Effects of chronic nicotine and methylphenidate in adults with attention deficit/hyperactivity disorder

Current nonstimulant medications for adults with attention-deficit/hyperactivity disorder

INTRODUCTION

Stimulants, including methylphenidate and amphetamines, are the first-line pharmacological treatment of ADHD in adults. However, in patients who do not respond or poorly tolerate stimulants, non-stimulant medications are usually recommended.

AREAS COVERED

The authors provide a narrative review of the literature on non-stimulant treatments for adult ADHD, including controlled and observational clinical studies conducted on adult samples. Atomoxetine has been extensively studied and showed significant efficacy in treating adult ADHD. Issues related to dosing, treatment duration, safety, and use in the case of psychiatric comorbidity are summarized. Among other compounds indicated for ADHD in adults, antidepressants sharing at least a noradrenergic or dopaminergic component, including tricyclic compounds, bupropion, and viloxazine, have shown demonstratable efficacy. Evidence is also available for antihypertensives, particularly guanfacine, as well as memantine, metadoxine, and mood stabilizers, while negative findings have emerged for galantamine, antipsychotics, and cannabinoids.

EXPERT OPINION

While according to clinical guidelines, atomoxetine may serve as the only second-line option in adults with ADHD, several other nonstimulant compounds may be effectively used in order to personalize treatment based on comorbid conditions and ADHD features. Nevertheless, further research is needed to identify and test more personalized treatment strategies for adults with ADHD.

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.

Extended-release methylphenidate for attention deficit hyperactivity disorder (ADHD) in adults

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) is a psychiatric diagnosis increasingly used in adults. The recommended first-line pharmacological treatment is central nervous system (CNS) stimulants, such as methylphenidate, but uncertainty remains about its benefits and harms.

OBJECTIVES

To assess the beneficial and harmful effects of extended-release formulations of methylphenidate in adults diagnosed with ADHD.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, nine other databases and four clinical trial registries up to February 2021. We searched 12 drug regulatory databases for clinical trial data up to 13 May 2020. In addition, we cross-referenced all available trial identifiers, handsearched reference lists, searched pharmaceutical company databases, and contacted trial authors.

SELECTION CRITERIA

Randomised, double-blind, parallel-group trials comparing extended-release methylphenidate formulations at any dose versus placebo and other ADHD medications in adults diagnosed with ADHD.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data. We assessed dichotomous outcomes as risk ratios (RRs), and rating scales and continuous outcomes as mean differences (MDs) or standardised mean differences (SMDs). We used the Cochrane risk of bias tool to assess risks of bias, and GRADE to assess the certainty of the evidence. We meta-analysed the data using a random-effects model. We assessed three design characteristics that may impair the trial results' 'generalisability'; exclusion of participants with psychiatric comorbidity; responder selection based on previous experience with CNS stimulants; and risk of withdrawal effects. Our prespecified primary outcomes were functional outcomes, self-rated ADHD symptoms, and serious adverse events. Our secondary outcomes included quality of life, ADHD symptoms rated by investigators and by peers such as family members, cardiovascular variables, severe psychiatric adverse events, and other adverse events.

MAIN RESULTS

We included 24 trials (5066 participants), of which 21 reported outcome data for this review. We also identified one ongoing study. We included documents from six drug regulatory agencies covering eight trials. Twenty-one trials had an outpatient setting and three were conducted in prisons. They were primarily conducted in North America and Europe. The median participant age was 36 years. Twelve trials (76% of participants) were industry-sponsored, four (14% of participants) were publicly funded with industry involvement, seven (10% of participants) were publicly funded, and one had unclear funding. The median trial duration was eight weeks. One trial was rated at overall unclear risk of bias and 20 trials were rated at overall high risk of bias, primarily due to unclear blinding of participants and investigators, attrition bias, and selective outcome reporting. All trials were impaired in at least one of the three design characteristics related to 'generalisability'; for example, they excluded participants with psychiatric comorbidity such as depression or anxiety, or included participants only with a previous positive response to methylphenidate, or similar drugs. This may limit the trials' usefulness for clinical practice, as they may overestimate the benefits and underestimate the harms. Extended-release methylphenidate versus placebo (up to 26 weeks) For the primary outcomes, we found very low-certainty evidence that methylphenidate had no effect on 'days missed at work' at 13-week follow-up (mean difference (MD) -0.15 days, 95% confidence interval (CI) -2.11 to 1.81; 1 trial, 409 participants) or serious adverse events (risk ratio (RR) 1.43, CI 95% CI 0.85 to 2.43; 14 trials, 4078 participants), whereas methylphenidate improved self-rated ADHD symptoms (small-to-moderate effect; SMD -0.37, 95% CI -0.43 to -0.30; 16 trials, 3799 participants). For secondary outcomes, we found very low-certainty evidence that methylphenidate improved self-rated quality of life (small effect; SMD -0.15, 95% CI -0.25 to -0.05; 6 trials, 1888 participants), investigator-rated ADHD symptoms (small-to-moderate effect; SMD -0.42, 95% CI -0.49 to -0.36; 18 trials, 4183 participants), ADHD symptoms rated by peers such as family members (small-to-moderate effect; SMD -0.31, 95% CI -0.48 to -0.14; 3 trials, 1005 participants), and increased the risk of experiencing any adverse event (RR 1.27, 95% CI 1.19 to 1.37; 14 trials, 4214 participants). We rated the certainty of the evidence as 'very low' for all outcomes, primarily due to high risk of bias and 'indirectness of the evidence'. One trial (419 participants) had follow-up at 52 weeks and two trials (314 participants) included active comparators, hence long-term and comparative evidence is limited.

AUTHORS' CONCLUSIONS

We found very low-certainty evidence that extended-release methylphenidate compared to placebo improved ADHD symptoms (small-to-moderate effects) measured on rating scales reported by participants, investigators, and peers such as family members. Methylphenidate had no effect on 'days missed at work' or serious adverse events, the effect on quality of life was small, and it increased the risk of several adverse effects. We rated the certainty of the evidence as 'very low' for all outcomes, due to high risk of bias, short trial durations, and limitations to the generalisability of the results. The benefits and harms of extended-release methylphenidate therefore remain uncertain.

Smoking and Neuropsychiatric Disease-Associations and Underlying Mechanisms

Despite extensive efforts to combat cigarette smoking/tobacco use, it still remains a leading cause of global morbidity and mortality, killing more than eight million people each year. While tobacco smoking is a major risk factor for non-communicable diseases related to the four main groups—cardiovascular disease, cancer, chronic lung disease, and diabetes—its impact on neuropsychiatric risk is rather elusive. The aim of this review article is to emphasize the importance of smoking as a potential risk factor for neuropsychiatric disease and to identify central pathophysiological mechanisms that may contribute to this relationship. There is strong evidence from epidemiological and experimental studies indicating that smoking may increase the risk of various neuropsychiatric diseases, such as dementia/cognitive decline, schizophrenia/psychosis, depression, anxiety disorder, and suicidal behavior induced by structural and functional alterations of the central nervous system, mainly centered on inflammatory and oxidative stress pathways. From a public health perspective, preventive measures and policies designed to counteract the global epidemic of smoking should necessarily include warnings and actions that address the risk of neuropsychiatric disease.

Association between e-cigarette use and parents' report of attention deficit hyperactivity disorder among US youth

INTRODUCTION

There is paucity of literature that evaluates e-cigarette use rates among the youth with attention deficit hyperactivity disorder (ADHD). The aim of this study is to compare the rates of cigarette only, e-cigarette only, dual use, and initiation age of regular use and trying to quit cigarettes or e-cigarettes among the youth with and without ADHD.

METHODS

We used Population Assessment of Tobacco and Health (PATH) study Wave 3 (2015–2016) youth data, a nationally representative cross-sectional study in the US. The main outcome was tobacco use status of youth and ADHD diagnosis was based on parent report.

RESULTS

The survey included 11801 youth (50%, 12–14 years; 49% female). Compared to youth without ADHD, the relative risk ratio (RRR) was 1.79 (95% CI: 1.02–3.21) for cigarette only use, 1.41 (95% CI: 1.01–2.21) for e-cigarette only use, 3.40 (95% CI: 1.69–6.84) for dual use, 1.75 (95% CI: 0.92–3.35) for cigarette and other product(s) use, 1.48 (95% CI: 0.58–3.77) for e-cigarette and other product(s) use, and 3.37 (95% CI: 1.88–6.17) for poly use among youth with ADHD, after adjusting for age group, sex, and race/ethnicity.

CONCLUSIONS

Cigarette only use, e-cigarette only use, dual use of cigarettes and e-cigarettes, and poly use of cigarettes, e-cigarettes, and other product(s) were significantly associated with parent report of an ADHD diagnosis. It is critical for healthcare providers to be screening youth for e-cigarette use, especially youth who are diagnosed with ADHD.

Pharmacologic treatment of attention deficit hyperactivity disorder in adults: A systematic review and network meta-analysis

Background

Attention deficit hyperactivity disorder (ADHD) affects approximately 3% of adults globally. Many pharmacologic treatments options exist, yet the comparative benefits and harms of individual treatments are largely unknown. We performed a systematic review and network meta-analysis to assess the relative effects of individual pharmacologic treatments for adults with ADHD.

Methods

We searched English-language published and grey literature sources for randomized clinical trials (RCTs) involving pharmacologic treatment of ADHD in adults (December 2018). The primary outcome was clinical response; secondary outcomes were quality of life, executive function, driving behaviour, withdrawals due to adverse events, treatment discontinuation, serious adverse events, hospitalization, cardiovascular adverse events, and emergency department visits. Data were pooled via pair-wise meta-analyses and Bayesian network meta-analyses. Risk of bias was assessed by use of Cochrane’s Risk of Bias tool, and the certainty of the evidence was assessed by use of the GRADE framework.

Results

Eighty-one unique trials that reported at least one outcome of interest were included, most of which were at high or unclear risk of at least one important source of bias. Notably, only 5 RCTs were deemed at overall low risk of bias. Included pharmacotherapies were methylphenidate, atomoxetine, dexamfetamine, lisdexamfetamine, guanfacine, bupropion, mixed amphetamine salts, and modafinil. As a class, ADHD pharmacotherapy improved patient- and clinician-reported clinical response compared with placebo (range: 4 to 15 RCTs per outcome); however, these findings were not conserved when the analyses were restricted to studies at low risk of bias, and the certainty of the finding is very low. There were few differences among individual medications, although atomoxetine was associated with improved patient-reported clinical response and quality of life compared with placebo. There was no significant difference in the risk of serious adverse events or treatment discontinuation between ADHD pharmacotherapies and placebo; however, the proportion of participants who withdrew due to adverse events was significantly higher among participants who received any ADHD pharmacotherapy. Few RCTs reported on the occurrence of adverse events over a long treatment duration.

Conclusions

Overall, despite a class effect of improving clinical response relative to placebo, there were few differences among the individual ADHD pharmacotherapies, and most studies were at risk of at least one important source of bias. Furthermore, the certainty of the evidence was very low to low for all outcomes, and there was limited reporting of long-term adverse events. As such, the choice between ADHD pharmacotherapies may depend on individual patient considerations, and future studies should assess the long-term effects of individual pharmacotherapies on patient-important outcomes, including quality of life, in robust blinded RCTs.

Registration

PROSPERO no. CRD 42015026049

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.

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

PURPOSE/BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Substance use through adolescence into early adulthood after childhood-diagnosed ADHD: findings from the MTA longitudinal study

BACKGROUND

Inconsistent findings exist regarding long-term substance use (SU) risk for children diagnosed with attention-deficit/hyperactivity disorder (ADHD). The observational follow-up of the Multimodal Treatment Study of Children with ADHD (MTA) provides an opportunity to assess long-term outcomes in a large, diverse sample.

METHODS

Five hundred forty-seven children, mean age 8.5, diagnosed with DSM-IV combined-type ADHD and 258 classmates without ADHD (local normative comparison group; LNCG) completed the Substance Use Questionnaire up to eight times from mean age 10 to mean age 25.

RESULTS

In adulthood, weekly marijuana use (32.8% ADHD vs. 21.3% LNCG) and daily cigarette smoking (35.9% vs. 17.5%) were more prevalent in the ADHD group than the LNCG. The cumulative record also revealed more early substance users in adolescence for ADHD (57.9%) than LNCG (41.9%), including younger first use of alcohol, cigarettes, marijuana, and illicit drugs. Alcohol and nonmarijuana illicit drug use escalated slightly faster in the ADHD group in early adolescence. Early SU predicted quicker SU escalation and more SU in adulthood for both groups.

CONCLUSIONS

Frequent SU for young adults with childhood ADHD is accompanied by greater initial exposure at a young age and slightly faster progression. Early SU prevention and screening is critical before escalation to intractable levels.

Exploring longitudinal course and treatment-baseline severity interactions in secondary outcomes of smoking cessation treatment in individuals with attention-deficit hyperactivity disorder

BACKGROUND

A double blind, placebo-controlled randomized trial (NCT00253747) evaluating osmotic-release oral system methylphenidate (OROS-MPH) for smoking-cessation revealed a significant interaction effect in which participants with higher baseline ADHD severity had better abstinence outcomes with OROS-MPH while participants with lower baseline ADHD severity had worse outcomes.

OBJECTIVES

This current report examines secondary outcomes that might bear on the mechanism for this differential treatment effect.

METHODS

Longitudinal analyses were conducted to evaluate the effect of OROS-MPH on three secondary outcomes (ADHD symptom severity, nicotine craving, and withdrawal) in the total sample (N = 255, 56% Male), and in the high (N = 134) and low (N = 121) baseline ADHD severity groups.

RESULTS

OROS-MPH significantly improved ADHD symptoms and nicotine withdrawal symptoms in the total sample, and exploratory analyses showed that in both higher and lower baseline severity groups, OROS-MPH statistically significantly improved these two outcomes. No effect on craving overall was detected, though exploratory analyses showed statistically significantly decreased craving in the high ADHD severity participants on OROS-MPH. No treatment by ADHD baseline severity interaction was detected for the outcomes.

CONCLUSIONS

Methylphenidate improved secondary outcomes during smoking cessation independent of baseline ADHD severity, with no evident treatment-baseline severity interaction. Our results suggest divergent responses to smoking cessation treatment in the higher and lower severity groups cannot be explained by concordant divergence in craving, withdrawal and ADHD symptom severity, and alternative hypotheses may need to be identified.

Nicotine and networks: Potential for enhancement of mood and cognition in late-life depression

Late-life depression is characterized by both lower mood and poor cognitive performance, symptoms that often do not fully respond to current antidepressant medications. Nicotinic acetylcholine receptor (nAChR) agonists such as nicotine may serve as a novel therapeutic approach for this population. Both preclinical and preliminary clinical studies suggest that nAChR agonists can improve depressive behavior in animal models and improve mood in depressed individuals. Substantial literature also supports that nAChR agonists benefit cognitive performance, particularly in older populations. These potential benefits may be mediated by the effects of nAChR stimulation on neural network function and connectivity. Functional neuroimaging studies detail effects of nAChR agonists on the default mode network, central-executive network, and salience network that may oppose or reverse network changes seen in depression. We propose that, given the existent literature and the clinical presentation of late-life depression, nicotine or other nAChR agonists may have unique therapeutic benefits in this population and that clinical trials examining nicotine effects on mood, cognition, and network dynamics in late-life depression are justified.

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

Cognitive Translation Using the Rodent Touchscreen Testing Approach

The development of novel therapeutic avenues for the treatment of cognitive deficits in psychiatric and neurodegenerative disease is of high importance, yet progress in this field has been slow. One reason for this lack of success may lie in discrepancies between how cognitive functions are assessed in experimental animals and humans. In an attempt to bridge this translational gap, the rodent touchscreen testing platform is suggested as a translational tool. Specific examples of successful cross-species translation are discussed focusing on paired associate learning (PAL), the 5-choice serial reaction time task (5-CSRTT), the rodent continuous performance task (rCPT) and reversal learning. With ongoing research assessing the neurocognitive validity of tasks, the touchscreen approach is likely to become increasingly prevalent in translational cognitive research.

Modulation of social deficits and repetitive behaviors in a mouse model of autism: the role of the nicotinic cholinergic system

RATIONALE

Accumulating evidence implicates the nicotinic cholinergic system in autism spectrum disorder (ASD) pathobiology. Neuropathologic studies suggest that nicotinic acetylcholine (ACh) receptor (nAChR) subtypes are altered in brain of autistic individuals. In addition, strategies that increase ACh, the neurotransmitter for nicotinic and muscarinic receptors, appear to improve cognitive deficits in neuropsychiatric disorders and ASD.

OBJECTIVE

The aim of this study is to examine the role of the nicotinic cholinergic system on social and repetitive behavior abnormalities and exploratory physical activity in a well-studied model of autism, the BTBR T(+) Itpr3 (tf) /J (BTBR) mouse.

METHODS

Using a protocol known to up-regulate expression of brain nAChR subtypes, we measured behavior outcomes before and after BTBR and C57BL/6J (B6) mice were treated (4 weeks) with vehicle or nicotine (50, 100, 200, or 400 μg/ml).

RESULTS

Increasing nicotine doses were associated with decreases in water intake, increases in plasma cotinine levels, and at the higher dose (400 μg/ml) with weight loss in BTBR mice. At lower (50, 100 μg/ml) but not higher (200, 400 μg/ml) doses, nicotine increased social interactions in BTBR and B6 mice and at higher, but not lower doses, it decreased repetitive behavior in BTBR. In the open-field test, nicotine at 200 and 400 μg/ml, but not 100 μg/ml compared with vehicle, decreased overall physical activity in BTBR mice.

CONCLUSIONS

These findings support the hypotheses that the nicotinic cholinergic system modulates social and repetitive behaviors and may be a therapeutic target to treat behavior deficits in ASD. Further, the BTBR mouse may be valuable for investigations of the role of nAChRs in social deficits and repetitive behavior.

Nicotinic receptors as targets for therapeutic discovery

Nicotinic acetylcholine receptors (nAChRs) represent a class of therapeutic targets with the potential to impact numerous diseases and disorders where significant unmet medical needs remain. The latter include cognitive and neurodegenerative diseases; psychotic disorders, such as schizophrenia; acute nociceptive, neuropathic and inflammatory pain; affective disorders, such as depression and inflammation, where nAChR subtypes modulate key cellular pathways involved in anti-inflammatory processes as well as cell survival. Our increased understanding of the heterogeneity of nAChR targets is defining the relationship of biologic effects to specific receptor subtypes, which in turn, will allow further refinement of desired therapeutic activities. Both preclinical and clinical evidence support the notion that novel compounds targeting specific nAChR subtypes will offer increased potency and efficacy, longer lasting effects, fewer side effects and a more rapid onset of action and less dependence, compared with existing therapies. Clinical proof-of-concept is rapidly emerging and will solidify the position of this new therapeutic approach.

Exposure to fluoridated water and attention deficit hyperactivity disorder prevalence among children and adolescents in the United States: an ecological association

BACKGROUND

Epidemiological and animal-based studies have suggested that prenatal and postnatal fluoride exposure has adverse effects on neurodevelopment. The aim of this study was to examine the relationship between exposure to fluoridated water and Attention-Deficit Hyperactivity Disorder (ADHD) prevalence among children and adolescents in the United States.

METHODS

Data on ADHD prevalence among 4-17 year olds collected in 2003, 2007 and 2011 as part of the National Survey of Children's Health, and state water fluoridation prevalence from the Centers for Disease Control and Prevention (CDC) collected between 1992 and 2008 were utilized.

RESULTS

State prevalence of artificial water fluoridation in 1992 significantly positively predicted state prevalence of ADHD in 2003, 2007 and 2011, even after controlling for socioeconomic status. A multivariate regression analysis showed that after socioeconomic status was controlled each 1% increase in artificial fluoridation prevalence in 1992 was associated with approximately 67,000 to 131,000 additional ADHD diagnoses from 2003 to 2011. Overall state water fluoridation prevalence (not distinguishing between fluoridation types) was also significantly positively correlated with state prevalence of ADHD for all but one year examined.

CONCLUSIONS

Parents reported higher rates of medically-diagnosed ADHD in their children in states in which a greater proportion of people receive fluoridated water from public water supplies. The relationship between fluoride exposure and ADHD warrants future study.

Toward personalized smoking-cessation treatment: Using a predictive modeling approach to guide decisions regarding stimulant medication treatment of attention-deficit/hyperactivity disorder (ADHD) in smokers

BACKGROUND AND OBJECTIVES

Osmotic-release oral system methylphenidate (OROS-MPH) did not show overall benefit as an adjunct smoking cessation treatment for adult smokers with ADHD in a randomized, placebo-controlled, multicenter clinical trial. A secondary analysis revealed a significant interaction between ADHD symptom severity and treatment-response to OROS-MPH, but did not account for other baseline covariates or estimate the magnitude of improvement in outcome if treatment were optimized. This present study addressed the gaps in how this relationship should inform clinical practice.

METHODS

Using data from the Adult Smokers with ADHD Trial (N = 255, six sites in five US States), we build predictive models to calculate the probability of achieving prolonged abstinence, verified by self-report, and expired carbon monoxide measurement. We evaluate the potential improvement in achieving prolonged abstinence with and without stratification on baseline ADHD severity.

RESULTS

Predictive modeling demonstrates that the interaction between baseline ADHD severity and treatment group is not affected by adjusting for other baseline covariates. A clinical trial simulation shows that giving OROS-MPH to patients with baseline Adult ADHD Symptom Rating Scale (ADHD-RS) >35 and placebo to those with ADHD-RS ≤35 would significantly improve the prolonged abstinence rate (52 ± 8% vs. 42 ± 5%, p < .001).

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

In smokers with ADHD, utilization of a simple decision rule that stratifies patients based on baseline ADHD severity can enhance overall achievement of prolonged smoking abstinence. Similar analysis methods should be considered for future clinical trials for other substance use disorders.

The Association Between Attention-Deficit Hyperactivity Disorder and Nicotine Use Among Adolescents and Young Adults

Previous research indicates that youth with ADHD are more susceptible to nicotine use compared to those without ADHD and one explanation for this association is the self-medication theory. The present study examines nicotine use in a prospective sample derived from a community sampling procedure rather than a clinical setting. Nicotine use was measured through young adulthood (mean ages: 18, 20 and 22) and three groups were compared based on childhood status: ADHD-only, ADHD-extemalizers and control groups. Results indicated that at all three data points, individuals with childhood ADHD plus an externalizing disorder reported higher nicotine use on all variables compared to the ADHD group absent of an externalizing disorder and the comparison group of non-ADHD youth. The group differences were significant even after controlling for possible confounding variables (age, gender, and current treatment with psychostimulant medication). Study results are discussed in light of the self-medication hypothesis and of the importance of including nicotine prevention programs for adolescents and young adults with ADHD and externalizing problems.

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.

Ecological momentary assessment of antecedents and consequences of smoking in adults with attention-deficit/hyperactivity disorder

The current study assessed antecedents and consequences of ad lib cigarette smoking in smokers diagnosed with attention-deficit/hyperactivity disorder (ADHD) using ecological momentary assessment (EMA). Adult smokers with ADHD (n = 17) completed 870 smoking and 622 nonsmoking electronic diary entries over a 7-day observation period of their naturalistic smoking behavior. Data collection occurred from 2011 to 2012. Generalized estimating equations indicated that ADHD smokers were more likely to smoke when urge to smoke, negative affect, boredom, stress, worry, and restlessness were elevated. In addition, participants were more likely to smoke in situations that elicited higher levels of nervousness and frustration. ADHD symptoms, in general, did not differ between smoking and nonsmoking contexts, though hyperactive-impulsive ADHD symptoms were elevated prior to smoking in frustrating situations. Additional situational antecedent variables were associated with smoking, including being in the presence of others smoking, being in a bar or restaurant, while outside, and while consuming caffeinated or alcoholic beverages. Participants also reported a significant improvement in urge to smoke, negative affect, stress, hunger, and ADHD symptoms after smoking a cigarette. Findings suggest certain contextual factors that may maintain ad lib cigarette smoking in smokers with ADHD and identify potential treatment targets in smoking cessation interventions for this at-risk group. Clinical implications and future research directions are discussed. Funding for this study was provided by the National Institute on Drug Abuse.

Tobacco smoking and mental illness: important considerations

Tobacco smoking is a contributory factor in the death of 50% of individuals who are regular or heavy smokers (The Office of Tobacco Control Ireland defines a regular smoker as someone who smokes 11-20 per day and a heavy smoker as someone who smokes 21 or more cigarettes per day). The World Health Organisation (WHO) regards tobacco smoking as the leading preventable cause of death worldwide. In Ireland, approximately 750,000 people smoke tobacco regularly (23.5% of the population) with 7,000 Irish people dying annually from smoking-related causes. Although there are no exact figures for prevalence rates of smoking in individuals with mental illness in Ireland, international studies unequivocally state that the prevalence of smoking is significantly higher in those with mental illness, with greater nicotine intake and increased prevalence of nicotine dependence also reported. Furthermore people with mental illness experience greater withdrawal symptoms and have lower cessation rates when attempting to stop smoking compared to the general population.

Stimulant treatment of ADHD and cigarette smoking: a meta-analysis

BACKGROUND AND OBJECTIVE

Individuals with attention-deficit/hyperactivity disorder (ADHD) have a significantly higher risk of cigarette smoking. The nature of the relationship between smoking and psychostimulant medications commonly used to treat ADHD is controversial. Our objective was to examine the relationship between stimulant treatment of ADHD and cigarette smoking by using meta-analysis, and to identify study and sample characteristics that moderate this relationship.

METHODS

Literature searches on PubMed and PsycInfo databases identified published studies for inclusion. Included studies compared cigarette smoking outcomes for stimulant-treated and untreated ADHD individuals. Seventeen studies met inclusion criteria, and 14 (total n = 2360) contained sufficient statistical information for inclusion in the meta-analysis. Two authors extracted odds ratios or frequencies of smokers in the treatment or nontreatment groups, and coded study characteristics including sample source, percentage of male participants, follow-up length, treatment consistency, type of smoking measure, prospective study, and controlling for comorbidities.

RESULTS

Meta-analysis revealed a significant association between stimulant treatment and lower smoking rates. Meta-regression indicated that effect sizes were larger for studies that used clinical samples, included more women, measured smoking in adolescence rather than adulthood, conceptualized stimulant treatment as consistent over time, and accounted for comorbid conduct disorder.

CONCLUSIONS

Nearly all studies were naturalistic, precluding causal inferences. Available data were insufficient to examine additional influences of patient demographics, treatment effectiveness, or other comorbidities. Consistent stimulant treatment of ADHD may reduce smoking risk; the effect was larger in samples with more severe psychopathology. Implications for further research, treatment of ADHD, and smoking prevention 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.

Adult attention-deficit/hyperactivity disorder and nicotine use: a qualitative study of patient perceptions

BACKGROUND

Adult Attention-Deficit/Hyperactivity Disorder (ADHD) is associated with high rates of comorbid substance use disorders, and cigarette smoking has a particularly high prevalence in this population. However, there is an ongoing debate as to whether this tobacco use is an attempt at "self-medication" or due to behavioral disinhibition. There is a surprising lack of qualitative studies that investigate the subjective perceptions of adults with ADHD regarding cigarette smoking. The present study was designed to fill this gap in the literature.

METHODS

We recruited twelve adult patients with ADHD and comorbid tobacco use from our ADHD consultation service, an outpatient facility of the Zurich University Psychiatric Hospital. Subjects were interviewed using qualitative methodology, and Mayring's qualitative content analysis was used to evaluate findings.

RESULTS

We identified two explanatory models linking ADHD and tobacco use: smoking as an attempt at self-medication and "smoking as a social behavior". On one hand, subjects considered tobacco a therapeutic aid, reporting positive effects on "inner tension" and cognitive function, and noted possible antidepressant properties as well. On the other hand, subjects considered smoking to enhance social functioning and to have a positive impact on interpersonal relationships. The majority believed that stimulant medications offered only a transient decrease in patterns of tobacco use because their ability to reduce nicotine cravings wore off quickly. Others believed that stimulants had no effect or even reinforced cigarette use.

CONCLUSIONS

Participants had different views about the link between cigarette smoking and ADHD. While the majority thought of nicotine as a sort of therapy, viewing smoking as a way to self-medicate symptoms of ADHD, motivations for nicotine use were also related to self-image, desire to belong to a peer-group, and a drive to undermine perceived social norms. Ultimately, these findings can be used by clinicians to improve treatment alliance and collaboration.

Acute effects of mecamylamine and varenicline on cognitive performance in non-smokers with and without schizophrenia

RATIONALE

Nicotinic acetylcholine receptors (nAChRs) have been implicated in the pathophysiology of cognitive deficits in the domains of attention and memory in schizophrenia. While nicotinic agonists and antagonists have been proposed as smoking cessation aids, few comparisons have been made of these agents on cognitive performance in individuals with schizophrenia.

OBJECTIVES

This study investigated the acute effects of a nAChR antagonist, mecamylamine, and partial agonist, varenicline, on cognitive function in non-smokers with and without schizophrenia.

METHODS

Single oral doses of mecamylamine 10 mg, varenicline 1 mg, and placebo were administered 1 week apart in random order to adults with schizophrenia (n = 30) and to healthy volunteers (n = 41) in a double-blind, crossover design. The primary outcome of interest was sustained attention as assessed with hit reaction time variability (HRT-SD) on the identical pairs continuous performance test (CPT-IP).

RESULTS

Mecamylamine worsened performance on CPT-IP HRT-SD, a measure of attention, compared to varenicline in both groups. Performance on mecamylamine was worse than performance on both placebo and varenicline on several additional measures of attention, including CPT-IP hit reaction time (HRT) and random errors at various levels of task difficulty. There was a treatment by diagnosis interaction, such that mecamylamine worsened performance on CPT-IP 2-digit HRT, 3-digit random errors, and 4-digit hit rate compared to placebo and varenicline in participants with schizophrenia; effects not observed in controls.

CONCLUSIONS

These findings support a role for nAChRs in attention and suggest that those with schizophrenia may be particularly sensitive to nAChR blockade.

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.

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.

Role of α7- and α4β2-nAChRs in the neuroprotective effect of nicotine in stress-induced impairment of hippocampus-dependent memory

We have previously shown that nicotine prevents stress-induced memory impairment. In this study, we have investigated the role of α7- and α4β2-nicotinic acetylcholine receptors (nAChRs) in the protective effect of nicotine during chronic stress conditions. Chronic psychosocial stress was induced using a form of rat intruder model. During stress, specific antagonist for either α7-nAChRs [methyllycaconitine (MLA)] or α4β2-nAChRs [dihydro-β-erythroidine (DHβE)] was infused into the hippocampus using a 4-wk osmotic pump at a rate of 82 μg/side.d and 41 μg/side.d, respectively. Three weeks after the start of infusion, all rats were subjected to a series of cognitive tests in the radial arm water maze (RAWM) for six consecutive days or until the animal reached days to criterion (DTC) in the fourth acquisition trial and in all memory tests. DTC is defined as the number of days the animal takes to make no more than one error in three consecutive days. In the short-term memory test, MLA-infused stressed/nicotine-treated rats made similar errors to those of stress and significantly more errors compared to those of stress/nicotine, nicotine or control groups. This finding was supported by the DTC values for the short memory tests. Thus, MLA treatment blocked the neuroprotective effect of nicotine during chronic stress. In contrast, DHβE infusion did not affect the RAWM performance of stress/nicotine animals. These results strongly suggest the involvement of α7-nAChRs, but not α4β2-nAChRs, in the neuroprotective effect of chronic nicotine treatment during chronic stress conditions.

Effects of chronic sazetidine-A, a selective α4β2 neuronal nicotinic acetylcholine receptors desensitizing agent on pharmacologically-induced impaired attention in rats

RATIONALE

Nicotine and nicotinic agonists have been shown to improve attentional function. Nicotinic receptors are easily desensitized, and all nicotinic agonists are also desensitizing agents. Although both receptor activation and desensitization are components of the mechanism that mediates the overall effects of nicotinic agonists, it is not clear how each of the two opposed actions contributes to attentional improvements. Sazetidine-A has high binding affinity at α4β2 nicotinic receptors and causes a relatively brief activation followed by a long-lasting desensitization of the receptors. Acute administration of sazetidine-A has been shown to significantly improve attention by reversing impairments caused by the muscarinic cholinergic antagonist scopolamine and the NMDA glutamate antagonist dizocilpine.

METHODS

In the current study, we tested the effects of chronic subcutaneous infusion of sazetidine-A (0, 2, or 6 mg/kg/day) on attention in Sprague-Dawley rats. Furthermore, we investigated the effects of chronic sazetidine-A treatment on attentional impairment induced by an acute administration of 0.02 mg/kg scopolamine.

RESULTS

During the first week period, the 6-mg/kg/day sazetidine-A dose significantly reversed the attentional impairment induced by scopolamine. During weeks 3 and 4, the scopolamine-induced impairment was no longer seen, but sazetidine-A (6 mg/kg/day) significantly improved attentional performance on its own. Chronic sazetidine-A also reduced response latency and response omissions.

CONCLUSIONS

This study demonstrated that similar to its acute effects, chronic infusions of sazetidine-A improve attentional performance. The results indicate that the desensitization of α4β2 nicotinic receptors with some activation of these receptors may play an important role in improving effects of sazetidine-A on attention.

Associations between attention deficit hyperactivity disorder symptom domains and DSM-IV lifetime substance dependence

BACKGROUND AND OBJECTIVES

Most studies of attention deficit hyperactivity disorder (ADHD) in the substance dependence literature have assessed ADHD as a single, categorical entity. This approach limits characterization across the spectrum of ADHD symptomatology and may mask differences across the two core domains of ADHD symptoms-hyperactive-impulsive (HI) and inattention (IN). Further, it is unclear whether relations of HI and IN symptoms to substance dependence extend across drug classes and to the general population.

METHODS

This cross-sectional study investigated associations of lifetime ADHD HI and IN symptom levels to individual classes of lifetime substance dependence (alcohol, nicotine, depressants, opioids, stimulants, cannabis, hallucinogens, polysubstance) in a population-based sample of 34,653 American adults.

RESULTS

HI and IN were associated with the majority of dependence diagnoses in a linear pattern, such that each additional symptom was associated with a proportional increase in odds of dependence. After adjusting for the overlap between symptom domains, both HI and IN uniquely associated with alcohol, nicotine, and polysubstance dependence, but only HI uniquely associated with dependence on illicit substances.

CONCLUSIONS AND SCIENTIFIC SIGNIFICANCE

These findings suggest that individuals in the general population with elevated levels of ADHD (particularly HI) symptoms are at risk for various forms of substance dependence and could benefit from preventive interventions.

Attention-deficit/hyperactivity disorder subtype differentially predicts smoking expectancies in adolescents

PURPOSE

Attention deficit hyperactivity disorder (ADHD) is an established risk factor for smoking; however, no studies have considered whether precursors to smoking behavior differ among adolescents with ADHD. Smoking expectancies are beliefs about the potential consequences of smoking, and they develop before smoking initiation. ADHD characteristics may contribute to the formation of expectancies and eventual smoking behavior. We evaluated whether clinical levels of ADHD subtypes differentially predicted smoking expectancies.

METHODS

Adolescents (n = 221; age mean = 12.67 years) completed the Smoking Expectancy Scale for Adolescents, answered standardized questions about their smoking behavior, and provided expired breath samples to verify never-smoking status. Parents completed the Conners' Parent Rating Scale for ADHD symptoms of inattention and hyperactivity/impulsivity.

RESULTS

Adolescents with clinical levels of inattention were significantly less likely to endorse negative consequences, including Expected Costs (odds ratio [OR] = .16), Appearance-Presentation Costs (OR = .29), Social Costs (OR = .19), Health Costs (OR = .21), and Addiction Costs (OR = .39). Inattentive female adolescents were significantly more likely to endorse Weight Control as a consequence. Adolescents with clinical levels of hyperactivity/impulsivity were more likely to endorse positive consequences, including Expected Benefits (OR = 5.31), Affect Control (OR = 2.60), and Boredom Reduction (OR = 3.14); they were less likely to endorse Social Costs (OR = .27).

CONCLUSIONS

ADHD subtype differentially predicted smoking expectancies. Adolescents with ADHD may be more vulnerable to developing pro-smoking expectancies due to subtype-related deficits in neurocognitive processing. These findings have potential implications for developing targeted smoking prevention programs.

Treatment discontinuation with methylphenidate in adults with attention deficit hyperactivity disorder: a meta-analysis of randomized clinical trials

BACKGROUND

Attention deficit hyperactivity disorder (ADHD) in adulthood is increasingly diagnosed and treated. Methylphenidate is frequently advocated as a first-line pharmacological treatment.

PURPOSE

The aim of our study was to compare all-cause discontinuation rate of methylphenidate and its pharmaceutical presentations with placebo in adults with ADHD.

METHODS

This was a systematic review and meta-analysis of randomized controlled trials comparing methylphenidate with placebo in adults with ADHD. All-cause treatment discontinuation was the primary endpoint. The efficacy in reducing ADHD symptoms and safety were the secondary endpoints.

RESULTS

Twelve studies (2,496 patients) met the inclusion criteria. Four racemic methylphenidate and one dexmethylphenidate presentations were investigated. The rate of all-cause treatment discontinuation was greater with methylphenidate than with placebo, but this difference was not statistically significant [odds ratio (OR) 1.19, 95 % confidence interval (95 % CI) 0.82-1.74, P = 0.37, I(2) = 64 %] This finding reached the conventional threshold of statistical significance after one outlier study was excluded (OR 1.44, 95 % CI 1.14-1.82, P = 0.002, I(2) = 0). Methylphenidate was more efficacious than placebo for reducing ADHD symptoms and it was associated with a higher proportion of patients dropping out due to adverse effects.

CONCLUSIONS

Despite reducing ADHD symptoms, methylphenidate showed no advantage over placebo in terms of treatment discontinuation. More attention should be given in the future to the endpoint "all-cause treatment discontinuation" when making regulatory decisions and developing clinical guidelines involving the treatment of ADHD in adulthood.

Distinguishing comorbidity and successful management of adult ADHD

OBJECTIVE

Given high rates of comorbidity, lack of awareness and global acceptance, and varying guidelines for its management, adult ADHD may be an especially difficult condition to diagnose and treat. The objective of this review was to explore and characterize similarities and differences among comorbidities associated with adult ADHD.

METHOD

A review of the literature over the past 10 years was performed using Ovid.

RESULTS

A myriad of comorbid conditions such as impulse-control/personality, anxiety, mood, substance use, learning, and sleep disorders overlap with adult ADHD. Furthermore, a number of such conditions have symptoms that can mimic those of ADHD, including hyperactivity, impulsivity, inattention, and disruption of circadian rhythms, adding to the complexity of recognition and diagnosis of ADHD in adults. Extensive research shows that adults with ADHD appear to benefit from treatment with stimulant medications in similar ways as children, including significant improvements on driving performance. However, fear surrounding the abuse of stimulants is an important issue. Nevertheless, evidence suggests that children with ADHD who are treated with stimulant medication are less likely to develop a substance use disorder in adolescence and adulthood.

CONCLUSION

There are a wide range of comorbidities with adult ADHD with many having overlapping symptoms. The benefits observed with ADHD treatment, however, emphasize the importance of recognition and treatment of adult ADHD.

Substance use in college students with ADHD

OBJECTIVE

The college years represent a developmental transition during which the initiation and escalation of heavy drinking set the stage for lifelong difficulties with alcohol and other drugs. Evidence from studies of adolescents and young adults with ADHD suggests that college students with the disorder may be uniquely vulnerable to alcohol- and drug-related problems. However, no studies have examined substance use in college students with ADHD.

METHOD

Tobacco, alcohol, illicit drug use, and associated impairment were examined in 91 college students with (n = 53) and without (n = 38) ADHD.

RESULTS

ADHD was associated with increased frequency of tobacco use, higher rates of dangerous or hazardous patterns of alcohol use, and higher levels of impairment related to marijuana and nonmarijuana illicit drug use, independent of conduct disorder history.

CONCLUSION

These findings suggest that college students with ADHD may be at elevated risk for problematic patterns of substance use.

Effects of smoking abstinence on impulsive behavior among smokers high and low in ADHD-like symptoms

RATIONALE

Impulsivity, a multifaceted construct that includes inhibitory control and heightened preference for immediate reward, is central to models of drug use and abuse. Within a self-medication framework, abstinence from smoking may lead to an increase in impulsive behavior and the likelihood of relapse, particularly among persons with disorders (e.g., attention-deficit/hyperactivity disorder, ADHD) and personality traits (e.g., impulsivity) linked to impulsive behavior.

OBJECTIVES

This study aimed to examine the effects of smoking abstinence on multiple measures of impulsivity among a non-clinical sample of adult smokers selected for high and low levels of ADHD symptoms.

METHODS

In a within-subjects design, participants selected for high or low levels of self-reported ADHD symptoms (N = 56) completed sessions following overnight abstinence and when smoking as usual (order counterbalanced). Measures of impulsive behavior included response inhibition (i.e., stop signal task), interference control (i.e., attentional modification of prepulse inhibition (PPI) of startle), and impulsive choice (i.e., hypothetical delay discounting).

RESULTS

As hypothesized, abstinence decreased response inhibition and PPI. Although ADHD symptoms moderated abstinence effects on impulsive choice and response inhibition, the pattern was opposite to our predictions: the low-ADHD group responded more impulsively when abstinent, whereas the high-ADHD group was relatively unaffected by abstinence.

CONCLUSIONS

These findings highlight the importance of utilizing multiple laboratory measures to examine a multifactorial construct such as impulsive behavior and raise questions about how best to assess symptoms of ADHD and impulsivity among non-abstinent smokers.

Simultaneous quantification of nicotine and metabolites in rat brain by liquid chromatography-tandem mass spectrometry

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous quantification of nicotine (NIC), cotinine (COT), nornicotine (NNIC), norcotinine (NCOT), nicotine-N-β-D-glucuronide (NIC GLUC), cotinine-N-β-D-glucuronide (COT GLUC), nicotine-1'-oxide (NNO), cotinine-N-oxide (CNO), trans-3'-hydroxycotinine (3-HC), anabasine (AB) and anatabine (AT) was modified and validated for quantification of these selected analytes in rat brain tissue. This analytical method provides support for preclinical NIC pharmacokinetic and toxicological studies after controlled dosing protocols. After brain homogenization and solid-phase extraction, target analytes and corresponding deuterated internal standards were chromatographically separated on a Discovery(®) HS F5 HPLC column with gradient elution and analyzed by LC-MS/MS in positive electrospray ionization (ESI) mode with multiple reaction monitoring (MRM) data acquisition. Method linearity was assessed and calibration curves were determined over the following ranges: 0.1-7.5 ng/mg for NIC, COT GLUC and AB; and 0.025-7.5 ng/mg for COT, NNIC, NCOT, NIC GLUC, NNO, CNO, 3-HC and AT (R(2)≥0.99 for all analytes). Extraction recoveries ranged from 64% to 115%, LC-MS/MS matrix effects were ≤21%, and overall process efficiency ranged from 57% to 93% at low and high quality control concentrations. Intra- and inter-assay imprecisions and accuracy for all analytes were ≤12.9% and ≥86%, respectively. The method was successfully applied to quantification of NIC and metabolites in the brain of post-natal day 90 rats that were sacrificed 2-h after a single 0.8 mg/kg s.c. administration of (-)NIC. In these tissues, striatal concentrations were 204.8±49.4, 138.2±14.2 and 36.1±6.1 pg/mg of NIC, COT and NNIC, respectively. Concentrations of NIC, COT and NNIC in the remaining whole brain (RWhB) were 183.3±68.0, 130.0±14.1 and 46.7±10.3 pg/mg, respectively. Quantification of these same analytes in plasma was also performed by a previously validated method. NIC, COT, NNIC, NCOT, NNO and CNO were detected in plasma with concentrations comparable to those reported in previous studies. However, and in contrast to brain tissues, COT concentrations in plasma were significantly higher than were those of NIC (194.6±18.6 ng/mL versus 52.7±12.9 ng/mL). Taken together, these results demonstrate that a sensitive and selective method has been developed for the determination of NIC biomarkers in rat brain.

Decreased α4β2 nicotinic receptor number in the absence of mRNA changes suggests post-transcriptional regulation in the spontaneously hypertensive rat model of ADHD

The spontaneously hypertensive rat (SHR) is widely used as a model of attention-deficit/hyperactivity disorder (ADHD). Deficits in central nicotinic receptors (nAChRs) have been previously observed in SHRs, which is interesting since epidemiological studies have identified an association between smoking and ADHD symptoms in humans. Here, we examine whether nAChR deficits in SHRs compared with Wistar Kyoto rat (WKY) controls are nAChR subtype-specific and whether these deficits correlate with changes at the level of mRNA transcription in specific brain regions. Levels of binding sites (B(max) ) and dissociation constants (K(d)) for nAChRs were determined from saturation curves of high-affinity [³H]epibatidine- and [³H] Methyllycaconitine (MLA) binding to membranes from cortex, striatum, hippocampus and cerebellum. In additional brain regions, nAChRs were examined by autoradiography with [¹²⁵I]A-85380 and [¹²⁵I]α-bungarotoxin. Levels of mRNA encoding nAChR subunits were measured using quantitative real-time PCR (qPCR). We showed that the number of α4β2 nAChR binding sites is lower globally in the SHR brain compared with WKY in the absence of significant differences in mRNA levels, with the exception of lower α4 mRNA in cerebellum of SHR compared with WKY. Furthermore, nAChR deficits were subtype- specific because no strain difference was found in α7 nAChR binding or α7 mRNA levels. Our results suggest that the lower α4β2 nAChR number in SHR compared with WKY may be a consequence of dysfunctional post-transcriptional regulation of nAChRs.

Efficacy and tolerability of pharmacotherapies for attention-deficit hyperactivity disorder in adults

This review examines the evidence regarding the efficacy and tolerability of long- and short-acting stimulant medications, as well as the non-stimulant medications atomoxetine and bupropion in the treatment of adult attention-deficit hyperactivity disorder (ADHD). Effect sizes in adults appear to be of almost the same magnitude as in school-age children when robust doses are used. There are adequate data demonstrating short-term efficacy and safety of medication in ADHD during adulthood but long-term studies are lacking, particularly in view of concerns regarding cardiovascular adverse events. There is some evidence that stimulant medication can improve driving performance in adults with ADHD. The extent to which medication may improve academic, occupational and social functioning in adults with ADHD is unclear, and future research should investigate these outcomes. Medication treatment of adults with ADHD in sports is controversial. Both stimulant and non-stimulant medications seem to be well tolerated. Monitoring of pulse and blood pressure is recommended with these drugs because of their cardiovascular effects. There have been extremely rare case reports of sudden death in adults and children treated with stimulants and atomoxetine, but it is difficult to clearly establish causality. In view of reports of treatment-related suicide-related behaviour with atomoxetine, it is recommended that adults should be observed for agitation, irritability, suicidal thinking, self-harming or unusual behaviour, particularly in the first months of treatment, or after a change of dose. ADHD in adults continues to remain an under-recognized disorder in many parts of the world and there is a lack of specialist clinics for assessment and treatment of adult ADHD. Studies to date have failed to show efficacy of medications in the treatment of ADHD in the substance misuse population. There is little evidence so far to suggest an increased misuse of stimulants or diversion amongst substance misusers; however, data are insufficient to draw firm conclusions. Further work is necessary to evaluate effective treatments in subgroups such as the substance misuse population, those with multiple co-morbidities and different ADHD subtypes.

Childhood ADHD symptoms and risk for cigarette smoking during adolescence: School adjustment as a potential mediator

Although a large body of research suggests that children with attention-deficit/hyperactivity disorder (ADHD) are at increased risk for cigarette smoking during adolescence compared with their non-ADHD peers, much less research has examined why. The current study addressed this gap in the literature by examining middle school adjustment, broadly defined, as a possible mediator of the relation between childhood ADHD symptoms and cigarette smoking during middle adolescence (10th grade). Longitudinal data were collected from a community sample of 754 youth using self-report and parent report along with school records, and a novel statistical technique was used in the process of testing for mediation. Consistent with hypotheses, school adjustment was found to mediate the relation between childhood ADHD symptoms and later cigarette smoking, even after controlling for early externalizing problems. Results have implications for etiological theories of adolescent deviant behavior and suggest that successful smoking prevention programs targeting youth with ADHD should include a school adjustment component.

Post-learning REM sleep deprivation impairs long-term memory: reversal by acute nicotine treatment

Rapid eye movement sleep deprivation (REM-SD) is associated with spatial learning and memory impairment. During REM-SD, an increase in nicotine consumption among habitual smokers and initiation of tobacco use by non-smokers have been reported. We have shown recently that nicotine treatment prevented learning and memory impairments associated with REM-SD. We now report the interactive effects of post-learning REM-SD and/or nicotine. The animals were first trained on the radial arm water maze (RAWM) task, then they were REM-sleep deprived using the modified multiple platform paradigm for 24h. During REM-SD period, the rats were injected with saline or nicotine (1mg/kg s.c. every 12h: a total of 3 injections). The animals were tested for long-term memory in the RAWM at the end of the REM-SD period. The 24h post-learning REM-SD significantly impaired long-term memory. However, nicotine treatment reversed the post-learning REM-SD-induced impairment of long-term memory. On the other hand, post-learning treatment of normal rats with nicotine for 24h enhanced long-term memory. These results indicate that post-learning acute nicotine treatment prevented the deleterious effect of REM-SD on cognitive abilities.