An open trial of adjunctive donepezil in attention-deficit/hyperactivity disorder

Use of donepezil for neurocognitive recovery after brain injury in adult and pediatric populations: a scoping review

There are few pharmacologic options for the treatment of cognitive deficits associated with traumatic brain injury in pediatric patients. Acetylcholinesterase inhibitors such as donepezil have been evaluated in adult patients after traumatic brain injury, but relatively less is known about the effect in pediatric populations. The goal of this review is to identify knowledge gaps in the efficacy and safety of acetylcholinesterase inhibitors as a potential adjuvant treatment for neurocognitive decline in pediatric patients with traumatic brain injury. Investigators queried PubMed to identify literature published from database inception through June 2023 describing the use of donepezil in young adult traumatic brain injury and pediatric patients with predefined conditions. Based on preselected search criteria, 340 unique papers were selected for title and abstract screening. Thirty-two records were reviewed in full after eliminating preclinical studies and papers outside the scope of the project. In adult traumatic brain injury, we review results from 14 papers detailing 227 subjects where evidence suggests donepezil is well tolerated and shows both objective and patient-reported efficacy for reducing cognitive impairment. In children, 3 papers report on 5 children recovering from traumatic brain injury, showing limited efficacy. An additional 15 pediatric studies conducted in populations at risk for cognitive dysfunction provide a broader look at safety and efficacy in 210 patients in the pediatric age group. Given its promise for efficacy in adults with traumatic brain injury and tolerability in pediatric patients, we believe further study of donepezil for children and adolescents with traumatic brain injury is warranted.

Durable recovery from amblyopia with donepezil

An elevated threshold for neuroplasticity limits visual gains with treatment of residual amblyopia in older children and adults. Acetylcholinesterase inhibitors (AChEI) can enable visual neuroplasticity and promote recovery from amblyopia in adult mice. Motivated by these promising findings, we sought to determine whether donepezil, a commercially available AChEI, can enable recovery in older children and adults with residual amblyopia. In this open-label pilot efficacy study, 16 participants (mean age 16 years; range 9-37 years) with residual anisometropic and/or strabismic amblyopia were treated with daily oral donepezil for 12 weeks. Donepezil dosage was started at 2.5 or 5.0 mg based on age and increased by 2.5 mg if the amblyopic eye visual acuity did not improve by 1 line from the visit 4 weeks prior for a maximum dosage of 7.5 or 10 mg. Participants < 18 years of age further patched the dominant eye. The primary outcome was visual acuity in the amblyopic eye at 22 weeks, 10 weeks after treatment was discontinued. Mean amblyopic eye visual acuity improved 1.2 lines (range 0.0-3.0), and 4/16 (25%) improved by ≥ 2 lines after 12 weeks of treatment. Gains were maintained 10 weeks after cessation of donepezil and were similar for children and adults. Adverse events were mild and self-limited. Residual amblyopia improves in older children and adults treated with donepezil, supporting the concept that the critical window of visual cortical plasticity can be pharmacologically manipulated to treat amblyopia. Placebo-controlled studies are needed.

Preclinical Evaluation of Attention and Impulsivity Relevant to Determining ADHD Mechanisms and Treatments

People with Attention-Deficit Hyperactivity Disorder (ADHD) exhibit inattention, hyperactivity, and/or impulsivity. Symptoms of ADHD emerge in childhood and can continue throughout adulthood. Clinical assessments to diagnose ADHD can include administration of continuous performance tests (CPTs). CPTs provide an objective measure of inattention, requiring individuals to respond to targets (attention), and inhibit response to non-targets (impulsivity). When investigating the mechanisms of, and novel treatments for, ADHD it is important to measure such behavioral domains (attention and impulsivity). Some well-established preclinical tasks purport to assess attention in rodents but, unlike CPTs, do not require non-target inhibition, limiting their ADHD-relevance.Recently developed tasks recreate CPTs for rodents. The 5-Choice CPT (5C-CPT) contains non-target stimuli, enabling use of signal detection theory to evaluate performance, consistent with CPTs. The 5C-CPT has been adapted for use in humans, enabling direct cross-species comparisons of performance. A newer task, the rodent CPT (rCPT), is a touchscreen-based analog of CPTs, utilizing symbols instead of a simple stimulus array. Currently, the rCPT may be more akin to a go/no-go task, equally presenting targets/non-targets, although numerous variants exist - a strength. The 5C-CPT and rCPT emulate human CPTs and provide the most up-to-date information on ADHD-relevant studies for understanding attention/impulsivity.

Functional Neuroimaging in Psychiatry-Aiding in Diagnosis and Guiding Treatment. What the American Psychiatric Association Does Not Know

While early efforts in psychiatry were focused on uncovering the neurobiological basis of psychiatric symptoms, they made little progress due to limited ability to observe the living brain. Today, we know a great deal about the workings of the brain; yet, none of this neurobiological awareness has translated into the practice of psychiatry. The categorical system which dominates psychiatric diagnosis and thinking fails to match up to the real world of genetics, sophisticated psychological testing, and neuroimaging. Nevertheless, the American Psychiatric Association (APA) recently published a position paper stating that neuroimaging provided no benefit to the diagnosis and treatment of psychiatric disorders. Using the diagnosis of depression as a model, we illustrate how setting aside the unrealistic expectation of a pathognomonic "fingerprint" for categorical diagnoses, we can avoid missing the biological and, therefore, treatable contributors to psychopathology which can and are visualized using functional neuroimaging. Infection, toxicity, inflammation, gut-brain dysregulation, and traumatic brain injury can all induce psychiatric manifestations which masquerade as depression and other psychiatric disorders. We review these and provide illustrative clinical examples. We further describe situations for which single photon emission computed tomography (SPECT) and positron emission tomography (PET) functional neuroimaging already meet or exceed the criteria set forth by the APA to define a neuroimaging biomarker, including the differential diagnosis of Alzheimer's disease and other dementias, the differential diagnosis of ADHD, and the evaluation of traumatic brain injury. The limitations, both real and perceived, of SPECT and PET functional neuroimaging in the field of psychiatry are also elaborated. An important overarching concept for diagnostic imaging in all its forms, including functional neuroimaging, is that imaging allows a clinician to eliminate possibilities, narrow the differential diagnosis, and tailor the treatment plan. This progression is central to any medical diagnostic process.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Current and emerging pharmacotherapy for the treatment of adult attention deficit hyperactivity disorder (ADHD)

Introduction: ADHD is characterized by a developmentally inappropriate level of inattentiveness, impulsivity and/or hyperactivity. In adults, the disorder is frequently accompanied by Emotional Dysregulation (ED), associated to a variety of related psychiatric comorbidities, complicating its recognition and treatment management. Areas covered: This paper reviews randomized active comparator-controlled or placebo-controlled trials evaluating the use of pharmacotherapy in adults with ADHD and ED, other neurodevelopmental disorders, Bipolar Disorder (BD) and Anxiety Disorders (ADs). When controlled data are unavailable, the authors have included open-label and observational studies. Expert opinion: ED in adult patients with ADHD is a very common and impairing problem that can be treated with stimulants or atomoxetine. ADHD studies in adults with other neurodevelopment disorders are scarce; stimulants seem to be the most effective and safe drugs in treating ADHD symptoms, without worsening the core features of other neurodevelopmental disorders. In patients with ADHD and comorbid BD, the treatment of BD alone may result in residual symptoms of ADHD. Patients should be treated hierarchically: BD should be treated first, while ADHD should be treated combining ADHD medications and mood stabilizers after mood stabilization. The available evidence for treating patients with ADHD and comorbid ADs in adults supports the idea of an anti-anxiety/ADHD-specific treatment association.

Adult ADHD: Risk Factor for Dementia or Phenotypic Mimic?

Attention-deficit hyperactivity disorder (ADHD) has historically been considered a disorder of childhood and adolescence. However, it is now recognized that ADHD symptoms persist into adulthood in up to 60% of individuals. Some of the cognitive symptoms that characterize ADHD (inability to provide sustained attention or mental effort, difficulty organizing or multi-tasking, forgetfulness) may closely resemble symptoms of prodromal dementia, also often referred to as mild cognitive impairment (MCI), particularly in patients over age 50. In addition to the overlap in cognitive symptoms, adults with ADHD and those with MCI may also share a number of behavioral and psychiatric symptoms, including sleep disturbances, depression, and anxiety. As a result, both syndromes may be difficult to distinguish clinically in older patients, particularly those who present to memory clinics with subjective cognitive complaints and fear the onset of a neurodegenerative process: is it ADHD, MCI, or both? Currently, it is unclear whether ADHD is associated with incipient dementia or is being misdiagnosed as MCI due to symptom overlap, as there exist data supporting either possibility. Here, we aim to elucidate this issue by outlining three hypothetical ways in which ADHD and MCI might relate to each other, providing an overview of the evidence relevant to each hypothesis, and delineating areas for future research. This is a question of considerable importance, with implications for improved diagnostic specificity of early dementia, improved accuracy of disease prevalence estimates, and better identification of individuals for targeted treatment.

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

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Innovations and recent trends in the treatment of ADHD

Initiatives to develop better-tolerated, more efficacious pharmacological agents with improved drug delivery systems have driven recent research in attention-deficit hyperactivity disorder (ADHD). While stimulants are the primary pharmacotherapy for ADHD, these drugs have a limited duration of action and a subset of patients will either fail to respond to these medications or have side effects that preclude their use. The development of atomoxetine, the first nonstimulant approved for ADHD, has been followed by additional innovative research, such as the methylphenidate transdermal system, modafinil, NRP-104 and cholinergic agents. This review highlights some of the recent trends in ADHD treatment and the current status of promising treatment options that may help to shape the future of ADHD treatment.

Background, clinical features and treatment of attention deficit hyperactivity disorder in children

INTRODUCTION

Attention deficit hyperactivity disorder (ADHD) is an early onset, clinically heterogeneous, complex neurobiological disorder, defined by symptoms of inattention and hyperactivity/impulsivity and has been associated with a broad range of impairments for those affected. Additionally, ADHD in children and adolescents is frequently associated with psychiatric comorbidities. This review provides an overview of the epidemiology, neurobiology, genetics, diagnosis and most recent pharmacological approaches for treatment with a focus on safety and efficacy and describes the use of medications used to treat ADHD in special populations.

AREAS COVERED

PubMed, Cochrane database, Essential Evidence and Uptodate were searched for relevant articles about stimulant and non-stimulant pharmacological approaches in ADHD.

EXPERT OPINION

Data supporting the safety and efficacy of both stimulant and non-stimulant formulations have significantly grown over the past decade and more efforts are being made to tailor medications to the needs of the patients and their families. Pharmacogenomics research is evolving, but predictors of treatment response and side effects remain largely unknown. Other unmet clinical needs include long-term follow-up studies of the safety and efficacy of medications for those with ADHD alone, or with comorbidities and in special populations including preschoolers.

The role of zebrafish (Danio rerio) in dissecting the genetics and neural circuits of executive function

Zebrafish have great potential to contribute to our understanding of behavioral genetics and thus to contribute to our understanding of the etiology of psychiatric disease. However, progress is dependent upon the rate at which behavioral assays addressing complex behavioral phenotypes are designed, reported and validated. Here we critically review existing behavioral assays with particular focus on the use of adult zebrafish to explore executive processes and phenotypes associated with human psychiatric disease. We outline the case for using zebrafish as models to study impulse control and attention, discussing the validity of applying extant rodent assays to zebrafish and evidence for the conservation of relevant neural circuits.

An update on the pharmacotherapy of attention-deficit/hyperactivity disorder in adults

Adults with attention-deficit/hyperactivity disorder (ADHD) are more frequently presenting for diagnosis and treatment. Medication is considered to be appropriate among available treatments for ADHD; however, the evidence supporting the use of pharmacotherapeutics for adults with ADHD remains less established. In this article, the effectiveness and dosing parameters of the various agents investigated for adult ADHD are reviewed. In adults with ADHD, short-term improvements in symptomatology have been documented through the use of stimulants and antidepressants. Studies suggest that methylphenidate and amphetamine maintained an immediate onset of action, whereas the ADHD response to the nonstimulants appeared to be delayed. At a group level, there appears to be some, albeit not entirely consistent, dose-dependent responses to amphetamine and methylphenidate. Generally speaking, variability in diagnostic criteria, dosing parameters and response rates between the various studies was considerable, and most studies were of a relatively short duration. The aggregate literature shows that the stimulants and catecholaminergic nonstimulants investigated had a clinically significant beneficial effect on treating ADHD in adults.

Cognitive enhancers for the treatment of ADHD

Attention-deficit hyperactivity disorder (ADHD) is associated with multiple cognition-related phenotypic features in both children and adults. This review aims to clarify the role of cognition in ADHD and how prevailing treatments, which are often highly effective at reducing the clinical symptoms of the disorder, fare in modulating ADHD-related cognitive processes. First, we consider how the broad construct of cognition can be conceptualized in the context of ADHD. Second, we review the available evidence for how a range of both pharmacological and non-pharmacological interventions have fared with respect to enhancing cognition in individuals affected by this pervasive disorder. Findings from the literature suggest that the effects across a broad range of pharmacological and non-pharmacological interventions on the characteristic symptoms of ADHD can be distinguished from their effects on cognitive impairments. As such the direct clinical relevance of cognition enhancing effects of different interventions is somewhat limited. Recommendations for future research are discussed, including the identification of cognition-related endophenotypes, the refinement of the ADHD clinical phenotype, and studying the difference between acute and chronic treatment regimens.

Donepezil use in children and adolescents with tics and attention-deficit/hyperactivity disorder: an 18-week, single-center, dose-escalating, prospective, open-label study

BACKGROUND

Striatal cholinergic dysfunction may be important in tics and attention-deficit/hyperactivity disorder (ADHD).

OBJECTIVE

The purpose of this study was to determine the safety profile of donepezil and whether it improves chronic tics in young patients with comorbid ADHD.

METHODS

This 18-week (14 weeks of open treatment followed by a 4-week washout period), single-center, dose-escalating, prospective, open-label trial was conducted in patients aged 7 to 17 years with tics, including chronic motor or vocal tics and Tourette's syndrome, and ADHD. Patients were treated with once-daily oral donepezil doses of 2.5 mg for 2 weeks, 5 mg for the next 6 weeks, and 10 mg for the last 6 weeks, followed by a 4-week washout period. Patients were evaluated using the Children's Global Assessment Scale; the Yale Global Tic Severity Scale (YGTSS); the Revised Conners' Parent Rating Scale; the Symbol and Digit Wisconsin Card Sorting Test; the Stroop black/white, color, and interference tests; the Rey Complex Figure Test; and the Children's Yale-Brown Obsessive Compulsive Scale at 4 visits: baseline, week 8 (5-mg dose), week 14 (10-mg dose), and week 18 (washout).

RESULTS

Seventeen males and 3 females (mean [SD] age, 11.3 [1.9] years [range, 8-14 years]; tic duration, 5.3 [1.9] years; ADHD duration, 6.5 [1.7] years) were included in this study. Tics were significantly reduced at the 10-mg (week-14) donepezil visit compared with the baseline and washout visits based on the total mean (SD) tic score of the YGTSS (18.6 [9.3] vs 12.2 [11.0]; P = 0.006). Fifty percent of patients withdrew and 65% experienced adverse events.

CONCLUSIONS

These preliminary results suggest that donepezil significantly reduced tics in these children and adolescents with comorbid ADHD who completed the study. No significant improvement in the symptoms of comorbid ADHD was found with the use of donepezil 10 mg. Donepezil 5 and 10 mg were not well tolerated in these children and adolescents.

Smoking, nicotine and neuropsychiatric disorders

Tobacco smoking is an extremely addictive and harmful form of nicotine (NIC) consumption, but unfortunately also the most prevalent. Although disproportionately high frequencies of smoking and its health consequences among psychiatric patients are widely known, the neurobiological background of this epidemiological association is still obscure. The diverse neuroactive effects of NIC and some other major tobacco smoke constituents in the central nervous system may underlie this association. This present paper summarizes the pharmacology of NIC and its receptors (nAChR) based on a systematic review of the literature. The role of the brain's reward system(s) in NIC addiction and the results of functional and structural neuroimaging studies on smoking-related states and behaviors (i.e. dependence, craving, withdrawal) are also discussed. In addition, the epidemiological, neurobiological, and genetic aspects of smoking in several specific neuropsychiatric disorders are reviewed and the clinical relevance of smoking in these disease states addressed.

Sensitization and cross-sensitization after chronic treatment with methylphenidate in adolescent Wistar rats

An increasing debate exists about the potential of early exposure to methylphenidate to increase the risk for drug abuse. In addition, little is known about the neurobiological effects of early exposure to methylphenidate. This study was designed to investigate whether chronic treatment with methylphenidate induces behavioral sensitization to subsequent methylphenidate and D-amphetamine challenge in adolescent Wistar rats. Young Wistar rats (P25) were treated with either methylphenidate (1, 2, or 10 mg/kg, intraperitoneally) or saline for 28 days. After 14 days of washout, animals were challenged with methylphenidate 2.5 mg/kg intraperitoneally or D-amphetamine 2 mg/kg intraperitoneally (P67). Locomotor behavior was assessed using the open field test. Rats chronically treated with methylphenidate in the adolescent period showed augmented locomotor sensitization to D-amphetamine but not to methylphenidate in the adult phase. These findings suggest that early exposure do methylphenidate might increase the risk for subsequent D-amphetamine abuse. Further studies focusing on the neurobiological effects of early exposure to methylphenidate are warranted.

Drug and non-drug treatments of children with ADHD and tic disorders

OBJECTIVE

To review the treatment of ADHD in children with chronic tic disorders.

BACKGROUND

Tic disorders are relatively common in school-age children and range from mild to severe. Children with mild tics may not require medication for the treatment of tics. The co-occurrence of attention deficit hyperactivity disorder (ADHD) and disruptive behavior are common in children with tic disorders and may be associated with significant morbidity.

METHODS

We conducted a literature search to identify reports of tics as an adverse effect to stimulant medication, the treatment of children with ADHD and tics as well as novel treatments that have been proposed for the treatment of ADHD in children with tic disorders.

RESULTS

The preponderance of evidence suggests that stimulant medications are safe and effective in the treatment of children with ADHD and tic disorders. A minority of children with tic disorders may show a worsening of tics or not tolerate stimulants for other reasons. The growing list of non-stimulants provides options for clinicians and parents of these children.

CONCLUSIONS

Treatment planning for children with ADHD and tic disorders involves careful discussion with parents on choosing the best course of action. Stimulants should be part of this discussion. More study is needed on non-pharmacological approaches to the treatment of tics and ADHD in this population.