Methylphenidate improves some but not all measures of attention, as measured by the TEA-Ch in medication-naïve children with ADHD

Mice with an autism-associated R451C mutation in neuroligin-3 show intact attention orienting but atypical responses to methylphenidate and atomoxetine in the mouse-Posner task

RATIONALE

Atypical attention orienting has been associated with some autistic symptoms, but the neural mechanisms remain unclear. The human Posner task, a classic attention orienting paradigm, was recently adapted for use with mice, supporting the investigation of the neurobiological underpinnings of atypical attention orienting in preclinical mouse models.

OBJECTIVE

The current study tested mice expressing the autism-associated R451C gene mutation in neuroligin-3 (NL3) on the mouse-Posner (mPosner) task.

METHODS

NL3R451C and wild-type (WT) mice were trained to respond to a validly or invalidly cued target on a touchscreen. The cue was a peripheral non-predictive flash in the exogenous task and a central spatially predictive image in the endogenous task. The effects of dopaminergic- and noradrenergic-modulating drugs, methylphenidate and atomoxetine, on task performance were assessed.

RESULTS

In both tasks, mice were quicker and more accurate in the validly versus invalidly cued trials, consistent with results in the human Posner task. NL3R451C and WT mice showed similar response times and accuracy but responded differently when treated with methylphenidate and atomoxetine. Methylphenidate impaired exogenous attention disengagement in NL3R451C mice but did not significantly affect WT mice. Atomoxetine impaired endogenous orienting in WT mice but did not significantly affect NL3R451C mice.

CONCLUSIONS

NL3R451C mice demonstrated intact attention orienting but altered responses to the pharmacological manipulation of the dopaminergic and noradrenergic networks. These findings expand our understanding of the NL3R451C mutation by suggesting that this mutation may lead to selective alterations in attentional processes.

Methylphenidate improves cognitive function and health-related quality of life in survivors of childhood brain tumours

OBJECTIVES

The growing population of survivors of childhood brain tumors present the challenge of long-term quality of survival. The domains most affected by tumor and treatment are those implicated in development of typical intellectual functions: attention, working memory, and processing speed, with consequent effects upon function and quality of life. In this paper we present service evaluation data on the 12-month effect upon processing speed, visual and auditory attentional domains in 29 patients receiving methylphenidate aged 5-16 years (Mean=10.6).

METHODS

Patients received immediate-release methylphenidate and were converted to modified-release as appropriate. Mean optimal dose of immediate-release methylphenidate was 0.34 mg/kg per dose (range 0.2-0.67).

RESULTS

Patients showed a significant positive impact of methylphenidate on attention in all tests of selective visual attention from the Test of Everyday Attention for Children 2. A significant improvement was also shown on response time. Significant change was not found on psychometric measures of sustained auditory or visual attention, or selective auditory attention. Ratings of Health-Related Quality of Life showed a positive benefit of methylphenidate at 12 months. Side effects were minimal and not statistically significant.

CONCLUSIONS

Survivors of childhood brain tumor with attentional and processing speed deficit show clinical benefit from methylphenidate.

The effects of first-dose methylphenidate on the neural signatures of visual selective attention in children with attention-deficit/hyperactivity disorder

Although methylphenidate (MPH) has been shown to significantly improve selective attention in children with attention-deficit/hyperactivity disorder (ADHD), the neural mechanism of this effect remains unclear. We investigated the effects of first-dose MPH on the neural signatures of visual selective attention in children with ADHD. We measured the impact of first-dose MPH on electrophysiological indexes from eighteen children with ADHD (8.9-15.2 years; 15 boys) while they performed a visual search task. MPH was administered in a double-blind placebo-controlled crossover design. MPH led to decreases in behavioral error rates and reaction times. For the electrophysiological indexes, MPH significantly increased the target-elicited N2pc amplitude and posterior P3 amplitude during the selective attention process. The trial-based correlation analysis revealed that the enhanced N2pc (more negative) and P3 (more positive) promoted the behavioral response speed for children with ADHD. The lower individual P3 amplitude was associated with higher severity of inattention symptoms. The severer inattention symptoms were related to weaker MPH effect on N2pc amplitude. These findings suggest that N2pc and P3 are closely related to the mechanism of MPH in the ADHD treatment.

Translating methylphenidate's efficacy on selective and sustained attentional deficits to those reported in childhood cancer survivors: A qualitative review

Whilst an increasing number of children survive previously incurable cancers of the central nervous system (CNS), associated treatments often result in significant neurocognitive late effects. Methylphenidate provides some signs of alleviating cognitive difficulties in different pediatric groups; however, a minimal amount of systematic work has explored its effectiveness isolated to vulnerable attentional domains. The current review aimed to explore the effectiveness of methylphenidate isolated to two attentional domains (sustained and selective attention)-with an aim to substantiate its utility in childhood cancer survivors. Five databases were comprehensively searched for relevant articles. A purpose-developed tool was used to assess each study's robustness and research quality. Eleven out of 1,865 identified articles were included within the review. Studies drew upon five clinical populations. Individual attentional domains demonstrate variation in their response to methylphenidate. Sustained attention demonstrated the most consistent benefit of methylphenidate, reported largely in attention-deficit/hyperactivity disorder (ADHD) groups. Gains in selective attention and higher-order cognitive functions appeared to follow initial gains in sustained attention. Childhood cancer survivors report greater gains in selective attention compared to sustained attention. Higher doses may yield greater benefit for children with more diffuse attentional deficits. There is a need to improve the validity of current attentional measures before further methylphenidate trials are conducted.

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.

Catecholaminergic Modulation of Semantic Processing in Sentence Comprehension

Catecholamine (CA) function has been widely implicated in cognitive functions that are tied to the prefrontal cortex and striatal areas. The present study investigated the effects of methylphenidate, which is a CA agonist, on the electroencephalogram (EEG) response related to semantic processing using a double-blind, placebo-controlled, randomized, crossover, within-subject design. Forty-eight healthy participants read semantically congruent or incongruent sentences after receiving 20-mg methylphenidate or a placebo while their brain activity was monitored with EEG. To probe whether the catecholaminergic modulation is task-dependent, in one condition participants had to focus on comprehending the sentences, while in the other condition, they only had to attend to the font size of the sentence. The results demonstrate that methylphenidate has a task-dependent effect on semantic processing. Compared to placebo, when semantic processing was task-irrelevant, methylphenidate enhanced the detection of semantic incongruence as indexed by a larger N400 amplitude in the incongruent sentences; when semantic processing was task-relevant, methylphenidate induced a larger N400 amplitude in the semantically congruent condition, which was followed by a larger late positive complex effect. These results suggest that CA-related neurotransmitters influence language processing, possibly through the projections between the prefrontal cortex and the striatum, which contain many CA receptors.

Paying attention to attention in depression

Attention is the gate through which sensory information enters our conscious experiences. Oftentimes, patients with major depressive disorder (MDD) complain of concentration difficulties that negatively impact their day-to-day function, and these attention problems are not alleviated by current first-line treatments. In spite of attention's influence on many aspects of cognitive and emotional functioning, and the inclusion of concentration difficulties in the diagnostic criteria for MDD, the focus of depression as a disease is typically on mood features, with attentional features considered less of an imperative for investigation. Here, we summarize the breadth and depth of findings from the cognitive neurosciences regarding the neural mechanisms supporting goal-directed attention in order to better understand how these might go awry in depression. First, we characterize behavioral impairments in selective, sustained, and divided attention in depressed individuals. We then discuss interactions between goal-directed attention and other aspects of cognition (cognitive control, perception, and decision-making) and emotional functioning (negative biases, internally-focused attention, and interactions of mood and attention). We then review evidence for neurobiological mechanisms supporting attention, including the organization of large-scale neural networks and electrophysiological synchrony. Finally, we discuss the failure of current first-line treatments to alleviate attention impairments in MDD and review evidence for more targeted pharmacological, brain stimulation, and behavioral interventions. By synthesizing findings across disciplines and delineating avenues for future research, we aim to provide a clearer outline of how attention impairments may arise in the context of MDD and how, mechanistically, they may negatively impact daily functioning across various domains.

Do mothers who are anxious during pregnancy have inattentive children?

BACKGROUND

Maternal somatic anxiety during pregnancy may affect neural foetal development via corticoid pathways. Using a large epidemiological cohort, this study explores the relationship between maternal somatic anxiety in pregnancy and child scores on the Test of Everyday Attention in Children (TEA-Ch).

METHODS

Linear regression was used to analyse the association of maternal somatic anxiety during pregnancy and performance of children on three subtests of the TEA-Ch at age 8.5 years that assess selective attention (Sky Search), sustained attention (Sky Search Dual Test) and attentional control (Opposite Worlds).

RESULTS

Children with complete data on each subtest were included in the analysis, comprising 4,198 children for the Sky Search subtest, 3,845 for the Sky Search Dual Test and 4,202 for the Opposite Worlds subtest. No association was found between exposure to maternal somatic anxiety and child's performance in any of the TEA-Ch subtests either before or after adjusting for confounders. The results did not change when stratifying by gender.

LIMITATIONS

Selective attrition, lack of sensitivity of tests and lack of adjustment for the postnatal environment are possible limitations to this study.

CONCLUSIONS

We found no evidence of an association between exposure to maternal somatic anxiety in pregnancy and TEA-Ch scores. These results suggest that anxiety during pregnancy does not affect the development of children's attentional skills measured by TEA-Ch.

Deficiency of Sustained Attention in ADHD and Its Potential Genetic Contributor MAOA

OBJECTIVE

To investigate the genetic contributors to ADHD sustained attention deficit among noradrenergic genes responsible for the synthesis (dopamine-β-hydroxylase gene, DBH), transport (norepinephrine transporter gene, NET1), reception (alpha-2A adrenergic receptor gene, ADRA2A), and metabolism (monoamine oxidase A gene, MAOA) of noradrenalin (NE).

METHOD

A total of 456 children with ADHD and 108 normal controls were included in a digit cancellation test (DCT). DNA was collected from 242 participants and genotyped for 14 single nucleotide polymorphisms (SNPs) of noradrenergic genes.

RESULTS

Compared with normal controls, children with ADHD showed a lower total score and higher mean error rate in the DCT, indicating poorer sustained attention function. Analysis of covariance showed an association between MAOA genotypes and ADHD performance in DCT, with poorer performance in risk allele carriers. No association was found for other noradrenergic genes.

CONCLUSION

Children with ADHD presented with a sustained attention deficit compared with normal controls. The sustained attention deficit of children with ADHD may be associated with genetic variant of MAOA.

No Medication for My Child! A Naturalistic Study on the Treatment Preferences for and Effects of Cogmed Working Memory Training Versus Psychostimulant Medication in Clinically Referred Youth with ADHD

In this naturalistic clinical study, we explored the applicability and clinical effectiveness of Cogmed WMT, pharmacotherapy, and their combination for clinically referred children and adolescents with attention-deficit/hyperactivity disorder (ADHD). Ninety youth with ADHD (ages 6-16 years) and their parents were offered the possibility to choose one of the three interventions. The motives for choosing various interventions were quite different. Medication was chosen because this treatment was expected to be most effective, but also because the Cogmed WMT program was regarded as too taxing. The choice for Cogmed WMT was mainly negatively motivated: participants tended to be strongly against the use of medication, found it a too rigorous step, or feared side effects and addiction problems. The choice for the combination treatment was strongly positively motivated: parents and youth indicated that they wanted to receive the best possible intervention and part of them also had high expectations of Cogmed WMT. In terms of clinical effectiveness, pharmacotherapy with stimulant medication and the combination treatment produced larger reductions in ADHD symptomatology than Cogmed WMT. Further, results indicated that Cogmed WMT selectively enhanced working memory performance. Finally, after conducting Cogmed WMT, youths and parents were more 'open' to accept pharmacotherapy as intervention, probably because the training increased greater insight in and awareness of the problematic features of ADHD.

Methylphenidate and environmental enrichment ameliorate the deleterious effects of prenatal stress on attention functioning

Either pre- or post-natal environmental factors seem to play a key role in brain and behavioral development and to exert long-term effects. Increasing evidence suggests that exposure to prenatal stress (PS) leads to motor and learning deficits and elevated anxiety, while enriched environment (EE) shows protective effects. The dopaminergic system is also sensitive to environmental life circumstances and affects attention functioning, which serves as the preliminary gate to cognitive processes. However, the effects of methylphenidate (MPH) on the dopaminergic system and attentional functioning, in the context of these life experiences, remain unclear. Therefore, we aimed to examine the effects of EE or PS on distinct types of attention, along with possible effects of MPH exposure. We found that PS impaired selective attention as well as partial sustained attention, while EE had beneficial effects. Both EE and MPH ameliorated the deleterious effects of PS on attention functioning. Considering the possible psychostimulant effect of MPH, we examined both anxiety-like behavior as well as motor learning. We found that PS had a clear anxiogenic effect, whereas EE had an anxiolytic effect. Nevertheless, the treatment with both MPH and/or EE recovered the deleterious effects of PS. In the motor-learning task, the PS group showed superior performance while MPH led to impaired motor learning. Performance decrements were prevented in both the PS + MPH and EE + MPH groups. This study provides evidence that peripubertal exposure to EE (by providing enhanced sensory, motor, and social opportunities) or MPH treatments might be an optional therapeutic intervention in preventing the PS long-term adverse consequences.