Guanfacine treatment of comorbid attention-deficit hyperactivity disorder and Tourette's syndrome: preliminary clinical experience

Pharmacological treatment of Tourette's syndrome: from the past to the future

Tourette's syndrome (TS) is a neuropsychiatric disease featuring tics and vocal tics, with a prevalence of approximately 1%, including 75% of the total number of male patients. TS seriously disturbs the patients' career, education, and life and brings a serious and unbearable psychological burden to the patients themselves and their families. At present, there are no specific clinical medications recommended for treating TS. Therefore, it is necessary to select the appropriate medication for symptomatic treatment based on the doctor's personal experience and the patient's symptoms, with the main goal of relieving symptoms, thus improving the patient's social skills and psychological problems. Here we conducted a comprehensive search on PubMed to review and organize the history and current status of the development of drug therapy for TS through a timeline format. We also systematically evaluated the effects of each drug for TS treatment to summarize the current problems and new research directions and to provide some ideas for clinical treatment.

Genetic mapping identifies Homer1 as a developmental modifier of attention

Attention is required for most higher-order cognitive functions. Prior studies have revealed functional roles for the prefrontal cortex and its extended circuits to enabling attention, but the underlying molecular processes and their impacts on cellular and circuit function remain poorly understood. To develop insights, we here took an unbiased forward genetics approach to identify single genes of large effect on attention. We studied 200 genetically diverse mice on measures of pre-attentive processing and through genetic mapping identified a small locus on chromosome 13 (95%CI: 92.22-94.09 Mb) driving substantial variation (19%) in this trait. Further characterization of the locus revealed a causative gene, Homer1, encoding a synaptic protein, where down-regulation of its short isoforms in prefrontal cortex (PFC) during early postnatal development led to improvements in multiple measures of attention in the adult. Subsequent mechanistic studies revealed that prefrontal Homer1 down-regulation is associated with GABAergic receptor up-regulation in those same cells. This enhanced inhibitory influence, together with dynamic neuromodulatory coupling, led to strikingly low PFC activity at baseline periods of the task but targeted elevations at cue onset, predicting short-latency correct choices. Notably high-Homer1, low-attentional performers, exhibited uniformly elevated PFC activity throughout the task. We thus identify a single gene of large effect on attention - Homer1 - and find that it improves prefrontal inhibitory tone and signal-to-noise (SNR) to enhance attentional performance. A therapeutic strategy focused on reducing prefrontal activity and increasing SNR, rather than uniformly elevating PFC activity, may complement the use of stimulants to improve attention.

Report of a Work Group on Sluggish Cognitive Tempo: Key Research Directions and a Consensus Change in Terminology to Cognitive Disengagement Syndrome

OBJECTIVE

The aim of this work was 2-fold: (1) to evaluate current knowledge and identify key directions in the study of sluggish cognitive tempo (SCT); and (2) to arrive at a consensus change in terminology for the construct that reflects the current science and may be more acceptable to researchers, clinicians, caregivers, and patients.

METHOD

An international Work Group was convened that, in early 2021, compiled an online archive of all research studies on SCT and summarized the current state of knowledge, noted methodological issues, and highlighted future directions, and met virtually on 10 occasions in 2021 to discuss these topics and terminology.

RESULTS

Major progress has been made over the last decade in advancing our understanding of SCT across the following domains of inquiry: construct measurement and stability; genetic, environmental, pathophysiologic, and neuropsychological correlates; comorbid conditions; functional impairments; and psychosocial and medication interventions. Findings across these domains are summarized, and potential avenues to pursue in the next generation of SCT-related research are proposed. Following repeated discussions on terminology, the Work Group selected "cognitive disengagement syndrome" (CDS) to replace "SCT" as the name for this construct. This term was deemed to best satisfy considerations that should apply when selecting terms for a condition or syndrome, as it does not overlap with established terms for other constructs, is not offensive, and reflects the current state of the science.

CONCLUSION

It is evident that CDS (SCT) has reached the threshold of recognition as a distinct syndrome. Much work remains to further clarify its nature (eg, transdiagnostic factor, separate disorder, diagnostic specifier), etiologies, demographic factors, relations to other psychopathologies, and linkages to specific domains of functional impairment. Investigators are needed with interests and expertise spanning basic, clinical, and translational research to advance our understanding and to improve the lives of individuals with this unique syndrome.

Pharmacologic Management of Cognitive Disengagement Syndrome (CDS) and Implications for Attention-Deficit/Hyperactivity Disorder (ADHD) Treatment: Emerging Treatments and Recommendations for Future Research

Although the study of cognitive disengagement syndrome (CDS; previously called sluggish cognitive tempo) first emerged in the 1980s, very little is known about treating CDS or its impact on evidence-based interventions for attention-deficit/hyperactivity disorder (ADHD) with which it frequently co-occurs. The objective of this leading article was to investigate the existing evidence on medication treatment and CDS, including studies that have examined CDS response to medication and CDS as a moderator of ADHD treatment response. A total of seven studies were identified. At present, the limited existing literature suggests that psychostimulants such as methylphenidate and lisdexamfetamine, as well as atomoxetine, may improve CDS symptoms, although replication and research on related medications is needed. However, there are indications that CDS symptoms may predict a reduced response to methylphenidate in children with ADHD. Although untested, research on the neurobiological, neuropsychological, and behavioral correlates of CDS point to a possible benefit of other ADHD medications (e.g., guanfacine), medications that treat narcolepsy (e.g., modafinil), and medications traditionally used to treat depression and anxiety (e.g., viloxazine, bupropion, fluvoxamine), some of which have also recently been used in ADHD management. The article concludes with recommendations for future research on pharmacologic treatment and CDS.

Adverse Effects of α-2 Adrenergic Agonists and Stimulants in Preschool-age Attention-deficit/Hyperactivity Disorder: A Developmental-Behavioral Pediatrics Research Network Study

OBJECTIVES

To characterize and compare the type and frequency of a range of common and uncommon adverse effects (AEs) associated with α-2 adrenergic agonist (A2A) and stimulant treatment of attention-deficit/hyperactivity disorder at preschool-age as well as to evaluate the impact of age on common AEs.

STUDY DESIGN

This was a retrospective electronic medical record review of children <72 months of age (n = 497) evaluated at outpatient developmental-behavioral pediatric practices at 7 US academic medical centers within the Developmental-Behavioral Pediatrics Research Network. Data on AEs were abstracted for children who had treatment initiated by a developmental-behavioral pediatrician with an A2A or stimulant medication between January 2013 and July 2017; follow-up was complete by February 2019.

RESULTS

A2A and stimulants had distinctive AE profiles. A2A compared with stimulants had a greater proportion with daytime sleepiness and headaches; stimulants had significantly greater proportions for most other AE, including moodiness/irritability, difficulty with sleep, appetite suppression, stomachaches, skin picking/repetitive behaviors, withdrawn behavior, and weight loss. Younger age was associated with disruptive behavior and difficulty with sleep.

CONCLUSIONS

Stimulants had a greater rate of most AEs compared with A2A. AE profiles, together with efficacy, should inform clinical decision-making. Prospective randomized clinical trials are needed to fully compare efficacy and AE profiles of A2A and stimulants.

Evidence-based pharmacological treatment options for ADHD in children and adolescents

Attention-deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by inattention, hyperactivity, and impulsivity, causing functional impairment. Its prevalence lies at approximately 5% in children and adolescents and at approximately 2.5% in adults. The disorder follows a multifactorial etiology and shows a high heritability. Patients show a high interindividual and intraindividual variability of symptoms, with executive deficits in several cognitive domains. Overall, ADHD is associated with high rates of psychiatric comorbidities, and insufficient treatment is linked to adverse long-term outcomes. Current clinical guidelines recommend an individualized multimodal treatment approach including psychoeducation, pharmacological interventions, and non-pharmacological interventions. Available medications include stimulants (methylphenidate, amphetamines) and non-stimulants (atomoxetine, guanfacine, clonidine). While available pharmacological treatment options for ADHD show relatively large effect sizes (in short-term trials) and overall good tolerability, there is still a need for improvement of current pharmacotherapeutic strategies and for the development of novel medications. This review summarizes available pharmacological treatment options for ADHD in children and adolescents, identifies current issues in research and evidence gaps, and provides an overview of ongoing efforts to develop new medications for the treatment of ADHD in children and adolescents by means of a systematic cross-sectional analysis of the clinical trials registry www.clinicaltrials.gov.

Efficacy and Safety of Medication for Attention-Deficit Hyperactivity Disorder in Children and Adolescents with Common Comorbidities: A Systematic Review

Introduction

Comorbid psychiatric conditions in children and adolescents with attention-deficit hyperactivity disorder (ADHD) occur frequently, complicate management, and are associated with substantial burden on patients and caregivers. Very few systematic reviews have assessed the efficacy and safety of medications for ADHD in children and adolescents with comorbidities. Of those that were conducted, most focused on a particular comorbidity or medication. In this systematic literature review, we summarize the efficacy and safety of treatments for children and adolescents with ADHD and comorbid autism spectrum disorders, oppositional defiant disorder, Tourette’s disorder and other tic disorders, generalized anxiety disorder, and major depressive disorder.

Methods

We searched MEDLINE, Embase, and ClinicalTrials.gov (to October 2019) for studies of patients (aged < 18 years) with an ADHD diagnosis and the specified comorbidities treated with amphetamines, methylphenidate and derivatives, atomoxetine (ATX), and guanfacine extended-release (GXR). For efficacy, placebo-controlled randomized controlled trials (RCTs) or meta-analyses of RCTs were eligible for inclusion; for safety, all study types were eligible. The primary efficacy outcome measure was ADHD Rating Scale IV (ADHD-RS-IV) total score.

Results

Of 2177 publications/trials retrieved, 69 were included in this systematic literature review (5 meta-analyses, 37 placebo-controlled RCTs, 16 cohort studies, 11 case reports). A systematic narrative synthesis is provided because insufficient data were retrieved to combine ADHD-RS-IV total scores or effect sizes. Effect sizes for ADHD-RS-IV total scores were available for ten RCTs and ranged from 0.46 to 1.0 for ATX and from 0.92 to 2.0 for GXR across comorbidities. The numbers and types of adverse events in children with comorbidities were consistent with those in children without comorbidities, but treatment should be individualized to ensure children can tolerate the lowest effective dose.

Conclusion

Limited information is available from placebo-controlled RCTs on the efficacy (by ADHD-RS-IV) or safety of medication in children with ADHD and psychiatric comorbidities. Further studies are required to support evidence-based drug selection for these populations.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40120-021-00249-0.

A Comprehensive Review of Tic Disorders in Children

Tics are characterized by sudden, rapid, recurrent, nonrhythmic movement or vocalization, and are the most common movement disorders in children. Their onset is usually in childhood and tics often will diminish within one year. However, some of the tics can persist and cause various problems such as social embarrassment, physical discomfort, or emotional impairments, which could interfere with daily activities and school performance. Furthermore, tic disorders are frequently associated with comorbid neuropsychiatric symptoms, which can become more problematic than tic symptoms. Unfortunately, misunderstanding and misconceptions of tic disorders still exist among the general population. Understanding tic disorders and their comorbidities is important to deliver appropriate care to patients with tics. Several studies have been conducted to elucidate the clinical course, epidemiology, and pathophysiology of tics, but they are still not well understood. This article aims to provide an overview about tics and tic disorders, and recent findings on tic disorders including history, definition, diagnosis, epidemiology, etiology, diagnostic approach, comorbidities, treatment and management, and differential diagnosis.

Current Management of Tics and Tourette Syndrome: Behavioral, Pharmacologic, and Surgical Treatments

Tourette syndrome is a heterogeneous neurobehavioral disorder manifested by childhood-onset motor and phonic tics, often accompanied by a variety of behavioral comorbidities, including attention deficit and obsessive compulsive disorder. Treatment must be tailored to the needs and goals of the individual patients and their families. All patients should receive education on the condition and, if possible, engage behavioral therapy targeted towards tics and/or comorbidities. Pharmacological therapies, such as alpha agonists, topiramate, and vesicular monoamine transport type 2 inhibitors, are generally used as first-line therapies in patients with troublesome tics that are not controlled by behavioral therapy or when the latter is not available or accessible. Botulinum toxin injections can be used in patients with bothersome focal tics. Second-line therapy includes antipsychotics, such as fluphenazine, aripiprazole, risperidone, and ziprasidone. These medications are generally efficacious but carry the risk of metabolic syndrome, tardive dyskinesia, and other side effects. Much more research is needed before novel therapies such as cannabis-derived products or transcranial magnetic stimulation can be recommended. There is promise in ongoing clinical trials with D1 receptor antagonist ecopipam and other experimental therapeutics. Patients with tics that are refractory to conventional treatments may be candidates for deep brain stimulation, but further studies are needed to determine the optimal target selection.

Central norepinephrine transmission is required for stress-induced repetitive behavior in two rodent models of obsessive-compulsive disorder

RATIONALE

Obsessive-compulsive disorder (OCD) is characterized by repetitive behaviors exacerbated by stress. Many OCD patients do not respond to available pharmacotherapies, but neurosurgical ablation of the anterior cingulate cortex (ACC) can provide symptomatic relief. Although the ACC receives noradrenergic innervation and expresses adrenergic receptors (ARs), the involvement of norepinephrine (NE) in OCD has not been investigated.

OBJECTIVE

To determine the effects of genetic or pharmacological disruption of NE neurotransmission on marble burying (MB) and nestlet shredding (NS), two animal models of OCD.

METHODS

We assessed NE-deficient (Dbh -/-) mice and NE-competent (Dbh +/-) controls in MB and NS tasks. We also measured the effects of anti-adrenergic drugs on NS and MB in control mice and the effects of pharmacological restoration of central NE in Dbh -/- mice. Finally, we compared c-fos induction in the locus coeruleus (LC) and ACC of Dbh -/- and control mice following both tasks.

RESULTS

Dbh -/- mice virtually lacked MB and NS behaviors seen in control mice but did not differ in the elevated zero maze (EZM) model of general anxiety-like behavior. Pharmacological restoration of central NE synthesis in Dbh -/- mice completely rescued NS behavior, while NS and MB were suppressed in control mice by anti-adrenergic drugs. Expression of c-fos in the ACC was attenuated in Dbh -/- mice after MB and NS.

CONCLUSION

These findings support a role for NE transmission to the ACC in the expression of stress-induced compulsive behaviors and suggest further evaluation of anti-adrenergic drugs for OCD is warranted.

The association between tic medication therapy and psychiatric comorbidities among patients with Tourette syndrome: A national population-based study in Taiwan

BACKGROUND

Tourette syndrome (TS) is often comorbid with attention deficit hyperactivity disorder, obsessive-compulsive disorder, and depression. Medications are the main treatment for TS. Relationships between TS medication therapy and psychiatric comorbidities remain unclear. This study explored the impacts of TS medication on the risk of psychiatric comorbidities using a nationally representative sample of TS in Taiwan.

METHODS

Data from National Health Insurance Research Database in Taiwan was used to identify 997,213 children and adolescents aged 6-18 years who had received a diagnosis of TS based on ICD-9-CM codes in 2000-2010. Cox's proportional hazard regression analysis was conducted to estimate the risk of comorbidities among subjects with and without tic medication therapy.

RESULTS

We found that in TS patients, a lower risk of psychiatric comorbidities occurred in the tic medication therapy group (p = 0.012) and the crude hazard ratio (HR) was 0.6 (95% confidence interval (CI) = 0.4-0.8, p < 0.001). After adjusting for potential confounders of gender, age, income, level of care, department visited, brain injury, and the number of suicide attempts, the risk of comorbidities was still significantly lower in the tic medication therapy group (adjusted HR = 0.5, 95% CI = 0.3-0.6, p < 0.001).

DISCUSSION

One limitation was that we did not include all mediations used to treat psychiatric comorbidities among TS patients. This study found the effectiveness of TS medications on improving psychiatric comorbidities.

CONCLUSIONS

Compared to those without medication, medication therapy appears to have a benefit of decreasing the risk of psychiatric comorbidities. Strategies to improve medication regimens should be considered in clinical settings.

Drug and Non-drug Treatment of Tourette Syndrome

Background:

Tourette Syndrome (TS) is a neurodevelopmental disorder characterized by multiple repetitive motor and vocal tics. In most patients, its clinical course has a waxing and waning nature and most patients, usually children, will benefit from tolerant environmental and psychoeducation. Patients with more complicated tics, in particular, those with significant comorbidities will require drug therapy.

Objective:

The present paper is a mini-review of the current therapeutic arsenal for TS with reference to drug and non-drug management approach.

Methods:

A systematic survey of medical literature regarding the treatment decision making and the reported clinical trials or accumulating experience with different medications or other therapeutic modalities which were proven beneficial over the years.

Results:

Reviewing the literature indicates that dopamine antagonists, such as haloperidol and pimozoide, are the most reliable agents in terms of treatment response. Due to numerous adverse effects, newer atypical anti-psychotic drugs have been shown effective. Other widely accepted medications include alpha-2 adrenergic agonists, benzamides, dopamine depleting agents, benzodiazepines and dopamine depleting agents. In more selective and intractable cases botulinum toxin, dopamine agonists and cannabinoids should be also considered. Non-pharmacologic therapies reported beneficial effects, which include on the one hand, non-invasive behavioral techniques, such as comprehensive behavior therapy for tics. While on the other hand, in cases with particular protracted pharmaco-resistant tics electric stimulation techniques, such as deep brain stimulation, have been shown to be successful.

Conclusion:

Currently, there are numerous multifarious options for treatment of tics and other comorbid symptoms of TS. Nevertheless, treatment options and decision-making algorithms are still a clinical challenge.

Area Covered:

A step by step decision-making and various drugs and non-pharmacologic modalities appropriate for the management of TS.

Effect of ADHD medication in male C57BL/6J mice performing the rodent Continuous Performance Test

RATIONALE

The rodent Continuous Performance Test (rCPT) is a novel rodent paradigm to assess attention and impulsivity that resembles the human CPT. This task measures the rodents' ability to discriminate between target and non-target stimuli. The effect of attention-deficit/hyperactivity disorder (ADHD) medication on rCPT performance in mice remains to be fully characterized.

OBJECTIVE

To investigate the predictive validity of the mouse rCPT by studying the effects of ADHD medication methylphenidate, atomoxetine, amphetamine, guanfacine, and modafinil in four behavioral subgroups based on performance and impulsivity levels.

METHODS

Two cohorts of male C57BL/6J mice were used, and the effect of treatment was tested in a variable stimulus duration probe. Performance and impulsive subgroups were made based on discriminability and percentage premature responses, respectively.

RESULTS

Methylphenidate, atomoxetine, and amphetamine improved performance in the low-performing animals, with no effect in the high-performers. These improvements were a result of increased hit rate and/or decreased false-alarm rate. Furthermore, these drugs decreased percentage premature responses in the high-impulsive group. Methylphenidate, guanfacine, and modafinil increased premature responses in the low-impulsive group. Modafinil impaired performance in the high-performers by increasing false-alarm rate.

CONCLUSION

The effect of ADHD treatment was dependent on baseline, as seen by increases in performance for the low-performers and decreases in impulsivity for the high-impulsive animals. These results agree with clinical data and may support the inverted U-shaped arousal-performance theory. The rCPT combined with behavioral separation into subgroups has high predictive validity, and our study is a step forward towards establishing the clinical translatability of the rCPT.

Weight and Height in Children and Adolescents with Attention-Deficit/Hyperactivity Disorder: A Longitudinal Database Study Assessing the Impact of Guanfacine, Stimulants, and No Pharmacotherapy

Objectives: To assess the impact of long-term pharmacotherapy with guanfacine immediate- or extended-release (GXR), administered alone or as an adjunctive to a stimulant, on weight and height in children and adolescents with attention-deficit/hyperactivity disorder (ADHD). Methods: Data were extracted from U.S. Department of Defense medical records for patients 4-17 years of age at index date (initiation of any study medication following a year without ADHD medications, or diagnosis if unmedicated) with weight/height measurements for the analysis period (January 2009-June 2013) and the previous year (baseline). Longitudinal weight and height z-scores were analyzed using multivariable regression in three cohorts: guanfacine (initial period of guanfacine exposure), first-line stimulant monotherapy (initial period of exposure), and unmedicated. Guanfacine cohort subgroups were based on previous/concurrent stimulant exposure. Results: The weight analyses included 47,910 patients (66.8% male) and the height analyses 41,248 (67.2% male). Mean initial exposure in the weight analyses was 237 days (standard deviation [SD] = 258, median = 142) for guanfacine and 257 days (SD = 284, median = 151) for first-line stimulant monotherapy, and was similar in the height analyses. Modeling indicated that guanfacine monotherapy was not associated with clinically meaningful deviations from normal z-score trajectories for weight (first-line, n = 943; nonfirst-line, n = 796) or height (first-line, n = 741; nonfirst-line, n = 644). In patients receiving guanfacine adjunctive to a stimulant, modeled weight (n = 1657) and height (n = 1343) z-scores followed declining trajectories. In this subgroup, mean standardized weight/height had decreased during previous stimulant monotherapy. For first-line stimulant monotherapy, modeled weight (n = 32,999) and height (n = 28,470) z-scores followed declining trajectories during year 1. In the unmedicated cohort, modeled weight (n = 11,515) and height (n = 10,050) z-scores were stable. Conclusions: Guanfacine monotherapy (first-line or nonfirst-line) was not associated with marked deviations from normal growth in this modeling study of children and adolescents with ADHD. In contrast, growth trajectories followed an initially declining course with stimulants, whether given alone or with adjunctive guanfacine.

Current Approaches and New Developments in the Pharmacological Management of Tourette Syndrome

Tourette syndrome (TS) is a neurodevelopmental disorder of unknown etiology characterized by spontaneous, involuntary movements and vocalizations called tics. Once thought to be rare, TS affects 0.3-1% of the population. Tics can cause physical discomfort, emotional distress, social difficulties, and can interfere with education and desired activities. The pharmacologic treatment of TS is particularly challenging, as currently the genetics, neurophysiology, and neuropathology of this disorder are still largely unknown. However, clinical experience gained from treating TS has helped us better understand its pathogenesis and, as a result, derive treatment options. The strongest data exist for the antipsychotic agents, both typical and atypical, although their use is often limited in children and adolescents due to their side-effect profiles. There are agents in a variety of other pharmacologic categories that have evidence for the treatment of TS and whose side-effect profiles are more tolerable than the antipsychotics; these include clonidine, guanfacine, baclofen, topiramate, botulinum toxin A, tetrabenazine, and deutetrabenazine. A number of new agents are being developed and tested as potential treatments for TS. These include valbenazine, delta-9-tetrahydrocannabidiol, and ecopipam. Additionally, there are agents with insufficient data for efficacy, as well as agents that have been shown to be ineffective. Those without sufficient data for efficacy include clonazepam, ningdong granule, 5-ling granule, omega-3 fatty acids, and n-acetylcysteine. The agents that have been shown to be ineffective include pramipexole and metoclopramide. We will review all of the established pharmacologic treatments, and discuss those presently in development.

Sex differences in guanfacine effects on stress-induced stroop performance in cocaine dependence

AIMS

Chronic drug abuse leads to sex-specific changes in drug cue and stress physiologic and neuroendocrine reactivity as well as in neural responses to stress and cue-related challenges and in executive function such as inhibitory control, cognitive flexibility and self control. Importantly, these functions have been associated with high risk of relapse and treatment. Alpha-2 agonism may enhance inhibitory cognitive processes in the face of stress with sex-specific effects, however this has not been previously assessed in cocaine dependence.

METHOD

Forty inpatient treatment-seeking cocaine dependent individuals (13F/27M) were randomly assigned to receive either placebo or up to 3mgs of Guanfacine. Three laboratory sessions were conducted following 3-4 weeks of abstinence, where patients were exposed to three 10-min personalized guided imagery conditions (stress, drug cue, combined stress/cue), one per day, on consecutive days in a random, counterbalanced order. The Stroop task was administered at baseline and immediately following imagery exposure.

RESULTS

Guanfacine treated women improved their performance on the Stroop task following exposure to all 3 imagery conditions compared with placebo women (p=0.02). This improvement in cognitive inhibitory performance was not observed in the men.

CONCLUSIONS

Enhancing the ability to cognitively regulate in the face of stress, drug cues and combined stress and drug cue reactivity may be key targets for medications development in cocaine dependent women.

A Review of the Neuropsychological Dimensions of Tourette Syndrome

Neurocognitive functioning in Tourette syndrome (TS) has been the subject of intensive research in the past 30 years. A variety of impairments, presumably related to frontal and frontostriatal dysfunctions, have been observed. These impairments were found in various domains, such as attention, memory, executive functions, language, motor and visuomotor functions, among others. In line with contemporary research, other neurocognitive domains have recently been explored in TS, bringing evidence of altered social reasoning, for instance. Therefore, the aims of this review are to give an overview of the neuropsychological dimensions of TS, to report how neuropsychological functions evolve from childhood to adulthood, and to explain how various confounding factors can affect TS patients' performance in neuropsychological tasks. Finally, an important contribution of this review is to show how recent research has confirmed or changed our beliefs about neuropsychological functioning in TS.

Treatment-refractory Tourette Syndrome

Tourette Syndrome (TS) is a complex neurodevelopmental condition marked by tics and frequently associated with psychiatric comorbidities. While most cases are mild and improve with age, some are treatment-refractory. Here, we review strategies for the management of this population. We begin by examining the diagnosis of TS and routine management strategies. We then consider emerging treatments for refractory cases, including deep brain stimulation (DBS), electroconvulsive therapy (ECT), repetitive transcranial magnetic stimulation (rTMS), and novel pharmacological approaches such as new vesicular monoamine transporter type 2 inhibitors, cannabinoids, and anti-glutamatergic drugs.

Targeting Prefrontal Cortical Systems for Drug Development: Potential Therapies for Cognitive Disorders

Medications to treat cognitive disorders are increasingly needed, yet researchers have had few successes in this challenging arena. Cognitive abilities in primates arise from highly evolved N-methyl-d-aspartate (NMDA) receptor circuits in layer III of the dorsolateral prefrontal cortex. These circuits have unique modulatory needs that can differ from the layer V neurons that predominate in rodents, but they offer multiple therapeutic targets. Cognitive improvement often requires low doses that enhance the pattern of information held in working memory, whereas higher doses can produce nonspecific changes that obscure information. Identifying appropriate doses for clinical trials may be helped by assessments in monkeys and by flexible, individualized dose designs. The use of guanfacine (Intuniv) for prefrontal cortical disorders was based on research in monkeys, supporting this approach. Coupling our knowledge of higher primate circuits with the powerful methods now available in drug design will help create effective treatments for cognitive disorders.

Guanfacine Extended Release: A New Pharmacological Treatment Option in Europe

Children/adolescents with attention-deficit/hyperactivity disorder (ADHD) may have a poor or inadequate response to psychostimulants or be unable to tolerate their side-effects; furthermore, stimulants may be inappropriate because of co-existing conditions. Only one non-stimulant ADHD pharmacotherapy, the noradrenaline transporter inhibitor atomoxetine, is currently approved for use in Europe. We review recent advances in understanding of the pathophysiology of ADHD with a focus on the roles of catecholamine receptors in context of the α2A-adrenergic receptor agonist guanfacine extended release (GXR), a new non-stimulant treatment option in Europe. Neuroimaging studies of children/adolescents with ADHD show impaired brain maturation, and structural and functional anomalies in brain regions and networks. Neurobiological studies in ADHD and medication response patterns support involvement of monoaminergic neurotransmitters (primarily dopamine and noradrenaline). Guanfacine is a selective α2A-adrenergic receptor agonist that has been shown to improve prefrontal cortical cognitive function, including working memory. The hypothesized mode of action of guanfacine centres on direct stimulation of post-synaptic α2A-adrenergic receptors to enhance noradrenaline neurotransmission. Preclinical data suggest that guanfacine also influences dendritic spine growth and maturation. Clinical trials have demonstrated the efficacy of GXR in ADHD, and it is approved as monotherapy or adjunctive therapy to stimulants in Canada and the USA (for children and adolescents). GXR was approved recently in Europe for the treatment of ADHD in children and adolescents for whom stimulants are not suitable, not tolerated or have been shown to be ineffective. GXR may provide particular benefit for children/adolescents who have specific co-morbidities such as chronic tic disorders or oppositional defiant disorder (or oppositional symptoms) that have failed to respond to first-line treatment options.

Clinical and Pharmacologic Considerations for Guanfacine Use in Very Young Children

OBJECTIVE

Guanfacine, in the immediate release form, remains a commonly used medication for the treatment of clinically significant hyperactivity, impulsivity, or disruptive behaviors. This article reviews the available literature regarding guanfacine use in very young children (<6 years of age), and explores some of the factors that may uniquely impact the clinical pharmacology of guanfacine in very young children and that deserve consideration when it is used in this patient population.

METHODS

The authors performed electronic literature searches in PubMed through October 2015 using the terms attention-deficit/hyperactivity disorder, guanfacine, and alpha agonists. We also performed an informal review of the literature and used selected articles from relevant reference lists. The result was a broad, qualitative review of the literature, with a focus on specific factors regarding guanfacine use in very young children.

RESULTS

Despite the fact that guanfacine is commonly used in very young children, there is a paucity of published studies that looked specifically at its use in this population. In reviewing the pharmacology of guanfacine, there are specific factors that may play a unique role in its disposition in very young children.

CONCLUSIONS

Guanfacine is an important medication option in very young children; however, there is a significant pharmacologic "information gap," and further research is needed to help establish appropriate, safe, and effective dosing of guanfacine in this population.

Clinical Correlates and Mediators of Self-Concept in Youth with Chronic Tic Disorders

This study investigated the clinical correlates and mediators of self-concept in youth with Chronic Tic Disorders (CTD). Ninety-seven youth aged 6-17 (M = 11.1 ± 2.89; 79.4 % male) with CTD were administered the Yale Global Tic Severity Scale, the Piers-Harris Children's Self-Concept Scale-Second Edition, and self-report and clinician-administered measures assessing behavioral and psychological difficulties and comorbid conditions. Youth with CTD had a slightly below average level of self-concept, with 20 % (n = 19) exhibiting low self-concept. Youth with CTD-only had greater self-concept relative to youth with CTD and obsessive-compulsive disorder (OCD) (p = 0.04) or CTD, OCD, and attention deficit hyperactivity disorder (ADHD) combined (p = 0.009). Medium-to-large-sized associations were observed between youth's self-concept and clinical characteristics (e.g., severity of ADHD, OCD and depressive symptoms). Youth's self-concept partially mediated the relationship between tic severity and depressive symptom severity, and the interaction between tic impairment and youth's reliance on avoidant coping strategies moderated youth's self-concept. Implications, limitations, and recommendations for future interventions are discussed.

Impact of a Step Therapy for Guanfacine Extended-Release on Medication Utilization and Health Care Expenditures Among Individuals Receiving Treatment for ADHD

BACKGROUND

While step therapy (ST) policies are generally effective at reducing cost through the managed utilization of targeted medications, the clinical implications of ST policies are not clear and may vary across therapeutic areas. Guanfacine extended-release (GXR) is approved by the FDA for the treatment of attention-deficit/hyperactivity disorder (ADHD) as both monotherapy and adjunctive to stimulant treatment. At the introduction of GXR to the market, Humana implemented an ST policy on GXR requiring the documentation of previous treatment, intolerance, or contraindication to generic clonidine or guanfacine.

OBJECTIVE

To examine the impact of a GXR ST coverage determination (i.e., approved vs. denied) on medication utilization and health care costs among members of a commercial health plan with an ST policy for GXR. 

METHODS

This study was a retrospective cohort study of administrative claims data. Humana commercial members prescribed GXR who had an ST coverage determination review were identified. All members included in this analysis were required to be aged 6-17 years, have a diagnosis of ADHD or be receiving stimulant medication, have an ST coverage determination (index event) between September 1, 2009, and May 30, 2012, and have 6 months of pre- and post-index continuous enrollment. Members were assigned to either the approved or denied group based on the outcome of the ST coverage determination. Medical and pharmacy claims data were used to measure baseline demographic and clinical characteristics and to measure medication utilization and health care costs. Outcomes assessed during follow-up included ADHD medication use, proportion of days covered (PDC) with any ADHD medication treatment, time to first observed post-index ADHD treatment, and all-cause and mental health (MH)-related health care costs. Administrative costs associated with the coverage determination process were also estimated. Bivariate and multivariable adjusted analyses were conducted to compare medication utilization and health care costs between the approved and denied groups.

RESULTS

A total of 642 members were included in the analysis (denied group n = 395 [61.5%], approved group n = 247 [38.5%]). The approved and denied groups were similar in terms of baseline demographics, provider characteristics, and baseline MH diagnoses, with the exception of anxiety disorders being more prevalent in the approved group compared with the denied group (18.2% vs. 10.6%, P = 0.006). A denied GXR coverage determination was associated with a greater percentage of members receiving no ADHD treatment post-index (13.9% vs. 3.2%, P  less than  0.001), greater mean [SD] number of days between index and first observed post-index ADHD medication claim (44.5 [59.6] vs. 17.6 [33.4], P  less than  0.001), and lower mean [SD] PDC with any ADHD medication post-index (0.59 [0.33] vs. 0.75 [0.26], P  less than  0.001). These findings remained statistically significant in multivariable regression models. Unadjusted pre-index median total health care costs and MH-related costs were greater among the approved group compared with the denied group (total health care: $1,582 vs. $1,465, P = 0.033; MH-related: $993 vs. $981, P = 0.020). Likewise, post-index median total health care and MH-related costs were greater among the approved group compared with the denied group (total: $2,056 vs. $1,420, P  less than  0.001; MH-related: $1,543 vs. $946, P  less than  0.001). After adjustment for potentially confounding covariates including pre-index costs, there were no statistically significant differences between the approved and denied groups in all-cause total health care (P = 0.393) or MH-related health care costs (P = 0.054). 

CONCLUSIONS

The current study found that GXR coverage denial was associated with lower rate of ADHD medication utilization, greater delay in receiving ADHD medication, and lower PDC with ADHD medication. There were no differences observed between the approved and denied group in terms of all-cause total health care or MH-related total health care costs after controlling for potentially confounding variables. Prior to implementation in the ADHD therapeutic area and others, payers should consider the potentially unintended consequences of ST policies, including delay in treatment and undertreatment.

Changing patterns of alpha agonist medication use in children and adolescents 2009-2011

OBJECTIVES

The purpose of this study was to describe rates and patterns of long- and short-acting alpha agonist use for behavioral problems in a primary care population following Food and Drug Administration (FDA) approval of the long-acting alpha agonists guanfacine and clonidine.

METHODS

Children and adolescents 4-18 years of age, who received an alpha agonist prescription between 2009 and 2011, were identified from a sample of 45 United States primary care practices in two electronic health record-based research networks. Alpha agonist receipt was identified using National Drug Codes and medication names. The proportion of subjects receiving long- and short-acting prescriptions in each year was calculated and examined with respect to reported mental health diagnoses, and whether indications for use were on-label, had evidence from clinical trials, or had no trial evidence.

RESULTS

In a cohort of 282,875 subjects, 27,671 (10%) received any psychotropic medication and only 4,227 subjects (1.5%) received at least one prescription for an alpha agonist, most commonly a short-acting formulation (83%). Only 20% of alpha agonist use was on-label (use of long-acting formulations for attention-deficit/hyperactivity disorder [ADHD]). Most subjects (68%) received alpha agonists for indications with evidence of efficacy from clinical trials but no FDA approval, primarily short-acting formulations for ADHD and autism; 12% received alpha agonists for diagnoses lacking randomized clinical trial evidence in children, including sleep disorders and anxiety, or for which there was no documented mental health diagnosis. Rates of long-acting alpha agonist use increased more than 20-fold from 0.2% to 4%, whereas rates of short-acting alpha agonist use grew only slightly between 2009 and 2011 from 10.6% to 11.3%.

CONCLUSIONS

Alpha agonist use was uncommon in this population, and most subjects received short-acting forms for conditions that were off-label, but with clinical trial evidence. The safety and efficacy of use for conditions, including sleep disorders and anxiety, lacking evidence from randomized trials, warrant further investigation.

Prefrontal cortical α2A-adrenoceptors and a possible primate model of attention deficit and hyperactivity disorder

Attention deficit and hyperactivity disorder (ADHD), a prevalent syndrome in children worldwide, is characterized by impulsivity, inappropriate inattention, and/or hyperactivity. It seriously afflicts cognitive development in childhood, and may lead to chronic under-achievement, academic failure, problematic peer relationships, and low self-esteem. There are at least three challenges for the treatment of ADHD. First, the neurobiological bases of its symptoms are still not clear. Second, the commonly prescribed medications, most showing short-term therapeutic efficacy but with a high risk of serious side-effects, are mainly based on a dopamine mechanism. Third, more novel and efficient animal models, especially in nonhuman primates, are required to accelerate the development of new medications. In this article, we review research progress in the related fields, focusing on our previous studies showing that blockade of prefrontal cortical α2A-adrenoceptors in monkeys produces almost all the typical behavioral symptoms of ADHD.

Targeting the noradrenergic system for gender-sensitive medication development for tobacco dependence

INTRODUCTION

Tobacco use remains the leading cause of morbidity and mortality for both women and men in the United States, and women often experience poorer smoking cessation outcomes than men. Preliminary evidence suggests there are sex differences in medication effectiveness for smoking cessation. However, current medications do not take into account gender-sensitive treatment development and efficacy, underscoring the importance of this underdeveloped area of research.

METHODS

We reviewed preclinical and clinical evidence for gender differences in the inability to quit smoking by examining (a) the effect of increased negative affect and stress reactivity on smoking outcomes in women and (b) smoking for nicotine reinforcement in men. We also reviewed the current literature targeting the noradrenergic system as a novel gender-sensitive treatment strategy for tobacco dependence.

RESULTS

We hypothesize that noradrenergic agents that normalize noradrenergic activity may differentially attenuate stress reactivity in women and nicotine-related reinforcement in men, indicating that targeting the noradrenergic system for smoking cessation may be effective for both genders, with benefits operating through sex-specific mechanisms.

CONCLUSIONS

Converging lines of preclinical and clinical evidence suggest that gender-sensitive approaches to medication development for smoking cessation are a critical next step for addressing low quit rates and exacerbated health risks among women. Evidence reviewed indicates that smoking activates different brain systems modulated by noradrenergic activity in women versus men, and noradrenergic compounds may preferentially target these gender-sensitive systems.

Guanfacine enhances inhibitory control and attentional shifting in early abstinent cocaine-dependent individuals

OBJECTIVES

Attenuation of adrenergic drive and cognitive enhancement, via stimulation of alpha2 pre- and post-synaptic receptors, may selectively enhance executive performance in early abstinent cocaine-dependent individuals. As these cognitive processes underpin important treatment-related behaviors, the alpha2 agonist, guanfacine HCl, may represent an effective pharmaco-therapeutic intervention.

METHODS

Twenty-five early abstinent cocaine-dependent individuals were administered a battery of neurocognitive tasks on entry into treatment (baseline) and again following 3 weeks of either placebo or guanfacine treatment (up to 3 mg). Tasks included: Stop Signal, Stroop, 3-Dimentional Intra-dimensional/Extra-dimensional (IDED) task, Spatial Working Memory (SWM), Paired Associates Learning (PAL), Verbal Fluency and the Rey Auditory Verbal Learning Test (RAVLT).

RESULTS

Compared with placebo, the guanfacine group demonstrated attenuated anxiety and negative affect as well as improved performance on selective executive tests. This included fewer directional errors on the stop signal task, fewer errors on the extra-dimensional shift component of the IDED task and better attentional switching during verbal fluency. Guanfacine did not improve strategic working memory or peripheral memory.

CONCLUSION

Guanfacine improves selective cognitive processes which may underlie salient treatment-related regulatory behaviors. Alpha2 agonists may therefore represent important agents for cocaine dependence.

Updates in medical and surgical therapies for Tourette syndrome

Tourette syndrome is a complex neurobehavioral disorder defined by multiple motor and at least 1 vocal tic, persisting over 1 year, waxing and waning in severity, and not explained by another condition. The condition may range from mild nuisance to debilitating and disabling in severity. Management includes counseling and reassurance, behavioral interventions, pharmacologic, and rarely, surgical interventions. Traditionally, alpha-2 agonists and dopamine receptor antagonists have been utilized. In addition, a number of different pharmacotherapies have been implemented in the search for improved management of tics with better tolerability. In rare, severely disabling cases, neuromodulation with deep brain stimulation may be indicated. Optimal brain targets and candidate selection are still in evolution. This article will review the evidence for current medical and surgical therapies with a focus on recent updates.

Efficacy and safety of extended-release guanfacine hydrochloride in children and adolescents with attention-deficit/hyperactivity disorder: a randomized, controlled, phase III trial

Guanfacine extended-release (GXR), a selective α2A-adrenergic agonist, is a non-stimulant treatment for attention-deficit/hyperactivity disorder (ADHD). This study assessed the efficacy (symptoms and function) and safety of dose-optimized GXR compared with placebo in children and adolescents with ADHD. An atomoxetine (ATX) arm was included to provide reference data against placebo. Patients (6-17 years) were randomized at baseline to dose-optimized GXR (0.05-0.12mg/kg/day - 6-12 years: 1-4mg/day; 13-17 years: 1-7mg/day), ATX (10-100mg/day) or placebo for 4 or 7 weeks. The primary efficacy measure was change from baseline in ADHD Rating Scale version IV (ADHD-RS-IV). Key secondary measures were Clinical Global Impression-Improvement (CGI-I) and the Weiss Functional Impairment Rating Scale-Parent Report (WFIRS-P; learning and school, and family domains). Safety assessments included treatment-emergent adverse events (TEAEs), electrocardiograms and vital signs. A total of 272 (80.5%) patients from Europe, the USA and Canada completed the study. Significant differences were observed in least squares mean change from baseline in ADHD-RS-IV total score (placebo-adjusted differences) (GXR: [-8.9, p<0.001]; ATX: [-3.8, p<0.05]), the difference from placebo in the percentage of patients showing improvement (1 ['very much improved'] or 2 ['much improved']) for CGI-I (GXR: [23.7, p<0.001]; ATX: [12.1, p<0.05]), WFIRS-P learning and school domain (GXR: [-0.22, p<0.01]; ATX: [-0.16, p<0.05]) and WFIRS-P family domain (GXR: [-0.21, p<0.01]; ATX: [-0.09, p=0.242]). Most common TEAEs for GXR were somnolence, headache and fatigue; 70.1% of GXR subjects reported mild-to-moderate TEAEs. GXR was effective and well tolerated in children and adolescents with ADHD.

Clinical pharmacology of nondopaminergic drugs in Tourette syndrome

Treatment of tics and Gilles de la Tourette syndrome (GTS) by nondopaminergic drugs was initiated more than three decades ago. These approaches were driven by the wish to circumvent antipsychotic-related side effects (metabolic disturbances, parkinsonian syndromes, tardive dyskinesia) or to use these treatments as a valuable add-on therapy in patients at least partially refractory to antipsychotics. In this review, we will therefore discuss the potential value of treating tics with alpha2 receptor agonists, nicotine, tetrabenazine, GABA agonists, botulinum toxin, cannabinoids, and immune modulators (plasmapheresis, intravenous immunoglobulins, antibiotic prophylaxis). Future directions for clinical trials based on our expanding understanding of the pathophysiology of GTS with regard to cholinergic, glutamatergic, and histaminergic neurotransmission will also be briefly outlined.

Alpha-2 agonists for attention-deficit/hyperactivity disorder in youth: a systematic review and meta-analysis of monotherapy and add-on trials to stimulant therapy

OBJECTIVE

To meta-analyze the efficacy and safety of α-2 agonists in pediatric attention-deficit/hyperactivity disorder (ADHD).

METHOD

We searched MEDLINE, EMBASE, Cochrane Library, CINAHL, and PsycINFO until May 2013 for randomized trials comparing α-2 agonists with placebo in ADHD youth. Primary outcome was reduction in overall ADHD symptoms. Secondary outcomes included hyperactivity/impulsivity, inattentiveness, oppositional defiant disorder symptoms (ODD symptoms), all-cause discontinuation, specific-cause discontinuation, and adverse effects. Standardized mean differences (SMD), relative risk (RR), and number-needed-to-treat/number-needed-to-harm (NNT/NNH) were calculated. Data were analyzed separately in monotherapy and as add-on to psychostimulants.

RESULTS

Altogether, 12 studies (N = 2,276) were included. Across 9 studies (n = 1,550), α-2 agonist monotherapy significantly reduced overall ADHD symptoms (SMD = -0.59, p < .00001), hyperactivity/impulsivity (SMD = -0.56, p < .00001), inattention (SMD = -0.57, p < .00001), and ODD symptoms (SMD = -0.44, p = .0004). Similarly, α-2 agonist add-on treatment (3 studies, n = 726) significantly reduced overall ADHD symptoms (SMD = -0.36, p < .0001), hyperactivity/impulsivity (SMD = -0.33, p < .0001), and inattention (SMD = -0.34, p < .0001), but effect sizes were lower than in monotherapy trials (p = .03-0.04). As monotherapy, α-2 agonists had lower all-cause (RR = 0.70, p = .01, NNT = 10) and inefficacy-related (RR = 0.39, p < .0001) discontinuations than did placebo; however, intolerability-related discontinuation was similar, despite significantly more common fatigue (NNH = 10), sedation (NNH = 17), and somnolence (NNH = 4) and significantly greater hypotensive (clonidine-IR), bradycardic (clonidine-IR), and QTc prolonging (guanfacine-XR) effects. Added to stimulants, α-2 agonists had all-cause and specific-cause discontinuations that were comparable to those of placebo, but somnolence (NNH = 10) was more common, and hypotensive and bradycardic effects (clonidine-XR and guanfacine-XR) were greater than with placebo.

CONCLUSIONS

α-2 Agonist monotherapy and, possibly to a lesser extent, co-treatment, are significantly superior to placebo for overall, hyperactivity, and inattentive ADHD symptoms. Efficacy advantages need to be balanced against fatigue, somnolence/sedation, hypotension, bradycardia, and possibly QTc prolongation.

The role of guanfacine as a therapeutic agent to address stress-related pathophysiology in cocaine-dependent individuals

The pathophysiology of cocaine addiction is linked to changes within neural systems and brain regions that are critical mediators of stress system sensitivity and behavioral processes associated with the regulation of adaptive goal-directed behavior. This is characterized by the upregulation of core adrenergic and corticotropin-releasing factor mechanisms that subserve negative affect and anxiety and impinge upon intracellular pathways in the prefrontal cortex underlying cognitive regulation of stress and negative emotional state. Not only are these mechanisms essential to the severity of cocaine withdrawal symptoms, and hence the trajectory of clinical outcome, but also they may be particularly pertinent to the demography of cocaine dependence. The ability of guanfacine to target overlapping stress, reward, and anxiety pathophysiology suggests that it may be a useful agent for attenuating the stress- and cue-induced craving state not only in women but also in men. This is supported by recent research findings from our own laboratory. Additionally, the ability of guanfacine to improve regulatory mechanisms that are key to exerting cognitive and emotional control over drug-seeking behavior also suggests that guanfacine may be an effective medication for reducing craving and relapse vulnerability in many drugs of abuse. As cocaine-dependent individuals are typically polydrug abusers and women may be at a greater disadvantage for compulsive drug use than men, it is plausible that medications that target catecholaminergic frontostriatal inhibitory circuits and simultaneously reduce stress system arousal may provide added benefits for attenuating cocaine dependence.

Practice parameter for the assessment and treatment of children and adolescents with tic disorders

Tic disorders, including Tourette's disorder, present with a wide range of symptom severity and associated comorbidity. This Practice Parameter reviews the evidence from research and clinical experience in the evaluation and treatment of pediatric tic disorders. Recommendations are provided for a comprehensive evaluation to include common comorbid disorders and for a hierarchical approach to multimodal interventions.

Clinical doses of atomoxetine significantly occupy both norepinephrine and serotonin transports: Implications on treatment of depression and ADHD

BACKGROUND

Atomoxetine (ATX), a drug for treatment of depression and ADHD, has a high affinity for the norepinephrine transporter (NET); however, our previous study showed it had a blocking effect similar to fluoxetine on binding of [(11)C]DASB, a selective serotonin transporter (SERT) ligand. Whether the therapeutic effects of ATX are due to inhibition of either or both transporters is not known. Here we report our comparative PET imaging studies with [(11)C]MRB (a NET ligand) and [(11)C]AFM (a SERT ligand) to evaluate in vivo IC50 values of ATX in monkeys.

METHODS

Rhesus monkeys were scanned up to four times with each tracer with up to four doses of ATX. ATX or saline (placebo) infusion began 2h before each PET scan, lasting until the end of the 2-h scan. The final infusion rates were 0.01-0.12mg/kg/h and 0.045-1.054mg/kg/h for the NET and SERT studies, respectively. ATX plasma levels and metabolite-corrected arterial input functions were measured. Distribution volumes (VT) and IC50 values were estimated.

RESULTS

ATX displayed dose-dependent occupancy on both NET and SERT, with a higher occupancy on NET: IC50 of 31±10 and 99±21ng/mL plasma for NET and SERT, respectively. At a clinically relevant dose (1.0-1.8mg/kg, approx. 300-600ng/mL plasma), ATX would occupy >90% of NET and >85% of SERT. This extrapolation assumes comparable free fraction of ATX in humans and non-human primates.

CONCLUSION

Our data suggests that ATX at clinically relevant doses greatly occupies both NET and SERT. Thus, therapeutic modes of ATX action for treatment of depression and ADHD may be more complex than selective blockade of NET.

A review of the rationale and clinical utilization of α2-adrenoceptor agonists for the treatment of attention-deficit/hyperactivity and related disorders

OBJECTIVE

Interest in the potential role for the α2-adrenoceptor agonists clonidine and guanfacine as treatments for attention-deficit/hyperactivity disorder (ADHD) has driven additional clinical studies as well as development of new formulations of these agents. This article reviews the published data that supported United States Food and Drug Administration approval and subsequent clinical use of α2-adrenoceptor agonists in the treatment of ADHD, and identifies promising directions for future research.

METHODS

Electronic searches were performed in PubMed through October 2012 using the base terms ADHD or attention deficit hyperactivity disorder and alpha agonists, as well as the following limits: humans, clinical trial, meta-analysis, practice guideline, randomized controlled trial, review, English. The electronic searches were complemented with reference lists from the articles retrieved by informal search of the literature, producing a qualitative review of published, pertinent drug-class preclinical and clinical data. Articles were selected for greater exposition based on hierarchy of evidence (e.g., randomized controlled trials), relevance, and quality of individual studies, as well as generalizability to clinical practice.

RESULTS

Results of clinical studies of immediate-release and extended-release formulations of α2-adrenoceptor agonists and basic science investigations of cognitive effects of these drugs are discussed. Studies of both clonidine and guanfacine extended-release formulations as monotherapy and adjunctive therapy with psychostimulants for the treatment of ADHD are also reviewed.

CONCLUSIONS

Large, randomized, placebo-controlled clinical trials support the efficacy and safety of α2-adrenoceptor agonists as monotherapy and adjunctive therapy with psychostimulants for the symptomatic treatment of ADHD. Future research could reveal whether there are cognitive benefits associated with this drug class and thus further define the role of α2-adrenoceptor agonists in the treatment of ADHD.

Medication efficacy: the impact of variability in defining and measuring ADHD and executive functioning

Attention-deficit hyperactivity disorder (ADHD) is a heavily studied topic in neuropsychology and general psychology, psychiatry, and pediatrics. The Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition, Text Revision (DSM-IV) is used to diagnose ADHD, but its criteria are behaviorally defined, while ADHD is a neurological dysfunction. The DSM-IV diagnostic criteria do not differentiate between attention and inhibition or executive functions (EF). As well, there is little agreement in the field about what constitutes ADHD and EFs or how to measure or diagnose them, let alone rule them out. When rendering an ADHD diagnosis, the responsible clinician considers DSM-IV criteria along with other reasons why an individual may express symptoms of ADHD, for reasons other than ADHD. This article discusses postulated mechanisms of action for some medications prescribed for ADHD, the variance of medication outcomes in research, the variance of assessment measures used in identifying ADHD subjects for research, and flaws with DSM-IV-based diagnosis. An argument is posed that the field of neuropsychology needs a cohesive and agreed-upon definition of ADHD and EF and how to measure it to more exactly research the topic, accurately diagnose the disorder, and assist prescribing professionals to use medications with improved first-trial precision.

Catecholamine modulation of prefrontal cortical cognitive function

The prefrontal cortex (PFC) utilizes working memory to guide behavior and to release the organism from dependence on environmental cues and is commonly disrupted in neuropsychiatric disorders, normal aging, or exposure to uncontrollable stress. This review posits that the PFC is very sensitive to changes in the neuromodulatory inputs it receives from norepinephrine (NE) and dopamine (DA) systems and that this sensitivity can lead to marked changes in the working-memory functions of the PFC. While NE and DA have important beneficial influences on processing in this area, very high levels of catecholamine release, for example, during exposure to uncontrollable stress, disrupt the cognitive functions of the PFC. This fresh understanding of the neurochemical influences on PFC function has led to new treatments for cognitive disorders such as Attention Deficit Hyperactivity Disorder (ADHD), and may help to elucidate the prevalence of PFC dysfunction in other mental disorders.

Pharmacotherapy of pediatric attention-deficit/hyperactivity disorder

This article describes the practical use of available attention-deficit/hyperactivity disorder (ADHD) pharmacotherapies, their formulations and durations of action, and the extent of Food and Drug Administration approvals. It provides data on short-term and long-term safety of these medications, their use in ADHD with comorbid conditions, and strategies for formulating individualized, effective, and well-tolerated pharmacotherapy treatment plans. A clinical vignette focusing on a male child with ADHD is presented. Summaries are presented of ADHD pharmacotherapies and Food and Drug Administration approval status, atomoxetine and stimulant comparator trials, adverse effects and ADHD pharmacotherapy, and delivery system and duration of effect.

Guanfacine ER for the treatment of adolescent attention-deficit/hyperactivity disorder

INTRODUCTION

Guanfacine extended release (GXR) is an alpha 1A noradrenergic agonist that has been approved by the FDA for the treatment of Attention-Deficit/Hyperactivity Disorder (ADHD) as a monotherapy, and as an adjunctive therapy to stimulants for the treatment of ADHD in children and adolescents age 6 - 17.

AREAS COVERED

PubMed, the Ovid Medline database, and the PsycInfo database were searched using the term 'guanfacine'. Results were then limited to criteria such as English and human, from 1990 through December 2011. The resulting yield from the comprehensive literature search was 4391 articles. The titles and abstracts of all articles were reviewed. Studies were selected for full-text review based upon their place in the hierarchy of evidence (e.g., randomized controlled trials), relevance and quality of individual studies, and generalizability to clinical practice. The search was augmented by further search of article reference lists. A total of 15 articles were selected for full-text examination.

EXPERT OPINION

Due to the absence of positive evidence for the efficacy of GXR for monotherapy in adolescents, clinicians should be guarded in the use of GXR for monotherapy in adolescents with ADHD. The use of GXR has considerable promise as an adjunct to stimulants for other behavioral conditions associated with ADHD.

Guanfacine effects on stress, drug craving and prefrontal activation in cocaine dependent individuals: preliminary findings

Cocaine dependence is associated with increased stress and drug cue-induced craving and physiological arousal but decreased prefrontal activity to emotional and cognitive challenge. As these changes are associated with relapse risk, we investigated the effects of α2 receptor agonist guanfacine on these processes. Twenty-nine early abstinent treatment-seeking cocaine dependent individuals were randomly assigned to either daily placebo or guanfacine (up to 3 mg) for four weeks. In a laboratory experiment, all patients were exposed to three 10-min guided imagery conditions (stress/stress, drug cue/drug cue, stress/drug cue), one per day, consecutively in a random, counterbalanced order. Subjective craving, anxiety and arousal as well as cardiovascular output were assessed repeatedly. Brain response to stress, drug cue and relaxing imagery was also assessed during a functional magnetic resonance (fMRI) imaging session. In the current study, guanfacine was found to be safe and well-tolerated. Lower basal heart rate and blood pressure was observed in the guanfacine versus placebo group. Guanfacine lowered stress and cue-induced nicotine craving and cue-induced cocaine craving, anxiety and arousal. The guanfacine group also showed increased medial and lateral prefrontal activity following stress and drug cue exposure compared with placebo. Data suggest further exploration of guanfacine is warranted in terms of its potential for reducing stress-induced and cue-induced drug craving and arousal.

Hyperpolarisation-activated cyclic nucleotide channel 4 (HCN4) involvement in Tourette's syndrome autoimmunity

OBJECTIVES

We previously found that antibodies in Tourette's syndrome (TS) patients' sera reacted with a 120 kDa protein from rat brain tissue. Here, we sought to identify this protein and determine if it was involved in TS pathogenesis.

METHODS

The 120 kDa protein was identified using immunoprecipitation, Western blotting, and mass spectrometry. ELISAs were used to quantify anti-120 kDa protein antibodies in serum of interest using samples from 32 TS patients, 47 patients with attention deficit hyperactivity disorder (ADHD) and 14 healthy controls. Involvement of the 120 kDa protein in TS was confirmed using co-localisation assays with GH3 cells. TS sera were micro-infused into SD rats' brain striatum and their stereotypical behaviours were monitored.

RESULTS

The brain protein was identified as hyperpolarisation-activated cyclic nucleotide channel 4 (HCN4). TS patients' sera contained significantly more anti-HCN4 antibodies than ADHD patient and control sera. After microinfusing TS serum, SD rats exhibited increased stereotyped tic behaviours, which were correlated with the amount of infused anti-HCN4 antibody.

CONCLUSIONS

Anti-HCN4 antibodies in the brain might contribute to the pathogenesis of tic symptoms in TS patients. However, further studies are needed to investigate the validity of this animal model of TS induced by microinfusing anti-HCN4 antibody.

The utility of rat models of impulsivity in developing pharmacotherapies for impulse control disorders

High levels of impulsive behaviours are a clinically significant symptom in a range of psychiatric disorders, such as attention deficit hyperactivity disorder, bipolar disorder, personality disorders, pathological gambling and substance abuse. Although often measured using questionnaire assessments, levels of different types of impulsivity can also be determined using behavioural tests. Rodent analogues of these paradigms have been developed, and similar neural circuitry has been implicated in their performance in both humans and rats. In the current review, the methodology underlying the measurement of different aspects of impulsive action and choice are considered from the viewpoint of drug development, with a focus on the continuous performance task (CPT), stop-signal task (SST), go/no-go and delay-discounting paradigms. Current issues impeding translation between animal and human studies are identified, and comparisons drawn between the acute effects of dopaminergic, noradrenergic and serotonergic compounds across species. Although the field could benefit from a more systematic determination of different pharmacological agents across paradigms, there are signs of strong concordance between the animal and human data. However, the type of impulsivity measured appears to play a significant role, with the SST and delay discounting providing more consistent effects for dopaminergic drugs, while the CPT and SST show better predictive validity so far for serotonergic and noradrenergic compounds. Based on the available data, it would appear that these impulsivity models could be used more widely to identify potential pharmacotherapies for impulse control disorders. Novel targets within the glutamatergic and serotonergic system are also suggested.

Canadian guidelines for the evidence-based treatment of tic disorders: pharmacotherapy

This article seeks to provide the practising clinician with guidance on the pharmacological management of tic disorders in children and adults. We performed a systematic review of the literature on the treatment of tic disorders. A multi-institutional group of 14 experts in psychiatry, child psychiatry, neurology, pediatrics, and psychology engaged in a consensus meeting. The evidence was presented and discussed, and nominal group techniques were employed to arrive at consensus on recommendations. A strong recommendation is made when the benefits of treatment clearly outweigh the risks and burdens, and can apply to most patients in most circumstances without reservation. With a weak recommendation, the benefits, risks, and burdens are more closely balanced, and the best action may differ depending on the circumstances. Based on these principles, weak recommendations were made for the use of pimozide, haloperidol, fluphenazine, metoclopramide (children only), risperidone, aripiprazole, olanzapine, quetiapine, ziprasidone, topiramate, baclofen (children only), botulinum toxin injections, tetrabenazine, and cannabinoids (adults only). Strong recommendations were made for the use of clonidine and guanfacine (children only). While the evidence supports the efficacy of many of the antipsychotics for the treatment of tics, the high rates of side effects associated with these medications resulted in only weak recommendations for these drugs. In situations where tics are not severe or disabling, the use of a medication with only a weak recommendation is not warranted. However, when tics are more distressing and interfering, the need for tic suppression to improve quality of life is stronger, and patients and clinicians may be more willing to accept the risks of pharmacotherapy.

The evidence-based pharmacological treatment of paediatric ADHD

Attention deficit hyperactivity disorder (ADHD) is common in children, adolescents, and adults, with extensive research establishing it as a valid neurobiological disorder. Without intervention, ADHD can result in significant impairment throughout the lifespan for the individuals it afflicts. Fortunately, multiple evidence-based options are available for the treatment of ADHD, including several efficacious pharmacotherapies. The role of medication, including stimulants as well as non-stimulants, is well-documented by an extensive body of literature. Although there may be less enthusiasm for behavioural and other psychosocial interventions as stand-alone treatments for moderate to severe ADHD, they are recommended as first-line treatment for ADHD management in preschool-aged children, for those patients with mild symptoms, and as an adjunct to medication in patients with comorbid disorders or suboptimal responses to pharmacotherapy. When planning treatment for individuals with ADHD, the potential risks associated with the available interventions must be carefully balanced against the risks of not treating, or not treating adequately. The treatment plan must also include ongoing re-assessment of the effectiveness of and the need for continued therapy. Recent practice parameters provide further specific guidance for the evidence-based assessment and treatment of children and adolescents with ADHD.

Molecular modulation of prefrontal cortex: rational development of treatments for psychiatric disorders

Dysfunction of the prefrontal cortex (PFC) is a central feature of many psychiatric disorders, such as attention deficit hyperactivity disorder (ADHD), posttraumatic stress disorder (PTSD), schizophrenia, and bipolar disorder. Thus, understanding molecular influences on PFC function through basic research in animals is essential to rational drug development. In this review, we discuss the molecular signaling events initiated by norepinephrine and dopamine that strengthen working memory function mediated by the dorsolateral PFC under optimal conditions, and weaken working memory function during uncontrollable stress. We also discuss how these intracellular mechanisms can be compromised in psychiatric disorders, and how novel treatments based on these findings may restore a molecular environment conducive to PFC regulation of behavior, thought and emotion. Examples of successful translation from animals to humans include guanfacine for the treatment of ADHD and related PFC disorders, and prazosin for the treatment of PTSD.