Effects of methylphenidate on cognitive functions in children and adolescents with attention-deficit/hyperactivity disorder: evidence from a systematic review and a meta-analysis

The effects of chronic administration of stimulant and non-stimulant medications on executive functions in ADHD: A systematic review and meta-analysis

Attention-Deficit/Hyperactivity Disorder (ADHD) is associated with executive function deficits that are improved with medications. However, meta-analyses of stimulant effects on cognition have mostly tested single-dose effects, and there is no meta-analysis of non-stimulant effects. This systematic review and meta-analysis tested the clinically more relevant longer-term effects of Methylphenidate (20 studies; minimum 1 week) and Atomoxetine (8 studies; minimum 3 weeks) on reaction time, attention, inhibition, and working memory, searching papers on PubMed, Embase, Ovid MEDLINE, and PsycINFO. The meta-analysis of 18 studies in 1667 subjects showed that methylphenidate was superior to placebo in all cognitive domains with small to medium effect sizes (Hedges g of 0.34-0.59). The meta-analysis of atomoxetine included 7 studies in 829 subjects and showed no effects in working memory, but superior effects in the other domains with medium to large effect sizes (Hedge's g of 0.36-0.64). Meta-regression analysis showed no drug differences on cognitive effects. The meta-analyses show for the first time that chronic Methylphenidate and Atomoxetine have comparable effects of improving executive functions in people with ADHD.

Adenosinergic System and Nucleoside Transporters in Attention Deficit Hyperactivity Disorder: Current Findings

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder with high heterogeneity that can affect individuals of any age. It is characterized by three main symptoms: inattention, hyperactivity, and impulsivity. These neurobehavioral alterations and neurochemical and pharmacological findings are mainly attributed to unbalanced catecholaminergic signaling, especially involving dopaminergic pathways within prefrontal and striatal areas. Dopamine receptors and transporters are not solely implicated in this imbalance, as evidence indicates that the dopaminergic signaling is modulated by adenosine activity. To this extent, alterations in adenosinergic signaling are probably involved in ADHD. Here, we review the current knowledge about adenosine's role in the modulation of chemical, behavioral and cognitive parameters of ADHD, especially regarding dopaminergic signaling. Current literature usually links adenosine receptors signaling to the dopaminergic imbalance found in ADHD, but there is evidence that equilibrative nucleoside transporters (ENTs) could also be implicated as players in dopaminergic signaling alterations seen in ADHD, since their involvement in other neurobehavioral impairments.

An Expanded Conceptual Framework for Understanding Irritability in Childhood: The Role of Cognitive Control Processes

Children prone to irritability experience significant functional impairments and internalising and externalising problems. Contemporary models have sought to elucidate the underlying mechanisms in irritability, such as aberrant threat and reward biases to improve interventions. However, the cognitive control processes that underlie threat (e.g., attention towards threats) and reward (e.g., attention towards reward-related cues) biases and the factors which influence the differential activation of positive and negative valence systems and thus leading to maladaptive activation of cognitive control processes (i.e., proactive and reactive control) are unclear. Thus, we aim to integrate extant theoretical and empirical research to elucidate the cognitive control processes underlying threat and reward processing that contribute to irritability in middle childhood and provide a guiding framework for future research and treatment. We propose an expanded conceptual framework of irritability that includes broad intraindividual and environmental vulnerability factors and propose proximal 'setting' factors that activate the negative valence and positive valence systems and proactive and reactive cognitive control processes which underpin the expression and progression of irritability. We consider the implications of this expanded conceptualisation of irritability and provide suggestions for future research.

The Impact of Stimulant Medication on the Relation Between Working Memory and Activity Level in ADHD

There is a positive association between heightened activity levels and improved working memory performance (WM) in individuals with Attention-Deficit/Hyperactivity Disorder (ADHD). Recent research suggests that stimulant medications may have a simultaneous positive impact on WM and motor skills. Yet, it is unclear the specific connection between movement, WM, and stimulant use. We examined how visuospatial (VS) and phonological (PH) WM performance varied with children's stimulant medication usage and naturally occurring activity level. In a repeated measures design, children with ADHD (n = 43; 7-12 years old) completed WM tasks while wearing actigraphy watches to monitor activity level on and off stimulant medication. Significant large sized main effects were observed for medication condition on PH (p < .05, ηp2 = .14) and VS (p < .001, ηp2 = .30) WM. Activity level also had significant medium sized main effects on PH (p < .01, ηp2 = .09) and VS (p < .005, ηp2 = .10) WM. There was a significant medium sized interaction for VS WM (p < .005, ηp2 = .11), indicating that the effect of medication on performance was greatest in the highest activity level category. The findings suggest that a combination of stimulant medication and an "optimal" level of movement may be most effective for improving VS WM.

Methylphenidate alleviates cognitive dysfunction caused by early manganese exposure: Role of catecholaminergic receptors

Environmental manganese (Mn) exposure is associated with impaired attention and psychomotor functioning, as well as impulsivity/hyperactivity in children and adolescents. We have shown previously that developmental Mn exposure can cause these same dysfunctions in a rat model. Methylphenidate (MPH) lessens impairments in attention, impulse control, and psychomotor function in children, but it is unknown whether MPH ameliorates these dysfunctions when induced by developmental Mn exposure. Here, we sought to (1) determine whether oral MPH treatment ameliorates the lasting attention and sensorimotor impairments caused by developmental Mn exposure, and (2) elucidate the mechanism(s) of Mn neurotoxicity and MPH effectiveness. Rats were given 50 mg Mn/kg/d orally over PND 1-21 and assessed as adults in a series of attention, impulse control and sensorimotor tasks during oral MPH treatment (0, 0.5, 1.5, or 3.0 mg/kg/d). Subsequently, selective catecholaminergic receptor antagonists were administered to gain insight into the mechanism(s) of action of Mn and MPH. Developmental Mn exposure caused persistent attention and sensorimotor impairments. MPH treatment at 0.5 mg/kg/d completely ameliorated the Mn attentional dysfunction, whereas the sensorimotor deficits were ameliorated by the 3.0 mg/kg/d MPH dose. Notably, the MPH benefit on attention was only apparent after prolonged treatment, while MPH efficacy for the sensorimotor deficits emerged early in treatment. Selectively antagonizing D1, D2, or α2A receptors had no effect on the Mn-induced attentional dysfunction or MPH efficacy in this domain. However, antagonism of D2R attenuated the Mn sensorimotor deficits, whereas the efficacy of MPH to ameliorate those deficits was diminished by D1R antagonism. These findings demonstrate that MPH is effective in alleviating the lasting attentional and sensorimotor dysfunction caused by developmental Mn exposure, and they clarify the mechanisms underlying developmental Mn neurotoxicity and MPH efficacy. Given that the cause of attention and psychomotor deficits in children is often unknown, these findings have implications for the treatment of environmentally induced attentional and psychomotor dysfunction in children more broadly.

Treating Executive Function in Youth With Attention Deficit Hyperactivity Disorder: A Review of Pharmacological and Non-Pharmacological Interventions

INTRODUCTION

Executive function (EF) deficits are common in youth with ADHD and pose significant functional impairments. The extent and effect of interventions addressing EF in youth with ADHD remain unclear.

METHODS

We conducted a systematic literature review using PRISMA guidelines. Included studies were randomized controlled trials of interventions to treat EF in youth with ADHD.

RESULTS

Our search returned 136 studies representing 11,443 study participants. We identified six intervention categories: nonstimulant pharmacological (N = 3,576 participants), neurological (N = 1,935), psychological (N = 2,387), digital (N = 2,416), physiological (N = 680), and combination (N = 366). The bulk of the evidence supported pharmacological interventions as most effective in mitigating EF, followed by psychological and digital interventions.

CONCLUSION

A breadth of treatments exists for EF in youth with ADHD. Pharmacological, psychotherapeutic, and digital interventions had the most favorable, replicable outcomes. A lack of outcome standardization across studies limited treatment comparison. More data on the persistence of intervention effects are necessary.

Sensorimotor dysfunction due to developmental manganese exposure is less severe in adult female than male rats and partially improved by acute methylphenidate treatment

Epidemiological studies have reported associations between elevated manganese (Mn) exposure and poorer psychomotor performance in children. Our studies in adult male rats have established that this relationship is causal and that prolonged methylphenidate (MPH) treatment is efficacious in treating this area of dysfunction. However, it is unclear if sensitivity to these Mn deficits differs between females and males, and whether existing pharmacological therapies are efficacious in improving sensorimotor dysfunction in females. To address these questions, we used our rat model of childhood environmental Mn exposure and the Montoya staircase test to determine whether 1) there are sex differences in the lasting sensorimotor dysfunction caused by developmental Mn exposure, and 2) MPH treatment is efficacious in ameliorating the sensorimotor deficits in females. Female and male neonates were treated orally with Mn (50 mg Mn/kg/d) from postnatal day 1 to 21 and evaluated for skilled forelimb sensorimotor performance as adults. Subsequently, the efficacy of acute oral MPH treatment (doses of 0, 0.5, and 3.0 mg MPH/kg/d) was assessed in females using a within-subject MPH treatment design. Developmental postnatal Mn exposure produced lasting sensorimotor reaching and grasping deficits that were milder in females than in males. Acute MPH treatment of Mn-exposed females with the 0.5 mg/kg/d dose attenuated the reaching dysfunction without alleviating grasping dysfunction. These findings show sex-based variations in sensitivity to the sensorimotor impairment caused by developmental Mn exposure, and they are consistent with prior studies showing less vulnerability of females to Mn-induced dysfunction in other functional domains, possibly due to the protective effects of estrogen. Given our previous work showing the efficacy of MPH treatment to alleviate Mn-induced inattention, impulsiveness, and sensorimotor dysfunctions in adult male rats, they also highlight the need for further research into sex-based differences in cognitive and behavioral areas of brain function, and the efficacy of therapeutics in treating behavioral dysfunction in females. Supported by NIEHS R01ES028369.

Elevated EEG heartbeat-evoked potentials in adolescents with more ADHD symptoms

INTRODUCTION

Symptoms of attention deficit hyperactivity disorder (ADHD) are associated with a variety of mental abnormalities, but little is known about the perception and processing of internal signals, i.e., interoception, in individuals with ADHD symptoms. This study aimed to investigate the association between ADHD symptoms and the heartbeat-evoked potential (HEP), known as a neural correlate of automatic interoceptive processing of cardiac signals, in adolescents.

METHODS

HEPs of 47 healthy adolescent participants (53.2 % female) with a mean age of 14.29 years were measured during an emotional face recognition task. In addition, participants completed a self-report screening for ADHD symptoms.

RESULTS

ADHD symptoms were positively related to the HEP activity during the task in three of eight EEG sectors in the left hemisphere, as well as in all sectors in the right hemisphere.

DISCUSSION

This study is the first to demonstrate preliminary a relationship between the strength of HEP activity and ADHD symptoms in awake subjects. This finding of higher HEP amplitudes in subjects with more ADHD symptoms can be interpreted in terms of (i) increased arousal, (ii) altered neural processing of internal processes in an emotion-relevant task, and (iii) a misaligned precision-weighting process of task-irrelevant stimuli according to the predictive coding framework. These different interpretations could be reflected by previous studies showing heterogeneity of psychological deficits in individuals with ADHD symptoms. However, the generalizability to patients with diagnosed ADHD is limited due to the measurement tool for ADHD symptoms and the sample characteristics.

A preliminary study of the effects of stimulant medications on estimates of psycholinguistic abilities for children with attention-deficit/hyperactivity disorder

Underlying deficits in inattention, hyperactivity, and/or impulsivity might contribute to suboptimal test-taking behaviours during language assessments that can lead to diagnostic errors. Considerations of potential medication effects on estimates of children's nonword repetition, sentence recall, tense-marking, and narrative abilities are warranted given long-standing enthusiasm for these indices to serve as clinical markers for developmental language disorder (DLD). A battery consisting of 1 nonverbal, 1 reading, and 6 verbal measures was administered twice to 26 children (6-9 years) with independently diagnosed combined-type attention-deficit/hyperactivity disorder (ADHD). All participants had been prescribed stimulant medications for the management of their ADHD symptoms and were assessed off- and on-medication, with order counter-balanced across participants. Half of the participants had concomitant DLD. Examiners were unaware of children's clinical status during assessments or when they were testing children who had received medication. Effect sizes were calculated for each measure. Significant score differences indicating a beneficial impact of stimulant medications on children's performances were observed on the recalling sentences subtest of the Clinical Evaluation of Language Fundamentals and the Picture Peabody Vocabulary Test. Adjustments may be needed when speech language pathologists use sentence recall or receptive vocabulary measures to make diagnostic decisions with children who have ADHD.

Methylphenidate alleviates cognitive dysfunction from early Mn exposure: Role of catecholaminergic receptors

Environmental manganese (Mn) exposure is associated with impaired attention and psychomotor functioning, as well as impulsivity/hyperactivity in children and adolescents. We have shown previously that developmental Mn exposure can cause these same dysfunctions in a rat model. Methylphenidate (MPH) lessens impairments in attention, impulse control, and sensorimotor function in children, but it is unknown whether MPH ameliorates these dysfunctions when induced by developmental Mn exposure. Here, we sought to (1) determine whether oral MPH treatment ameliorates the lasting attention and sensorimotor impairments caused by developmental Mn exposure, and (2) elucidate the mechanism(s) of Mn neurotoxicity and MPH effectiveness. Rats were given 50 mg Mn/kg/d orally over PND 1-21 and assessed as adults in a series of attention, impulse control and sensorimotor tasks during oral MPH treatment (0, 0.5, 1.5, or 3.0 mg/kg/d). Subsequently, selective catecholaminergic receptor antagonists were administered to gain insight into the mechanism(s) of action of Mn and MPH. Developmental Mn exposure caused persistent attention and sensorimotor impairments. MPH treatment at 0.5 mg/kg/d completely ameliorated the Mn attentional dysfunction, whereas the sensorimotor deficits were ameliorated by the 3.0 mg/kg/d MPH dose. Notably, the MPH benefit on attention was only apparent after prolonged treatment, while MPH efficacy for the sensorimotor deficits emerged early in treatment. Selectively antagonizing D1, D2, or α2A receptors had no effect on the Mn-induced attentional dysfunction or MPH efficacy in this domain. However, antagonism of D2R attenuated the Mn sensorimotor deficits, whereas the efficacy of MPH to ameliorate those deficits was diminished by D1R antagonism. These findings demonstrate that MPH is effective in alleviating the lasting attention and sensorimotor dysfunction caused by developmental Mn exposure, and they clarify the mechanisms underlying developmental Mn neurotoxicity and MPH efficacy. Given that the cause of attention and psychomotor deficits in children is often unknown, these findings have implications for the treatment of environmentally-induced attentional and psychomotor dysfunction in children more broadly.

Single-dose effects of methylphenidate and atomoxetine on functional connectivity during an n-back task in boys with ADHD

RATIONALE

Working memory deficits and associated neurofunctional abnormalities are frequently reported in attention-deficit/hyperactivity disorder (ADHD). Methylphenidate and atomoxetine improve working memory performance and increase activation of regions under-functioning in ADHD. Additionally, methylphenidate has been observed to modulate functional networks involved in working memory. No research, however, has examined the effects of atomoxetine or compared the two drugs.

OBJECTIVES

This study aimed to test methylphenidate and atomoxetine effects on functional connectivity during working memory in boys with ADHD.

METHODS

We tested comparative effects of methylphenidate and atomoxetine on functional connectivity during the n-back task in 19 medication-naïve boys with ADHD (10-15 years old) relative to placebo and assessed potential normalisation effects of brain dysfunctions under placebo relative to 20 age-matched neurotypical boys. Patients were scanned in a randomised, double-blind, cross-over design under single doses of methylphenidate, atomoxetine, and placebo. Controls were scanned once, unmedicated.

RESULTS

Patients under placebo showed abnormally increased connectivity between right superior parietal gyrus (rSPG) and left central operculum/insula. This hyperconnectivity was not observed when patients were under methylphenidate or atomoxetine. Furthermore, under methylphenidate, patients showed increased connectivity relative to controls between right middle frontal gyrus (rMFG) and cingulo-temporo-parietal and striato-thalamic regions, and between rSPG and cingulo-parietal areas. Interrogating these networks within patients revealed increased connectivity between both rMFG and rSPG and right supramarginal gyrus under methylphenidate relative to placebo. Nonetheless, no differences across drug conditions were observed within patients at whole brain level. No drug effects on performance were observed.

CONCLUSIONS

This study shows shared modulating effects of methylphenidate and atomoxetine on parieto-insular connectivity but exclusive effects of methylphenidate on connectivity increases in fronto-temporo-parietal and fronto-striato-thalamic networks in ADHD.

Non-prescribed pharmaceutical stimulants use among adolescents: A way to self-care or peer success?

BACKGROUND

the use of pharmaceutical stimulants without a medical prescription (PSWMP) among adolescents is considered an established public health issue. The present study aimed to investigate the potential links between different patterns of non-medical use of pharmaceutical stimulants, psycho-social factors, and other risky behaviours (e.g. psychoactive substance use).

METHODS

For this purpose, data from a sample of 14,685 adolescents aged 15-19 participating in the ESPAD®Italia 2019 study were analysed by conducting descriptive analyses and multinomial logistic regressions.

RESULTS

The findings highlight the key role of psycho-social factors and engagement in other risky behaviours in either reducing or promoting the risk of PSWMP use. Particularly, being satisfied with peer relationships and with oneself is significantly associated with lower use of PSWMP. Conversely, the consumption of other psychoactive substances (both legal and illegal) and engagement in other risky behaviours (e.g., gambling and cyberbullying) may increase this phenomenon.

CONCLUSIONS

Considering their representativeness, the results of the present study could be used as groundwork for the development of effective and targeted prevention programs and interventions.

Efficacy of non-pharmacological interventions on executive functions in children and adolescents with ADHD: A systematic review and meta-analysis

OBJECTIVE

Although front-line doctors recommend medications, this kind of treatment has limited efficacy in improving executive functions (EFs) in children and adolescents with attention-deficit/hyperactivity disorder (ADHD). This study explored the effects of non-pharmacological intervention on EFs in children and adolescents with ADHD.

METHODS

In accordance with the Preferred Reporting Items for Systematic Review and Meta-analyses guidelines, we searched seven electronic databases: APA PsycINFO, CINAHL Complete, EMBASE, ERIC, Medline, Pubmed, and Web of Science, from inception to March 2022. Two authors independently screened studies for eligibility, extracted data, and assessed bias risk using the Physiotherapy Evidence Database scale. Our analyses included randomized controlled trials and non-randomized comparison studies of non-pharmacological interventions and assessed EFs through neurocognitive tasks in children and adolescents between 5 and 18 years.

RESULTS

Sixty-seven studies with 3147 participants met the inclusion criteria. The final meta-analysis included 74 independent interventions categorized into six categories: cognitive training, EF-specific curriculum, game-based training, mindfulness practice, neurofeedback training, and physical exercise. Overall, non-pharmacological interventions (combined) produced significant moderate to large effects on overall EFs in children and adolescents with ADHD (g=0.673). Physical exercise had a large positive effect on domain-specific EFs, including inhibitory control (g=0.900) and cognitive flexibility (g=1.377). Cognitive training had a large training effect on working memory (g=0.907), and an EF-specific curriculum had a small to moderate beneficial effect on planning performance (g=0.532).

CONCLUSION

Non-pharmacological interventions, particularly physical exercise, cognitive training, and an EF-specific curriculum, appear to have beneficial effects on EFs in children and adolescents with ADHD.

Case report: ADHD and prognosis in tyrosinemia type 1

Neurometabolic disorders such as tyrosinemia type 1 (TYRSN1) may interfere with brain metabolism and show symptoms of attention-deficit hyperactivity disorder (ADHD) in patients treated with the enzyme inhibitor nitisinone [2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione, NTBC]. It has been reported that ADHD treatment improves treatment compliance, which is imperative for the long-term prognosis of patients with TYRSN1. In this study, we report the case of a male patient who was diagnosed with TYRSN1 at 3 months of age and was subsequently treated with NTBC, restricted protein intake, and amino acids supplementation. At 7 years of age, he was referred for neuropsychiatric assessment, diagnosed with ADHD, and treated with methylphenidate. The effects of the treatment were monitored via parental interviews, questionnaires covering ADHD symptoms, and a continuous performance test. A reduction in ADHD symptoms, particularly inattentiveness, was observed across all measures. The early identification of ADHD and the treatment of neurometabolic disorders, such as TYRSN1, may be important from a lifetime perspective as this may improve the prognosis of the medical condition as well.

Methylphenidate is more effective to improve inhibitory control and working memory compared to tDCS in children and adolescents with attention deficit/hyperactivity disorder: a proof-of-concept study

Introduction

Attention-deficit/hyperactivity disorder (ADHD) is characterized by an inappropriate, pervasive and persistent pattern of inattention, hyperactivity, and/or impulsivity and associated with substantial functional impairment. Despite considerable advances in the understanding and management of ADHD, some patients do not respond well to methylphenidate (MPH), the first-choice pharmacological treatment. Over the past decades, among non-invasive brain stimulation techniques, transcranial direct current stimulation (tDCS) has proven to be an effective and safe technique to improve behavior and cognition in children with neurodevelopmental disorders, including ADHD, by modifying cortical excitability. However, the effect of tDCS has never been directly compared with that of the MPH. The present randomized sham-controlled trial evaluated the effect of a single session of anodal tDCS compared with the administration of a single dose of MPH in children and adolescents with ADHD.

Methods

After completing baseline assessment (T0), 26 children and adolescents with ADHD were exposed to 3 conditions with a 24-h interval-sessions: (A) a single session of anodal tDCS over the left dorsolateral prefrontal cortex (DLPFC); (B) a single session of sham tDCS over the left DLPFC; (C) a single dose of MPH.

Results

Our results showed that after administering a single dose of MPH, children and adolescents with ADHD improved inhibitory control and visual-spatial WM compared with baseline, anodal, and sham tDCS. However, a single session of active tDCS over the left DLPFC was not effective compared with either baseline or sham tDCS.

Discussion

In conclusion, our protocol in ADHD involving a single tDCS session did not demonstrate consistent improvements in neurocognitive features compared with baseline, sham tDCS, or single MPH administration. Different protocols need to be developed to further test the effectiveness of tDCS in improving ADHD symptoms.

Annual Research Review: Perspectives on progress in ADHD science - from characterization to cause

The science of attention-deficit/hyperactivity disorder (ADHD) is motivated by a translational goal - the discovery and exploitation of knowledge about the nature of ADHD to the benefit of those individuals whose lives it affects. Over the past fifty years, scientific research has made enormous strides in characterizing the ADHD condition and in understanding its correlates and causes. However, the translation of these scientific insights into clinical benefits has been limited. In this review, we provide a selective and focused survey of the scientific field of ADHD, providing our personal perspectives on what constitutes the scientific consensus, important new leads to be highlighted, and the key outstanding questions to be addressed going forward. We cover two broad domains - clinical characterization and, risk factors, causal processes and neuro-biological pathways. Part one focuses on the developmental course of ADHD, co-occurring characteristics and conditions, and the functional impact of living with ADHD - including impairment, quality of life, and stigma. In part two, we explore genetic and environmental influences and putative mediating brain processes. In the final section, we reflect on the future of the ADHD construct in the light of cross-cutting scientific themes and recent conceptual reformulations that cast ADHD traits as part of a broader spectrum of neurodivergence.

Methylphenidate Enhances Spontaneous Fluctuations in Reward and Cognitive Control Networks in Children With Attention-Deficit/Hyperactivity Disorder

BACKGROUND

Methylphenidate, a first-line treatment for attention-deficit/hyperactivity disorder (ADHD), is thought to influence dopaminergic neurotransmission in the nucleus accumbens (NAc) and its associated brain circuitry, but this hypothesis has yet to be systematically tested.

METHODS

We conducted a randomized, placebo-controlled, double-blind crossover trial including 27 children with ADHD. Children with ADHD were scanned twice with resting-state functional magnetic resonance imaging under methylphenidate and placebo conditions, along with assessment of sustained attention. We examined spontaneous neural activity in the NAc and the salience, frontoparietal, and default mode networks and their links to behavioral changes. Replicability of methylphenidate effects on spontaneous neural activity was examined in a second independent cohort.

RESULTS

Methylphenidate increased spontaneous neural activity in the NAc and the salience and default mode networks. Methylphenidate-induced changes in spontaneous activity patterns in the default mode network were associated with improvements in intraindividual response variability during a sustained attention task. Critically, despite differences in clinical trial protocols and data acquisition parameters, the NAc and the salience and default mode networks showed replicable patterns of methylphenidate-induced changes in spontaneous activity across two independent cohorts.

CONCLUSIONS

We provide reproducible evidence demonstrating that methylphenidate enhances spontaneous neural activity in NAc and cognitive control networks in children with ADHD, resulting in more stable sustained attention. Our findings identified a novel neural mechanism underlying methylphenidate treatment in ADHD to inform the development of clinically useful biomarkers for evaluating treatment outcomes.

A post hoc analysis of the effect of viloxazine extended-release capsules on learning and school problems in children and adolescents with attention-deficit/hyperactivity disorder

Improvement in attention-deficit/hyperactivity disorder (ADHD) symptoms vs. placebo was reported in a series of pediatric clinical trials of viloxazine extended-release capsules (viloxazine ER; Qelbree™). This post hoc analysis of those studies evaluated the effect of viloxazine ER on learning and school problems (LSPs). We used data from four Phase 3 placebo-controlled trials of 100-600 mg/day viloxazine ER (N = 1354; 6-17 years of age). LSPs were evaluated using the School domain of the Weiss Functional Impairment Rating Scale-Parent Report (WFIRS-P-S) and the Learning Problems content scale of the Conners 3rd Edition-Parent Short Form (C3PS-LP) at baseline and end of study (≥ Week 6). ADHD symptoms were assessed weekly using the ADHD Rating Scale 5th Edition. The analyses were performed using the general linear mixed model with participant as a random effect. The responder analyses were performed using the Chi-square test. Viloxazine ER demonstrated significantly greater improvements in WFIRS-P-S (p < 0.0001) and C3PS-LP (p = 0.0113) scores vs. placebo. The response rate for the WFIRS-P-S was significantly greater for viloxazine ER vs. placebo (p = 0.001), and the number needed to treat (NNT) was 10.3 (effect size 0.7). Conversely, response rates for C3PS-LP did not differ between groups (p = 0.9069). In addition to ADHD symptoms improvement demonstrated in previous studies, viloxazine ER significantly reduced LSPs in pediatric subjects with ADHD. The responder analyses and NNT estimates indicate that a substantial number of children and adolescents with ADHD treated with viloxazine ER improved in clinically assessed LSPs.

Fronto-Cerebellar Neurometabolite Alterations After Methylphenidate in Children and Adolescents With ADHD: A Proton Magnetic Resonance Spectroscopy Study

OBJECTIVE

The fronto-cerebellar circuit is involved in ADHD pathophysiology. Methylphenidate, as a first-line medication for ADHD, affects different brain regions, however, its effect on the fronto-cerebellar circuit is not investigated sufficiently. We aimed to investigate the effect of 8-week treatment with methylphenidate on neurometabolite ratios in the fronto-cerebellar circuit in ADHD participants using magnetic resonance spectroscopy (MRS).

METHODS

Fifteen drug-naïve ADHD children and adolescents were enrolled in the present study. Two single-voxel MR spectra were acquired from the right dorsolateral prefrontal cortex (DLPFC) and left Crus 1, before and after the medication. Also, neuropsychological and behavioral assessments were administered.

RESULTS

After medication, the glutamate/creatine in the DLPFC and the choline/creatine in the Crus 1 decreased in the ADHD participants.

CONCLUSION

These findings propose that methylphenidate-induced metabolite changes in the fronto-cerebellar circuit could be associated with improvement in cognitive/behavioral characteristics in ADHD. Also, results highlighted cerebellar engagement in ADHD pathophysiology.

Evidence-based prescribing of medications for ADHD: where are we in 2023?

INTRODUCTION

A large number of randomized controlled trials (RCTs) and observational studies on the pharmacotherapy of ADHD are available.

AREAS COVERED

Based on a search in PubMed and PsycInfo (up to 15 September 2022), this review addresses to which extent this body of research is currently able to inform routine prescribing practice, in terms of the choice of medication, titration strategy, augmentation treatments, and use of alternative, non-approved treatments.

EXPERT OPINION

A growing body of evidence is informing prescribers on some, but certainly not all, aspects related to the pharmacological treatment of ADHD in the daily clinical practice, with important weaknesses/gaps that need to be addressed. First, evidence synthesis of RCTs is not able to inform decision-making at the individual patient level. Second, the maximum safe and effective doses, possibly beyond those currently recommended, are not well understood. Third, evidence from RCTs on augmenting strategies is still limited. Fourth, no novel agents with the same or higher effect size of stimulants, in terms of efficacy, but with better tolerability and lower abuse potential, have been found. Implementation of precision psychiatry approaches and stratification of patients in future RCTs will be key to, respectively, individualize the treatment strategies and test etiopathophysiology-based agents.

Computer-based multiple component cognitive training in children with ADHD: a pilot study

BACKGROUND

ADHD is associated with deficits in executive functions. Cognitive training is a promising nonpharmacological intervention for ADHD, however, there is insufficient evidence to guide the selection of training for individuals with ADHD. This pilot study aims to investigate the efficacy of executive function training targeting key executive dysfunctions in ADHD, compared with general executive function training which targets other executive functions.

METHODS

A total of 127 subjects (6-12 years) diagnosed with ADHD were allocated to receive one of two different cognitive trainings. ADHD symptoms and cognitive functions were evaluated using parent-rated scales and CANTAB cognitive assessments. All participants were required to complete 48 training sessions within a two-month period.

RESULTS

94 out of 127 children completed the required training and assessments. Both ADHD executive function training group and general executive function training group showed significant improvement in ADHD symptoms on the ADHD Rating Scale and in executive function on the assessment of CANTAB. There was no significant difference in improvements between the two groups. Subgroup analysis suggested that children who had ADHD-RS total scores less than or equal to 28 at baseline showed greater improvement following ADHD executive function training.

CONCLUSIONS

This study indicates that cognitive training can improve ADHD symptoms and executive function, with no difference in efficacy between targeted and generalized cognitive training. In addition, individuals with lower symptom severity may benefit more from training targeting key ADHD executive dysfunctions.

Parent Training for ADHD: No Generalization of Effects From Clinical to Neuropsychological Outcomes in a Randomized Controlled Trial

OBJECTIVE

We examined whether neuropsychological function in ADHD can be improved by the New Forest Parenting Programme (NFPP), that combines standard parenting strategies with self-regulatory skills training, or predict ADHD and quality of life (QoL) treatment effects.

METHOD

Participants were 93 medication-naive preschool children with ADHD (3-7 years) randomized to either NFPP (n = 49) or treatment as usual (TAU; n = 44) in a recent randomized trial. Laboratory measures of executive function, reaction time variability, and delay of gratification were collected along with parent ratings of ADHD and QoL at baseline and post treatment. Ratings were collected again at 3-month follow-up.

RESULTS

NFPP did not improve neuropsychological function (compared to TAU), and baseline neuropsychological function did not predict treatment-related ADHD or QoL effects.

CONCLUSION

Although NFPP includes a neuropsychological training element and has been shown to improve several clinical outcomes, it did not improve the neuropsychological functions it targets.

Effect of short-term methylphenidate on social impairment in children with attention deficit/hyperactivity disorder: systematic review

Attention Deficit/Hyperactivity disorder (ADHD) is one of the most common disorders in school-age children. In addition to learning difficulties associated with the disorder's core symptoms of inattention and hyperactivity, children with ADHD display substantial social impairments. Methylphenidate (MPH) in formulations such as Ritalin or Concerta mitigates inattention and hyperactivity, but the effects of the therapy on social behavior in children with ADHD are not clear. This review aims to determine the effectiveness of short term (up to 6 months) MPH treatment on three domains of social skills in children aged 6-14 with ADHD: (i) Recognition of nonverbal emotional expressions, which are a marker of inherent (unlearned) social understanding, (ii) theory of mind (ToM) components that relate to learned cognition and social communication, and (iii) social competence in everyday environments. 15 relevant studies were identified based on inclusion/exclusion criteria. The results show mixed effects: the overall social performance as evaluated by parents, teachers or peers, and some components of ToM, were found to improve following a weeks-long course of MPH treatment. However, the effects of the medication are less clear when evaluating momentary/nonverbal social responses such as reactions to emotional facial expressions. While the findings of this review indicate that an MPH medication regime of order weeks to months could improve, to a degree, social impairment in children with ADHD, more studies are required to identify the medications' mechanism and confirm such a conclusion.

Immediate and Sustained Effects of Neurofeedback and Working Memory Training on Cognitive Functions in Children and Adolescents with ADHD: A Multi-Arm Pragmatic Randomized Controlled Trial

OBJECTIVE

To evaluate the effects of neurocognitive training methods on targeted cognitive functions in children and adolescent with ADHD.

METHOD

A pragmatic four-arm randomized controlled trial compared two types of neurofeedback (Slow Cortical Potential and Live Z-score) and Working-memory training (WMT) with treatment as usual. N = 202 participants with ADHD aged 9 to 17 years were included. A battery of cognitive function tests was completed pretreatment, posttreatment, and after 6-months.

RESULTS

The effects of WMT on spatial and verbal working-memory were superior to neurofeedback and treatment as usual at posttreatment, but only partially sustained at follow-up. No other consistent effects were observed. We found no clear indications that effects were moderated by ADHD presentation, ongoing medication, age, or sex.

CONCLUSION

The sustained effects of neurocognitive training on cognitive functioning in children and adolescents with ADHD may be limited. Future research should focus on more personalized forms of neurocognitive training.

Hospital-Based Modified Cogmed Working Memory Training for Youth With ADHD

OBJECTIVE

This study evaluated a modified working memory training program, Cogmed, for ADHD youth.

METHOD

Forty youth were randomized to modified Cogmed training (MCT) or treatment as usual (CON). MCT was delivered in an outpatient mental health clinic in 3 weekly 35-minute sessions with a dedicated coach for 10 weeks. Participants completed assessments at baseline, after the intervention, and again 3 months later.

RESULTS

After controlling for baseline, groups were comparable on working memory, academics, and ADHD symptoms. The MCT group was rated by parents and teachers as having fewer executive function challenges and youth endorsed better self-concept compared with the CON group.

CONCLUSIONS

MCT was associated with some improvement, which could not be attributed to increased working memory capacity and may reflect other facets of the program. Results question the usefulness of Cogmed but highlight considerations for optimizing adherence, engagement, and the therapeutic alliance in interventions for ADHD youth.

Stimulant and non-stimulant drug therapy for people with attention deficit hyperactivity disorder and epilepsy

BACKGROUND

Attention Deficit Hyperactivity Disorder (ADHD) can co-occur in up to 40% of people with epilepsy. There is debate about the efficacy and tolerability of stimulant and non-stimulant drugs used to treat people with ADHD and co-occurring epilepsy.

OBJECTIVES

To assess the effect of stimulant and non-stimulant drugs on children and adults with ADHD and co-occurring epilepsy in terms of seizure frequency and drug withdrawal rates (primary objectives), as well as seizure severity, ADHD symptoms, cognitive state, general behaviour, quality of life, and adverse effects profile (secondary objectives).

SEARCH METHODS

We searched the following databases on 12 October 2020: Cochrane Register of Studies (CRS Web), MEDLINE (Ovid, 1946 to 9 October 2020), CINAHL Plus (EBSCOhost, 1937 onwards). There were no language restrictions. CRS Web includes randomised or quasi-randomised controlled trials from PubMed, Embase, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (ICTRP), the Cochrane Central Register of Controlled Trials (CENTRAL), and the Specialised Registers of Cochrane Review Groups including Epilepsy.  SELECTION CRITERIA: We included randomised controlled trials of stimulant and non-stimulant drugs for people of any age, gender or ethnicity with ADHD and co-occurring epilepsy.

DATA COLLECTION AND ANALYSIS

We selected articles and extracted data according to predefined criteria. We conducted primary analysis on an intention-to-treat basis. We presented outcomes as risk ratios (RRs) with 95% confidence intervals (CIs), except for individual adverse effects where we quoted 99% CIs. We conducted best- and worst-case sensitivity analyses to deal with missing data. We carried out a risk of bias assessment for each included study using the Cochrane risk of bias tool and assessed the overall certainty of evidence using the GRADE approach.

MAIN RESULTS

We identified two studies that matched our inclusion criteria: a USA study compared different doses of the stimulant drug osmotic-release oral system methylphenidate (OROS-MPH) with a placebo in 33 children (mean age 10.5 ± 3.0 years), and an Iranian study compared the non-stimulant drug omega-3 taken in conjunction with risperidone and usual anti-seizure medication (ASM) with risperidone and ASM only in 61 children (mean age 9.24 ± 0.15 years). All children were diagnosed with epilepsy and ADHD according to International League Against Epilepsy and Diagnostic and Statistical Manual of Mental Disorders, fourth edition, criteria, respectively. We assessed both studies to be at low risk of detection and reporting biases, but assessments varied from low to high risk of bias for all other domains. OROS-MPH No participant taking OROS-MPH experienced significant worsening of epilepsy, defined as: 1. a doubling of the highest 14-day or highest two-day seizure rate observed during the 12 months before the trial; 2. a generalised tonic-clonic seizure if none had been experienced in the previous two years; or 3. a clinically meaningful intensification in seizure duration or severity (33 participants, 1 study; low-certainty evidence). However, higher doses of OROS-MPH predicted an increased daily risk of a seizure (P < 0.001; 33 participants, 1 study; low-certainty evidence). OROS-MPH had a larger proportion of participants receiving 'much improved' or 'very much improved' scores for ADHD symptoms on the Clinical Global Impressions for ADHD-Improvement tool (33 participants, 1 study; low-certainty evidence). OROS-MPH also had a larger proportion of people withdrawing from treatment (RR 2.80; 95% CI 1.14 to 6.89; 33 participants, 1 study; moderate-certainty evidence). Omega-3 Omega-3 with risperidone and ASM were associated with a reduction in mean seizure frequency by 6.6 seizures per month (95% CI 4.24 to 8.96; 56 participants, 1 study; low-certainty evidence) and an increase in the proportion of people achieving 50% or greater reduction in monthly seizure frequency (RR 2.79, 95% CI 0.84 to 9.24; 56 participants, 1 study; low-certainty evidence) compared to people on risperidone and ASM alone. Omega-3 with risperidone and ASM also had a smaller proportion of people withdrawing from treatment (RR 0.65, 95% CI 0.12 to 3.59; 61 participants, 1 study; low-certainty evidence) but a larger proportion of people experiencing adverse drug events (RR 1.40, 95% CI 0.44 to 4.42; 56 participants, 1 study; low-certainty evidence) compared to people on risperidone and ASM alone.

AUTHORS' CONCLUSIONS

In children with a dual-diagnosis of epilepsy and ADHD, there is some evidence that use of the stimulant drug OROS-MPH is not associated with significant worsening of epilepsy, but higher doses of it may be associated with increased daily risk of seizures; the evidence is of low-certainty. OROS-MPH is also associated with improvement in ADHD symptoms. However, this treatment was also associated with a large proportion of treatment withdrawal compared to placebo. In relation to the non-stimulant drug omega-3, there is some evidence for reduction in seizure frequency in children who are also on risperidone and ASM, compared to children who are on risperidone and ASM alone. Evidence is inconclusive whether omega-3 increases or decreases the risk of adverse drug events. We identified only two studies - one each for OROS-MPH and omega-3 - with low to high risk of bias. We assessed the overall certainty of evidence for the outcomes of both OROS-MPH and omega-3 as low to moderate. More studies are needed. Future studies should include: 1. adult participants; 2. a wider variety of stimulant and non-stimulant drugs, such as amphetamines and atomoxetine, respectively; and 3. additional important outcomes, such as seizure-related hospitalisations and quality of life. Clusters of studies which assess the same drug - and those that build upon the evidence base presented in this review on OROS-MPH and omega-3 - are needed to allow for meta-analysis of outcomes.

Meta-analysis: Altered Perceptual Timing Abilities in Attention-Deficit/Hyperactivity Disorder

OBJECTIVE

We meta-analyzed studies comparing perceptual timing abilities in the range of milliseconds to several seconds in persons with attention-deficit/hyperactivity disorder (ADHD) and neurotypical participants, using the well-established time discrimination, time estimation, time production, and time reproduction paradigms.

METHOD

We searched PubMed, OVID databases, and Web of Knowledge through September 17, 2020. From 2,266 records, 55 studies were retained and meta-analyzed with random effects models. We conducted meta-regression analyses to explore moderating effects of task parameters and neuropsychological measures of working memory, attention, and inhibition on timing performance.

RESULTS

Compared with persons without ADHD, those with ADHD had significantly more severe difficulties in discriminating stimuli of very brief durations, especially in the sub-second range. They also had more variability in estimating the duration of stimuli lasting several seconds. Moreover, they showed deficits in time estimation and time production accuracy, indicative of an accelerated internal clock. Additional deficits in persons with ADHD were also found in the time reproduction paradigm, involving attentional (slower counting at short time intervals due to distraction) and motivational (faster counting at long time intervals due to increased delay aversion) functions.

CONCLUSION

There is meta-analytic evidence of a broad range of timing deficits in persons with ADHD. Results have implications for advancing our knowledge in the field (eg, for refinement of recent timing models in ADHD) and clinical practice (eg, testing timing functions to characterize the clinical phenotype of the patient and implementation of interventions to improve timing abilities).

The Association between Sleep Problems and Neuropsychological Deficits in Medication-naïve Children with ADHD

BACKGROUND

Children with ADHD are reported to have sleep problems and neuropsychological deficits, but studies examining a potential association between the two are scarce and the use of varying methodology can complicate conclusions.

PARTICIPANTS

A clinical sample of 59 medication-naïve children with ADHD between the ages of 6 and 14 years (71% male).

METHODS

Children underwent polysomnography and multiple sleep latency test, and parent rated sleep habits on the Children's Sleep Habits Questionnaire. Children also completed an extensive neuropsychological battery of executive function and delay aversion tasks, and parents and teachers rated executive function behavior on the Behavior Rating Inventory of Executive Function. Linear regression analyses were conducted with each of the neuropsychological outcomes included as the outcome variable and the sleep parameters as the predictor variables.

RESULTS

The correlations between sleep and neuropsychological outcomes were generally modest, but some sleep parameters (primarily sleep stages and sleep latencies) were associated with objectively and subjectively measured executive function and delay aversion.

CONCLUSIONS

Using objective and subjective gold standard assessment procedures this study supports a (modest) association between sleep and neuropsychological function in children with ADHD.

Can Neurocognitive Outcomes Assist Measurement-Based Care for Children with Attention-Deficit/Hyperactivity Disorder? A Systematic Review and Meta-Analyses of the Relationships Among the Changes in Neurocognitive Functions and Clinical Outcomes of Attention-Deficit/Hyperactivity Disorder in Pharmacological and Cognitive Training Interventions

Attention-deficit/hyperactivity disorder (ADHD) is one of the most common neurodevelopmental conditions among school-age children. Early intervention and ongoing evaluation of treatment effectiveness are essential to minimize the life-long negative impact of ADHD. Neurocognitive functions have been reported to improve with pharmacological and cognitive training interventions for children with ADHD. We evaluated the value of measuring change in neurocognitive functions following ADHD interventions as a treatment outcome. We systematically reviewed randomized control trials of two distinctive types of ADHD interventions-pharmacological treatments and cognitive training-and summarized the changes in neurocognitive and clinical outcomes using a series of meta-analyses. Both pharmacological and cognitive training interventions showed positive effects on some aspects of neurocognitive functions. However, there were no significant correlations between changes in neurocognitive function (e.g., inhibition) and changes in ADHD behavioral symptoms (e.g., impulsive behavior). Although the associations between changes in neurocognitive function and clinical outcomes are not well studied, based on current findings, it is not suitable to use change in neurocognitive outcomes as a proxy for change in ADHD clinical symptom-based outcomes. There is, however, notable value in monitoring changes in neurocognitive function associated with ADHD interventions to achieve the following aims: (1) understanding full treatment effect on children with ADHD, (2) identifying ancillary indicators of subclinical changes, and (3) provision of objective and less biased measures of treatment effects. These findings are important evidence that changes in neurocognitive function could be a co-occurring objective indication that parallels the clinical effects of ADHD treatments.

Personalization of pharmacological treatments for ADHD: Why it is advisable and possible options to achieve it

Abstract:

Attention-deficit hyperactivity disorder is a neurodevelopmental disorder diagnosed primarily in children, although it is also present in adults. Patients present inattention, impulsivity, and hyperactivity symptoms that create difficulties in their daily lives. Pharmacological treatment with stimulants or non-stimulants is used most commonly to reduce ADHD symptoms. Although generally effective and safe, pharmacological treatments have different effects among patients, including lack of response and adverse reactions. The reasons for these differences are not fully understood, but they may derive from the highly diverse etiology of ADHD. Strategies to guide optimal pharmacological treatment selection on the basis of individual patients’ physiological markers are being developed. In this review, we describe the main pharmacological ADHD treatments used and their main drawbacks. We present alternatives under study that would allow the customization of pharmacological treatments to overcome these drawbacks and achieve more reliable improvement of ADHD symptoms.

Methylphenidate remediates aberrant brain network dynamics in children with attention-deficit/hyperactivity disorder: a randomized controlled trial

Methylphenidate is a widely used first-line treatment for attention deficit/hyperactivity disorder (ADHD), but the underlying circuit mechanisms are poorly understood. Here we investigate whether a single dose of osmotic release oral system methylphenidate can remediate attention deficits and aberrancies in functional circuit dynamics in cognitive control networks, which have been implicated in ADHD. In a randomized placebo-controlled double-blind crossover design, 27 children with ADHD were scanned twice with resting-state functional MRI and sustained attention was examined using a continuous performance task under methylphenidate and placebo conditions; 49 matched typically-developing (TD) children were scanned once for comparison. Dynamic time-varying cross-network interactions between the salience (SN), frontoparietal (FPN), and default mode (DMN) networks were examined in children with ADHD under both administration conditions and compared with TD children. Methylphenidate improved sustained attention on a continuous performance task in children with ADHD, when compared to the placebo condition. Children with ADHD under placebo showed aberrancies in dynamic time-varying cross-network interactions between the SN, FPN and DMN, which were remediated by methylphenidate. Multivariate classification analysis confirmed that methylphenidate remediates aberrant dynamic brain network interactions. Furthermore, dynamic time-varying network interactions under placebo conditions predicted individual differences in methylphenidate-induced improvements in sustained attention in children with ADHD. These findings suggest that a single dose of methylphenidate can remediate deficits in sustained attention and aberrant brain circuit dynamics in cognitive control circuits in children with ADHD. Findings identify a novel brain circuit mechanism underlying a first-line pharmacological treatment for ADHD, and may inform clinically useful biomarkers for evaluating treatment outcomes.

Meta-analysis: Dose-Dependent Effects of Methylphenidate on Neurocognitive Functioning in Children With Attention-Deficit/Hyperactivity Disorder

OBJECTIVE

Neurocognitive deficits are at the heart of explanatory models of attention-deficit/hyperactivity disorder (ADHD), and lead to significant impairments in daily life. Determining the dosing effects of methylphenidate (MPH) on a broad range of neurocognitive functions and investigating possible impairing effects of high doses is therefore important.

METHOD

Placebo-controlled trials were included that investigated MPH dosing effects on neurocognitive functions in children and adolescents (aged 5-18 years) diagnosed with ADHD. Effect sizes (standardized mean differences [SMDs]) were calculated for different neurocognitive functions (baseline speed, variability in responding, nonexecutive memory and executive memory, inhibitory control, and cognitive flexibility) and, if available, for ADHD symptoms. Meta-regression analysis were used to investigate linear effects of dose (mg/kg/dose), and separate meta-analyses compared SMDs for 3 MPH dose ranges: low (0.10-0.30 mg/kg/dose), medium (0.31-0.60 mg/kg/dose), and high (0.61-1.00 mg/kg/dose).

RESULTS

A total of 31 studies fulfilled inclusion criteria, comprising 804 children with ADHD. Methylphenidate had beneficial effects on all neurocognitive functions (d = 0.20-0.73). Significant linear dosing effects were found for ADHD symptoms and lower-order neurocognitive functions (baseline speed, variability in responding, nonexecutive memory), with greater enhancement of functioning with increasing dose. No dosing effects were found for higher-order neurocognitive functions (executive memory, inhibitory control, and cognitive flexibility). No detrimental effects of MPH were found on any of the investigated functions.

CONCLUSION

Methylphenidate was superior to placebo in improving ADHD symptoms and a broad range of neurocognitive functions; however, effects sizes regarding the effects of dose vary substantially between functions. Our data highlight the importance of considering both neurocognitive and symptomatic aspects of ADHD in clinical practice.

Editorial: Evidence Concerning Dose-Dependent Effects of Stimulants on Neurocognitive Function in Children With Attention-Deficit/Hyperactivity Disorder

The question of how stimulants affect cognitive function in children with attention-deficit/hyperactivity disorder (ADHD) is a challenging one that has been investigated across many studies. Part of the challenge lies in the difficulty of examining the range of cognitive functions that are now evidenced as areas of difficulty within a single study. A lack of studies examining the long-term effects of medication has also challenged advancement of knowledge in this area. When the available research is integrated, what is the conclusion regarding effects of stimulants on neurocognitive function?

Comparing the Effect of Methylphenidate and Anodal tDCS on Inhibitory Control and Working-Memory in Children and Adolescents with Attention Deficit/Hyperactivity Disorder: A Study Protocol for a Randomized, within-Subject Trial

Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder characterized by inappropriate levels of attention, hyperactivity, and impulsivity that interfere with individual functioning. The international guidelines recommend targeting ADHD-related neurochemical brain abnormalities by intervening via drug treatment, such as methylphenidate (MPH), as first choice. Drug treatments are usually associated with a huge amount of cost for families and the healthcare system, suspension for low compliance, poor long-term efficacy, and side effects. Transcranial direct current stimulation (tDCS) has been suggested as a possible noninvasive means to safely manipulate brain activity and, in turn, improve behavior and cognition in developmental ages. Several studies have shown that tDCS has the potential to improve ADHD-related cognitive deficits, but the effect of tDCS compared with MPH has never been evaluated. The aim of the present within-subject, sham-controlled, randomized proof-of-concept study is to demonstrate the positive effect of one-session anodal tDCS analogous to the MPH drug on inhibitory control and working memory in children and adolescents with ADHD. We strongly believe that this study protocol will serve to accelerate research into low-cost, drug-free, feasible interventions for ADHD.

An evaluation of the effect of methylphenidate on working memory, time perception, and choice impulsivity in children with ADHD

Individuals with Attention-Deficit Hyperactivity Disorder (ADHD) consistently exhibit a stronger preference for immediate rewards than for larger rewards available following a delay on tasks measuring choice impulsivity (CI). Despite this, however, there remains a dearth of studies examining the impact of stimulant treatment on CI as well as associated higher order (e.g., working memory [WM]) and perceptual (e.g., time perception) cognitive processes. The present study examines the effect of osmotic release oral system methylphenidate (OROS-MPH) on CI, WM and time perception processes as well as the relation among these processes before and after taking a regimen of OROS-MPH. Thirty-five children (aged 7-12 years) with a diagnosis of ADHD participating in a concurrent stimulant medication study were recruited to complete computerized assessments of CI, WM, and time perception. Children completed the assessments after administration of a placebo as well as their lowest effective dose of OROS-MPH following a 2-week titration period. The results from one-sample t-tests indicated that OROS-MPH improves both CI and WM in youth with ADHD but does not impact time perception. Further, results revealed no significant association among the various indices of cognitive performance while taking placebo or OROS-MPH. Overall, the findings suggest that while OROS-MPH improves both CI and WM in youth with ADHD, improvements in CI as a result of OROS-MPH are unlikely to be associated with the improvements in WM given the lack of association among the two. Future studies should consider alternate cognitive, emotional, and motivational mechanisms that may account for the impact of OROS-MPH on CI. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

White matter microstructure in children and adolescents with ADHD

•

A systematic review of diffusion MRI studies in children and adolescents with ADHD.

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46 studies included, encompassing multiple diffusion MRI techniques.

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Reduced white matter microstructure was reported in several studies.

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Mixed evidence linking white matter differences with specific cognitive processes.

•

Common limitations included sample size, head motion and medication status.

Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder. Advances in diffusion magnetic resonance imaging (MRI) acquisition sequences and analytic techniques have led to growing body of evidence that abnormal white matter microstructure is a core pathophysiological feature of ADHD. This systematic review provides a qualitative assessment of research investigating microstructural organisation of white matter amongst children and adolescents with ADHD. This review included 46 studies in total, encompassing multiple diffusion MRI imaging techniques and analytic approaches, including whole-brain, region of interest and connectomic analyses. Whole-brain and region of interest analyses described atypical organisation of white matter microstructure in several white matter tracts: most notably in frontostriatal tracts, corpus callosum, superior longitudinal fasciculus, cingulum bundle, thalamic radiations, internal capsule and corona radiata. Connectomic analyses, including graph theory approaches, demonstrated global underconnectivity in connections between functionally specialised networks. Although some studies reported significant correlations between atypical white matter microstructure and ADHD symptoms or other behavioural measures there was no clear pattern of results. Interestingly however, many of the findings of disrupted white matter microstructure were in neural networks associated with key neuropsychological functions that are atypical in ADHD. Limitations to the extant research are outlined in this review and future studies in this area should carefully consider factors such as sample size, sex balance, head motion and medication status.

A 24-Month Effects of Methylphenidate Use on Growth in Children and Adolescents With Attention Deficit Hyperactivity Disorder

OBJECTIVE

The primary objective of this study was to investigate the effect of methylphenidate (MPH) on height, weight, and body mass index (BMI) in drug-naive children and adolescents with attention deficit hyperactivity disorder (ADHD) over 24 months. The secondary objective was to investigate whether the age of MPH initiation and sex act as risk factors for growth retardation.

METHODS

A total of 82 patients with ADHD were included. Weight, height, and BMI were measured at baseline and every 6 months up to 24 months. Weight, height, and BMI data were converted to z-scores and analyzed using two-way repeated-measures ANOVA and multiple linear regression.

RESULTS

The z-score of height, weight and BMI decreased from the baseline values. The z-scores of height were at baseline 0.002; 6 months -0.100; 12 months -0.159; 18 months -0.159; 24 months -0.186. The z-scores of weight were at baseline 0.104; 6 months -0.155; 12 months -0.256; 18 months -0.278; 24 months -0.301. Here were no age and sex differences of height, weight, and BMI.

CONCLUSION

The use of MPH was associated with attenuation of weight and height gain rates in children and adolescents with ADHD.

Moderators and Other Predictors of Methylphenidate Response in Children and Adolescents with ADHD

Methylphenidate (MPH) is the treatment of first choice for developmental ADHD. To date, no reliable method to predict how patients will respond to MPH exists and conflicting results are reported on clinical characteristics of responders. The present study aims to give a more precise characterization of the patients who will respond best to MPH to help clinicians in defining the treatment plan. Age, neuropsychological functioning (i.e., attention and working memory), and behavioral/emotional symptoms of 48 drug-naïve children and adolescents with ADHD (42 boys and 6 girls, age-range 6–16 years, mean age 10.5 ± 2.5 years, mean IQ 101.3 ± 11.2) were studied to assess how these different characteristics affected a single-dose MPH response. Four hierarchical linear regression models were used to explore whether age, neuropsychological measures at baseline, and behavioral/emotional symptoms could predict attention and working memory measures after a single-dose MPH administration. We found that improvement in attention and working memory was predicted by age, neuropsychological measures at baseline, and severity of ADHD symptoms. No behavioral and emotional symptoms predicted single-dose MPH response with the exception of conduct symptoms.

The Benefits and Limitations of Stimulants in Treating ADHD

This chapter focusses on the benefits and limitations of stimulant medications in the treatment of ADHD. We highlight the key similarities and differences between the different stimulants used to treat ADHD and briefly discuss mechanisms of action, pharmacokinetics, and pharmacodynamics. We will discuss some of the political, ethical, and moral discussions about the use of stimulants including a consideration of the treatment of subsyndromal ADHD and the use of stimulants as cognitive enhancers. We review the comparative efficacy and effectiveness between stimulants and non-pharmacological treatments for ADHD, between stimulant classes and formulations and between stimulant and non-stimulant medications. We discuss the effects on core symptoms, common associated symptoms, cognition, and more distal outcomes including quality of life and functioning and issues related to tolerance, tolerability and adverse effects. Looking at the clinical implications of these findings, we discuss the importance of measurement-based care in the treatment of ADHD. Finally, we will look at the benefits and limitations of stimulants across several different populations and clinical subgroups.

Neuropsychological Characterization of Aggressive Behavior in Children and Adolescents with CD/ODD and Effects of Single Doses of Medications: The Protocol of the Matrics_WP6-1 Study

Aggressive behaviors and disruptive/conduct disorders are some of the commonest reasons for referral to youth mental health services; nevertheless, the efficacy of therapeutic interventions in real-world clinical practice remains unclear. In order to define more appropriate targets for innovative pharmacological therapies for disruptive/conduct disorders, the European Commission within the Seventh Framework Programme (FP7) funded the MATRICS project (Multidisciplinary Approaches to Translational Research in Conduct Syndromes) to identify neural, genetic, and molecular factors underpinning the pathogenesis of aggression/antisocial behavior in preclinical models and clinical samples. Within the program, a multicentre case-control study, followed by a single-blind, placebo-controlled, cross-over, randomized acute single-dose medication challenge, was conducted at two Italian sites. Aggressive children and adolescents with conduct disorder (CD) or oppositional defiant disorder (ODD) were compared to the same age (10–17 y) typically developing controls (TDC) on a neuropsychological tasks battery that included both “cold” (e.g., inhibitory control, decision making) and “hot” executive functions (e.g., moral judgment, emotion processing, risk assessment). Selected autonomic measures (heart rate variability, skin conductance, salivary cortisol) were recorded before/during/after neuropsychological testing sessions. The acute response to different drugs (methylphenidate/atomoxetine, risperidone/aripiprazole, or placebo) was also examined in the ODD/CD cohort in order to identify potential neuropsychological/physiological mechanisms underlying aggression. The paper describes the protocol of the clinical MATRICS WP6-1 study, its rationale, the specific outcome measures, and their implications for a precision medicine approach.

Effects of methylphenidate on executive functioning in children and adolescents with ADHD after long-term use: a randomized, placebo-controlled discontinuation study

BACKGROUND

Methylphenidate may improve executive functioning in children with attention-deficit/hyperactivity disorder (ADHD). However, it is unclear if there are still acute effects of methylphenidate on executive functioning after long-term use.

METHODS

In a randomized double-blind, placebo-controlled discontinuation study, 94 children and adolescents (ages 8-18 years) who used methylphenidate beyond two years were either assigned to seven weeks of continued treatment with 36 or 54 mg of extended-release methylphenidate or to gradual withdrawal over three weeks to placebo for four weeks. Performance on neuropsychological tasks, measuring working memory, response inhibition, attentional flexibility and psychomotor speed was compared between both groups using mixed models for repeated measures. Additionally, we investigated within the discontinuation group if a deterioration on the investigator-rated Clinical Global Impressions Improvement scale after withdrawing to placebo was related to a worse performance on the neuropsychological tasks. This study was registered in the Netherlands Trial Register (www. Trialregister.nl) with identifier 5252.

RESULTS

After withdrawal of methylphenidate, the discontinuation group made more errors on working memory (β = -1.62, SD = 0.56, t = -2.88, p = .01, Cohen's f2 = .14), independent from reaction time compared to baseline, in contrast to the continuation group. We did not find differences in changes in response inhibition, attentional flexibility and psychomotor speed between the two groups. Also, there were no significant differences in task measures between the participants who deteriorated clinically and those who did not.

CONCLUSIONS

Our study shows that methylphenidate has a beneficial effect on working memory after two years of use. Future studies should explore whether cognitive outcomes may aid clinical decision-making on the continued use of methylphenidate, given dissociation between cognitive and behavioural effects of stimulant medication.

Psychiatric Comorbidities in 1p36 Deletion Syndrome and Their Treatment-A Case Report

1p36 deletion syndrome represents the most common terminal deletion observed in humans. Major clinical findings comprise developmental delay/intellectual disability, poor or absent expressive language, congenital central muscular hypotonia, brain anomalies, brachydactyly/camptodactyly, short feet, and characteristic facial features like straight eyebrows, deep-set eyes, and midface hypoplasia. So far, there is very limited knowledge about comorbid psychiatric disorders and their effective treatment in this special population. To fill this gap, this case report presents an initially four-year-old girl with 1p36.33-1p36.32 deletion, moderate intellectual disability, insomnia, oppositional-defiant disorder and attention deficit/hyperactivity disorder covering a period of time of about 1.5 years comprising initial psychological/psychiatric assessment, subsequent day clinic/outpatient treatment (amongst others including off-label use of melatonin and methylphenidate as well as parent-child interaction therapy) and follow-up assessment. Follow-up results indicated good efficacy of melatonin and methylphenidate medication without any adverse effects. Multidisciplinarity in diagnosis and treatment are mandatory to meet needs of patients with complex genetic disorders like 1p36 deletion syndrome. Off-label use of melatonin (for insomnia) and methylphenidate (for attention deficit/hyperactivity disorder) should be considered in young children with 1p36 deletion syndrome if behavioral interventions are not sufficient.

Clinical trials were missing from regulatory documents of extended-release methylphenidate for ADHD in adults: a case study of public documents

OBJECTIVES

To assess whether drug regulatory agencies decided on applications for extended-release methylphenidate for use in adult ADHD based on select samples of trials.

STUDY DESIGN AND SETTING

Case series of publicly available regulatory documents. We matched an index of extended-release methylphenidate trials for adult ADHD with trials appearing in regulatory documents of extended-release methylphenidate applications. Trials and regulatory documents were identified as part of this systematic review (https://doi.org/10.1002/14651858.CD012857). We sought to identify missing trials in the regulatory documents and to clarify regulatory submission requirements.

RESULTS

We indexed 18 trials and matched those with 13 drug applications (11 approved, 2 rejected) published by 7 agencies. There were trials missing in 7 (54%) of 13 applications, median 4 trials (range 1-6). The median proportion of missing trial participants was 45% (range 23% - 72%). Regulators seemingly require that all trials must be included in new drug applications, but wording is ambiguous.

CONCLUSION

In this sample of extended-release methylphenidate drug applications for adult ADHD, 7 of 13 regulatory decisions were missing entire trials according to public documents, even though regulatory requirements seem to stipulate that all available trials should be included in drug applications.

Outcomes of a 12-week ecologically valid observational study of first treatment with methylphenidate in a representative clinical sample of drug naïve children with ADHD

Randomized placebo-controlled trials have reported efficacy of methylphenidate (MPH) for Attention-deficit/hyperactivity disorder (ADHD); however, selection biases due to strict entry criteria may limit the generalizability of the findings. Few ecologically valid studies have investigated effectiveness of MPH in representative clinical populations of children. This independently funded study aims to describe treatment responses and their predictors during the first 12 weeks of MPH treatment using repeated measurements of symptoms and adverse reactions (ARs) to treatment in 207 children recently diagnosed with ADHD. The children were consecutively included from the Child and Adolescent Mental Health Centre, Mental Health Services, The Capital Region of Denmark. The children (mean age, 9.6 years [range 7–12], 75.4% males) were titrated with MPH, based on weekly assessments of symptoms (18-item ADHD-rating scale scores, ADHD-RS-C) and ARs. At study-end 187 (90.8%) children reached a mean end-dose of 1.0 mg/kg/day. A normalisation/borderline normalisation on ADHD-RS-C was achieved for 168 (81.2%) children on the Inattention and/or the Hyperactivity-Impulsivity subscale in week 12, and 31 (15.0%) children were nonresponders, which was defined as absence of normalisation/borderline normalisation (n = 19) or discontinuation due to ARs (n = 12), and eight (3.8%) children dropped out from follow-up. Nonresponders were characterised by more severe symptoms of Hyperactivity-Impulsivity and global impairment before the treatment. ARs were few; the most prominent were appetite reduction and weight loss. A decrease in AR-like symptoms during the treatment period questions the validity of currently available standard instruments designed to measure ARs of MPH. This ecologically valid observational study supports prior randomized placebo-controlled trials; 81.2% of the children responded favourably in multiple domains with few harmful effects to carefully titrated MPH.

Clinical trial registration: ClinicalTrials.gov with registration number NCT04366609.

Cognition during active methamphetamine use versus remission

OBJECTIVE

To evaluate whether cognitive performance in adults with active methamphetamine use (MA-ACT) differs from cognitive performance in adults in remission from MA use disorder (MA-REM) and adults without a history of substance use disorder (CTLs).

METHOD

MA-ACT (n = 36), MA-REM (n = 48), and CTLs (n = 62) completed the Neuropsychological Assessment Battery (NAB).

RESULTS

The MA-ACT group did not perform significantly worse than CTLs on any NAB Index. The MA-REM group performed significantly (p < 0.050) worse than CTLs on the NAB Memory Index. The MA-ACT group performed significantly better than CTLs and the MA-REM group on the Executive Functions Index.

CONCLUSIONS

Some cognitive deficits are apparent during remission from MA use, but not during active use; this may result in clinical challenges for adults attempting to maintain recovery and continue with treatment.

Sevoflurane in electroconvulsive therapy: A systematic review and meta-analysis of randomised trials

Sevoflurane is the most commonly used inhaled anaesthetic in electroconvulsive therapy (ECT). The objective of this study was to provide an up-to-date and comprehensive review on how the use of sevoflurane affects seizure adequacy (seizure duration and postictal suppression index [PSI]) and circulatory dynamics in ECT. We performed a meta-analysis of RCTs that investigated seizure adequacy and circulatory dynamics in patients treated with ECT using sevoflurane (sevoflurane group) and intravenous anaesthetics (non-sevoflurane group). A total of 12 RCTs (377 patients and 1339 ECT sessions) were included. Sevoflurane significantly decreased the electroencephalogram (EEG) seizure durations in comparison with intravenous anaesthetics, whereas no significant difference was observed in PSI (EEG: 9 studies, standardized mean difference (SMD) = 0.74, 95% confidence interval (CI) = -1.11 to -0.38, p = 0.0002; PSI: 4 studies, SMD = -0.06, CI -0.13 to 0.25, p = 0.59). The use of sevoflurane in ECT significantly increased heart rate (HR) compared with intravenous anaesthetics (9 studies, SMD = 0.31, CI 012-0.51, p = 0.004). In the pre-planned subgroup analysis, sevoflurane significantly reduced seizure duration compared with other types of anaesthetics, including propofol, barbiturates and ketamine. Furthermore, it was found that the risk of adverse events in ECT with sevoflurane were not significantly different from intravenous anaesthetics (6 studies, risk ratio = 1.33, CI 0.95-1.86, p = 0.09), with agitaion being the most common adverse effects. The results of our study suggest that using sevoflurane for ECT significantly reduces seizure duration, increases maximum HR and brings about no difference in the adverse event risk compared with those using intravenous anaesthetics for ECT. Therefore, there may not be compelling evidence favouring sevoflurane use for ECT, except in cases where intravenous access is difficult.

Practitioner's review: medication for children and adolescents with autism spectrum disorder (ASD) and comorbid conditions

Alleviating the multiple problems of children with autism spectrum disorder (ASD) and its comorbid conditions presents major challenges for the affected children, parents, and therapists. Because of a complex psychopathology, structured therapy and parent training are not always sufficient, especially for those patients with intellectual disability (ID) and multiple comorbidities. Moreover, structured therapy is not available for a large number of patients, and pharmacological support is often needed, especially in those children with additional attention deficit/hyperactivity and oppositional defiant, conduct, and sleep disorders.

Selective Effects of Methylphenidate on Attention and Inhibition in 22q11.2 Deletion Syndrome: Results From a Clinical Trial

BACKGROUND

Attention deficit and/or hyperactivity disorder (ADHD) is the most prevalent psychiatric disorder in children with 22q11.2 deletion syndrome (22q11DS) and frequently persists into adulthood. Although medication with stimulant has been demonstrated to be highly effective in idiopathic ADHD, evidence in 22q11DS is still scarce. Previous studies have shown safety and effectiveness of methylphenidate (MPH) on core symptoms of ADHD as well as improvement of associated cognitive deficits. However, only a limited number of cognitive domains have been explored.

METHODS

Twenty-three participants with 22q11DS and attention difficulties, aged 8-24 years, entered a clinical trial aiming to specify the effects of MPH on clinical symptoms, cognition, and daily-life behavior. The effects of treatment were compared with/without medication in a within-subject design. The trial included both participants naïve to the molecule and chronic users.

RESULTS

Benefit from the treatment was demonstrated through a decrease in core ADHD symptoms, specifically inattention symptoms, and improvement of cognitive measures of attention and inhibition. Conversely, no significant change was found for other executive functions (such as cognitive flexibility, working memory, initiation), learning, or memory. Moreover, no significant improvement on ecological measures of daily-life executive functioning was found, possibly because of the short treatment period. We replicated safety, and although very frequent, side effects were of mild intensity and comparable with previous findings.

CONCLUSIONS

This study extends the current knowledge on the effects of MPH in patients with 22q11DS. Treatment was found to be effective for core ADHD symptoms and cognitive measures of attention and inhibition.