COVCOG: Immediate and long-term cognitive improvement after cognitive versus emotion management psychoeducation programs - a randomized trial in covid patients with neuropsychological difficulties.

BACKGROUND: Cognitive difficulties are a frequent complaint in long COVID and persist for more than a year post- infection. There is a lack of evidence-based data on effective intervention strategies. Non-pharmacological intervention programs that are used with other neurological populations have not yet been the subject of controlled trials. COVCOG is a multicentric, randomized trial comparing cognitive intervention and a cognitive-behavioural counselling. METHODS/DESIGN: Patients with long covid are selected and recruited at least three months post-infection. Patients are randomised in a 1:1 ratio into the cognitive (neuropsychological psychoeducation) and affective (emotion management with cognitive-behavioural counselling) intervention arms. The inclusion of 130 patients is planned. The cognitive intervention includes psycho-educational modules on fatigue and sleep, attention and working memory, executive functions and long-term memory. The affective intervention includes modules on emotion recognition and communication, uncertainty management and behavioral activation. The main objective is to reduce cognitive complaints 2 months after the intervention. A Follow-up is also planned at 8 months. DISCUSSION: Given the long-term effects of Covid on cognition and the negative effects of cognitive impairment on quality of life and social participation, it is important to determine whether low-dose, non-pharmacological interventions can be effective. The trial will determine which of the usual types of intervention is the most effective. TRIAL REGISTRATION: Clinicaltrials.gov Number: NCT05167266 (21/12/ 2021).

Dimensional model on how familial vulnerability and environmental factors impact transitional age youth psychopathology: The Transition_psy study.

Background: Understanding psychopathology in transitional age youth (TAY) requires a complex model, incorporating familial vulnerability and environmental factors. A trans-diagnostic and dimensional approach seems the most appropriate. Transition_psy study aims to assess factors playing a role in TAY psychopathology and to define predictors. Materials and methods: This article presents part of the Transition_psy study results, a case-control observational study. Youth aged 17 years old were recruited between June 2020 and December 2021, from both clinical [clinical population (CP) group] and non-clinical settings [non-clinical population (NCP) group]. Participants completed self-report questionnaires. The primary outcome to assess TAY psychopathology was the Youth-Self Report (YSR). We evaluated care needs with the Health of The Nation Outcome Scales For Children And Adolescents (HoNOSCA-SR) and quality of life with the World Health Organization Quality of Life - BREF (WHOQoL-BREF). Exposure factors included familial vulnerability, childhood, and present environmental factors, such as first-degree family history of psychopathology, the Childhood Trauma Questionnaire (CTQ) and the Family Assessment Device (FAD). YSR scores were compared, between groups, according to exposure factors with ANOVA and linear regression. We performed best subsets selection of multivariable analyses based on the Akaike Information Criterion. This study was registered with ClinicalTrials.gov (Identifier: NCT04333797). Results: A total of 220 TAY (CP = 106, NCP = 114) were included in the study. Participants were aged 17 years old. The majority were female (69.1%), single (96.8%), and born in Belgium (82.3%). Clinical data were all significantly different between CP and NCP groups. YSR scores were found statistically different according to group (p < 0.001), first-degree family history of psychopathology (p < 0.001), CTQ (p < 0.001), and FAD (p < 0.001). Predictive dimensional model suggested that TAY psychopathology can be predicted by group, CTQ and FAD. Significant positive correlation was found between YSR and HoNOSCA (rho = 0.81) and negative correlation between YSR and physical and psychological health (rho = -0.69 and -0.71, respectively). Conclusion: This study findings allowed to present a predictive dimensional model on TAY psychopathology, including belonging to a clinical population at transitional age, childhood trauma, and family dysfunction. Further research is needed to replicate Transition_psy study results in other samples. The proposed model could be used in clinical practice to improve assessment of TAY psychopathology.

Child attachment and ADHD: a systematic review.

Attention Deficit/Hyperactivity Disorder (ADHD) is a frequent neurodevelopmental disorder in children. ADHD has a multifactorial origin, combining genetic and environmental factors. Several studies suggested an influence of early parent-child relationships on the symptomatic expression of ADHD. In this review, we examine the studies that have investigated the links between attachment and ADHD in children. We searched for studies published between January 2000 and November 2019 on PsychInfo, PubMed, and Scopus. Selected studies included a theoretically based measure of attachment and an explicit measure of ADHD symptoms or an ADHD diagnosis. Studies that included children from adoption, institutionalization, or mistreatment were not included. We found only 26 studies meeting the inclusion criteria. Almost all these studies indicated a link between the attachment type and the presence of attentional difficulties and hyperactivity. However, associations were better explained, in several studies, by confounding factors such as comorbidities, cognitive difficulties, or contextual factors. The method used to assess attachment and parental mental health also had an impact. An increasing number of studies show a link between the type of attachment and the presence of attentional difficulties and hyperactivity in children. However, the nature of this link remains unclear. Implications for future research are discussed.

Impact of Human Immunodeficiency Virus and Recreational Drugs on Cognitive Functions.

BACKGROUND: This prospective study characterizes the structural and metabolic cerebral correlates of cognitive impairments found in a preclinical setting that considers the lifestyle of young European men exposed to human immunodeficiency virus (HIV), including recreational drugs. METHODS: Simultaneous structural brain magnetic resonance imaging (MRI) and positron emission tomography using [18F]-fluorodeoxyglucose (FDG-PET) were acquired on a hybrid PET-MRI system in 23 asymptomatic young men having sex with men with HIV (HIVMSM; mean age, 33.6 years [range, 23-60 years]; normal CD4+ cell count, undetectable viral load). Neuroimaging data were compared with that of 26 young seronegative men under HIV preexposure prophylaxis (PrEPMSM), highly well matched for age and lifestyle, and to 23 matched young seronegative men (controls). A comprehensive neuropsychological assessment was also administered to the HIVMSM and PrEPMSM participants. RESULTS: HIVMSM had lower performances in executive, attentional, and working memory functions compared to PrEPMSM. No structural or metabolic differences were found between those 2 groups. Compared to controls, HIVMSM and PrEPMSM exhibited a common hypometabolism in the prefrontal cortex that correlated with the level of recreational drug use. No structural brain abnormality was found. CONCLUSIONS: Abnormalities of brain metabolism in our population of young HIVMSM mainly relate to recreational drug use rather than HIV per se. A complex interplay between recreational drugs and HIV might nevertheless be involved in the cognitive impairments observed in this population.

Study Protocol: Transition_psy a Multicenter Prospective Longitudinal Cohort Study Assessing Risk and Protective Factors to Develop Psychopathology in Transitional Age Youth in Belgium.

Introduction: Emerging adults are a particularly at-risk population in mental health. The primary aim of the Transition_psy study is to evaluate changes in mental health care need and quality of life during transition from Child and Adolescent Mental Health Services (CAMHS) to Adult Mental Health Services (AMHS). The relationship between these changes and genetic or environmental vulnerabilities and clinical dimensions representing risk and protective factors to the development of psychopathology will be analyzed. We also aim to explore how each factor plays, specifically, a role in developing internalizing and externalizing symptoms, in order to predict the most common paths of psychopathology in transitional age youth (TAY). Methods and Analysis: Transition_psy is a multicenter prospective longitudinal cohort study. The transversal and trans-diagnostic approach consists of a dimensional evaluation: 300 youth at the age of 17 will be included in a cohort of in-patients, out-patients and control group. Participants will be assessed at baseline (T0) and 24 months later (T1). The primary objective to determine changes in self-rated Health Of The Nation Outcome Scales For Children And Adolescents (HONOSCA-SR) and WHO Quality of Life-BREF (WHOQOL-BREF) scores between T0 and T1. Pearson correlation and mediation analysis will be performed. A secondary objective analysis using mediation and moderation models with several dimensional aspects, including self-reported and cognitive measures, will be conducted to disentangle the potential relationships between the two scores. Discussion: Transition from CAMHS to AMHS occurs at a crucial age in terms of the continuum between adolescent and adulthood psychopathology. This collaborative and cohesive protocol between CAMHS and AMHS represents the first national cohort study about Transition Psychiatry in French-speaking Belgium. Ethics and Dissemination: The study protocol was approved by the Institutional Review Boards (IRB) of the three participating sites. Results will be published in peer-reviewed journals and disseminated at national and international conferences. This trial was registered in ClinicalTrials.gov (Identifier: NCT04333797) on 3 April 2020.

Immediate Psychological Responses, Stress Factors, and Coping Behaviors in Military Health-Care Professionals During the COVID-19 Pandemic in Tunisia.

Objective: The COVID-19 epidemic began in Tunisia in March 2020; health-care workers (HCWs) were suddenly confronted with a particularly stressful situation. The aim of this study was to assess the psychological responses of HCWs during the epidemic, determine the stressors and identify ways to cope. Methods: This cross-sectional study used an online questionnaire that included 62 questions. ANOVAs and t-tests were used to compare the responses between professional groups, age groups, and genders. Results: Questionnaires were completed by 368 HCWs. HCWs believed they had a social and professional obligation to continue working long hours (95.3%). They were anxious regarding their safety (93.7%) and the safety of their families (97.8%). Youthful age (p = 0.044) and female gender (ps <0.046) were identified as stressors. The availability of personal protective equipment (PPE; 99.7%) and good communication between colleagues (98.1%) and managers (91.6%) were important protective factors. Family and friend support (95.9%), following strict protective measures (99.4%), knowing more about COVID-19 (94.8%), adopting a positive attitude (89.6%), and engaging in leisure activities (96.1%) helped in dealing with this epidemic. Conclusion: This study highlights the importance of providing HCWs with infection control guidelines and adequate PPE. Communication and support within the team and maintaining family support help in coping with this stressful situation.

Context-dependent irritability in Attention Deficit/Hyperactivity Disorder: correlates and stability of family-restricted versus cross-situational temper outbursts.

BACKGROUND: Impairing irritability is highly prevalent in children with attention deficit/hyperactivity disorder (ADHD), although manifestations of irritability are not necessarily present in all settings (home, school, with peers). At the moment, little is known about the relative prevalence, stability, and etiologies of contextual versus cross-situational manifestations of irritability in ADHD. In this study, levels of dysfunctional parenting practices and sleep problems were compared in irritable versus nonirritable children with ADHD, in cases of family-restricted versus cross-situational irritability, and examined as predictors of irritability levels over a one-year interval. Stability of irritability manifestations over time was investigated, and prevalence of cross-situational disruptive mood dysregulation disorder (DMDD) versus 'family-restricted' DMDD was compared. METHOD: One hundred and seventy children with ADHD (age 6-11) were examined. Parents completed a semi-structured interview and questionnaire to assess irritability, and parent-report questionnaires were used to evaluate parenting practices and sleep problems. Questionnaires were completed for a second time after a one-year interval. RESULTS: Parenting practices were more dysfunctional in the irritable group compared to the nonirritable group, while sleep problems did not differ between these two groups. Levels of parenting practices and sleep problems did not predict later irritability after correction for multiple comparison nor did they differ between the family-restricted and cross-situational irritable groups. Finally, family-restricted irritability was as prevalent and as stable over time as cross-situational irritability and family-restricted DMDD as prevalent as cross-situational DMDD. CONCLUSIONS: Factors associated with contextual versus cross-situational manifestations of irritability in ADHD remain elusive. More subtle measures of parenting practices should be considered, including psychological control or accommodation, and other constructs such as social inhibition. Despite not being captured by current nosography, severe forms of family-restricted irritability may be as prevalent as severe forms of cross-situational irritability.

Disorder-specific brain volumetric abnormalities in Attention-Deficit/Hyperactivity Disorder relative to Autism Spectrum Disorder.

The overlap/distinctiveness between Attention-Deficit/Hyperactivity Disorder (ADHD) and Autism Spectrum Disorder (ASD) has been increasingly investigated in recent years, particularly since the DSM-5 allows the dual diagnosis of ASD and ADHD, but the underlying brain mechanisms remain unclear. Although both disorders are associated with brain volumetric abnormalities, it is necessary to unfold the shared and specific volume abnormalities that could contribute to explain the similarities and differences in the clinical and neurocognitive profiles between ADHD and ASD. In this voxel-based morphometry (VBM) study, regional grey matter volumes (GMV) were compared between 22 children with ADHD, 18 children with ASD and 17 typically developing (TD) children aged 8 to 12 years old, controlling for age and total intracranial volume. When compared to TD children or children with ASD, children with ADHD had a larger left precuneus, and a smaller right thalamus, suggesting that these brain abnormalities are specific to ADHD relative to ASD. Overall, this study contributes to the delineation of disorder-specific structural abnormalities in ADHD and ASD.

Anesthetic Management Using Multiple Closed-loop Systems and Delayed Neurocognitive Recovery: A Randomized Controlled Trial.

BACKGROUND: Cognitive changes after anesthesia and surgery represent a significant public health concern. We tested the hypothesis that, in patients 60 yr or older scheduled for noncardiac surgery, automated management of anesthetic depth, cardiac blood flow, and protective lung ventilation using three independent controllers would outperform manual control of these variables. Additionally, as a result of the improved management, patients in the automated group would experience less postoperative neurocognitive impairment compared to patients having standard, manually adjusted anesthesia. METHODS: In this single-center, patient-and-evaluator-blinded, two-arm, parallel, randomized controlled, superiority study, 90 patients having noncardiac surgery under general anesthesia were randomly assigned to one of two groups. In the control group, anesthesia management was performed manually while in the closed-loop group, the titration of anesthesia, analgesia, fluids, and ventilation was performed by three independent controllers. The primary outcome was a change in a cognition score (the 30-item Montreal Cognitive Assessment) from preoperative values to those measures 1 week postsurgery. Secondary outcomes included a battery of neurocognitive tests completed at both 1 week and 3 months postsurgery as well as 30-day postsurgical outcomes. RESULTS: Forty-three controls and 44 closed-loop patients were assessed for the primary outcome. There was a difference in the cognition score compared to baseline in the control group versus the closed-loop group 1 week postsurgery (-1 [-2 to 0] vs. 0 [-1 to 1]; difference 1 [95% CI, 0 to 3], P = 0.033). Patients in the closed-loop group spent less time during surgery with a Bispectral Index less than 40, had less end-tidal hypocapnia, and had a lower fluid balance compared to the control group. CONCLUSIONS: Automated anesthetic management using the combination of three controllers outperforms manual control and may have an impact on delayed neurocognitive recovery. However, given the study design, it is not possible to determine the relative contribution of each controller on the cognition score.

Relationship Between White Matter Abnormalities and Neuropsychological Measures in Children With ADHD.

Objective: Using Diffusion Tensor Imaging (DTI), to investigate microstructural white matter differences between ADHD and typically developing children (TDC), and their association with inhibition and working memory performance usually impaired in ADHD. Method: Fractional anisotropy (FA) and mean diffusivity (MD) were estimated in 36 noncomorbid children with a Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSM-IV-TR) diagnosis of combined type ADHD and 20 TDC. Correlations between FA/MD and Stop Signal Task and N-Back performance parameters were computed. Results: Working memory performance was significantly associated with MD in the superior longitudinal fasciculus (SLF) and the cingulum in the ADHD group. No between-group differences in FA/MD reached significance, after controlling for between-group head motion differences. Conclusion: The association between white matter integrity in the cingulum and the SLF and working memory performance confirms previous studies. Our results also show that when critical conditions are controlled (age, comorbidity, head motion), no ADHD-related structural abnormality (FA/MD) are observed, in line with prior suggestions.

Dopamine transporter genotype modulates brain activity during a working memory task in children with ADHD.

Dopamine active transporter gene (DAT1) is a candidate gene associated with attention-deficit/hyperactivity disorder (ADHD). The DAT1 variable number tandem repeat (VNTR)-3' polymorphism is functional and 9R carriers have been shown to produce more DAT than 10R homozygotes. We used functional magnetic resonance imaging (fMRI) to investigate the effects of this polymorphism on the neural substrates of working memory (WM) in a small but selected population of children with ADHD, naïve of any psychotropic treatment and without comorbidity. MRI and genotype data were obtained for 36 children (mean age: 10,36 +/- 1,49 years) with combined-type ADHD (9R n = 15) and 25 typically developing children (TDC) (mean age: 9,55 +/- 1,25 years) (9R n = 12). WM performance was similar between conditions. We found a cross-over interaction effect between gene (9R vs. 10R) and diagnosis (TDC vs. ADHD) in the orbito-frontal gyrus, cerebellum and inferior temporal lobe. In these areas, WM-related activity was higher for 9R carriers in ADHD subjects and lower in TDC. In ADHD children only, 10R homozygotes exhibited higher WM-related activity than 9R carriers in a network encompassing the parietal and the temporal lobes, the ventral visual cortex, the orbito-frontal gyrus and the head of the caudate nucleus. There was no significant results in TDC group. Our preliminary findings suggest that DAT1 VNTR polymorphism can modulate WM-related brain activity ADHD children.

Decreased prefrontal connectivity parallels cognitive fatigue-related performance decline after sleep deprivation. An optical imaging study.

Fatigue induced by sustained cognitive demands often entails decreased behavioural performance and the unavailability of brain resources, either due to reduced levels or impaired access. In the present study, we investigated the neural dynamics underlying preserved behavioural performance after inducing cognitive fatigue (CF) in a sleep deprivation (SD) condition in which resources are naturally compromised. Using functional near infrared spectroscopy (fNIRS), we recorded cortical brain activity during task-related CF induction in the evening, in the middle of the night and early in the morning. Although cortical oxygenation similarly increased over the 3 sessions, decreased intra-hemispheric connectivity between left anterior frontal and frontal areas paralleled a sudden drop in task performance in the early morning. Our data indicate that decreased sustained attention after the induction of cognitive fatigue in a situation of high sleep pressure results from impaired connectivity between left prefrontal cortical areas rather than from a mere modulation in brain resources.

Hemispatial neglect and serial order in verbal working memory.

Working memory refers to our ability to actively maintain and process a limited amount of information during a brief period of time. Often, not only the information itself but also its serial order is crucial for good task performance. It was recently proposed that serial order is grounded in spatial cognition. Here, we compared performance of a group of right hemisphere-damaged patients with hemispatial neglect to healthy controls in verbal working memory tasks. Participants memorized sequences of consonants at span level and had to judge whether a target consonant belonged to the memorized sequence (item task) or whether a pair of consonants were presented in the same order as in the memorized sequence (order task). In line with this idea that serial order is grounded in spatial cognition, we found that neglect patients made significantly more errors in the order task than in the item task compared to healthy controls. Furthermore, this deficit seemed functionally related to neglect severity and was more frequently observed following right posterior brain damage. Interestingly, this specific impairment for serial order in verbal working memory was not lateralized. We advance the hypotheses of a potential contribution to the deficit of serial order in neglect patients of either or both (1) reduced spatial working memory capacity that enables to keep track of the spatial codes that provide memorized items with a positional context, (2) a spatial compression of these codes in the intact representational space.

Transcranial Direct Current Stimulation Does Not Counteract Cognitive Fatigue, but Induces Sleepiness and an Inter-Hemispheric Shift in Brain Oxygenation.

Sustained cognitive demands may result in cognitive fatigue (CF), eventually leading to decreased behavioral performance and compromised brain resources. In the present study, we tested the hypothesis that transcranial direct current stimulation (tDCS) would counteract the behavioral and neurophysiological effects of CF. Twenty young healthy participants were tested in a within-subject counterbalanced order across two different days. Anodal tDCS (real vs. sham) was applied over the left prefrontal cortex. In the real tDCS condition, a current of 1.5 mA was delivered for 25 min. Cortical oxygenation changes were measured using functional Near Infrared Spectroscopy (fNIRS) on the frontal cortices. CF was triggered using the TloadDback task, a sustained working memory paradigm that allows tailoring task demands according to each individual's maximal cognitive capacity. Sustained cognitive load-related effects were assessed using pre- versus post-task subjective fatigue and sleepiness scales, evolution of performance accuracy within the task, indirect markers of dopaminergic activity (eye blinks), and cortical oxygenation changes (fNIRS) both during the task and pre- and post-task resting state periods. Results consistently disclosed significant CF-related effects on performance. Transcranial DCS was not effective to counteract the behavioral effects of CF. In the control (sham tDCS) condition, cerebral oxygen exchange (COE) levels significantly increased in the right hemisphere during the resting state immediately after the induction of CF, suggesting a depletion of brain resources. In contrast, tDCS combined with CF induction significantly shifted interhemispheric oxygenation balance during the post-training resting state. Additionally, increased self-reported sleepiness was associated with brain activity in the stimulated hemisphere after recovery from CF during the tDCS condition only, which might reflect a negative middle-term effect of tDCS application.

Cognitive Fatigue, Sleep and Cortical Activity in Multiple Sclerosis Disease. A Behavioral, Polysomnographic and Functional Near-Infrared Spectroscopy Investigation.

Patients with multiple sclerosis (MS) disease frequently experience fatigue as their most debilitating symptom. Fatigue in MS partially refers to a cognitive component, cognitive fatigue (CF), characterized by a faster and stronger than usual development of the subjective feeling of exhaustion that follows sustained cognitive demands. The feeling of CF might result from supplementary task-related brain activity following MS-related demyelination and neurodegeneration. Besides, CF in MS disease might also stem from disrupted sleep. The present study investigated the association between the triggering of CF, task-related brain activity and sleep features. In a counterbalance mixed design, 10 patients with MS and 11 healthy controls were exposed twice for 16 min to a CF-inducing dual working memory updating task (TloadDback) under low or high cognitive demands conditions, counterbalanced. Considering known inter-individual differences and potential cognitive deficits in MS, the maximal cognitive load of the task was individually adapted to each participant's own upper limits. During the experimental sessions, cortical brain activity was measured using near-infrared spectroscopy (NIRS) during the CF-induction task, and in a resting state immediately before and after. Ambulatory polysomnography recordings were obtained on the nights preceding experimental sessions. When cognitive load was individually adapted to their processing capabilities, patients with MS exhibited similar than healthy controls levels of subjectively perceived CF, evolution of performance during the task, and brain activity patterns. Linear mixed models indicate a negative association between oxygenation level changes in the dorsolateral prefrontal cortex (DLPFC) and the triggering of subjective CF in patients with MS only. Longer total sleep time was also associated with higher CF in MS patients. These results suggest that controlling for cognitive load between individuals with and without MS results in a similar task-related development of subjective CF. Besides comparable performance and cortical brain activity between groups, mixed model analyses suggest a possible association between CF, DLPFC activity and sleep duration in MS disease.

The impact of sleep deprivation on visual perspective taking.

Total sleep deprivation (TSD) is known to alter cognitive processes. Surprisingly little attention has been paid to its impact on social cognition. Here, we investigated whether TSD alters levels-1 and -2 visual perspective-taking abilities, i.e. the capacity to infer (a) what can be seen and (b) how it is seen from another person's visual perspective, respectively. Participants completed levels-1 and -2 visual perspective-taking tasks after a night of sleep and after a night of TSD. In these tasks, participants had to take their own (self trials) or someone else's (other trials) visual perspective in trials where both perspectives were either the same (consistent trials) or different (inconsistent trials). An instruction preceding each trial indicated the perspective to take (i.e. the relevant perspective). Results show that TSD globally deteriorates social performance. In the level-1 task, TSD affects the selection of relevant over irrelevant perspectives. In the level-2 task, the effect of TSD cannot be unequivocally explained. This implies that visual perspective taking should be viewed as partially state-dependent, rather than a wholly static trait-like characteristic.

Sleep Deprivation Triggers Cognitive Control Impairments in Task-Goal Switching.

STUDY OBJECTIVES: This study investigates the impact of sleep deprivation (SD) on task-goal switching, a key component of cognitive flexibility. METHODS: Task-goal switching performance was tested after one night of regular sleep (n = 17 participants) or of total SD (n = 18). To understand the relationships between task-switching performance and other cognitive processes following SD, participants were tested for other key attentional (alertness and vigilance) and executive (inhibition and working memory) functions. Spontaneous eye blink rate (EBR) was also measured as an indirect marker of striatal dopaminergic function. RESULTS: SD negatively affects task-goal switching as well as attentional and inhibition measures, but not working memory. Changes in task-goal switching performance were not significantly correlated with changes in objective and subjective markers of fatigue and sleepiness, response inhibition, or spontaneous EBR. CONCLUSIONS: Altogether, our results show differentiated effects of SD on key executive functions such as working memory, inhibition, and task-goal switching.

Hyperactivity in motor response inhibition networks in unmedicated children with attention deficit-hyperactivity disorder.

OBJECTIVES: Hypo/reduced activity in motor response inhibition (RI) cerebral networks was recently proposed as a promising specific neurobiological marker of attention deficit-hyperactivity disorder (ADHD). Before adopting such a pattern as a key diagnosis tool, we aim to replicate in an independent study the mechanisms underlying reduced RI-related activity in ADHD, after controlling for potentially confounding effects. METHODS: In this fMRI study, we investigated the neural networks mediating successful and failed motor RI in children with ADHD and typically developing children (TDC) using the stop-signal task (SST) paradigm. RESULTS: In contrast to hypofrontality predictions, children with ADHD exhibit increased neural activity during successful response inhibition in an RI-related brain network encompassing the indirect and/or hyperdirect pathways between the basal ganglia and cortex. Voxel-based morphometry analyses have further evidenced reduced grey matter volume in the left caudate in children with ADHD, which paralleled higher functional responses. Finally, connectivity analyses disclosed tighter coupling between a set of cortical regions and the right caudate as well as the right IFG, networks involved in successful RI. CONCLUSIONS: Hypo/reduced activity in RI cerebral networks in children with ADHD cannot at this time be considered as a systematic biomarker for ADHD.

EEG Dynamics of a Go/Nogo Task in Children with ADHD.

BACKGROUND: Studies investigating event-related potential (ERP) evoked in a Cue-Go/NoGo paradigm have shown lower frontal N1, N2 and central P3 in children with attention-deficit/hyperactivity disorder (ADHD) compared to typically developing children (TDC). However, the electroencephalographic (EEG) dynamics underlying these ERPs remain largely unexplored in ADHD. METHODS: We investigate the event-related spectral perturbation and inter-trial coherence linked to the ERP triggered by visual Cue-Go/NoGo stimuli, in 14 children (7 ADHD and 7 TDC) aged 8 to 12 years. RESULTS: Compared to TDC, the EEG dynamics of children with ADHD showed a lower theta-alpha ITC concomitant to lower occipito-parietal P1-N2 and frontal N1-P2 potentials in response to Cue, Go and Nogo stimuli; an upper alpha power preceding lower central Go-P3; a lower theta-alpha power and ITC were coupled to a lower frontal Nogo-N3; a lower low-gamma power overall scalp at 300 ms after Go and Nogo stimuli. CONCLUSION: These findings suggest impaired ability in children with ADHD to conserve the brain oscillations phase associated with stimulus processing. This physiological trait might serve as a target for therapeutic intervention or be used as monitoring of their effects.