A preliminary study of the effects of working memory training on brain function

Trajectory Analysis for Identifying Classes of Attention Deficit Hyperactivity Disorder (ADHD) in Children of the United States

Background

Attention Deficit Hyperactivity Disorder (ADHD) is a mental health disorder that affects attention and behavior. People with ADHD frequently encounter challenges in social interactions, facing issues, like social rejection and difficulties in interpersonal relationships, due to their inattention, impulsivity, and hyperactivity.

Methods

A National Longitudinal Survey of Youth (NLSY) database was employed to identify patterns of ADHD symptoms. The children who were born to women in the NLSY study between 1986 and 2014 were included. A total of 1,847 children in the NLSY 1979 cohort whose hyperactivity/inattention score was calculated when they were four years old were eligible for this study. A trajectory modeling method was used to evaluate the trajectory classes. Sex, baseline antisocial score, baseline anxiety score, and baseline depression score were adjusted to build the trajectory model. We used stepwise multivariate logistic regression models to select the risk factors for the identified trajectories.

Results

The trajectory analysis identified six classes for ADHD, including (1) no sign class, (2) few signs since preschool being persistent class, (3) few signs in preschool but no signs later class, (4) few signs in preschool that magnified in elementary school class, (5) few signs in preschool that diminished later class, and (6) many signs since preschool being persistent class. The sensitivity analysis resulted in a similar trajectory pattern, except for the few signs since preschool that magnified later class. Children's race, breastfeeding status, headstrong score, immature dependent score, peer conflict score, educational level of the mother, baseline antisocial score, baseline anxious/depressed score, and smoking status 12 months prior to the birth of the child were found to be risk factors in the ADHD trajectory classes.

Conclusion

The trajectory classes findings obtained in the current study can (a) assist a researcher in evaluating an intervention (or combination of interventions) that best decreases the long-term impact of ADHD symptoms and (b) allow clinicians to better assess as to which class a child with ADHD belongs so that appropriate intervention can be employed.

The High Rates of Comorbidity among Neurodevelopmental Disorders: Reconsidering the Clinical Utility of Distinct Diagnostic Categories

The boundaries between neurodevelopmental disorders are often indistinct, even among specialists. But do these boundaries exist, or do experts struggle to distinguish and categorize symptoms in order to arrive at a dominant diagnosis while comorbidity continually leaves questions about where each disorder ends and begins? What should be reconsidered? The introduction of the term 'spectrum of neurodevelopmental disorders' could pave the way for a re-appraisal of the clinical continuum of neurodevelopmental disorders. This study aims to highlight the problems that emerge in the field of the differential diagnosis of neurodevelopmental disorders and propose a renegotiation of the distinctiveness criteria.

Neurophysiological measures and correlates of cognitive load in attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD) and dyslexia: A scoping review and research recommendations

Working memory is integral to a range of critical cognitive functions such as reasoning and decision-making. Although alterations in working memory have been observed in neurodivergent populations, there has been no review mapping how cognitive load is measured in common neurodevelopmental conditions such as attention-deficit/hyperactivity disorder (ADHD), autism spectrum disorder (ASD) and dyslexia. This scoping review explores the neurophysiological measures used to study cognitive load in these specific populations. Our findings highlight that electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) are the most frequently used methods, with a limited number of studies employing functional near-infrared spectroscopy (fNIRs), magnetoencephalography (MEG) or eye-tracking. Notably, eye-related measures are less commonly used, despite their prominence in cognitive load research among neurotypical individuals. The review also highlights potential correlates of cognitive load, such as neural oscillations in the theta and alpha ranges for EEG studies, blood oxygenation level-dependent (BOLD) responses in lateral and medial frontal brain regions for fMRI and fNIRS studies and eye-related measures such as pupil dilation and blink rate. Finally, critical issues for future studies are discussed, including the technical challenges associated with multimodal approaches, the possible impact of atypical features on cognitive load measures and balancing data richness with participant well-being. These insights contribute to a more nuanced understanding of cognitive load measurement in neurodivergent populations and point to important methodological considerations for future neuroscientific research in this area.

Experimental Therapeutics: Opportunities and Challenges Stemming From the National Institute of Mental Health Workshop on Novel Target Discovery and Psychosocial Intervention Development

There has been slow progress in the development of interventions that prevent and/or reduce mental-health morbidity and mortality. The National Institute of Mental Health (NIMH) launched an experimental-therapeutics initiative with the goal of accelerating the development of effective interventions. The emphasis is on interventions designed to engage a target mechanism. A target mechanism is a process (e.g., behavioral, neurobiological) proposed to underlie change in a defined clinical endpoint and through change in which an intervention exerts its effect. This article is based on discussions from an NIMH workshop conducted in February 2020 and subsequent conversations among researchers using this approach. We discuss the components of an experimental-therapeutics approach such as clinical-outcome selection, target definition and measurement, intervention design and selection, and implementation of a team-science strategy. We emphasize the important contributions of different constituencies (e.g., patients, caregivers, providers) in deriving hypotheses about novel target mechanisms. We highlight strategies for target-mechanism identification using published and hypothetical examples. We consider the decision-making dilemmas that arise with different patterns of results in purported mechanisms and clinical outcomes. We end with considerations of the practical challenges of this approach and the implications for future directions of this initiative.

Artificial Cognitive Systems Applied in Executive Function Stimulation and Rehabilitation Programs: A Systematic Review

This article presents a systematic review of studies on cognitive training programs based on artificial cognitive systems and digital technologies and their effect on executive functions. The aim has been to identify which populations have been studied, the characteristics of the implemented programs, the types of implemented cognitive systems and digital technologies, the evaluated executive functions, and the key findings of these studies. The review has been carried out following the PRISMA protocol; five databases have been selected from which 1889 records were extracted. The articles were filtered following established criteria, to give a final selection of 264 articles that have been used for the purposes of this study in the analysis phase. The findings showed that the most studied populations were school-age children and the elderly. The most studied executive functions were working memory and attentional processes, followed by inhibitory control and processing speed. Many programs were commercial, customizable, gamified, and based on classic tasks. Some more recent initiatives have begun to incorporate user-machine interfaces, robotics, and virtual reality, although studies on their effects remain scarce. The studies recognize multiple benefits of computerized neuropsychological stimulation and rehabilitation programs for executive functions in different age groups, but there is a lack of studies in specific population sectors and with more rigorous research designs.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13369-022-07292-5.

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.

The neural correlates of working memory training in typically developing children

Working memory training improves children's cognitive performance on untrained tasks; however, little is known about the underlying neural mechanisms. This was investigated in 32 typically developing children aged 10-14 years (19 girls and 13 boys) using a randomized controlled design and multi-modal magnetic resonance imaging (Devon, UK; 2015-2016). Training improved working memory performance and increased intrinsic functional connectivity between the bilateral intraparietal sulci. Furthermore, improvements in working memory were associated with greater recruitment of the left middle frontal gyrus on a complex span task. Repeated engagement of fronto-parietal regions during training may increase their activity and functional connectivity over time, affording greater working memory performance. The plausibility of generalizable cognitive benefits from a neurobiological perspective and implications for neurodevelopmental theory are discussed.

Effects of Working Memory Training on Children’s Memory and Academic Performance: the Role of Training Task Features and Trainee’s Characteristics

Learning and academic performance are explained mainly by basic limited-capacity processes, most notably by working memory (WM). Consequently, training WM has been considered a promising approach to fostering these abilities. However, school-based investigations are rare. This study examined the effects of training task features and trainees’ characteristics on transfer to cognitive and academic measures. Eighty-six typically developing 8–12-year-old children completed 6 weeks of either WM training with n-back and complex span tasks or a control training with perceptual-matching tasks in a regular school setting. The study also assessed some personal variables of the children, such as neuroticism, conscientiousness, joy of learning, and power of endurance. The WM training group showed increased WM and math performance compared to the control group. Also, there was a trend toward some improvements in vocabulary after WM training, and overall improvements after both trainings were observed in fluid intelligence and reading. Analyses of individual differences in the WM training group indicated increased training performance in relation to emotional stability, conscientiousness, power of endurance, as well as teacher-reported joy of learning and social integration of participants. Thus, the results indicate the potential of WM training to improve WM capacity and mathematical skills and reveal the impact of regulative, motivational, and social factors on cognitive training performance.

Annual Research Review: The contributions of the RDoC research framework on understanding the neurodevelopmental origins, progression and treatment of mental illnesses

The National Institute of Mental Health (NIMH) proposed the Research Domain Criteria (RDoC) initiative as an alternate way to organize research of mental illnesses, by looking at dimensions of functioning rather than being tied to categorical diagnoses. This paper briefly discusses the motivation for and organization of RDoC, and then explores the NIMH portfolio and recent work to monitor the utility and progress that RDoC has afforded developmental research. To examine how RDoC has influenced the NIMH developmental research portfolio over the last decade, we employed a natural language processing algorithm to identify the number of developmental science grants classified as incorporating an RDoC approach. Additional portfolio analyses examine temporal trends in funded RDoC-relevant grants, publications and citations, and research training opportunities. Reflecting on how RDoC has influenced the focus of grant applications, we highlight examples from research on Attention-Deficit Hyperactivity Disorder (ADHD), childhood irritability, and Autism Spectrum Disorder (ASD). Lastly, we consider how the dimensional and transdiagnostic approaches emphasized in RDoC have facilitated research on personalized intervention for heterogeneous disorders and preventive/early interventions targeting emergent or subthreshold psychopathology.

Functional connectivity patterns of trait empathy are associated with age

Empathy is the capacity to feel and understand others' mental states. In some individuals, there is an imbalance between the affective and cognitive components of empathy, which can lead to deficits. This study investigated the functional connectivity of the anterior insula (AI) and dorsomedial prefrontal cortex (dmPFC), which play key roles in empathy, in covariation with the affective and cognitive subscales of the Interpersonal Reactivity Index (IRI), as a function of age and sex, as an exploratory analysis. Seed-based functional connectivity analyses were performed on 33 healthy participants that were subdivided according to their age (16 adults and 17 adolescents) and sex (16 women and 17 men). Adolescents reported lower cognitive empathy than adults and men less affective empathy than women. The connectivity of the dmPFC and AI, in covariation with the cognitive and affective subscales of empathy, respectively, differed between adolescents and adults, but was similar in men and women. Adolescents had patterns of negative covariations between the regions of interest and many brain regions associated with the default-mode and salience networks. These findings support that lower self-report levels of empathy in certain individuals could be reflected in the functional connectivity patterns of the dmPFC and AI.

Correlation between brain function and ADHD symptom changes in children with ADHD following a few-foods diet: an open-label intervention trial

Research into the effect of nutrition on attention-deficit hyperactivity disorder (ADHD) in children has shown that the few-foods diet (FFD) substantially decreases ADHD symptoms in 60% of children. However, the underlying mechanism is unknown. In this open-label nutritional intervention study we investigated whether behavioural changes after following an FFD are associated with changes in brain function during inhibitory control in 79 boys with ADHD, aged 8–10 years. Parents completed the ADHD Rating Scale before (t1) and after the FFD (t2). Functional magnetic resonance imaging (fMRI) scans were acquired during a stop-signal task at t1 and t2, and initial subject-level analyses were done blinded for ARS scores. Fifty (63%) participants were diet responders, showing a decrease of ADHD symptoms of at least 40%. Fifty-three children had fMRI scans of sufficient quality for further analysis. Region-of-interest analyses demonstrated that brain activation in regions implicated in the stop-signal task was not associated with ADHD symptom change. However, whole-brain analyses revealed a correlation between ADHD symptom decrease and increased precuneus activation (p_FWE(cluster) = 0.015 for StopSuccess > Go trials and p_FWE(cluster) < 0.001 for StopSuccess > StopFail trials). These results provide evidence for a neurocognitive mechanism underlying the efficacy of a few-foods diet in children with ADHD.

Effects of computerized cognitive training as add-on treatment to stimulants in ADHD: a pilot fMRI study

The neurofunctional effects of Cognitive training (CT) are poorly understood. Our main objective was to assess fMRI brain activation patterns in children with ADHD who received CT as an add-on treatment to stimulant medication. We included twenty children with ADHD from a clinical trial of stimulant medication and CT (10 in medication + CT and 10 in medication + non-active training). Between-group differences were assessed in performance and in brain activation during 3 fMRI paradigms of working memory (N-back: 0-back, 1-back, 2-back, 3-back), sustained attention (Sustained Attention Task - SAT: 2 s, 5 s and 8 s delays) and inhibitory control (Go/No-Go). We found significant group x time x condition interactions in working memory (WM) and sustained attention on brain activation. In N-back, decreases were observed in the BOLD signal change from baseline to endpoint with increasing WM load in the right insula, right putamen, left thalamus and left pallidum in the CT compared to the non-active group; in SAT - increases in the BOLD signal change from baseline to endpoint with increasing delays were observed in bilateral precuneus, right insula, bilateral associative visual cortex and angular gyrus, right middle temporal, precentral, postcentral, superior frontal and middle frontal gyri in the CT compared to the non-active group. CT in ADHD was associated with changes in activation in task-relevant parietal and striato-limbic regions of sustained attention and working memory. Changes in brain activity may precede behavioral performance modifications in working memory and sustained attention, but not in inhibitory control.

Cognitive Control in Pediatric Obsessive-Compulsive and Anxiety Disorders: Brain-Behavioral Targets for Early Intervention

The DSM provides distinct criteria for obsessive-compulsive disorder (OCD) and various types of anxiety disorders, but phenomenological overlap, high rates of comorbidity, and early onset suggest common underlying mechanisms. This notion is further supported by use of the same treatments-cognitive behavioral therapy and serotonin reuptake inhibitor medication-for managing both OCD and non-OCD anxiety disorders in clinical settings. While early intervention with these gold standard treatments is recommended for pediatric OCD and anxiety disorders, young patients often remain symptomatic even after treatment. To guide the development of novel, mechanistically targeted treatments to better resolve OCD and anxiety symptoms, the identification of neural circuits underlying psychological constructs with relevance across disorders has been recommended. One construct that may be relevant for understanding pediatric OCD and anxiety disorders is cognitive control, given the difficulty that young patients experience in dismissing obsessions, compulsions, and worry despite recognition that these symptoms are excessive and unreasonable. In this review, we examine findings from a growing body of literature implicating brain-behavioral markers of cognitive control in pediatric OCD and anxiety disorders, including before and after treatment. We conclude by suggesting that interventions designed to enhance the functioning of the task control circuits underlying cognitive control may facilitate brain maturation to help affected youth overcome symptoms.

The Effects of Working Memory Training on Brain Activity

This study aimed to investigate if two weeks of working memory (WM) training on a progressive N-back task can generate changes in the activity of the underlying WM neural network. Forty-six healthy volunteers (23 training and 23 controls) were asked to perform the N-back task during three fMRI scanning sessions: (1) before training, (2) after the half of training sessions, and (3) at the end. Between the scanning sessions, the experimental group underwent a 10-session training of working memory with the use of an adaptive version of the N-back task, while the control group did not train anything. The N-back task in the scanning sessions was relatively easy (n = 2) in order to ensure high accuracy and a lack of between-group differences at the behavioral level. Such training-induced differences in neural efficiency were expected. Behavioral analyses revealed improved performance of both groups on the N-back task. However, these improvements resulted from the test-retest effect, not the training outside scanner. Performance on the non-trained stop-signal task did not demonstrate any transfer effect. Imaging analysis showed changes in activation in several significant clusters, with overlapping regions of interest in the frontal and parietal lobes. However, patterns of between-session changes of activation did not show any effect of training. The only finding that can be linked with training consists in strengthening the correlation between task performance accuracy and activation of the parietal regions of the neural network subserving working memory (left superior parietal lobule and right supramarginal gyrus posterior). These results suggest that the effects of WM training consist in learning that, in order to ensure high accuracy in the criterion task, activation of the parietal regions implicated in working memory updating must rise.

Training-Induced Neural Plasticity in Youth: A Systematic Review of Structural and Functional MRI Studies

Experience-dependent neural plasticity is high in the developing brain, presenting a unique window of opportunity for training. To optimize existing training programs and develop new interventions, it is important to understand what processes take place in the developing brain during training. Here, we systematically review MRI-based evidence of training-induced neural plasticity in children and adolescents. A total of 71 articles were included in the review. Significant changes in brain activation, structure, microstructure, and structural and functional connectivity were reported with different types of trainings in the majority (87%) of the studies. Significant correlation of performance improvement with neural changes was reported in 51% of the studies. Yet, only 48% of the studies had a control condition. Overall, the review supports the hypothesized neural changes with training while at the same time charting empirical and methodological desiderata for future research.

Working memory training restores aberrant brain activity in adult attention-deficit hyperactivity disorder

The development of treatments for attention impairments is hampered by limited knowledge about the malleability of underlying neural functions. We conducted the first randomized controlled trial to determine the modulations of brain activity associated with working memory (WM) training in adults with attention-deficit hyperactivity disorder (ADHD). At baseline, we assessed the aberrant functional brain activity in the n-back WM task by comparing 44 adults with ADHD with 18 healthy controls using fMRI. Participants with ADHD were then randomized to train on an adaptive dual n-back task or an active control task. We tested whether WM training elicits redistribution of brain activity as observed in healthy controls, and whether it might further restore aberrant activity related to ADHD. As expected, activity in areas of the default-mode (DMN), salience (SN), sensory-motor (SMN), frontoparietal (FPN), and subcortical (SCN) networks was decreased in participants with ADHD at pretest as compared with healthy controls, especially when the cognitive load was high. WM training modulated widespread FPN and SN areas, restoring some of the aberrant activity. Training effects were mainly observed as decreased brain activity during the trained task and increased activity during the untrained task, suggesting different neural mechanisms for trained and transfer tasks.

Autism Spectrum Disorder and Disruptive Behavior Disorders Comorbidities Delineate Clinical Phenotypes in Attention-Deficit Hyperactivity Disorder: Novel Insights from the Assessment of Psychopathological and Neuropsychological Profiles

Although childhood-onset psychiatric disorders are often considered as distinct and separate from each other, they frequently co-occur, with partial overlapping symptomatology. Autism spectrum disorder (ASD) and attention-deficit/hyperactivity disorder (ADHD) commonly co-occur with each other and with other mental disorders, particularly disruptive behavior disorders, oppositional defiant disorder/conduct disorder (ODD/CD). Whether these associated comorbidities represent a spectrum of distinct clinical phenotypes is matter of research. The aim of our study was to describe the clinical phenotypes of youths with ADHD with and without ASD and/or ODD/CD, based on neuropsychological and psychopathological variables. One-hundred fifty-one participants with ADHD were prospectively recruited and assigned to four clinical groups, and assessed by means of parent-reported questionnaires, the child behavior checklist and the behavior rating inventory of executive functions. The ADHD alone group presented a greater impairment in metacognitive executive functions, ADHD+ASD patients presented higher internalizing problems and deficits in Shifting tasks, and ADHD+ODD/CD subjects presented emotional-behavioral dysregulation. Moreover, ADHD+ASD+ODD/CD individuals exhibited greater internalizing and externalizing problems, and specific neuropsychological impairments in the domains of emotional regulation. Our study supports the need to implement the evaluation of the psychopathological and neuropsychological functioning profiles, and to characterize specific endophenotypes for a finely customized establishment of treatment strategies.

Updates in technology-based interventions for attention deficit hyperactivity disorder

PURPOSE OF REVIEW

Technological advancement has led to the development of novel treatment approaches for attention deficit hyperactivity disorder (ADHD). This review aims to review recent studies which employ the use of technology to treat ADHD, with particular focus on studies published during a 1-year period from February 2019 to February 2020.

RECENT FINDINGS

Most recent studies involved children aged 12 years and below. Interventions included cognitive training through games, neurofeedback and a combination of several approaches. More novel approaches included trigeminal nerve stimulation and brain-computer interface, and studies had utilized technology such as X-box Kinect and eye tracker. There was a shift towards delivering intervention at home and in school, enabled by technology. The study outcomes were variable and mainly included executive functioning measures and clinical ratings. These interventions were generally safe with few reported adverse events.

SUMMARY

Technology has enabled interventions to be delivered outside of the clinic setting and presented an opportunity for increased access to care and early intervention. Better quality studies are needed to inform on the efficacy of these interventions.

Training effects of attention and EF strategy-based training "Nexxo" in school-age students

Given the importance of attention and executive functions in children's behavior, programs directed to improve these processes are of interest. Nexxo-training combines the use of the Nexxo touchscreen application (go/no-go and stop signal tasks) with procedural metacognitive strategies. The present paper reports a test of Nexxo's impact on children aged 6-7 and 8-9 years. We conducted a randomized active-controlled trial involving 108 typically-developing children: 1st grade (N = 61, M = 6.46 years, SD = 0.35) and 3rd grade (N = 47, M = 8.5 years, SD = 0.27), randomly assigned to: (1) experimental, (2) active-control, or (3) passive-control groups. A 2-month follow-up was carried out after the intervention. The 3rd grade experimental group displayed a significant reduction in attentional problems at follow-up compared to both control groups. Executive Function problems were also reduced at follow-up in the experimental group. Participants in this group improved in Supervision (self-monitoring) at post-intervention and follow-up compared to passive-controls. Although group effect was not significant at t1, it was significant at post measures in experimental group compared to passive-controls. Nexxo-training revealed a trend-level improvement in attention and executive functions for children in the 3rd grade.

Working memory performance with online-tDCS in schizophrenia: A randomized, double-blinded, sham-controlled, partial cross-over proof-of-concept study

Combining cognitive retraining with transcranial direct current stimulation (tDCS) has been hypothesized to improve cognitive deficits in schizophrenia. The effect of combining a neuropsychological/psychophysiological task with tDCS, called "online-tDCS" for cognitive enhancement in schizophrenia is not rigorously assessed. In this proof-of-concept study, we aimed at evaluating the effect of a single session online-tDCS on working memory(WM) and its transferability to other cognitive functions. Numerical n-back(NNB), digit symbol substitution test(DSST), emotional matching and labelling test(E-MALT), and anti-saccade eye movement beeforefore and after 20 min tDCS (anode: left dorsolateral prefrontal cortex and cathode: left temporoparietal junction) applied during Sternberg's task(WM-task) were assessed. Twenty-three schizophrenia patients with cognitive deficits were randomized to receive either online-tDCS or offline-tDCS (without simultaneous Sternberg's task) sessions. All patients received one session each of active and sham tDCS in a randomized counterbalanced double-blind cross-over design. RMANOVA revealed a significant interaction effect between tDCS type (Online/Offline) x activeness (active/sham) of tDCS; the reaction time during 2-back performance in the NNB test improved in online-sham (F = 5.23, p < 0.038) but not online-active tDCS session. No significant changes were noted in DSST, E-MALT, and anti-saccade performance. Improved performance after online-sham tDCS suggests that performing the Sternberg's task enhanced 2-back performance. The counterintuitive observation was noted with respect to the non-enhancement of WM performance on combining the task to tDCS. Aberrant plasticity in schizophrenia might attain a transitional ceiling that would have resulted in restriction of enhancement on combining the two plasticity modulators. The transferability of improvement to other cognitive domains could not be ascertained.

A Preliminary Study on the Functional Benefits of Computerized Working Memory Training in Children With Pediatric Bipolar Disorder and Attention Deficit Hyperactivity Disorder

Twenty-nine pediatric patients (age range, 10–16 years) with working memory (WM) deficits, including children with pediatric bipolar disorder (PBD) with and without attention-deficit hyperactivity disorder (ADHD) comorbidity and children with ADHD, underwent a Cogmed WM training program. For both patient groups, WM performance on Cogmed tasks and on the Digit Span test improved significantly after training. Moreover, the PBD group improved on Trails Making Test A and on the Inhibition Scale, the Behavior Regulation Index, and the Global Executive Composite of the Behavioral Rating Inventory of Executive Function. The ADHD group improved significantly on the Trails Making Test B, the Spatial Span Test, and the Reading Fluency Test of the Woodcock–Johnson III, as well as on depressive symptoms. The present findings suggest that working memory training is beneficial not only in youths with ADHD but also in youths with PBD. They also show evidence of near and far transfer of WM improvement in these patients, although in different ways for the two patient groups. Future studies examining the mechanisms of cognitive remediation in pediatric patients will aid in creating tailored illness-specific cognitive interventions.

Exploring memory function in earthquake trauma survivors with resting-state fMRI and machine learning

BACKGROUND

Traumatized earthquake survivors may develop poor memory function. Resting-state functional magnetic resonance imaging (rs-fMRI) and machine learning techniques may one day aid the clinical assessment of individual psychiatric patients. This study aims to use machine learning with Rs-fMRI from the perspectives of neurophysiology and neuroimaging to explore the association between it and the individual memory function of trauma survivors.

METHODS

Rs-fMRI data was acquired for eighty-nine survivors (male (33%), average age (SD):45.18(6.31) years) of Wenchuan earthquakes in 2008 each of whom was screened by experienced psychiatrists based on the clinician-administered post-traumatic stress disorder (PTSD) scale (CAPS), and their memory function scores were determined by the Wechsler Memory Scale-IV (WMS-IV). We explored which memory function scores were significantly associated with CAPS scores. Using simple multiple kernel learning (MKL), Rs-fMRI was used to predict the memory function scores that were associated with CAPS scores. A support vector machine (SVM) was also used to make classifications in trauma survivors with or without PTSD.

RESULTS

Spatial addition (SA), which is defined by spatial working memory function, was negatively correlated with the total CAPS score (r = - 0.22, P = 0.04). The use of simple MKL allowed quantitative association of SA scores with statistically significant accuracy (correlation = 0.28, P = 0.03; mean squared error = 8.36; P = 0.04). The left middle frontal gyrus and the left precuneus contributed the largest proportion to the simple MKL association frame. The SVM could not make a quantitative classification of diagnosis with statistically significant accuracy.

LIMITATIONS

The use of the cross-sectional study design after exposure to an earthquake and the leave-one-out cross-validation (LOOCV) increases the risk of overfitting.

CONCLUSION

Spontaneous brain activity of the left middle frontal gyrus and the left precuneus acquired by rs-fMRI may be a brain mechanism of visual working memory that is related to PTSD symptoms. Machine learning may be a useful tool in the identification of brain mechanisms of memory impairment in trauma survivors.

Working memory training and brain structure and function in extremely preterm or extremely low birth weight children

This study in children born extremely preterm (EP; <28 weeks' gestational age) or extremely low birth weight (ELBW; <1,000 g) investigated whether adaptive working memory training using Cogmed® is associated with structural and/or functional brain changes compared with a placebo program. Ninety-one EP/ELBW children were recruited at a mean (standard deviation) age of 7.8 (0.4) years. Children were randomly allocated to Cogmed or placebo (45-min sessions, 5 days a week over 5-7 weeks). A subset had usable magnetic resonance imaging (MRI) data pretraining and 2 weeks posttraining (structural, n = 48; diffusion, n = 43; task-based functional, n = 18). Statistical analyses examined whether cortical morphometry, white matter microstructure and blood oxygenation level-dependent (BOLD) signal during an n-back working memory task changed from pretraining to posttraining in the Cogmed and placebo groups separately. Interaction analyses between time point and group were then performed. There was a significant increase in neurite density in several white matter regions from pretraining to posttraining in both the Cogmed and placebo groups. BOLD signal in the posterior cingulate and precuneus cortices during the n-back task increased from pretraining to posttraining in the Cogmed but not placebo group. Evidence for group-by-time interactions for the MRI measures was weak, suggesting that brain changes generally did not differ between Cogmed and placebo groups. Overall, while some structural and functional MRI changes between the pretraining and posttraining period in EP/ELBW children were observed, there was little evidence of training-induced neuroplasticity, with changes generally identified in both groups. Trial registration Australian New Zealand Clinical Trials Registry, anzctr.org.au; ACTRN12612000124831.

Working Memory Training Following Neonatal Critical Illness: A Randomized Controlled Trial

OBJECTIVES

To test the immediate and long-term effectiveness of Cogmed Working Memory Training following extracorporeal membrane oxygenation and/or congenital diaphragmatic hernia.

DESIGN

A nationwide randomized controlled trial assessing neuropsychologic outcome immediately and 1 year post Cogmed Working Memory Training, conducted between October 2014 and June 2017. Researchers involved in the follow-up assessments were blinded to group allocation.

SETTING

Erasmus MC-Sophia Children's Hospital, Rotterdam, and Radboud University Medical Center, Nijmegen, the Netherlands.

PATIENTS

Eligible participants were neonatal extracorporeal membrane oxygenation and/or congenital diaphragmatic hernia survivors (8-12 yr) with an intelligence quotient greater than or equal to 80 and a z score less than or equal to -1.5 on at least one (working) memory test at first assessment.

INTERVENTIONS

Cogmed Working Memory Training, comprising 25 45-minute training sessions for 5 consecutive weeks at home.

MEASUREMENTS AND MAIN RESULTS

Participants were randomized to Cogmed Working Memory Training (n = 19) or no intervention (n = 24) (two dropped out after T0). Verbal working memory (estimated coefficient = 0.87; p = 0.002) and visuospatial working memory (estimated coefficient=0.96, p = 0.003) significantly improved at T1 post Cogmed Working Memory Training but was similar between groups at T2 (verbal, p = 0.902; visuospatial, p = 0.416). Improvements were found at T2 on long-term visuospatial memory following Cogmed Working Memory Training (estimated coefficient = 0.95; p = 0.003). Greater improvements in this domain at T2 following Cogmed Working Memory Training were associated with better self-rated school functioning (r = 0.541; p = 0.031) and parent-rated attention (r = 0.672; p = 0.006).

CONCLUSIONS

Working memory improvements after Cogmed Working Memory Training disappeared 1 year post training in neonatal extracorporeal membrane oxygenation and/or congenital diaphragmatic hernia survivors. Gains in visuospatial memory persisted 1 year post intervention. Cogmed Working Memory Training may be beneficial for survivors with visuospatial memory deficits.

Effects of Executive Function Training on Attentional, Behavioral and Emotional Functioning and Self-Perceived Competence in Very Preterm Children: A Randomized Controlled Trial

OBJECTIVE

Very preterm children have poorer attentional, behavioral and emotional functioning than term-born children. Problems on these domains have been linked to poorer executive function (EF). This study examined effects of a game-formatted, comprehensive EF training on attentional, behavioral and emotional functioning and self-perceived competence in very preterm children.

STUDY DESIGN

Eighty-five children participated in a multi-center, double-blind, placebo and waitlist-controlled randomized trial. Children were recruited from neonatal follow-up units of two academic medical centers in The Netherlands. Eligible for inclusion were 8-12 year old children born very preterm (<30 weeks of gestation) and/or with extremely low birthweight (<1000 g) with parent reported attention problems. Children were randomly assigned to one of three treatment arms: EF training, placebo training or waitlist. The EF and placebo training involved a 6 weeks, 25 (30-45 min) sessions training program. Attentional functioning (Attention Network Test), behavioral and emotional functioning (parent and teacher Strengths and Difficulties questionnaire) and self-perceived competence (Self-Perception Profile for Children) were assessed at baseline, at the end of the training program and 5 months after the training was finished. Data analyses involved linear mixed model analyses.

RESULTS

Children in the EF training arm significantly improved on all training tasks over the course of the EF training program. Despite these improvements on the EF training tasks, there were no significant differences over time on any of the outcome measures between the three treatment arms, indicating that this computerized EF training program had no beneficial effects.

CONCLUSION

Although there were significant improvements in the EF training tasks, there was no generalization of these improvements to any of the outcome measures. Thus, our findings do not support the use of computerized EF training programs. Future research should investigate effectivity of more ecologically valid, real-world like EF training programs.

Attention deficit hyperactivity disorder and comorbidity: A review of literature

Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder with onset in early childhood. It is a clinically heterogenous condition with comorbidity posing a distinct challenge to diagnosing and managing these children and adolescents. This review aims to provide an overview of comorbidity with ADHD including other neurodevelopmental disorders, learning disorders, externalising and internalising disorders. Challenges in screening for, diagnosing and managing comorbidity with ADHD are summarised. Also, methodological challenges and future directions in research in this interesting field are highlighted.

Processing Speed Predicts Behavioral Treatment Outcomes in Children with Attention-Deficit/Hyperactivity Disorder Predominantly Inattentive Type

Neuropsychological functioning underlies behavioral symptoms of attention-deficit/hyperactivity disorder (ADHD). Children with all forms of ADHD are vulnerable to working memory deficits and children presenting with the inattentive form of ADHD (ADHD-I) appear particularly vulnerable to processing speed deficits. As ADHD-I is the most common form of ADHD presented by children in community settings, it is important to consider how treatment interventions for children with ADHD-I may be affected by deficits in processing speed and working memory. We utilize data collected from 199 children with ADHD-I, aged 7 to 11 years, who participated in a randomized clinical trial of a psychosocial-behavioral intervention. Our aims are first to determine whether processing speed or working memory predict treatment outcomes in ADHD-I symptom severity, and second whether they moderate treatment effects on ADHD-I symptom severity. Results of linear regression analyses reveal that baseline processing speed significantly predicts posttreatment ADHD-I symptom severity when controlling for baseline ADHD-I symptom severity, such that better processing speed is associated with greater symptom improvement. However, predictive effects of working memory and moderation effects of both working memory and processing speed are not supported in the present study. We discuss study limitations and implications of the relation between processing speed and treatment benefits from psychosocial treatments for children with ADHD-I.

Brain Training in Children and Adolescents: Is It Scientifically Valid?

Background: Brain training products are becoming increasingly popular for children and adolescents. Despite the marketing aimed at their use in the general population, these products may provide more benefits for specific neurologically impaired populations. A review of Brain Training (BT) products analyzing their efficacy while considering the methodological limitations of supporting research is required for practical applications. Method: searches were made of the PubMed database (until March 2017) for studies including: (1) empirical data on the use of brain training for children or adolescents and any effects on near transfer (NT) and/or far transfer (FT) and/or neuroplasticity, (2) use of brain training for cognitive training purposes, (3) commercially available training applications, (4) computer-based programs for children developed since the 1990s, and (5) relevant printed and peer-reviewed material. Results: Database searches yielded a total of 16,402 references, of which 70 met the inclusion criteria for the review. We classified programs in terms of neuroplasticity, near and far transfer, and long-term effects and their applied methodology. Regarding efficacy, only 10 studies (14.2%) have been found that support neuroplasticity, and the majority of brain training platforms claimed to be based on such concepts without providing any supporting scientific data. Thirty-six studies (51.4%) have shown far transfer (7 of them are non-independent) and only 11 (15.7%) maintained far transfer at follow-up. Considering the methodology, 40 studies (68.2%) were not randomized and controlled; for those randomized, only 9 studies (12.9%) were double-blind, and only 13 studies (18.6%) included active controls in their trials. Conclusion: Overall, few independent studies have found far transfer and long-term effects. The majority of independent results found only near transfer. There is a lack of double-blind randomized trials which include an active control group as well as a passive control to properly control for contaminant variables. Based on our results, Brain Training Programs as commercially available products are not as effective as first expected or as they promise in their advertisements.

Computerized cognitive training for children with neurofibromatosis type 1: A pilot resting-state fMRI study

In this pilot study, we examined training effects of a computerized working memory program on resting state functional magnetic resonance imaging (fMRI) measures in children with neurofibromatosis type 1 (NF1). We contrasted pre- with post-training resting state fMRI and cognitive measures from 16 participants (nine males; 11.1 ± 2.3 years) with NF1 and documented working memory difficulties. Using non-parametric permutation test inference, we found significant regionally specific differences (family-wise error corrected) in two of four voxel-wise resting state measures: fractional amplitude of low frequency fluctuations (indexing peak-to-trough intensity of spontaneous oscillations) and regional homogeneity (indexing local intrinsic synchrony). Some cognitive task improvement was observed as well. These preliminary findings suggest that regionally specific changes in resting state fMRI indices may be associated with treatment-related cognitive amelioration in NF1. Nevertheless, current results must be interpreted with caution pending independent controlled replication.

fMRI Neurofeedback Training for Increasing Anterior Cingulate Cortex Activation in Adult Attention Deficit Hyperactivity Disorder. An Exploratory Randomized, Single-Blinded Study

Attention Deficit Hyperactivity Disorder (ADHD) is characterized by poor cognitive control/attention and hypofunctioning of the dorsal anterior cingulate cortex (dACC). In the current study, we investigated for the first time whether real-time fMRI neurofeedback (rt-fMRI) training targeted at increasing activation levels within dACC in adults with ADHD leads to a reduction of clinical symptoms and improved cognitive functioning. An exploratory randomized controlled treatment study with blinding of the participants was conducted. Participants with ADHD (n = 7 in the neurofeedback group, and n = 6 in the control group) attended four weekly MRI training sessions (60-min training time/session), during which they performed a mental calculation task at varying levels of difficulty, in order to learn how to up-regulate dACC activation. Only neurofeedback participants received continuous feedback information on actual brain activation levels within dACC. Before and after the training, ADHD symptoms and relevant cognitive functioning was assessed. Results showed that both groups achieved a significant increase in dACC activation levels over sessions. While there was no significant difference between the neurofeedback and control group in clinical outcome, neurofeedback participants showed stronger improvement on cognitive functioning. The current study demonstrates the general feasibility of the suggested rt-fMRI neurofeedback training approach as a potential novel treatment option for ADHD patients. Due to the study’s small sample size, potential clinical benefits need to be further investigated in future studies.

Trial Registration: ISRCTN12390961

Adaptive working memory training improved brain function in human immunodeficiency virus-seropositive patients

Objective

We aimed to evaluate the effectiveness of an adaptive working memory (WM) training (WMT) program, the corresponding neural correlates, and LMX1A‐rs4657412 polymorphism on the adaptive WMT, in human immunodeficiency virus (HIV) participants compared to seronegative (SN) controls.

Methods

A total of 201 of 206 qualified participants completed baseline assessments before randomization to 25 sessions of adaptive WMT or nonadaptive WMT. A total of 74 of 76 (34 HIV, 42 SN) completed adaptive WMT and all 40 completed nonadaptive WMT (20 HIV, 20 SN) and were assessed after 1 month, and 55 adaptive WMT participants were also assessed after 6 months. Nontrained near‐transfer WM tests (Digit‐Span, Spatial‐Span), self‐reported executive functioning, and functional magnetic resonance images during 1‐back and 2‐back tasks were performed at baseline and each follow‐up visit, and LMX1A‐rs4657412 was genotyped in all participants.

Results

Although HIV participants had slightly lower cognitive performance and start index than SN at baseline, both groups improved on improvement index (>30%; false discovery rate [FDR] corrected p < 0.0008) and nontrained WM tests after adaptive WMT (FDR corrected, p ≤ 0.001), but not after nonadaptive WMT (training by training type corrected, p = 0.01 to p = 0.05) 1 month later. HIV participants (especially LMX1A‐G carriers) also had poorer self‐reported executive functioning than SN, but both groups reported improvements after adaptive WMT (Global: training FDR corrected, p = 0.004), and only HIV participants improved after nonadaptive WMT. HIV participants also had greater frontal activation than SN at baseline, but brain activation decreased in both groups at 1 and 6 months after adaptive WMT (FDR corrected, p < 0.0001), with normalization of brain activation in HIV participants, especially the LMX1A‐AA carriers (LMX1A genotype by HIV status, cluster‐corrected‐p < 0.0001).

Interpretation

Adaptive WMT, but not nonadaptive WMT, improved WM performance in both SN and HIV participants, and the accompanied decreased or normalized brain activation suggest improved neural efficiency, especially in HIV‐LMX1A‐AA carriers who might have greater dopaminergic reserve. These findings suggest that adaptive WMT may be an effective adjunctive therapy for WM deficits in HIV participants. ANN NEUROL 2017;81:17–34

Long-term far-transfer effects of working memory training in children with ADHD: a randomized controlled trial

ADHD affects working memory (WM) and other executive functions (EFs) and thereby negatively impacts school performance, clinical symptoms and functional impairment. The main aim of this study was to analyse the efficacy of computerized WM training (CWMT) on EF rating scales. A secondary objective was to assess its efficacy on performance-based measures of EF (PBMEF), learning, clinical symptoms and functional impairment. 66 children with combined-type ADHD between 7 and 12 years of age from the Child and Adolescent Psychiatric Unit (Spain) were included in this randomized, double-blind, placebo-controlled, parallel-group clinical trial. The participants were randomized (1:1) to an experimental group (EG) (CWMT) (n = 36) or a control group (CG) (placebo training). Assessments were conducted at baseline (T0), 1-2 weeks (T1), and 6 months post-intervention (T2) with the administration of EF rating scales, PBMEF, measures of academic achievement, and questionnaires regarding clinical symptoms and functional impairment. Participants, parents, teachers and professionals who performed the cognitive assessments were blinded. Adjusted multiple linear regression analysis showed significant improvements in EF scales-parent version, from T1 to T2, on the metacognition index [p = 0.03, d' = -0.78 (95 % CI -1.28 to -0.27)] and on WM (also significant at T2-T0) and plan/organize subscales. Significant improvements were also noted in EF scales-teacher version, from T0 to T1 and T2, on the metacognitive index [p = 0.05, d' = -0.37 (95 % CI -0.86 to 0.12) T1-T0, p = 0.02, d' = -0.81 (95 % CI -1.31 to -0.30) T2-T0] and on the initiate, WM, monitor and shift subscales. There were also significant improvements in PBMEF, ADHD symptoms, and functional impairment. CWMT had a significant impact on ADHD deficits by achieving long-term far-transfer effects.

A debate on working memory and cognitive control: can we learn about the treatment of substance use disorders from the neural correlates of anorexia nervosa?

BACKGROUND

Anorexia Nervosa (AN) is a debilitating, sometimes fatal eating disorder (ED) whereby restraint of appetite and emotion is concomitant with an inflexible, attention-to-detail perfectionist cognitive style and obsessive-compulsive behaviour. Intriguingly, people with AN are less likely to engage in substance use, whereas those who suffer from an ED with a bingeing component are more vulnerable to substance use disorder (SUD).

DISCUSSION

This insight into a beneficial consequence of appetite control in those with AN, which is shrouded by the many other unhealthy, excessive and deficit symptoms, may provide some clues as to how the brain could be trained to exert better, sustained control over appetitive and impulsive processes. Structural and functional brain imaging studies implicate the executive control network (ECN) and the salience network (SN) in the neuropathology of AN and SUD. Additionally, excessive employment of working memory (WM), alongside more prominent cognitive deficits may be utilised to cope with the experience of negative emotions and may account for aberrant brain function. WM enables mental rehearsal of cognitive strategies while regulating, restricting or avoiding neural responses associated with the SN. Therefore, high versus low WM capacity may be one of the factors that unites common cognitive and behavioural symptoms in those suffering from AN and SUD respectively. Furthermore, emerging evidence suggests that by evoking neural plasticity in the ECN and SN with WM training, improvements in neurocognitive function and cognitive control can be achieved. Thus, considering the neurocognitive processes of excessive appetite control and how it links to WM in AN may aid the application of adjunctive treatment for SUD.