Atomoxetine: a selective noradrenaline reuptake inhibitor for the treatment of attention-deficit/hyperactivity disorder

The effects of methylphenidate and atomoxetine on Drosophila brain at single-cell resolution and potential drug repurposing for ADHD treatment

The stimulant methylphenidate (MPH) and the non-stimulant atomoxetine (ATX) are frequently used for the treatment of attention-deficit/hyperactivity disorder (ADHD); however, the function of these drugs in different types of brain cells and their effects on related genes remain largely unknown. To address these questions, we built a pipeline for the simultaneous examination of the activity behavior and transcriptional responses of Drosophila melanogaster at single-cell resolution following drug treatment. We selected the Drosophila with significantly increased locomotor activities (hyperactivity-like behavior) following the administration of each drug in comparison with the control (same food as the drug-treated groups with 5% sucrose, yeast, and blue food dye solution) using EasyFlyTracker. Subsequently, single cell RNA sequencing (scRNASEQ) was used to capture the transcriptome of 82,917 cells, unsupervised clustering analysis of which yielded 28 primary cell clusters representing the major cell types in adult Drosophila brain. Indeed, both neuronal and glial cells responded to MPH and ATX. Further analysis of differentially expressed genes (DEGs) revealed distinct transcriptional changes associated with these two drugs, such as two well-studied dopamine receptor genes (Dop2R and DopEcR) were responsive to MPH but not to ATX at their optimal doses, in addition to genes involved in dopamine metabolism pathways such as Syt1, Sytalpha, Syt7, and Ih in different cell types. More importantly, MPH also suppressed the expression of genes encoding other neurotransmitter receptors and synaptic signaling molecules in many cell types, especially those for Glu and GABA, while the responsive effects of ATX were much weaker. In addition to monoaminergic neuronal transmitters, other neurotransmitters have also shown a similar pattern with respect to a stronger effect associated with MPH than with ATX. Moreover, we identified four distinct glial cell subtypes responsive to the two drugs and detected a greater number of differentially expressed genes associated with ensheathing and astrocyte-like glia. Furthermore, our study provides a rich resource of candidate target genes, supported by drug set enrichment analysis (P = 2.10E-4; hypergeometric test), for the further exploration of drug repurposing. The whole list of candidates can be found at ADHDrug ( http://adhdrug.cibr.ac.cn/ ). In conclusion, we propose a fast and cost-efficient pipeline to explore the underlying molecular mechanisms of ADHD drug treatment in Drosophila brain at single-cell resolution, which may further facilitate drug repurposing applications.

Affective Temperaments Misdiagnosed as Adult Attention Deficit Disorder: Prevalence and Treatment Effects

ABSTRACT

Adult attention-deficit disorder (ADD) is a common diagnosis, and amphetamine medications are increasingly used. Recent reports suggest high prevalence of affective temperaments, such as cyclothymia, in adult ADD. This study reexamines prevalence rates as reflecting misdiagnosis and reports for the first time on the effects of amphetamine medications on mood/anxiety and cognition in relation to affective temperaments. Among outpatients treated at the Tufts Medical Center Mood Disorders Program (2008-2017), 87 cases treated with amphetamines were identified, versus 163 non-amphetamine-treated control subjects. Using the Temperament Scale of Memphis, Pisa, Paris and San Diego-Autoquestionnaire, 62% had an affective temperament, most commonly cyclothymia (42%). In amphetamine-treated cases, mood/anxiety symptoms worsened notably in 27% ( vs. 4% in the control group, risk ratio [RR] 6.2, confidence interval [CI], 2.8-13.8), whereas 24% had moderate improvement in cognition ( vs. 6% in the control group; RR, 3.93; CI, 1.9-8.0). Affective temperaments, especially cyclothymia, are present in persons about one-half of persons diagnosed with adult ADD and/or treated with amphetamines.

Atomoxetine Does Not Improve Complex Attention in Idiopathic Parkinson's Disease Patients with Cognitive Deficits: A Meta-Analysis

Objectives

To evaluate the effects of atomoxetine on complex attention and other neurocognitive domains in idiopathic Parkinson's disease (PD).

Methods

Interventional trials reporting changes in complex attention and other neurocognitive functions (Diagnostic and Statistical Manual of Mental Disorders-5) following administration of atomoxetine for at least 8 weeks in adults with idiopathic PD were included. Effect sizes (Cohen's d), the standardized mean difference in the scores of each cognitive domain, were compared using a random-effects model (MetaXL version 5.3).

Results

Three studies were included in the final analysis. For a change in complex attention in PD with mild cognitive impairment (MCI), the estimated effect size was small and nonsignificant (0.16 (95% CI: −0.09, 0.42), n = 42). For changes in executive function, perceptual-motor function, language, social cognition, and learning and memory, the estimated effect sizes were small and medium, but nonsignificant. A deteriorative trend in executive function was observed after atomoxetine treatment in PD with MCI. For a change in global cognitive function in PD without MCI, the estimated effect size was large and significant.

Conclusion

In idiopathic PD with MCI, atomoxetine does not improve complex attention. Also, a deteriorative trend in the executive function was noted.

A Signature of Attention-Elicited Electrocortical Activity Distinguishes Response From Non-Response to the Non-Stimulant Atomoxetine in Children and Adolescents With ADHD

OBJECTIVE

Atomoxetine has several characteristics that make it an attractive alternative to stimulants for treating ADHD, but there are currently no tests identifying individuals for whom the medication should be a first-line option.

METHOD

Within the ADHD Controlled Trial Investigation Of a Non-stimulant (ACTION) study, we examined neuro-cortical activity in 52 youth with ADHD. Baseline event-related potentials (ERP) were compared between those who subsequently responded to 6 weeks of atomoxetine versus those who did not.

RESULTS

Responders were distinguished by significantly lower auditory oddball N2 amplitudes than both non-responders and typically developing controls, particularly in the right frontocentral region ( p = .002, Cohen's d = 1.1). Leave-one-out cross validation determined that N2 amplitude in this region was able to accurately predict non-responders with a specificity of 80.8%. There were no P3 differences between responders and non-responders.

CONCLUSION

The N2 amplitude is a biomarker that may have utility in predicting response to atomoxetine for youth with ADHD.

Dasotraline in Children with Attention-Deficit/Hyperactivity Disorder: A Six-Week, Placebo-Controlled, Fixed-Dose Trial

OBJECTIVE

Dasotraline is a potent inhibitor of presynaptic dopamine and norepinephrine reuptake with a pharmacokinetic profile characterized by slow absorption and a long elimination half-life. The aim of this study was to evaluate the efficacy and safety of dasotraline in children with attention-deficit/hyperactivity disorder (ADHD).

METHODS

Children aged 6-12 years with a Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) diagnosis of ADHD were randomized to 6 weeks of double-blind once-daily treatment with dasotraline (2 or 4 mg) or placebo. The primary efficacy endpoint was change from baseline in the ADHD Rating Scale Version IV-Home Version (ADHD RS-IV HV) total score at week 6.

RESULTS

A total of 342 patients were randomized to dasotraline or placebo (mean age 9.1 years, 66.7% male). Treatment with dasotraline was associated with significant improvement at study endpoint in the ADHD RS-IV HV total score for the 4 mg/day dose versus placebo (-17.5 vs. -11.4; p < 0.001; effect size [ES], 0.48), but not for the 2 mg/day dose (-11.8 vs. -11.4; ns; ES, 0.03). A regression analysis confirmed a significant linear dose-response relationship for dasotraline. Significant improvement for dasotraline 4 mg/day dose versus placebo was also observed across the majority of secondary efficacy endpoints, including the Clinical Global Impression (CGI)-Severity score, the Conners Parent Rating Scale-Revised scale (CPRS-R) ADHD index score, and subscale measures of hyperactivity and inattentiveness. Discontinuation rates due to adverse events (AEs) were higher in the dasotraline 4 mg/day group (12.2%) compared with the 2 mg/day group (6.3%) and placebo (1.7%). The most frequent AEs associated with dasotraline were insomnia, decreased appetite, decreased weight, and irritability. Psychosis-related symptoms were reported as AEs by 7/219 patients treated with dasotraline in this study. There were no serious AEs or clinically meaningful changes in blood pressure or heart rate on dasotraline.

CONCLUSION

In this placebo-controlled study, treatment with dasotraline 4 mg/day significantly improved ADHD symptoms and behaviors, including attention and hyperactivity, in children aged 6-12 years. The most frequently reported AEs observed on dasotraline included insomnia, decreased appetite, decreased weight, and irritability.

The Role of Nutritional Supplements in the Treatment of ADHD: What the Evidence Says

Attention-deficit hyperactivity disorder (ADHD) is a common behavioral disorder in children and adolescents and may persist into adulthood. Insufficient nutritional supply of long-chain polyunsaturated fatty acids (LC-PUFAs) and other components including various minerals has been suggested to play a role in the development of ADHD symptoms. This review presents the evidence regarding the role of nutritional PUFA, zinc, iron, and magnesium supplements in the treatment of ADHD with a focus on the critical evaluation of the relevant literature published from 2014 to April 2016. The evaluation of therapeutic nutritional LC-PUFA supplementation in ADHD has shown mixed and inconclusive results and at best marginal beneficial effects. The benefits of PUFAs are much smaller than the effect sizes observed for traditional pharmacological treatments of ADHD. The effectiveness of PUFA supplements in reducing medication dosage has been suggested but needs to be confirmed. Zinc, iron, and magnesium supplementation may reduce ADHD symptoms in children with or at high risk of deficiencies in these minerals. However, convincing evidence in this regard is lacking.

Atomoxetine effects on attentional bias to drug-related cues in cocaine dependent individuals

RATIONALE

Biased attention towards drug-related cues and reduced inhibitory control over the regulation of drug-intake characterize drug addiction. The noradrenaline system has been critically implicated in both attentional and response inhibitory processes and is directly affected by drugs such as cocaine.

OBJECTIVES

We examined the potentially beneficial effects of the noradrenaline reuptake inhibitor atomoxetine in improving cognitive control during two tasks that used cocaine- and non-cocaine-related stimuli.

METHODS

A double-blind, placebo-controlled, and cross-over psycho-pharmacological design was employed. A single oral dose of atomoxetine (40 mg) was administered to 28 cocaine-dependent individuals (CDIs) and 28 healthy controls. All participants performed a pictorial attentional bias task involving both cocaine- and non-cocaine-related pictures as well as a verbal go/no-go task composed of cocaine- and food-related words.

RESULTS

As expected, CDIs showed attentional bias to cocaine-related cues whilst controls did not. More importantly, however, atomoxetine, relative to placebo, significantly attenuated attentional bias in CDIs (F ₂₆ = 6.73, P = 0.01). During the go/no-go task, there was a treatment × trial × group interaction, although this finding only showed a trend towards statistical significance (F ₂₆ = 3.38, P = 0.07).

CONCLUSIONS

Our findings suggest that atomoxetine reduces attentional bias to drug-related cues in CDIs. This may result from atomoxetine's modulation of the balance between tonic/phasic activity in the locus coeruleus and the possibly parallel enhancement of noradrenergic neurotransmission within the prefrontal cortex. Studying how cognitive enhancers such as atomoxetine influence key neurocognitive indices in cocaine addiction may help to develop reliable biomarkers for patient stratification in future clinical trials.

Methylphenidate HCl: therapy for attention deficit hyperactivity disorder

Methylphenidate is a first-line therapy for attention deficit hyperactivity disorder, the most prevalent neuropsychiatric disorder of childhood. The compound is a piperidine and the D-threo-isomer is considered the biologically active form. The compound is available in multiple short- and long-acting preparations, having different delivery systems leading to varying kinetics without clear superiority in efficacy or tolerability at the group level. Common adverse effects are insomnia, appetite disturbance, stomach ache, headache and dizziness. Its mechanism of action is linked to the monoamines dopamine and norepinephrine. The compound appears to predominantly increase the synaptic concentration of dopamine, presumably via inhibition of the dopamine transporter DAT1. There also appears to be effects on presynaptic vesicular trafficking and distribution of dopamine. Both immediate- and sustained-release preparations of methylphenidate have proven efficacy in children and adults with attention deficit hyperactivity disorder. Analysis of the National Institutes of Health-sponsored multimodal treatment study of attention deficit hyperactivity disorder supports a combined medication and behavioral therapy approach.

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.

Cellular, molecular, and genetic substrates underlying the impact of nicotine on learning

Addiction is a chronic disorder marked by long-lasting maladaptive changes in behavior and in reward system function. However, the factors that contribute to the behavioral and biological changes that occur with addiction are complex and go beyond reward. Addiction involves changes in cognitive control and the development of disruptive drug-stimuli associations that can drive behavior. A reason for the strong influence drugs of abuse can exert on cognition may be the striking overlap between the neurobiological substrates of addiction and of learning and memory, especially areas involved in declarative memory. Declarative memories are critically involved in the formation of autobiographical memories, and the ability of drugs of abuse to alter these memories could be particularly detrimental. A key structure in this memory system is the hippocampus, which is critically involved in binding multimodal stimuli together to form complex long-term memories. While all drugs of abuse can alter hippocampal function, this review focuses on nicotine. Addiction to tobacco products is insidious, with the majority of smokers wanting to quit; yet the majority of those that attempt to quit fail. Nicotine addiction is associated with the presence of drug-context and drug-cue associations that trigger drug seeking behavior and altered cognition during periods of abstinence, which contributes to relapse. This suggests that understanding the effects of nicotine on learning and memory will advance understanding and potentially facilitate treating nicotine addiction. The following sections examine: (1) how the effects of nicotine on hippocampus-dependent learning change as nicotine administration transitions from acute to chronic and then to withdrawal from chronic treatment and the potential impact of these changes on addiction, (2) how nicotine usurps the cellular mechanisms of synaptic plasticity, (3) the physiological changes in the hippocampus that may contribute to nicotine withdrawal deficits in learning, and (4) the role of genetics and developmental stage (i.e., adolescence) in these effects.

Atomoxetine facilitates attentional set shifting in adolescent rats

Adolescent rats show immaturities in executive function and are less able than adult rats to learn reinforcement reversals and shift attentional set. These two forms of executive function rely on the functional integrity of the orbitofrontal and prelimbic cortices respectively. Drugs used to treat attention deficit disorder, such as atomoxetine, that increase cortical catecholamine levels improve executive functions in humans, non-human primates and adult rats with prefrontal lesions. Cortical noradrenergic systems are some of the last to mature in primates and rats. Moreover, norepinephrine transporters (NET) are higher in juvenile rats than adults. The underdeveloped cortical noradrenergic system and higher number of NET are hypothesized to underlie the immaturities in executive function found in adolescents. We assessed executive function in male Long-Evans rats using an intra-dimensional/extradimensional set shifting task. We administered the NET blocker, atomoxetine (0.0, 0.1, 0.9 mg/kg/ml; i.p.), prior to the test of attentional set shift and a reinforcement reversal. The lowest dose of drug facilitated attentional set shifting but had no effect on reversal learning. These data demonstrate that NET blockade allows adolescent rats to more easily perform attentional set shifting.

Animal models to guide clinical drug development in ADHD: lost in translation?

We review strategies for developing animal models for examining and selecting compounds with potential therapeutic benefit in attention-deficit hyperactivity disorder (ADHD). ADHD is a behavioural disorder of unknown aetiology and pathophysiology. Current understanding suggests that genetic factors play an important role in the aetiology of ADHD. The involvement of dopaminergic and noradrenergic systems in the pathophysiology of ADHD is probable. We review the clinical features of ADHD including inattention, hyperactivity and impulsivity and how these are operationalized for laboratory study. Measures of temporal discounting (but not premature responding) appear to predict known drug effects well (treatment validity). Open-field measures of overactivity commonly used do not have treatment validity in human populations. A number of animal models have been proposed that simulate the symptoms of ADHD. The most commonly used are the spontaneously hypertensive rat (SHR) and the 6-hydroxydopamine-lesioned (6-OHDA) animals. To date, however, the SHR lacks treatment validity, and the effects of drugs on symptoms of impulsivity and inattention have not been studied extensively in 6-OHDA-lesioned animals. At the present stage of development, there are no in vivo models of proven effectiveness for examining and selecting compounds with potential therapeutic benefit in ADHD. However, temporal discounting is an emerging theme in theories of ADHD, and there is good evidence of increased value of delayed reward following treatment with stimulant drugs. Therefore, operant behaviour paradigms that measure the effects of drugs in situations of delayed reinforcement, whether in normal rats or selected models, show promise for the future.

Blockade of noradrenaline re-uptake sites improves accuracy and impulse control in rats performing a five-choice serial reaction time tasks

RATIONALE

Atomoxetine, reboxetine and methylphenidate all act at the noradrenaline transporter (NAT) and atomoxetine and methylphenidate are licensed for the treatment of ADHD. The five-choice serial reaction time task (5CSRTT) provides a valid model to study attention and impulsivity in rodents. Studies using this task have largely failed to demonstrate improvements in attention with atomoxetine and methylphenidate and reboxetine has not been investigated previously.

OBJECTIVES

The present study used modifications to the standard rat 5CSRTT and demonstrated that blockade of NAT improves attention and reduces premature responding.

METHODS

Rats were trained in a fixed inter-trial interval (ITI), 5CSRTT then tested at baseline and under conditions to acutely challenge attention and/or impulse control following vehicle or atomoxetine (0.3 mg/kg, i.p.).

RESULTS

Atomoxetine (0.3 mg/kg, i.p.) significantly improved impulse control under all conditions (p < 0.05) but had no significant effects on accuracy. To increase the attentional demands of the task, rats were re-baselined in a non-paced, variable ITI task where presentations of the stimuli were unpredictable. In the VITI task, atomoxetine (0.0-0.3 mg/kg, i.p.) induced a dose-dependent improvement in accuracy (p < 0.05) and reduction in premature responses (p < 0.05). Reboxetine (0.0-1.0 mg/kg, i.p.) and methylphenidate (1-10 mg/kg, p.o.) did not significantly improve accuracy in the whole population but median split analysis revealed a significant improvement with both drugs, as well as atomoxetine, in the poor performing animals (p < 0.05).

CONCLUSIONS

These data suggest that blockade of noradrenaline re-uptake sites is an important target in terms of enhancing both attention and impulse control.

Adjunctive atomoxetine to SSRIs or SNRIs in the treatment of adult ADHD patients with comorbid partially responsive generalized anxiety (GA): an open-label study

To examine changes in partially responsive anxiety symptoms utilizing adjunctive treatment with atomoxetine in the treatment of adult ADHD patients with comorbid partially responsive anxiety symptoms. Consenting adult patients (n=29) with confirmed diagnosis of generalized anxiety and comorbid attention deficit hyperactivity disorder (ADHD) participated in this open-label study. All patients had significant comorbid anxiety symptoms (HAM-A>7) and failed to respond to 8-week trials of selective serotonin reuptake inhibitors (SSRIs) or noradrenaline reuptake inhibitors (SNRIs). All patients were treated with atomoxetine as adjunctive to SSRIs or to SNRIs and were followed for at least 12 weeks. The primary outcome measure was the Clinical Global Impression severity subscale. Other scales included the Hamilton Anxiety Scale (HAM-A), the adult ADHD Self-Report Scale (ASRS-v1.1) symptom checklist, and Sheehan's Disability Scale. Baseline measures prior to the treatment with atomoxetine were compared to those at 4, 8, and at 12 weeks of treatment. Monitoring for pulse, blood pressure, and weight changes was carried out at baseline and at end point. Twenty-seven patients (93%) completed this open-label study. There was significant resolution of symptoms of all outcome measures, including the symptoms of anxiety, as shown by changes from baseline in HAM-A, ASRS-v1.1, and CGI at 12 weeks (P<.001). Also, there was significant reduction in the disability score at 12 weeks. Patients completed the study, tolerated the adjunctive treatment, and there were no significant cardiovascular or weight changes. Two patients withdrew from the study during the first 4 weeks of treatment due to side effects. Atomoxetine can be used as an adjunctive treatment in adult patients with ADHD and comorbid partially responsive anxiety symptoms.

InforMatrix for attention deficit hyperactivity disorder

The purpose of this review is to facilitate discussion on drug selection for the treatment of ADHD by using only clinically relevant selection criteria and providing an up-to-date overview. The InforMatrix method was used to select drugs to treat attention deficit hyperactivity disorder (ADHD). The following selection criteria were applied: clinical efficacy, safety, tolerability, ease of use, applicability, and cost. The drugs approved for ADHD in the Netherlands were included in the analysis, namely: atomoxetine, immediate-release methylphenidate, and various formulations of slow-release methylphenidate (Concerta, Equasym and Medikinet). Most studies are of limited quality, duration, and size. In one study, Concerta was more effective than atomoxetine. Although no relevant differences were seen in other comparative studies, the clinical experience with atomoxetine is still limited and unexpected toxicity cannot be excluded; few studies have been published with Equasym and Medikinet. No major differences were seen in general tolerability between the drugs. The ease of use of immediate-release methylphenidate is less than for the other drugs. The acquisition cost of immediate-release methylphenidate is considerably lower than that of the slow-release formulations. Atomoxetine is the most expensive drug. The InforMatrix program is available in an interactive format. It enables the user to judge both the importance of the selection criteria and the properties of each therapeutic option per criterion on the basis of his or her own personal expertise and/or the present document.

High impulsivity predicts relapse to cocaine-seeking after punishment-induced abstinence

BACKGROUND

Relapse is a hallmark feature of cocaine addiction and a main challenge for treatment strategies. Human studies indicate a link between impulsivity and increased susceptibility to relapse.

METHODS

Rats were screened for high (HI) and low impulsivity (LI) on the 5-choice serial reaction time task. The HI and LI rats were trained to self-administer cocaine under a seeking-taking chained schedule: responses on the seeking lever resulted in presentation of the taking lever, responding upon which resulted in cocaine reinforcement. After the establishment of stable responding, an intermittent punishment schedule was introduced: completion of the seeking link resulted in the random presentation of either the taking lever or a mild footshock. This resulted in a progressive decrease in cocaine-seeking approaching abstinence. Relapse was assessed 7 days after punishment, during which responding on the seeking lever resulted in the presentation of the cocaine-associated stimuli (i.e., in the absence of cocaine or footshock).

RESULTS

The HI and LI animals significantly reinstated the cocaine-seeking response after a single phase of seeking punishment. However, after a second punishment phase only the HI rats reinitiated suppressed seeking responses and relapsed, an effect that was facilitated by prior extended cocaine access. In a preliminary study we found that the selective noradrenaline reuptake inhibitor, atomoxetine, a drug known to reduce impulsivity, prevented the reinstatement of cocaine-seeking.

CONCLUSIONS

Impulsivity pre-dating drug abuse increases the susceptibility to relapse after abstinence. Medications targeting impulsivity might have utility as treatment interventions for relapse prevention and the promotion of abstinence.

Preclinical evaluation of the abuse potential of the analgesic bicifadine

The abuse liability of the analgesic bicifadine was investigated in animal models used to predict the abuse potential of psychostimulants in humans. Bicifadine, cocaine, d-amphetamine, bupropion, and desipramine were evaluated for the production of cocaine-like discriminative stimulus effects in rats. Cocaine, d-amphetamine, and bupropion dose-dependently and fully substituted for cocaine. Bicifadine and desipramine produced a maximum mean cocaine-lever selection of 80 and 69%, respectively, but doses yielding peak substitution strongly suppressed response rates. Microdialysis studies in normal waking rats indicated that d-amphetamine increased dopamine levels in the nucleus accumbens and striatum to a much greater degree than bicifadine, but bicifadine increased 5-hydroxytryptamine levels in the nucleus accumbens and striatum more than d-amphetamine. Bicifadine was also tested for intravenous self-administration in rhesus monkeys experienced with cocaine administration. Reinforcing effects of bicifadine were observed in only two of four subjects, whereas cocaine, d-amphetamine, and bupropion served as reinforcers in all four monkeys. When evaluated under a progressive ratio procedure, no dose of bicifadine maintained responding to the extent of cocaine, d-amphetamine, or bupropion. The discriminative stimulus effects associated with bicifadine were similar, but not identical, to those of psychostimulants. Although bicifadine maintained self-administration behavior in some subjects, its reinforcing efficacy was very low relative to cocaine, d-amphetamine, and bupropion. These results are consistent with the microdialysis findings of lower dopamine levels and higher 5-hydroxytryptamine levels after administration of bicifadine relative to d-amphetamine. Overall, the current findings support a low abuse potential of bicifadine, more resembling that of antidepressants than psychostimulants.

Atomoxetine reverses attentional deficits produced by noradrenergic deafferentation of medial prefrontal cortex

BACKGROUND

The majority of studies assessing executive function in attention deficit disorder (ADD) have shown deficits in attentional set shifting using either the Wisconsin card sorting task or the intra-dimensional/extra-dimensional set-shifting task (ID/ED). Damage to the prefrontal cortex in humans, primates, and rodents impairs extra-dimensional (ED) shifts. Noradrenergic depletion of the medial prefrontal cortex in rats is sufficient to impair attentional set shifting. Atomoxetine, a selective norepinephrine (NE) re-uptake inhibitor, is hypothesized to produce beneficial effects in patient with ADD by augmenting NE release in prefrontal cortex.

MATERIALS AND METHODS

We assessed the effects of systemic administration of atomoxetine (0.0, 0.1, 0.3, and 0.9 mg/kg/ml) in normal and noradrenergically lesioned (NE-LX) rats on attentional-set shifts. We replicated findings showing NE-LX rats are selectively impaired on the ED shifts but not reversals or other discriminations.

RESULTS

Atomoxetine remediated the attentional set-shifting impairments in NE-LX rats but impaired ED performance of non-lesioned rats.

DISCUSSION

Though atomoxetine is neurochemically selective, it is not wholly specific at doses >0.3 mg/kg. All doses of the drug were similar in their efficacy in reversing the ED deficit, but the effectiveness of the 0.1 mg/kg dose supports the hypothesis that increases in prefrontal NE alone are sufficient to improve attention in NE-LX rats. Moreover, the detrimental effects of the drug in non-lesioned rats support the hypothesis that optimal levels of NE in prefrontal cortex are critical to attentional set shifting with both supra- and sub-optimal levels producing attentional impairments.

Similar effects of the selective noradrenaline reuptake inhibitor atomoxetine on three distinct forms of impulsivity in the rat

Atomoxetine is a noradrenaline-specific reuptake inhibitor used clinically for the treatment of childhood and adult attention deficit hyperactivity disorder (ADHD). Studies in human volunteers and patient groups have shown that atomoxetine improves stop-signal reaction time (SSRT) performance, an effect consistent with a reduction in motor impulsivity. However, ADHD is a heterogeneous disorder and it is of interest to determine whether atomoxetine is similarly effective against other forms of impulsivity, as well as the attentional impairment present in certain subtypes of ADHD. The present study examined the effects of atomoxetine on impulsivity using an analogous SSRT task in rats and two additional tests of impulsivity; delay discounting of reward and the five-choice serial reaction time task (5CSRTT), the latter providing an added assessment of sustained visual attention. Atomoxetine produced a significant dose-dependent speeding of SSRT. In addition, atomoxetine produced a selective, dose-dependent decrease in premature responding on the 5CSRTT. Finally, on the delay-discounting task, atomoxetine significantly decreased impulsivity by increasing preference for the large-value reward across increasing delay. These findings conclusively demonstrate that atomoxetine decreases several distinct forms of impulsivity in rats. The apparent contrast of these effects with stimulant drugs such as amphetamine and methylphenidate, which generally act to increase impulsivity on the 5CSRTT, may provide new insights into the mechanisms of action of stimulant and nonstimulant drugs in ADHD.

Detecting attention-deficit/hyperactivity disorder (ADHD) in adults with intellectual disability The use of Conners' Adult ADHD Rating Scales (CAARS)

There is an increasing interest in the diagnosis of attention-deficit/hyperactivity disorder (ADHD) in adulthood. It is also thought that ADHD is more prevalent in the field of intellectual disability (ID) than in the general population, but there are not many experimental studies. Since ADHD diagnosis in adults is more difficult, specific rating scales correlated to the main diagnostic systems have been created but have not been applied to people with ID. This work presents an application of an ADHD screening rating scale, the Conners' Adult ADHD Rating Scales (CAARS) screening version to 46 adults with ID. The resulting prevalence of "ADHD-positive" was 19.6%. These data are in accord with results reported in the general adult literature. Our data suggest that ID and attention disorders can co-occur. Therefore, not only can ADHD be a valid psychiatric diagnosis for a child with ID but for an adult with ID as well. The CAARS can be considered a useful clinical instrument to survey ADHD in ID.

Emotional expression in children treated with ADHD medication: development of a new measure

OBJECTIVE

Although existing instruments contain items addressing the effect of ADHD medications on emotional expression, a review of measures did not yield any instruments that thoroughly evaluated positive and negative aspects of emotional expression.

METHOD

The Expression and Emotion Scale for Children (EESC), a parent-report measure, was developed from an analysis of qualitative data from parent focus groups and expert opinion. Data from 179 parents and children treated with stimulants or atomoxetine are used to examine the psychometric properties of the EESC.

RESULTS

The EESC demonstrates good internal consistency and test-retest reliability. A factor analysis yields three factors (positive, flat, and emotional lability) that were consistent with the predicted structure of the measure. Small to moderate correlations between the EESC and psychological symptom measures are found, with the strength of the relationships varying by symptom measure.

CONCLUSION

The EESC shows appropriate psychometric properties and is appropriate for use in clinical and research settings.

Meta-analysis of suicide-related behavior events in patients treated with atomoxetine

OBJECTIVE

The present work examined suicide-related events in acute, double-blind, and placebo- or active comparator-controlled trials with atomoxetine.

METHOD

Fourteen trials in pediatric patients were included. Potential events were identified in the adverse events database using a text-string search. Potential suicide-related events were categorized according to U.S. Food and Drug Administration-defined codes using blinded patient summaries. The meta-analyses used the Mantel-Haenszel incidence difference and Mantel-Haenszel risk ratio methods.

RESULTS

No patient in atomoxetine attention-deficit/hyperactivity disorder (ADHD) trials committed suicide. The frequency of suicidal ideation was 0.37% (5/1357) in pediatric patients taking atomoxetine versus 0% (0/851) for the placebo group; Mantel-Haenszel incidence difference of 0.46 (95% confidence interval 0.09-0.83; p =.016) and Mantel-Haenszel risk ratio of 2.92 (95% confidence interval 0.63-13.57; p =.172). Frequencies of suicide-related events in pediatric patients with ADHD did not differ between methylphenidate and atomoxetine treatments (Mantel-Haenszel incidence difference of -0.12 (95% confidence interval -0.62 to 0.38; p =.649). The number needed to harm in pediatric patients for an additional suicide-related event is 227 compared to the number needed to treat of five to achieve remission of ADHD symptoms.

CONCLUSIONS

Although uncommon, suicidal ideation was significantly more frequent in pediatric ADHD patients treated with atomoxetine compared to those treated with placebo. Retrospective analysis has limitations in ascertaining intent.

Treatment of cognitive deficits associated with schizophrenia: potential role of catechol-O-methyltransferase inhibitors

In the last two decades, understanding of the dynamics of dopamine function in the prefrontal cortex and its role in prefrontal cortex physiology has opened up new avenues for therapeutic interventions in conditions in which prefrontal cortex function is compromised. Neuropsychological and imaging studies of prefrontal information processing have confirmed specific cognitive and neurophysiological abnormalities in individuals with schizophrenia. Because such findings are also observed in the healthy siblings of patients with schizophrenia, they may represent intermediate phenotypes related to schizophrenia susceptibility genes.Catechol-O-methyltransferase (COMT) represents an important candidate as a susceptibility gene for cognitive dysfunction in schizophrenia because of the unique role this enzyme plays in regulating prefrontal dopaminergic function. A functional COMT polymorphism (Val158Met) predicts performance in tasks of prefrontal executive function and the neurophysiological response measured with electroencephalography and functional magnetic resonance imaging in tasks assessing working memory. In fact, individuals with the Val/Val genotype, which encodes for the high-activity enzyme resulting in lower dopamine concentrations in the prefrontal cortex, perform less well and are less efficient physiologically than Met/Met individuals. These findings raise the possibility of new pharmacological interventions for the treatment of prefrontal cortex dysfunction and of predicting outcome based on COMT genotype. One strategy consists of the use of CNS-penetrant COMT inhibitors such as tolcapone. A second strategy is to increase extracellular dopamine concentrations in the frontal cortex by blocking the noradrenaline (norepinephrine) reuptake system, a secondary mechanism responsible for the disposal of dopamine from synaptic clefts in the prefrontal cortex. A third possibility involves the use of modafinil, a drug with an unclear mechanism of action but with positive effects on working memory in rodents. The potential of these drugs to improve executive cognitive function by selectively increasing dopamine load in the frontal cortex but not in subcortical territories, and the possibility that response to them may be modified by a COMT polymorphism, provides a novel genotype-based targeted pharmacological approach without abuse potential for the treatment of cognitive disorder in schizophrenia and in other conditions involving prefrontal cortex dysfunction.

Atomoxetine reverses nicotine withdrawal-associated deficits in contextual fear conditioning

Recent evidence suggests that the cognitive symptoms of nicotine withdrawal and the cognitive symptoms of attention deficit hyperactivity disorder (ADHD) may share neural correlates. Thus, therapeutics that ameliorate ADHD symptoms may also ameliorate nicotine-withdrawal symptoms. The present research tested this hypothesis in an animal model of nicotine withdrawal-associated cognitive deficits using atomoxetine, a norepinephrine reuptake inhibitor that is approved by the FDA to treat the symptoms of ADHD. C57BL/6 mice were prepared with osmotic minipumps that administered 6.3 mg/kg/day of nicotine or saline, and the minipumps were removed after 12 days of continuous treatment. Twenty-four hours later, mice were trained in delay fear conditioning using two paired presentations of an auditory conditioned stimulus (CS) with a footshock unconditioned stimulus. Testing for freezing in response to the training context and for freezing in response to the CS occurred the next day. Nicotine-withdrawn mice and their saline-treated counterparts received either saline or atomoxetine before training and the context test. Consistent with previous research, the results indicate that mice withdrawn from chronic nicotine demonstrated lower levels of contextual fear conditioning than mice that were not withdrawn from chronic nicotine. Atomoxetine dose-dependently reversed the deficit, suggesting that nicotine withdrawal may be associated with changes in noradrenergic function, acetylcholinergic function, and/or with changes in cell signaling cascades that are activated by both nicotine and norepinephrine. These data suggest that atomoxetine may be efficacious for treating nicotine withdrawal-associated cognitive deficits that promote relapse in abstinent smokers.

A multi-centre, randomised, open-label study of atomoxetine compared with standard current therapy in UK children and adolescents with attention-deficit/hyperactivity disorder (ADHD)

OBJECTIVE

To assess the broader efficacy (i.e., improvements in quality of life/functional outcomes) of atomoxetine compared with standard current therapy (SCT) in UK paediatric patients with ADHD and to explore clinician/parent/child perceptions of ADHD.

RESEARCH DESIGN AND METHODS

A total of 201 patients with ADHD were randomised into this multi-centre, open-label study to receive atomoxetine (n = 104) or SCT (n = 97) for 10 weeks. Broader efficacy was assessed using the parent-rated Child Health and Illness Profile-Child Edition (CHIP-CE) total (global) t-score. Secondary outcome measures included the five CHIP-CE domains; parent-rated Family Burden of Illness Module (FBIM); investigator-rated ADHD-Rating Scale; investigator-rated Clinical Global Impression (CGI)-Severity/Improvement scales; and child-rated Harter Self-Perception Profile (HSPP).

RESULTS

Quality of life of children/adolescents with ADHD was extremely compromised at baseline (CHIP-CE total t-scores: atomoxetine, 23.2 +/- 12.2; SCT, 23.9 +/- 11.0), and improved during the 10-week study for both groups; the CHIP-CE score was statistically significantly higher for patients treated with atomoxetine (38.4 +/- 1.3) compared with SCT (30.8 +/- 1.3) at week 10 (p < 0.001). ADHD-RS, CGI-Severity, and CGI-Improvement scores were significantly different between the groups in favour of atomoxetine (p < 0.001). There was a statistically significant difference between the groups in the HSPP Social Acceptance domain in favour of atomoxetine, but not in the five other HSPP domains or FBIM total score. Atomoxetine was well-tolerated.

CONCLUSIONS

Results from this open-label trial show that atomoxetine is superior to SCT in addressing broader efficacy and functional outcomes in UK children/adolescents with ADHD. This study contributes to the understanding of broader efficacy in children with ADHD, and is timely in light of recent NICE guidance.

Calcium-dependent interactions of the human norepinephrine transporter with syntaxin 1A

The norepinephrine (NE) transporter (NET) terminates noradrenergic signaling by clearing released NE at synapses. The activity of NET can be rapidly regulated by depolarization and receptor activation via Ca2+ and kinase/phosphatase-linked pathways. The SNARE protein syntaxin 1A (SYN1A) interacts with NET and influences transporter surface trafficking and catalytic activity. In this study, we establish a link between changes in intracellular Ca2+ and SYN1A/NET interactions. SYN1A influenced NE transport only in the presence of Ca2+ in brain cortical synaptosomes. Although NET/SYN1A associations were sensitive to manipulations of Ca2+ in CHO cells, in vitro binding experiments using purified NET and SYN1A fusion proteins demonstrated a lack of direct Ca2+ sensitivity. Disruption of NET/SYN1A interaction abolished inhibition of NE transport by phorbol ester (PMA) to activate protein kinase C (PKC), but had no effect on transport inhibition by the Ca2+ calmodulin kinase (CaMK) inhibitor KN93. Furthermore, PMA enhanced Ca2+-dependent modulation of NE transport in synaptosomes. Our data reveal roles for SYN1A in the Ca2+-dependent regulation of NET, likely reliant on regulation by PKC signaling, but independent of CaMK.

Atomoxetine treatment in children and adolescents with attention-deficit hyperactivity disorder: what are the long-term health-related quality-of-life outcomes?

OBJECTIVE

Numerous investigations have examined the efficacy of pharmacological treatment for attention-deficit/hyperactivity disorder (ADHD) in children. However, relatively few studies have addressed the impact of treatment on long-term subjective, psychosocial outcomes, such as health-related quality of life (HRQL). This study examines the long-term effects of pharmacological treatment with atomoxetine on HRQL in children and adolescents with ADHD.

METHODS

Participants included 6- to 17-year-old children and adolescents (n = 912) with ADHD enrolled in a 24-month, multicenter, open-label trial of atomoxetine. Outcomes included clinician ratings of ADHD, parent ratings of ADHD, and a widely used measure of HRQL (The Child Health Questionnaire (CHQ)). Treatment response rates were calculated based on a CHQ improvement of at least 1 standard error of measurement.

RESULTS

Significant improvements in HRQL were found following both acute and long-term treatment for psychosocial but not physical health. Of participants who completed treatment (n = 312 or 34.2% of those enrolled), 81% responded to acute treatment and 78% responded to long-term treatment. Improvements noted after acute treatment were maintained during long-term treatment with the majority of participants (86%) continuing to respond to treatment.

CONCLUSIONS

Atomoxetine is associated with improvements in HRQL, and the improvements are generally stable over time.

The Texas Children's Medication Algorithm Project: revision of the algorithm for pharmacotherapy of attention-deficit/hyperactivity disorder

OBJECTIVE

In 1998, the Texas Department of Mental Health and Mental Retardation developed algorithms for medication treatment of attention-deficit/hyperactivity disorder (ADHD). Advances in the psychopharmacology of ADHD and results of a feasibility study of algorithm use in community mental health centers caused the algorithm to be modified and updated.

METHOD

We convened a consensus conference of academic clinicians and researchers, practicing clinicians, administrators, consumers, and families to revise the algorithms for the pharmacotherapy of ADHD itself as well as ADHD with specific comorbid disorders. New research was reviewed by national experts, and rationales were provided for proposed changes and additions to the algorithms. The changes to the algorithms were discussed and approved both by the national experts and experienced clinicians from the Texas public mental health system.

RESULTS

The panel developed consensually agreed-upon algorithms for ADHD with and without comorbid disorders. The major changes included elimination of pemoline as a treatment option, adding atomoxetine to the algorithm, and refining guidelines for treating ADHD with comorbid depression, aggressive behaviors, and tic disorders.

CONCLUSIONS

Medication algorithms for ADHD can be modified to keep abreast of developments in the field. Although these evidence- and consensus-based treatment recommendations may be a useful approach to guide the treatment of ADHD in children, additional research is needed to determine how these algorithms can be used to maximally benefit child outcomes.

Pharmacogenetic tools for the development of target-oriented cognitive-enhancing drugs

The identification of the anatomical and physiological substrates involved in the regulation of the dorsolateral prefrontal cortex function in humans provided the basis for the understanding of mechanisms involved in cognitive and executive function under normal as well as pathological conditions. In this context, substantial evidence indicates that alterations in monaminergic function in the dorsolateral prefrontal cortex significantly contributes to the cognitive impairments present in schizophrenia, attention deficit disorders, and other neuropsychiatric conditions. The development of a number of compounds that selectively increase extracellular dopamine (DA) concentrations in the dorsolateral prefrontal cortex but not in subcortical areas by either blocking its metabolism or reuptake, or increasing its release, or that directly activate postsynaptic DA-1 receptor mechanisms provided powerful pharmacotherapeutic tools to mitigate the cognitive deficits brought about by the dopaminergic alterations of the prefrontal cortex. More recently, the findings that polymorphisms of the catecholamine-O-methyl-transferase gene may also modify the effect of these drugs on the prefrontal cortex points toward a more specific genotype-based neuropsychopharmacology for the treatment of cognitive deficits in schizophrenia as well as in a number of other neuropsychiatric conditions. The ability of these compounds to increase DA load selectively in the frontal cortex and not on subcortical systems allows a targeted intervention without the stimulant-like effects observed with older drugs used to treat those conditions.

Cataplexy associated with narcolepsy: epidemiology, pathophysiology and management

Although narcolepsy was first described over 100 years ago, most of what is known about the pathological changes in the CNS that are responsible for this unusual disease has been learned during the past few years. It is now known that narcolepsy is caused by the loss of a relatively few neurons that are responsible for producing the neuropeptide hypocretin in the CNS. The onset of narcolepsy typically occurs in early adulthood and may consist of a variety of symptoms; however, cataplexy (an abrupt, bilateral loss of skeletal muscle tone) is most specific to narcolepsy. TCAs were found to be beneficial for the treatment of cataplexy over 40 years ago and, more recently, the SSRIs have been used to treat the condition. The recent availability of sodium oxybate (the first drug to receive regulatory approval for the treatment of cataplexy) represents a significant advance in the treatment of narcolepsy, as it is highly efficacious for the treatment of cataplexy and shows promise for the treatment of excessive sleepiness and for improving sleep quality in patients with narcolepsy.

[Principles of managing chemotherapy-induced nausea and vomiting]

Chemotherapy-induced nausea and vomiting (emesis) can significantly affect a patient's quality of life, leading to poor compliance with further chemotherapy treatment. For patients treated with emetogenic chemotherapy, it is very important to prevent nausea and vomiting completely. The incidence and severity of nausea and/or vomiting in patients receiving chemotherapy are affected by numerous factors, including: 1) the specific chemotherapeutic agents used; 2) their dosage; 3) the schedule and route of administration; and 4) individual patient variability. Approximately 70 to 80% of all cancer patients receiving chemotherapy experience emesis, whereas 10% to 44% experience anticipatory emesis. The following general principles are recommended. 1) A 5-HT3 receptor antagonist should be administered prior to each day's 1st dose of moderately or highly emetogenic chemotherapy. 2) Dexamethasone should be administered once daily either orally or intravenously for every day of moderately or highly-emetogenic chemotherapy and for 2-3 days after chemotherapy for regimens that are likely to cause significant delayed-emesis. 3) The most effective way to treat anticipatory nausea and/or vomiting is to prevent it by using optimal antiemetic therapy during every cycle of treatment.

The safety of non-stimulant agents for the treatment of attention-deficit hyperactivity disorder

Due to their well-established efficacy and safety, stimulants are the drugs of first choice if medication for attention-deficit hyperactivity disorder (ADHD) is required. Nevertheless, for some individuals other, non-stimulant treatments are needed for several reasons. If so, atomoxetine is recommended as a second-line treatment. In addition, several tricyclic antidepressants, such as desipramine or imipramine, as well as alpha-2 agonists, especially clonidine or bupropion, might be efficient in treating ADHD, in particular in specific co-morbid conditions. Despite the fact that non-stimulant treatments in ADHD are usually well-tolerated with side effects being mostly moderate and transient, special safety aspects and precautions, specific for each drug, have to be considered whenever a non-stimulant treatment is chosen. This review focuses on the tolerability, occurrence of adverse events, precautions required to prevent severe adverse events, and essential pharmacological interaction in the treatment of ADHD symptoms by non-stimulants.

Proteomic analysis of human norepinephrine transporter complexes reveals associations with protein phosphatase 2A anchoring subunit and 14-3-3 proteins

The norepinephrine transporter (NET) terminates noradrenergic signals by clearing released NE at synapses. NET regulation by receptors and intracellular signaling pathways is supported by a growing list of associated proteins including syntaxin1A, protein phosphatase 2A (PP2A) catalytic subunit (PP2A-C), PICK1, and Hic-5. In the present study, we sought evidence for additional partnerships by mass spectrometry-based analysis of proteins co-immunoprecipitated with human NET (hNET) stably expressed in a mouse noradrenergic neuroblastoma cell line. Our initial proteomic analyses reveal multiple peptides derived from hNET, peptides arising from the mouse PP2A anchoring subunit (PP2A-Ar) and peptides derived from 14-3-3 proteins. We verified physical association of NET with PP2A-Ar via co-immunoprecipitation studies using mouse vas deferens extracts and with 14-3-3 via a fusion pull-down approach, implicating specifically the hNET NH2-terminus for interactions. The transporter complexes described likely support mechanisms regulating transporter activity, localization, and trafficking.

Safety, efficacy and extended duration of action of mixed amphetamine salts extended-release capsules for the treatment of ADHD

Stimulant medications have proven to be effective in reducing the core symptoms of hyperactivity, impulsivity and inattention and are considered the first line of therapy for patients with attention-deficit/hyperactivity disorder (ADHD). Mixed amphetamine salts extended-release capsules (MAS XR; Adderall XR, Shire Pharmaceuticals Group) include immediate-release pellets of mixed amphetamine salts that release the first half of the dose upon ingestion and delayed-release pellets that begin to release active drug approximately 4 h later. The MAS XR capsule contains the same 3:1 ratio of dextroamphetamine to levoamphetamine as do mixed amphetamine salts immediate-release tablets (MAS IR; Adderall), Shire Pharmaceuticals Group), and the bioavailability and pharmacokinetic profiles of MAS XR 20 mg are comparable to those with MAS IR 10 mg b.i.d. MAS XR has a rapid onset of action--within 1.5 h--and provides 12 h coverage. The efficacy, safety and extended duration of action of MAS XR have been established through clinical studies in school-age children, adolescents and adults.

Treatment of attention-deficit/hyperactivity disorder: overview of the evidence

The American Academy of Pediatrics' Committee on Quality Improvement, Subcommittee on Attention-Deficit/Hyperactivity Disorder, reviewed and analyzed the current literature for the purpose of developing an evidence-based clinical practice guideline for the treatment of the school-aged child with attention-deficit/hyperactivity disorder (ADHD). This review included several key reports, including an evidence review from the McMaster Evidence-Based Practice Center (supported by the Agency for Healthcare Research and Quality), a report from the Canadian Coordinating Office for Health Technology Assessment, the Multimodal Treatment for ADHD comparative clinical trial (supported by the National Institute of Mental Health), and supplemental reviews conducted by the subcommittee. These reviews provided substantial information about different treatments for ADHD and their efficacy in improving certain characteristics or outcomes for children with ADHD as well as adverse effects and benefits of multiple modes of treatment compared with single modes (eg, medication or behavior therapies alone). The reviews also compared the effects of different medications. Other evidence documents the long-term nature of ADHD in children and its classification as a chronic condition, meriting the application of general concepts of chronic-condition management, including an individual treatment plan with a focus on ongoing parent and child education, management, and monitoring. The evidence strongly supports the use of stimulant medications for treating the core symptoms of children with ADHD and, to a lesser degree, for improving functioning. Behavior therapy alone has only limited effect on symptoms or functioning of children with ADHD, although combining behavior therapy with medication seems to improve functioning and may decrease the amount of (stimulant) medication needed. Comparison among stimulants (mainly methylphenidate and amphetamines) did not indicate that 1 class outperformed the other.

Managing attention deficit/hyperactivity disorder: unmet needs and future directions

The management of attention deficit/hyperactivity disorder (ADHD) requires a multimodal approach. Although shared-care protocols are suggested, uptake by general practice has been tentative. Behavioural management, both on its own and in combination with pharmacotherapy, reduces core symptoms and associated behaviours, such as oppositional defiant disorder (ODD). Links with education and social support are also important for helping children and their families. Psychostimulants have shown to be effective in the treatment of ADHD, however, their short duration of action highlights potential limitations. Other drugs used in the management of ADHD and comorbid disorders include antidepressants, clonidine and its analogues, newer atypical neuroleptics, and atomoxetine, a novel, non-stimulant therapy that has potential to fulfil some unmet treatment needs. Further research is needed in preschool children, girls, those with epilepsy, young adults, and in those with associated sleep disturbance. Selected rating scales and careful history taking, allied to close links with schools, are vital for the initial and ongoing assessment of ADHD and its comorbidities.

Atomoxetine: a new pharmacotherapeutic approach in the management of attention deficit/hyperactivity disorder

Atomoxetine is a novel, non-stimulant, highly selective noradrenaline reuptake inhibitor that has been studied for use in the treatment of attention deficit/hyperactivity disorder (ADHD). Data from clinical trials show it to be well tolerated and effective in the treatment of ADHD in children, adolescents, and adults. Improvements were seen not only in core symptoms of ADHD, but also in broader social and family functioning and self esteem. Once-daily dosing of atomoxetine has been shown to be effective in providing continuous symptom relief. Atomoxetine does not appear to have abuse potential and is associated with a benign side effect profile. The development of atomoxetine thus represents an important advance in the pharmacological management of ADHD.

Non-stimulant medications in the treatment of ADHD

BACKGROUND

Stimulants are the first-line medication in the psychopharmacological treatment of attention-deficit hyperactivity disorder (ADHD). However, 10 to 30% of all children and adults with ADHD either do not respond to or do not tolerate treatment with stimulants.

OBJECTIVE

To describe alternative treatment approaches with various non-stimulant agents, especially atomoxetine.

METHOD

General review of empirically based literature concerning efficacy and safety of the substances.

RESULTS

A large and still increasing body of data supports the usefulness of atomoxetine, a once daily dosing, and new selective noradrenalin reuptake inhibitor, with few side effects. Atomoxetine has been licensed in the US for use in ADHD across the lifespan, and is currently under consideration in Europe. Other non-stimulant substances, such as tricyclic antidepressants (TCAs) and alpha-2-adrenergic agonists, which are used to treat ADHD, are also reviewed. TCAs have been well studied and shown to be efficacious in the treatment of ADHD, but are limited by side effects. The number of studies documenting the efficacy of alpha-2-adrenergic agonists is still limited. Some experimental studies support a potential role of cholinergic drugs such as acetylcholinesterase inhibitors (tacrine, donepezil) as well as novel nicotinic analogues (ABT-418).

CONCLUSION

Non-stimulant agents have been shown to be effective in treatment of ADHD. Especially, atomoxetine seems promising and newline drugs are in development.

Atomoxetine and nicotine enhance prepulse inhibition of acoustic startle in C57BL/6 mice

Deficits in sensory-gating, often measured as deficits in prepulse inhibition of acoustic startle (PPI), are associated multiple with disorders including schizophrenia, attention deficit and hyperactivity disorder (ADHD), and withdrawal from nicotine. Drugs that can reverse deficits in PPI may serve as therapeutic agents for nicotine withdrawal, ADHD, and/or schizophrenia. The present study investigated the effects of acute atomoxetine, a norepinephrine reuptake inhibitor, nicotine, and mecamylamine, a nicotinic acetylcholinergic antagonist, on PPI and acoustic startle in C57BL/6 mice. Three doses of atomoxetine (0.2, 2.0, and 20 mg/kg) were administered prior to testing PPI and startle. The 0.2 and 2.0 mg/kg doses enhanced PPI and the 20 mg/kg dose enhanced startle. A second experiment investigated the effects of 2.0 mg/kg atomoxetine and 1.0mg/kg mecamylamine administered alone or together on PPI and startle. As before, atomoxetine enhanced PPI. Mecamylamine did not alter PPI and did not block the enhancement of PPI by atomoxetine. Neither drug altered startle. A third experiment investigated the effects of 2.0 mg/kg atomoxetine and 0.125 mg/kg nicotine administered alone or together on PPI and startle. Both drugs enhanced PPI when administered alone. However, when co-administered, no enhancement of PPI was seen. Neither nicotine nor atomoxetine altered startle. The present results demonstrate that acute doses of nicotine and atomoxetine enhance PPI independent of effects on startle and that the enhancement of PPI by atomoxetine occurs independent of the nicotinic acetylcholinergic system. Thus, the newly available medication for ADHD, atomoxetine, could be a potential therapeutic agent for disorders associated with disrupted PPI such as withdrawal from nicotine.

On the potential role of glutamate transport in mental fatigue

Mental fatigue, with decreased concentration capacity, is common in neuroinflammatory and neurodegenerative diseases, often appearing prior to other major mental or physical neurological symptoms. Mental fatigue also makes rehabilitation more difficult after a stroke, brain trauma, meningitis or encephalitis. As increased levels of proinflammatory cytokines are reported in these disorders, we wanted to explore whether or not proinflammatory cytokines could induce mental fatigue, and if so, by what mechanisms.

It is well known that proinflammatory cytokines are increased in major depression, "sickness behavior" and sleep deprivation, which are all disorders associated with mental fatigue. Furthermore, an influence by specific proinflammatory cytokines, such as interleukin (IL)-1, on learning and memory capacities has been observed in several experimental systems. As glutamate signaling is crucial for information intake and processing within the brain, and due to the pivotal role for glutamate in brain metabolism, dynamic alterations in glutamate transmission could be of pathophysiological importance in mental fatigue. Based on this literature and observations from our own laboratory and others on the role of astroglial cells in the fine-tuning of glutamate neurotransmission we present the hypothesis that the proinflammatory cytokines tumor necrosis factor-α, IL-1β and IL-6 could be involved in the pathophysiology of mental fatigue through their ability to attenuate the astroglial clearance of extracellular glutamate, their disintegration of the blood brain barrier, and effects on astroglial metabolism and metabolic supply for the neurons, thereby attenuating glutamate transmission. To test whether our hypothesis is valid or not, brain imaging techniques should be applied with the ability to register, over time and with increasing cognitive loading, the extracellular concentrations of glutamate and potassium (K⁺) in humans suffering from mental fatigue. At present, this is not possible for technical reasons. Therefore, more knowledge of neuronal-glial signaling in in vitro systems and animal experiments is important.

In summary, we provide a hypothetic explanation for a general neurobiological mechanism, at the cellular level, behind one of our most common symptoms during neuroinflammation and other long-term disorders of brain function. Understanding pathophysiological mechanisms of mental fatigue could result in better treatment.