotinic agonists are viable as treatments for adult ADHD. Measuring cognitive endophenotypes related to both the disorder and mechanism of treatment may help further rational drug development for dimensional features that cross-cut psychiatric disorders.

Cognition as a therapeutic target in late-life depression: potential for nicotinic therapeutics

Depression is associated with impairments to cognition and brain function at any age, but such impairments in the elderly are particularly problematic because of the additional burden of normal cognitive aging and in some cases, structural brain pathology. Individuals with late-life depression exhibit impairments in cognition and brain structural integrity, alongside mood dysfunction. Antidepressant treatment improves symptoms in some but not all patients, and those who benefit may not return to the cognitive and functional level of nondepressed elderly. Thus, for comprehensive treatment of late-life depression, it may be necessary to address both the affective and cognitive deficits. In this review, we propose a model for the treatment of late-life depression in which nicotinic stimulation is used to improve cognitive performance and improve the efficacy of an antidepressant treatment of the syndrome of late-life depression. The cholinergic system is well-established as important to cognition. Although muscarinic stimulation may exacerbate depressive symptoms, nicotinic stimulation may improve cognition and neural functioning without a detriment to mood. While some studies of nicotinic subtype specific receptor agonists have shown promise in improving cognitive performance, less is known regarding how nicotinic receptor stimulation affects cognition in depressed elderly patients. Late-life depression thus represents a new therapeutic target for the development of nicotinic agonist drugs. Parallel treatment of cognitive dysfunction along with medical and psychological approaches to treating mood dysfunction may be necessary to ensure full resolution of depressive illness in aging.

Methylphenidate does not influence smoking-reinforced responding or attentional performance in adult smokers with and without attention deficit hyperactivity disorder (ADHD)

Individuals with Attention Deficit Hyperactivity Disorder (ADHD) smoke cigarettes at rates higher than the general population and questions have been raised about how stimulant drugs-the frontline pharmacological treatment for ADHD-influence smoking risk and behavior in those with ADHD. In the present study adult regular smokers with (n = 16) and without (n = 17) ADHD participated in 3 experimental sessions in which they completed a Progressive Ratio (PR) task to measure the relative reinforcing effects of cigarette smoking and money after oral administration of placebo and 2 active doses of methylphenidate (10 mg and 40 mg). We also measured attention and inhibitory control via a Continuous Performance Test (CPT). Methylphenidate had no effect on smoking-reinforced responding, attention, or inhibitory control in either group. Attention and inhibitory control were associated with smoking-reinforced responding, but unsystematically and only in the non-ADHD group. Several design features, such as the value of the monetary response option, the PR schedule, and the potential effects of smoking on attention and inhibitory control, could have contributed to the negative findings and are discussed as such. Although inconsistent with some previous human laboratory studies of stimulant drugs and smoking, results are consistent with recent trials of stimulant drugs as adjuncts for smoking cessation in adult smokers with ADHD. In general, methylphenidate at mild and moderate doses did not influence the relative reinforcing effects of cigarette smoking in adults with and without ADHD.

The effects of acute nicotine, chronic nicotine, and withdrawal from chronic nicotine on performance of a cued appetitive response

Nicotine is a widely used addictive drug, with an estimated 73 million Americans 12 years of age or older having used a tobacco product in the last month, despite documented risks to personal health. Nicotine alters cognitive processes, which include effects on attention and impulsivity, a mechanism that may contribute to the addictive properties of the drug. Individuals with a variety of psychological disorders ranging from attention deficit hyperactivity disorder (ADHD) to schizophrenia smoke at a higher rate than the rest of the population and show deficits in impulse control. The present studies evaluated the effects of acute, chronic, and withdrawal from chronic nicotine on an operant task that measured premature and signaled nose pokes, as well as performance efficiency in C57BL/6J mice. Results indicate that acute nicotine (0.09 mg/kg intraperitoneally) does not alter the acquisition of the task, but does significantly increase performance efficiency once the behavior has been learned. In contrast, chronic nicotine (0, 6.3, 12.6, and 36 mg/kg/day subcutaneously) and withdrawal from chronic nicotine had no effect on performance efficiency. These results suggest that initial nicotine use may have beneficial effects on inhibitory control, but these effects are not maintained with chronic nicotine consumption as tolerance develops. The findings may provide an explanation for higher rates of smoking in patients with impulse control issues, as the smoking may represent an initial attempt at self-medication.

Complex relationships of nicotinic receptor actions and cognitive functions

Nicotine has been shown in a variety of studies to improve cognitive function including learning, memory and attention. Nicotine both stimulates and desensitizes nicotinic receptors, thus acting both as an agonist and a net antagonist. The relative roles of these two actions for nicotine-induced cognitive improvement have not yet been fully determined. We and others have found that acute nicotinic antagonist treatment can improve learning and attention. Nicotine acts on a variety of nicotinic receptor subtypes. The relative role and interactions of neuronal nicotinic receptor subtypes for cognition also needs to be better characterized. Nicotine acts on nicotinic receptors in a wide variety of brain areas. The role of some of these areas such as the hippocampus has been relatively well studied but other areas like the thalamus, which has the densest nicotinic receptor concentration are still only partially characterized. In a series of studies we characterized nicotinic receptor actions, anatomic localization and circuit interactions, which are critical to nicotine effects on the cognitive functions of learning, memory and attention. The relative role of increases and decreases in nicotinic receptor activation by nicotine were determined in regionally specific studies of the hippocampus, the amygdala, the frontal cortex and the mediodorsal thalamic nucleus with local infusions of antagonists of nicotinic receptor subtypes (α7 and α4β2). The understanding of the functional neural bases of cognitive function is fundamental to the more effective development of nicotinic drugs for treating cognitive dysfunction.

Long-term relationship between methylphenidate and tobacco consumption and nicotine craving in adults with ADHD in a prospective cohort study

Patients with Attention-Deficit/Hyperactivity disorder (ADHD) have higher smoking rates, a younger age of smoking onset, and increased difficulty to stop smoking as compared to controls. Methylphenidate induced acute effects of increased smoking in laboratory studies, but long-term effects are unknown. We studied the acute and long-term relationship between methylphenidate use and tobacco consumption and nicotine craving among ADHD patients naïve for methylphenidate (N=325). Patients filled out the Smoking Questionnaire (SQ) at baseline, and after two-weeks and three-months of methylphenidate use. The SQ involved questions on demographics, tobacco consumption, nicotine craving, life events, psychiatric diagnoses and use of medication. At baseline, smoking prevalence of ADHD patients was twice as high (50.2%) as the national norm (25.6%; p<.001). Tobacco consumption increased with 1.3 cigarettes per day after three-months of methylphenidate use. When translated into pack years, tobacco consumption increased by about 23 packs per year. Reports of increased nicotine craving after methylphenidate, increased with 20.3% after two weeks and 29.2% after three months. Light smokers (1-12 cigarettes/day) were especially at risk for increased tobacco consumption (p<.05). Thus although methylphenidate is the drug of choice in medical treatment for ADHD, tobacco consumption and nicotine craving increased acutely and stabilized at increased levels after three-months of methylphenidate use. Although the net effect of methylphenidate on smoking behavior and craving should be further investigated within a randomized, placebo-controlled design, the results suggest that active prevention of increased smoking is needed in patients prescribed methylphenidate.