The present study investigated developmental trends in response inhibition and preparation by studying behavior and event-related brain activity in a cued go/nogo task, administered to nine-year-old children and young adults. Hits, false alarms, inattention, and impulsivity scores and ERP measures of inhibition (fronto-central nogo-N2 and P3), target selection (parietal go-nogo P3 difference), and response preparation (contingent negative variation; CNV) were collected. Higher false alarm and impulsivity scores and the absence of the fronto-central nogo P3 all suggest a developmental lag in response inhibition in children. A developmental lag in sustained attention processes was suggested by worse target detection and larger parietal target/nontarget P3 effects in children. Cue orientation and response preparation processes were respectively measured by early and late CNV activity. Children displayed smaller early CNV amplitudes at fronto-central locations, but mature late CNV. The smaller early CNV activity might indicate inefficient cue-orientation processes caused by incomplete frontal lobe development.

Previous reviews and meta-analyses that addressed abnormal Stroop interference in attention-deficit/ hyperactivity disorder (ADHD) yielded mixed results. The authors of the present study argue that the inconsistencies may reflect the problematic nature of 2 frequently used methods to quantify Stroop interference-the difference score and Golden's method (C. J. Golden, 1978). Golden's method correction for base-word reading is inadequate, and the difference score is sensitive to the nature of the outcome variable. The latter can be remedied with a ratio score. Contrasting previous meta-analyses, this meta-analysis covers all age groups and all Stroop test variants, and it excludes studies using the Golden quantification method. Mean effect sizes for interference in ADHD as quantified by difference scores relative to control scores were 0.24 across all studies but 1.11 for time-per-item studies; outcome variable was a significant moderator variable, reflecting the sensitivity of the difference score to this variable. Consistency analysis of ratio scores across 19 studies reveals more interference for the ADHD groups relative to the control groups. It is concluded that interference control is consistently compromised in individuals with ADHD.Keywords: meta-analysis, Stroop interference, attention-deficit/hyperactivity disorder, Stroop color and word task Attention-deficit/hyperactivity disorder (ADHD) is defined by inappropriate degrees of inattention, hyperactivity, and impulsivity. Barkley (1997) suggested that behavioral disinhibition is the primary deficit in ADHD (predominantly hyperactive-impulsive type and combined type) and distinguished three interrelated forms of behavioral inhibition. The first form is inhibition of an initial prepotent response to an event, that is, a response for which immediate reinforcement is available or with which reinforcement has been previously associated. The second form is stopping an ongoing response or response pattern. This causes a delay in the decision to respond or to continue responding. The third form is interference control, defined as protecting the period of delay and self-directed responses that occur within it from disruption by competing events and responses.Continuous performance tests (CPTs) and stop-signal tasks can be used to assess both inhibition of prepotent responses and stopping of ongoing responses. Several reviews and meta-analyses (Corkum & Siegel, 1993;Lijffijt, Kenemans, Verbaten, & van Engeland, 2005;Losier, McGrath, & Klein, 1996;Oosterlaan, Logan, & Sergeant, 1998;Riccio, Reynolds, & Lowe, 2001) demonstrated that individuals with ADHD perform worse on a CPT and stop-signal task as compared with normal control participants, reflecting poor response inhibition in ADHD patients. The Stroop test (Stroop, 1935) can be used to quantify interference control. Inconsistent findings have been reported regarding deficient interference control in ADHD. Stroop Test and ADHDThree versions of the Stroop test have been used in ADHD research: the standard Stroop ...

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Electroencephalography (EEG)-neurofeedback has been shown to offer therapeutic benefits to patients with attention-deficit/hyperactivity disorder (ADHD) in several, mostly uncontrolled studies. This pilot study is designed to test the feasibility and safety of using a double-blind placebo feedback-controlled design and to explore the initial efficacy of individualized EEG-neurofeedback training in children with ADHD. Fourteen children (8–15 years) with ADHD defined according to the DSM-IV-TR criteria were randomly allocated to 30 sessions of EEG-neurofeedback (n = 8) or placebo feedback (n = 6). Safety measures (adverse events and sleep problems), ADHD symptoms and global improvement were monitored. With respect to feasibility, all children completed the study and attended all study visits and training sessions. No significant adverse effects or sleep problems were reported. Regarding the expectancy, 75% of children and their parent(s) in the active neurofeedback group and 50% of children and their parent(s) in the placebo feedback group thought they received placebo feedback training. Analyses revealed significant improvements of ADHD symptoms over time, but changes were similar for both groups. This pilot study shows that it is feasible to conduct a rigorous placebo-controlled trial to investigate the efficacy of neurofeedback training in children with ADHD. However, a double-blind design may not be feasible since using automatic adjusted reward thresholds may not work as effective as manually adjusted reward thresholds. Additionally, implementation of active learning strategies may be an important factor for the efficacy of EEG-neurofeedback training. Based on the results of this pilot study, changes are made in the design of the ongoing study.Electronic supplementary materialThe online version of this article (doi:10.1007/s00702-010-0524-2) contains supplementary material, which is available to authorized users.

BackgroundSynaptic loss is a major hallmark of Alzheimer’s disease (AD). Disturbed organisation of large-scale functional brain networks in AD might reflect synaptic loss and disrupted neuronal communication. The medical food Souvenaid, containing the specific nutrient combination Fortasyn Connect, is designed to enhance synapse formation and function and has been shown to improve memory performance in patients with mild AD in two randomised controlled trials.ObjectiveTo explore the effect of Souvenaid compared to control product on brain activity-based networks, as a derivative of underlying synaptic function, in patients with mild AD.DesignA 24-week randomised, controlled, double-blind, parallel-group, multi-country study.Participants179 drug-naïve mild AD patients who participated in the Souvenir II study.InterventionPatients were randomised 1∶1 to receive Souvenaid or an iso-caloric control product once daily for 24 weeks.OutcomeIn a secondary analysis of the Souvenir II study, electroencephalography (EEG) brain networks were constructed and graph theory was used to quantify complex brain structure. Local brain network connectivity (normalised clustering coefficient gamma) and global network integration (normalised characteristic path length lambda) were compared between study groups, and related to memory performance.ResultsThe network measures in the beta band were significantly different between groups: they decreased in the control group, but remained relatively unchanged in the active group. No consistent relationship was found between these network measures and memory performance.ConclusionsThe current results suggest that Souvenaid preserves the organisation of brain networks in patients with mild AD within 24 weeks, hypothetically counteracting the progressive network disruption over time in AD. The results strengthen the hypothesis that Souvenaid affects synaptic integrity and function. Secondly, we conclude that advanced EEG analysis, using the mathematical framework of graph theory, is useful and feasible for assessing the effects of interventions.Trial registrationDutch Trial Register NTR1975.