Deficits in visuo-spatial working memory, inhibition and oculomotor control in boys with ADHD and their non-affected brothers

Effects of Auditory and Visual White Noise on Oculomotor Inhibition in Children With Attention-Deficit/Hyperactivity Disorder: Protocol for a Crossover Study

BACKGROUND

In attention-deficit/hyperactivity disorder (ADHD), poor inhibitory control is one of the main characteristics, with oculomotor inhibition impairments being considered a potential biomarker of the disorder. While auditory white noise has demonstrated the ability to enhance working memory in this group, visual white noise is still unexplored and so are the effects of both types of white noise stimulation on oculomotor inhibition.

OBJECTIVE

This crossover study aims to explore the impact of auditory and visual white noise on oculomotor inhibition in children with ADHD and typically developing (TD) children. The study will investigate the impact of different noise levels (25% and 50% visual, 78 dB auditory), and performance will be evaluated both with and without noise stimulation. We hypothesize that exposure to white noise will improve performance in children with ADHD and impair the performance for TD children.

METHODS

Memory-guided saccades and prolonged fixations, known for their sensitivity in detecting oculomotor disinhibition in ADHD, will be used to assess performance. Children diagnosed with ADHD, withdrawing from medication for 24 hours, and TD children without psychiatric disorders were recruited for the study.

RESULTS

Data collection was initiated in October 2023 and ended in February 2024. A total of 97 participants were enrolled, and the first results are expected between September and November 2024.

CONCLUSIONS

This study will examine whether cross-modal sensory stimulation can enhance executive function, specifically eye movement control, in children with ADHD. In addition, the study will explore potential differences between auditory and visual noise effects in both groups. Our goal is to identify implications for understanding how noise can be used to improve cognitive performance.

TRIAL REGISTRATION

ClinicalTrials.gov NCT06057441; https://clinicaltrials.gov/study/NCT06057441.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/56388.

Oculomotor deficits in attention deficit hyperactivity disorder: a systematic review and meta-analysis

There is equivocal evidence on the presence of oculomotor deficits among children with attention deficit hyperactivity disorder (ADHD), which can be an additional challenge in this population, especially with reading-related tasks. This study aimed to review the deficits in the oculomotor parameters among children with ADHD compared with age-matched controls. The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. A search of original research articles on various databases was done using key terms, such as "oculomotor deficit," "attention deficit hyperactivity disorder," or related terms. We included case-control studies and excluded studies in which children received medications during the test. Twelve original research studies were considered for this review. Ten studies reported data on various types of saccades, two studies reported data on fixation, and one study reported data on pursuit. Among various oculomotor deficits, the forest-plot analysis of an antisaccade task showed that children with ADHD made more direction errors compared to controls. Although independent studies report that ADHD children have poorer performance compared to control populations during oculomotor tasks, there is a lack of evidence to draw a strong conclusion. Children with ADHD are less precise in performing eye movements and need more time to complete the oculomotor tasks than those without ADHD. The overall results provide minimal evidence regarding the presence of various oculomotor deficits in ADHD.

The Eyes Have It: A Meta-analysis of Oculomotor Inhibition in Attention-Deficit/Hyperactivity Disorder

BACKGROUND

Diminished inhibitory control is one of the main characteristics of attention-deficit/hyperactivity disorder (ADHD), and impairments in oculomotor inhibition have been proposed as a potential biomarker of the disorder. The present meta-analysis summarizes the effects reported in studies comparing oculomotor inhibition in ADHD patients and healthy control subjects.

METHODS

Inhibitory outcomes were derived from oculomotor experimental paradigms including the antisaccade (AS), memory-guided saccade, and prolonged fixation tasks. Temporal and spatial measures were also extracted from these tasks and from visually guided saccade tasks as secondary outcomes. Data were available from k = 31 studies (N = 1567 participants). Summary effect sizes were computed using random-effects models and a restricted maximum-likelihood estimator.

RESULTS

Among inhibitory outcomes, direction errors in AS, after correcting for publication bias, showed a moderate effect and large between-study heterogeneity (k = 18, n = 739, g = 0.57, 95% confidence interval [CI] [0.27, 0.88], I²= 74%); anticipatory saccades in memory-guided saccade showed a large effect and low heterogeneity (k = 11, n = 487; g = 0.86, 95% CI [0.64, 1.08], I² = 17.7%); and saccades during prolonged fixation evidenced large effect size and heterogeneity (k = 6, n = 325 g = 1.11, 95% CI [0.56, 1.65], I² = 79.1%) partially related to age. Among secondary outcomes, saccadic reaction time in AS (k = 22, n = 932, g = 0.34, 95% CI [0.06, 0.63], I² = 53.12%) and coefficient of variability in visually guided saccade (k = 5, n = 282, g = 0.53, 95% CI [0.28, 0.78], I² = 0.01%) indicated significant effects with small to moderate effects sizes.

CONCLUSIONS

ADHD groups commit more oculomotor inhibition failures than control groups. The substantial effects support the conclusion that oculomotor disinhibition is a relevant ADHD-related mechanism. Moderate effects observed in saccadic reaction time variability suggest that fluctuant performance in oculomotor tasks is another relevant characteristic of ADHD.

Working memory and reaction time variability mediate the relationship between polygenic risk and ADHD traits in a general population sample

Endophenotypes are heritable and quantifiable traits indexing genetic liability for a disorder. Here, we examined three potential endophenotypes, working memory function, response inhibition, and reaction time variability, for attention-deficit hyperactivity disorder (ADHD) measured as a dimensional latent trait in a large general population sample derived from the Adolescent Brain Cognitive Development^SM Study. The genetic risk for ADHD was estimated using polygenic risk scores (PRS) whereas ADHD traits were quantified as a dimensional continuum using Bartlett factor score estimates, derived from Attention Problems items from the Child Behaviour Checklist and Effortful Control items from the Early Adolescent Temperament Questionnaire-Revised. The three candidate cognitive endophenotypes were quantified using task-based performance measures. Higher ADHD PRSs were associated with higher ADHD traits, as well as poorer working memory performance and increased reaction time variability. Lower working memory performance, poorer response inhibition, and increased reaction time variability were associated with more pronounced ADHD traits. Working memory and reaction time variability partially statistically mediated the relationship between ADHD PRS and ADHD traits, explaining 14% and 16% of the association, respectively. The mediation effect was specific to the genetic risk for ADHD and did not generalise to genetic risk for four other major psychiatric disorders. Together, these findings provide robust evidence from a large general population sample that working memory and reaction time variability can be considered endophenotypes for ADHD that mediate the relationship between ADHD PRS and ADHD traits.

Oculomotor deficits in attention deficit hyperactivity disorder (ADHD): A systematic review and comprehensive meta-analysis

Atypical motor coordination and cognitive processes, such as response inhibition and working memory, have been extensively researched in individuals with attention deficit hyperactivity disorder (ADHD). Oculomotor neural circuits overlap extensively with regions involved in motor planning and cognition, therefore studies of oculomotor function may offer unique insights into motor and cognitive control in ADHD. We performed a series of pairwise meta-analyses based on data from 26 oculomotor studies in ADHD to examine whether there were differences in performance on visually-guided saccade, gap, antisaccade, memory-guided, pursuit eye movements and fixation tasks. These analyses revealed oculomotor disturbances in ADHD, particularly for difficulties relating to saccade inhibition, memorizing visual target locations and initiating antisaccades. There was no evidence for pursuit eye movement disturbances or saccade dysmetria. Investigating oculomotor abnormalities in ADHD may provide insight into top-down cognitive control processes and motor control, and may serve as a promising biomarker in ADHD research and clinical practice.

Social and non-social gaze cueing in autism spectrum disorder, attention-deficit/hyperactivity disorder and a comorbid group

Recent trends in literature, along with the changes to the Diagnostic and Statistical Manual (DSM), make it imperative to study Attention-Deficit/Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) together, in order to better understand potential aetiological commonalities between these highly comorbid disorders. The present study examines social cueing, a highly studied construct in ASD, and intra-subject variability (ISV), a potential endophenotype of ADHD, in four groups of typically developing (TD), ADHD, ASD- (ASD without ADHD), ASD+ (ASD with ADHD) participants (N = 85) aged 10-13 years. Results showed that social cueing is intact in the 'pure' ASD group when task expectations are clear. The ADHD group showed faster saccadic reaction times, no increased ISV and a pattern of viewing comparable to the TD group. However, the ASD + group showed a differences in processing style and ISV. A secondary analysis gives evidence of non-additive effects of the ASD and ADHD factors.

Tactile Discrimination, Praxis and Cognitive Impulsivity in ADHD Children: A Cross-Sectional Study

Background: The study of attention deficit hyperactivity disorder (ADHD) has traditionally focused on deficit of inhibitory control and cognitive impulsivity. However, the pathophysiology of ADHD has also been associated with the somatosensory cortex. The aim of this study was to explore if there were differences in tactile discrimination and praxis between neurotypical and ADHD children and whether these differences could be explained by cognitive impulsivity. Methods: A cross-sectional study was conducted. The sample comprised 74 children aged 7 to 11 years divided in two groups: 43 with neurotypical development, 31 with ADHD. To assess tactile discrimination, the finger localization and the graphestesia tests were used. Praxis was assessed with the Kaufman Assesment Battery for Children (K-ABC) hand movement subtest, the action program and the Zoo Map subtests of the Behavioral Assessment of Dysexecutive Syndrome, and the complex figure of Rey–Osterrieth test (ROCF). Cognitive impulsivity was assessed using the Magallanes Computerized Impulsivity Scale test (EMIC). Results: Children with ADHD showed greater cognitive impulsivity (p = 0.038) and scored lower in Zoo Map (p = 0.023) and hand-movement subtests (p = 0.002), and in ROCF test (p = 0.004). Differences in praxis skills still remained after controlling by gender and cognitive impulsivity. Conclusion: Praxis deficit might have repercussions not only on the characterization of ADHD but also on its treatment.

Saccade eye movement in children with attention deficit hyperactivity disorder

Objects: This study aims to investigate the saccade/anti-saccade eye movement in children with attention deficit/hyperactivity disorder (ADHD).Methods: Twelve children (8.8 ± 0.8 years) diagnosed with ADHD (DSM-V) and 12 control (9.1 ± 0.3 years) were invited to participate in the experiment where the iView Hi-SPEED eyetracker, with the sample rate at 500 Hz Binocular, was employed. The visual guided saccade (VGS) task was used to collect saccade latency and accuracy values. The anti-saccade task was used to collect saccade latency and accuracy values as well as the percentage of direction errors (PDE).Results: Children with ADHD showed a significant difference in latency in the 7.5° target and imprecision in both targets (7.5° and 15°) during the VGS task. Moreover, the ADHD group exhibited shorter latency (15° target) and significantly higher numbers in the Percentage of Direction Errors in the anti-saccade tasks than the control group.Conclusions: The results suggest that children with ADHD have the following difficulties: precise oculomotor control, oculomotor response inhibition function and basic visual attention.

Associations between Attention-Deficit/Hyperactivity Disorder and Ocular Abnormalities in Children: A Population-based Study

Purpose: Attention-deficit/hyperactivity disorder (ADHD) was reported to be associated with disturbances in the prefrontal circuitry and seems to be associated with dysfunctions of eye motility. This study aimed to explore associations between ADHD and ocular abnormalities, including amblyopia, hypermetropia, astigmatism, and heterotropia, using a large, nationwide population-based dataset in Taiwan.Methods: We retrieved our sample for this cross-sectional study from the Taiwan National Health Insurance Research Database. In total, 116,308 children with ADHD were selected as the study group and 116,308 randomly selected children without ADHD as the comparison group. We used conditional logistic regression analyses to examine the odds ratios (ORs) of amblyopia, hypermetropia, astigmatism, and heterotropia between children with and those without ADHD.Results: We found that children with ADHD had significantly higher prevalences of amblyopia (1.6% vs. 0.9%, p< .001), hypermetropia (2.4% vs. 1.3%, p < .001), astigmatism (0.2% vs. 0.1%, p < .001), and heterotropia (1.1% vs. 0.5%, p < .001) than children without ADHD. The ORs of amblyopia, hypermetropia, astigmatism and heterotropia for children with ADHD were 1.89 (95% confidence interval (CI) = 1.76 ~ 2.05), 1.82 (95% CI = 1.68 ~ 1.92), 1.73 (95% CI = 1.34 ~ 2.16), and 2.01 (95% CI = 1.82 ~ 2.21) compared to children without ADHD.Conclusions: The findings suggest that ADHD is associated with ocular abnormalities, including amblyopia, hypermetropia, astigmatism, and heterotropia.

Availability of Striatal Dopamine Transporter in Healthy Individuals With and Without a Family History of ADHD

OBJECTIVE

ADHD is the most prevalent neurodevelopmental disorder. It is highly heritable and multifactorial, but the definitive causes remain unknown. Abnormal dopamine transporter (DAT) availability has been reported, but the data are inconsistent. The aim of this study was to examine whether DAT availability differs between healthy parents with and without ADHD offspring.

METHOD

Eleven healthy parents with ADHD offspring and 11 age- and sex-matched healthy controls without ADHD offspring were recruited. The availability of DAT was approximated using single-photon emission computed tomography, with [^99mTc] TRODAT-1 as the ligand.

RESULTS

DAT availability in the basal ganglia, caudate nucleus, and putamen was significantly lower in the parents with ADHD offspring than in the healthy controls without ADHD offspring.

CONCLUSION

The results suggest that ADHD could be heritable via abnormal DAT activities.

Binocular rivalry transitions predict inattention symptom severity in adult ADHD

Attention deficit and hyperactivity disorder (ADHD) is a prevalent childhood disorder that is often maintained throughout the development and persists into adulthood. Established etiology models suggest that deficient inhibition underlies the core ADHD symptoms. While experimental evidence for impaired motor inhibition is overwhelming, little is known about the sensory inhibition processes, their changes throughout the development, and the relationship to ADHD symptoms. Here, we used the well-established binocular rivalry (BR) paradigm to investigate for the very first time the inhibitory processes related to visual perception in adults with ADHD. In BR, perception alternates between two dichoptically presented images throughout the viewing period, with shorter dominant percept durations and longer transition periods indicating poorer suppression/inhibition. Healthy controls (N = 28) and patients with ADHD (N = 32) were presented with two dissimilar images (orthogonal gratings) separately to each eye through a mirror stereoscope and asked to report their perceptual experiences. There were no differences between groups in any of the BR markers. However, an association between transition durations and symptom severity emerged in the ADHD group. Importantly, an exploratory multiple regression analysis revealed that inattention symptoms were the sole predictor for the duration of transition periods. The lack of impairments to sensory inhibition in adult, but not pediatric ADHD may reflect compensatory changes associated with development, while a correlation between inhibition and inattention symptoms may reveal an invariant core of the disorder.

Augmented Go/No-Go Task: Mouse Cursor Motion Measures Improve ADHD Symptom Assessment in Healthy College Students

Attention deficit/hyperactivity disorder (ADHD) is frequently characterized as a disorder of executive function (EF). However, behavioral tests of EF, such as go/No-go tasks, often fail to grasp the deficiency in EF revealed by questionnaire-based measures. This inability is usually attributed to questionnaires and behavioral tasks assessing different constructs of EFs. We propose an additional explanation for this discrepancy. We hypothesize that this problem stems from the lack of dynamic assessment of decision-making (e.g., continuous monitoring of motor behavior such as velocity and acceleration in choice reaching) in classical versions of behavioral tasks. We test this hypothesis by introducing dynamic assessment in the form of mouse motion in a go/No-go task. Our results indicate that, among healthy college students, self-report measures of ADHD symptoms become strongly associated with performance in behavioral tasks when continuous assessment (e.g., acceleration in the mouse-cursor motion) is introduced.

Usefulness of the measurement of saccadic refixation in the diagnosis of attention-deficit hyperactivity disorder/hyperkinetic disorder in adults

Background:

The aim of the research is to evaluate the usefulness of the measurement of saccadic refixation in the diagnosis of attention-deficit hyperactivity disorder (ADHD)/hyperkinetic disorder (HKD) in adults.

Methods:

Seventy-eight individuals were examined: 40 with ADHD/HKD and 38 healthy ones. A noninvasive eye movement examination using the Saccadometer (Advanced Clinical Instrumentation, Cambridge, UK) was applied. Two saccadic tests, prosaccades task (PT) and antisaccades task (AT), were carried out.

Results:

Based on the results, we can assume that selected parameters, such as latency, standard deviation of latency, promptness, and correctness (directional errors), in individuals with ADHD/HKD differ statistically in the relevant parameters from the healthy ones. The latency and the standard deviation of latency in ADHD/HKD participants are greater when compared to healthy ones. ADHD/HKD participants have a greater number of directional errors in comparison to healthy ones.

Conclusions:

The standard deviation of latency prosaccades is a good parameter for distinguishing people from both groups. An important and innovative solution in this study in comparison to the studies of other authors, who reached similar results, is the use of an automatically calibrating system (autonomous) adapted for clinical use as well as a quantitative analysis of the saccadic parameters.

Cognitive impairments are different in single-incidence and multi-incidence ADHD families

BACKGROUND

We may improve our understanding of the role of common versus unique risk factors in attention-deficit/hyperactivity disorder (ADHD) by examining ADHD-related cognitive deficits in single- (SPX), and multi-incidence (MPX) families. Given that individuals from multiplex (MPX) families are likely to share genetic vulnerability for the disorder, whereas simplex (SPX) ADHD may be the result of sporadic (non-)genetic causes unique to the patient, we hypothesized that cognitive impairments may be different in SPX and MPX ADHD as indicated by (a) the presence of cognitive deficits in MPX, but not SPX unaffected siblings and (b) dissimilar cognitive profiles in SPX and MPX ADHD patients.

METHODS

Tasks measuring total IQ, verbal attention, executive functioning, motor functioning, and time estimation were administered to 31 SPX/264 MPX ADHD probands, 47 SPX/123 MPX unaffected siblings, and 263 controls, aged 6-19 years.

RESULTS

SPX unaffected siblings were unimpaired compared to controls, except for verbal working memory, whereas MPX unaffected siblings showed impairments on most cognitive domains. The cognitive profiles of SPX and MPX probands were highly similar, except that verbal attention, response inhibition and motor control deficits were more pronounced in MPX probands, and -compared to their unaffected siblings- impairments in IQ, visual working memory and timing abilities were more pronounced in SPX cases.

CONCLUSIONS

Our results support the hypothesis that a partly different cognitive architecture may underlie SPX and MPX forms of ADHD, which becomes evident when contrasting cognitive performances within families. Cognitive factors underlying MPX forms of ADHD are familial, whereas nonfamilial in SPX ADHD. SPX-MPX stratification may be a step forward in unraveling diverse causal pathways.

Memory-guided saccades in youth-onset psychosis and attention deficit hyperactivity disorder (ADHD)

AIM

Working memory deficits have been shown to be present in children and adolescents with schizophrenia and attention deficit hyperactivity disorder. Considering the differences in clinical characteristics between these disorders, it was the goal of this study to assess differences in the specific components of working memory in children and adolescents with psychosis and attention deficit hyperactivity disorder.

METHODS

Children and adolescents (age range 8-20 years) with either a non-affective psychotic disorder (n = 25), attention deficit hyperactivity disorder (n = 33) and controls (n = 58) were administered an oculomotor delayed-response task using both a recall and a control condition. Memory-guided saccades were measured during delay periods of 2, 8 and 20 s.

RESULTS

Although both clinical groups were less accurate than controls, there was no evidence of a disproportionate impairment in recall. In addition, there was no evidence of a delay-dependent impairment in psychosis; however, there was a delay-dependent impairment in attention deficit hyperactivity disorder when corrective saccades were included. Speed of information processing was correlated with distance errors in psychosis, suggesting that speed of encoding the stimulus location may have constrained the accuracy of the saccades.

CONCLUSIONS

Our findings support impairments during encoding in the psychosis group and a delay-dependent deficit in the attention deficit hyperactivity disorder group.

The role of prefrontal catecholamines in attention and working memory

While much progress has been made in identifying the brain regions and neurochemical systems involved in the cognitive processes disrupted in mental illnesses, to date, the level of detail at which neurobiologists can describe the chain of events giving rise to cognitive functions is very rudimentary. Much of the intense interest in understanding cognitive functions is motivated by the hope that it might be possible to understand these complex functions at the level of neurons and neural circuits. Here, we review the current state of the literature regarding how modulations in catecholamine levels within the prefrontal cortex (PFC) alter the neuronal and behavioral correlates of cognitive functions, particularly attention and working memory.

No effect of acute tryptophan depletion on verbal declarative memory in young persons with ADHD

OBJECTIVE

Animal experiments and studies in adults have shown that the neurotransmitter serotonin (5-HT) plays an important role in learning and memory processes. However, data on this relationship in young persons are scarce, and neurodietary research in this age group is limited compared with the extensive literature on adults. Here, we aimed to explore the effects of a diminished central nervous 5-HT synthesis, which is achieved by acute tryptophan depletion (ATD) Moja-De , on memory function in young males with attention deficit hyperactivity disorder (ADHD).

METHOD

Twenty-two male patients with ADHD (ages 9-15 years, mean 10.95 ± 1.17 years) received ATD, thus diminishing central nervous 5-HT synthesis, and a tryptophan-balanced amino acid load (BAL) in a randomized, double-blind, within-subject, crossover design study. Approximately 1.7 h after administration of ATD/BAL, verbal declarative memory was assessed using the 'Auditory Verbal-Learning-Test' (AVLT).

RESULTS

There were no significant effects of ATD administration on verbal declarative memory function.

CONCLUSION

In this study, changes in 5-HT neurotransmission were not associated with specific aspects of verbal declarative memory in young persons with ADHD. Future studies with healthy control groups that address effects of covarying attentional processes are warranted.

Working memory and response inhibition as one integral phenotype of adult ADHD? A behavioral and imaging correlational investigation

OBJECTIVE

It is an open question whether working memory (WM) and response inhibition (RI) constitute one integral phenotype in attention deficit hyperactivity disorder (ADHD).

METHOD

The authors investigated 45 adult ADHD patients and 41 controls comparable for age, gender, intelligence, and education during a letter n-back and a stop-signal task, and measured prefrontal oxygenation by means of functional near-infrared spectroscopy.

RESULTS

The authors replicated behavioral and cortical activation deficits in patients compared with controls for both tasks and also for performance in both control conditions. In the patient group, 2-back performance was correlated with stop-signal reaction time. This correlation did not seem to be specific for WM and RI as 1-back performance was correlated with go reaction time. No significant correlations of prefrontal oxygenation between WM and RI were found.

CONCLUSION

The authors' findings do not support the hypothesis of WM and RI representing one integral phenotype of ADHD mediated by the prefrontal cortex.

No behavioral or ERP evidence for a developmental lag in visual working memory capacity or filtering in adolescents and adults with ADHD

Attention-deficit/hyperactivity disorder (ADHD) patients have both working memory (WM) and attention problems. Good attention skills are important for WM performance; individuals have higher WM capacity when being able to prevent storage of irrelevant information through efficient filtering. Since it is unknown how filtering ability is associated with WM performance in ADHD, this was investigated in the present study. A visuospatial working memory (VSWM) change detection task with distracting stimuli was administered to adolescents (12–16 years old) and adults (20–46 years old) with and without ADHD matched on education/IQ. Besides performance, contralateral delay activity (CDA) was measured; a neural correlate of the number of targets and distracters encoded and maintained in WM during the retention interval. Performance data showed similar WM-load, WM-distracter interference and developmental effects in ADHD and control groups. Adolescents’ performance on the WM task deteriorated more than that of adults in the presence of distracters and with higher WM-load, irrespective of Diagnosis. The CDA data suggested that initially all groups encoded/maintained distracting information, but only adults were able to bounce this information from memory later in the retention interval, leading to better WM performance. The only effect of Diagnosis was a smaller CDA in adolescents and adults with ADHD than in age/IQ-matched controls when maintaining a low 1-item load, which was possibly related to an inability to keep attention focused at cued stimuli with low task demands. Overall, the development of filtering efficiency and VSWM storage capacity in adolescents with ADHD was not different from that in typically developing peers.

Impaired volitional saccade control: first evidence for a new candidate endophenotype in obsessive-compulsive disorder

Recent research suggests that patients with obsessive-compulsive disorder (OCD) have deficits in the volitional control of saccades. Specific evidence comes from increased latencies of saccadic eye movements when they were volitionally executed but not when they were visually guided. The present study sought to test whether this deviance represents a cognitive endophenotype. To this end, first-degree relatives of OCD patients as genetic risk carriers were compared with OCD patients and healthy controls without a family history of OCD. Furthermore, as volitional response generation comprises selection and initiation of the required response, the study also sought to specify the cognitive mechanisms underlying impaired volitional response generation. Twenty-two unaffected first-degree relatives of OCD patients, 22 unmedicated OCD patients, and 22 healthy comparison subjects performed two types of volitional saccade tasks measuring response selection or only response initiation, respectively. Visually guided saccades were used as a control condition. Our results showed that unaffected first-degree relatives and OCD patients were significantly slowed compared to healthy comparison subjects in volitional response selection. Patients and relatives did not differ from each other. There was no group difference in the visually guided control condition. Taken together, the study provides first evidence that dysfunctional volitional response selection is a candidate endophenotype for OCD.

Interventions to improve executive functioning and working memory in school-aged children with AD(H)D: a randomised controlled trial and stepped-care approach

BACKGROUND

Deficits in executive functioning are of great significance in attention-deficit/hyperactivity disorder (ADHD). One of these executive functions, working memory, plays an important role in academic performance and is often seen as the core deficit of this disorder. There are indications that working memory problems and academic performance can be improved by school-oriented interventions but this has not yet been studied systematically. In this study we will determine the short- and long-term effects of a working memory--and an executive function training applied in a school situation for children with AD(H)D, taking individual characteristics, the level of impairment and costs (stepped-care approach) into account.

METHODS/DESIGN

The study consists of two parts: the first part is a randomised controlled trial with school-aged children (8-12 yrs) with AD(H)D. Two groups (each n = 50) will be randomly assigned to a well studied computerized working memory training 'Cogmed', or to the 'Paying attention in class' intervention which is an experimental school-based executive function training. Children will be selected from regular -and special education primary schools in the region of Amsterdam, the Netherlands. The second part of the study will determine which specific characteristics are related to non-response of the 'Paying attention in class' intervention. School-aged children (8-12 yrs) with AD(H)D will follow the experimental school-based executive function training 'Paying attention in class' (n = 175). Academic performance and neurocognitive functioning (primary outcomes) are assessed before, directly after and 6 months after training. Secondary outcome measures are: behaviour in class, behaviour problems and quality of life.

DISCUSSION

So far, there is limited but promising evidence that working memory - and other executive function interventions can improve academic performance. Little is know about the applicability and generalization effects of these interventions in a classroom situation. This study will contribute to this lack of information, especially information related to real classroom and academic situations. By taking into account the costs of both interventions, level of impairment and individual characteristics of the child (stepped-care approach) we will be able to address treatment more adequately for each individual in the future.

TRIAL REGISTRATION

Nederlands Trial Register NTR3415.

Saccadic eye movement applications for psychiatric disorders

OBJECTIVE

The study presented here analyzed the patterns of relationship between oculomotor performance and psychopathology, focusing on depression, bipolar disorder, schizophrenia, attention-deficit hyperactivity disorder, and anxiety disorder.

METHODS

Scientific articles published from 1967 to 2013 in the PubMed/Medline, ISI Web of Knowledge, Cochrane, and SciELO databases were reviewed.

RESULTS

Saccadic eye movement appears to be heavily involved in psychiatric diseases covered in this review via a direct mechanism. The changes seen in the execution of eye movement tasks in patients with psychopathologies of various studies confirm that eye movement is associated with the cognitive and motor system.

CONCLUSION

Saccadic eye movement changes appear to be heavily involved in the psychiatric disorders covered in this review and may be considered a possible marker of some disorders. The few existing studies that approach the topic demonstrate a need to improve the experimental paradigms, as well as the methods of analysis. Most of them report behavioral variables (latency/reaction time), though electrophysiological measures are absent.

CDH13 is associated with working memory performance in attention deficit/hyperactivity disorder

Different analytic strategies, including linkage, association and meta-analysis support a role of CDH13 in the susceptibility to attention deficit/hyperactivity disorder (ADHD). CDH13 codes for cadherin 13 (or H-cadherin), which is a member of a family of calcium-dependent cell-cell adhesion proteins and a regulator of neural cell growth. We tested the association between CDH13 on three executive functioning tasks that are promising endophenotypes of ADHD. An adjusted linear regression analysis was performed in 190 ADHD-affected Dutch probands of the IMAGE project. Three executive functions were examined: inhibition, verbal and visuo-spatial working memory (WM). We tested 2632 single nucleotide polymorphisms (SNPs) within CDH13 and 20 kb up- and downstream of the gene (capturing regulatory sequences). To adjust for multiple testing within the gene, we applied stringent permutation steps. Intronic SNP rs11150556 is associated with performance on the Verbal WM task. No other SNP showed gene-wide significance with any of the analyzed traits, but a 72-kb SNP block located 446 kb upstream of SNP rs111500556 showed suggestive evidence for association (P-value range 1.20E-03 to 1.73E-04) with performance in the same Verbal WM task. This study is the first to examine CDH13 and neurocognitive functioning. The mechanisms underlying the associations between CDH13 and the clinical phenotype of ADHD and verbal WM are still unknown. As such, our study may be viewed as exploratory, with the results presented providing interesting hypotheses for further testing.

Neuropsychological profile of executive function in girls with attention-deficit/hyperactivity disorder

The majority of research on neurobehavioral functioning among children with Attention-Deficit/Hyperactivity Disorder (ADHD) is based on samples comprised primarily (or exclusively) of boys. Although functional impairment is well established, available research has yet to specify a neuropsychological profile distinct to girls with ADHD. The purpose of this study was to examine performance within four components of executive function (EF) in contemporaneously recruited samples of girls and boys with ADHD. Fifty-six children with ADHD (26 girls) and 90 controls (42 girls), ages 8-13, were administered neuropsychological tests emphasizing response inhibition, response preparation, working memory, and planning/shifting. There were no significant differences in age or SES between boys or girls with ADHD or their sex-matched controls; ADHD subtype distribution did not differ by sex. Compared with controls, children with ADHD showed significant deficits on all four EF components. Girls and boys with ADHD showed similar patterns of deficit on tasks involving response preparation and working memory; however, they manifested different patterns of executive dysfunction on tasks related to response inhibition and planning. Girls with ADHD showed elevated motor overflow, while boys with ADHD showed greater impairment during conscious, effortful response inhibition. Girls, but not boys with ADHD, showed impairment in planning. There were no differences between ADHD subtypes on any EF component. These findings highlight the importance of studying boys and girls separately (as well as together) when considering manifestations of executive dysfunction in ADHD.

Executive functions as endophenotypes in ADHD: evidence from the Cambridge Neuropsychological Test Battery (CANTAB)

BACKGROUND

Little is known about executive functions among unaffected siblings of children with attention deficit/hyperactivity disorder (ADHD), and there is lack of such information from non-Western countries. We examined verbal and nonverbal executive functions in adolescents with ADHD, unaffected siblings and controls to test whether executive functions could be potential endophenotypes for ADHD.

METHODS

We assessed 279 adolescents (age range: 11-17 years) with a childhood diagnosis of DSM-IV ADHD, 136 biological siblings (108 unaffected, 79.4%), and 173 unaffected controls by using psychiatric interviews, the Wechsler Intelligence Scale for Children - 3rd edition (WISC-III), including digit spans, and the tasks involving executive functions of the Cambridge Neuropsychological Test Automated Battery (CANTAB): Intra-dimensional/Extra-dimensional Shifts (IED), Spatial Span (SSP), Spatial Working Memory (SWM), and Stockings of Cambridge (SOC).

RESULTS

Compared with the controls, adolescents with ADHD and unaffected siblings had a significantly shorter backward digit span, more extra-dimensional shift errors in the IED, shorter spatial span length in the SSP, more total errors and poorer strategy use in the SWM, and fewer problems solved in the minimum number of moves and shorter initial thinking time in the SOC. The magnitudes of the differences in the SWM and SOC increased with increased task difficulties. In general, neither persistent ADHD nor comorbidity was associated with increased deficits in executive functions among adolescents with ADHD.

CONCLUSIONS

The lack of much difference in executive dysfunctions between unaffected siblings and ADHD adolescents suggests that executive dysfunctions may be useful cognitive endophenotypes for ADHD genetic studies.

Neural circuitry associated with risk for alcohol use disorders

The core features of risk for alcohol use disorders (AUD), including behavioral disinhibition, affective dysregulation, and executive dysfunction, map onto distinct neural circuits that have been found to be abnormal in the offspring of alcohol dependent individuals. Components of the cerebellothalamocortical system and the extended limbic network may provide the underpinnings for the behavioral and emotional dysfunction observed in individuals at heightened risk for AUD. In addition, abnormalities in these structures appear to be altered in individuals with the predisposition for other psychiatric conditions that may share a similar genetic diathesis. This review proposes several neurobehavioral mechanisms of genetic vulnerability that may account for phenotypic characteristics in individuals at risk for AUD.

Duration discrimination in the range of milliseconds and seconds in children with ADHD and their unaffected siblings

BACKGROUND

Detecting genetic factors involved in attention deficit hyperactivity disorder (ADHD) is complicated because of their small effect sizes and complex interactions. The endophenotype approach eases this by coming closer to the relevant genes. Different aspects of temporal information processing are known to be affected in ADHD. Thus, some of these aspects could represent candidate endophenotypes for ADHD.

METHOD

Fifty-four sib-pairs with at least one child with ADHD and 40 control children aged 6-18 years were recruited and asked to perform two duration discrimination tasks, one with a base duration of 50 ms on automatic timing and one with a base duration of 1000 ms on cognitively controlled timing.

RESULTS

Whereas children with ADHD, but not their unaffected siblings, were impaired in discrimination of longer intervals, both groups were impaired in discriminating brief intervals. Furthermore, a significant within-family correlation was found for discrimination of brief intervals. Task performances of subjects of the control group correlated with individual levels of hyperactivity/impulsivity for discrimination of brief intervals, but not of longer intervals.

CONCLUSIONS

Cognitively controlled and also automatic processes of temporal information processing are impaired in children with ADHD. Discrimination of longer intervals appears as a typical 'disease marker' whereas discrimination of brief intervals shows up as a 'vulnerability marker'. Discrimination of brief intervals was found to be familial and linked to levels of hyperactivity/impulsivity. Taken together, discrimination of brief intervals represents a candidate endophenotype of ADHD.

Oculomotor anomalies in attention-deficit/hyperactivity disorder: evidence for deficits in response preparation and inhibition

OBJECTIVE

To examine patterns of executive and oculomotor control in a group of both boys and girls with attention-deficit/hyperactivity disorder (ADHD).

METHOD

Cross-sectional study of 120 children aged 8 to 12 years, including 60 with ADHD (24 girls) and 60 typically developing controls (29 girls). Oculomotor paradigms included visually guided saccades (VGS), antisaccades, memory-guided saccades, and a go/no-go test, with variables of interest emphasizing response preparation, response inhibition, and working memory.

RESULTS

As a group, children with ADHD demonstrated significant deficits in oculomotor response preparation (VGS latency and variability) and response inhibition but not working memory. Girls, but not boys with ADHD, had significantly longer VGS latencies, even after controlling for differences in ADHD symptom severity. The ADHD subtypes did not differ on response preparation or inhibition measures; however, children with the Inattentive subtype were less accurate on the working memory task than those with the Combined subtype.

CONCLUSIONS

Sex differences in children with ADHD extend beyond symptom presentation to the development of oculomotor control. Saccade latency may represent a specific deficit among girls with ADHD.

Neuropsychologische Diagnostik bei Kindern mit ADHS

Aktuelle Modelle zur Ätiopathogenese der Aufmerksamkeitsdefizit-/Hyperaktivitätsstörung (ADHS) postulieren vor allem Defizite in den exekutiven Funktionen sowie motivationale Störungen als zentrale neuropsychologische Komponenten bei den betroffenen Patienten. Um die kognitiven und exekutiven Defizite der ADHS zu erfassen, finden derzeitig vor allem im englischen Sprachraum Testverfahren Anwendung, die auf der PASS-Theorie basieren. Durch die Erfassung der dynamischen kognitiven Prozesse Planungsfähigkeit und Aufmerksamkeit sowie sequenzielle und simultane Informationsverarbeitung zeigt sich die PASS-Theorie sensibel bezüglich der spezifischen kognitiven Probleme und exekutiven Defizite von Kindern mit Störungen der Aufmerksamkeit oder Hyperaktivität. Die Übersicht setzt sich ausführlich mit den neuropsychologischen Grundlagen der ADHS auseinander und stellt entsprechende diagnostische Verfahren vor. Die Rolle aktueller, auf der PASS-Theorie basierender Testverfahren für den diagnostischen Prozess und daraus resultierende Implikationen für den klinischen Alltag werden diskutiert.

A review on eye movement studies in childhood and adolescent psychiatry

The neural substrates of eye movement measures are largely known. Therefore, measurement of eye movements in psychiatric disorders may provide insight into the underlying neuropathology of these disorders. Visually guided saccades, antisaccades, memory guided saccades, and smooth pursuit eye movements will be reviewed in various childhood psychiatric disorders. The four aims of this review are (1) to give a thorough overview of eye movement studies in a wide array of psychiatric disorders occurring during childhood and adolescence (attention-deficit/hyperactivity disorder, oppositional deviant disorder and conduct disorder, autism spectrum disorders, reading disorder, childhood-onset schizophrenia, Tourette's syndrome, obsessive compulsive disorder, and anxiety and depression), (2) to discuss the specificity and overlap of eye movement findings across disorders and paradigms, (3) to discuss the developmental aspects of eye movement abnormalities in childhood and adolescence psychiatric disorders, and (4) to present suggestions for future research. In order to make this review of interest to a broad audience, attention will be given to the clinical manifestation of the disorders and the theoretical background of the eye movement paradigms.