Impaired conflict resolution and alerting in children with ADHD: evidence from the Attention Network Task (ANT)

An important theory of attention suggests that there are three separate networks that execute discrete cognitive functions. The 'alerting' network acquires and maintains an alert state, the 'orienting' network selects information from sensory input and the 'conflict' network resolves conflict that arises between potential responses. This theory holds promise for dissociating discrete patterns of cognitive impairment in disorders where attentional deficits may often be subtle, such as in attention deficit hyperactivity disorder (ADHD).

Absence of the 7-repeat variant of the DRD4 VNTR is associated with drifting sustained attention in children with ADHD but not in controls

Many genetic studies have demonstrated an association between the 7-repeat (7r) allele of a 48-base pair variable number of tandem repeats (VNTR) in exon 3 of the DRD4 gene and the phenotype of attention deficit hyperactivity disorder (ADHD). Previous studies have shown inconsistent associations between the 7r allele and neurocognitive performance in children with ADHD. We investigated the performance of 128 children with and without ADHD on the Fixed and Random versions of the Sustained Attention to Response Task (SART). We employed timeseries analyses of reaction-time data to allow a fine-grained analysis of reaction time variability, a candidate endophenotype for ADHD. Children were grouped into either the 7r-present group (possessing at least one copy of the 7r allele) or the 7r-absent group. The ADHD group made significantly more commission errors and was significantly more variable in RT in terms of fast moment-to-moment variability than the control group, but no effect of genotype was found on these measures. Children with ADHD without the 7r allele made significantly more omission errors, were significantly more variable in the slow frequency domain and showed less sensitivity to the signal (d') than those children with ADHD the 7r and control children with or without the 7r. These results highlight the utility of time-series analyses of reaction time data for delineating the neuropsychological deficits associated with ADHD and the DRD4 VNTR. Absence of the 7-repeat allele in children with ADHD is associated with a neurocognitive profile of drifting sustained attention that gives rise to variable and inconsistent performance. (c) 2008 Wiley-Liss, Inc.

Dissociation in performance of children with ADHD and high-functioning autism on a task of sustained attention

Attention deficit hyperactivity disorder (ADHD) and autism are two neurodevelopmental disorders associated with prominent executive dysfunction, which may be underpinned by disruption within fronto-striatal and fronto-parietal circuits. We probed executive function in these disorders using a sustained attention task with a validated brain-behaviour basis. Twenty-three children with ADHD, 21 children with high-functioning autism (HFA) and 18 control children were tested on the Sustained Attention to Response Task (SART). In a fixed sequence version of the task, children were required to withhold their response to a predictably occurring no-go target (3) in a 1-9 digit sequence; in the random version the sequence was unpredictable. The ADHD group showed clear deficits in response inhibition and sustained attention, through higher errors of commission and omission on both SART versions. The HFA group showed no sustained attention deficits, through a normal number of omission errors on both SART versions. The HFA group showed dissociation in response inhibition performance, as indexed by commission errors. On the Fixed SART, a normal number of errors was made, however when the stimuli were randomised, the HFA group made as many commission errors as the ADHD group. Greater slow-frequency variability in response time and a slowing in mean response time by the ADHD group suggested impaired arousal processes. The ADHD group showed greater fast-frequency variability in response time, indicative of impaired top-down control, relative to the HFA and control groups. These data imply involvement of fronto-parietal attentional networks and sub-cortical arousal systems in the pathology of ADHD and prefromal cortex dysfunction in children with HFA. (c) 2007 Elsevier Ltd. All rights reserved.

Psychological problems in children with hemiplegia: a European multicentre survey

Objective: To describe the prevalence and determinants of psychological problems in European children with hemiplegia. Design: Cross-sectional survey. Setting: Home visits in nine European regions by research associates who administered standard questionnaires to parents. Patients: 279 children with hemiplegia aged 8–12 years were recruited from population-based case registers. Outcome measure: Strengths and Difficulties Questionnaire comprising emotion, conduct, hyperactivity, peer problems and prosocial domains. An “impact score” (IS) measures the social and psychological impact of the child’s difficulties. Results: Children with hemiplegia had higher mean scores on the total difficulties score (TDS) compared with a normative sample (p<0.001). 48% and 57% of children, respectively, had borderline–abnormal TDS and IS. Significant, independent associations were observed between intellectual impairment and an increased risk for hyperactivity (odds ratio; OR 8.4, 95% CI 3.4 to 20.8), peer problems (OR 3.1, 95% CI 1.7 to 5.5), psychological and social impact (OR 3.0, 95% CI 1.6 to 5.6) when children with an intellectual quotient (IQ) <50 were compared with those with an IQ >70. Boys had an increased risk for conduct (OR 2.1, 95% CI 1.2 to 3.7) and hyperactivity disorders (OR 2.5, 95% CI 1.4 to 4.6). Poor self-esteem was associated with an increased risk for peer problems (OR 5.8, 95% CI 2.5 to 13.4) and poor prosocial skills (OR 7.5, 95% CI 2.4 to 23.2) compared with those with high self-esteem. Other determinants of psychological adjustment were impaired communication, severe pain and living with a single parent. Conclusions: Many of the psychological problems identified are amenable to treatment. Special attention should be given to those at highest risk of developing psychological difficulties.

Community participation and inclusion: People with disabilities defining their place

Disability-related public policy currently emphasises reducing the number of people experiencing exclusion from the spaces of the social and economic majority as being the pre-eminent indicator of inclusion. Twenty-eight adult, New Zealand vocational service users collaborated in a participatory action research project to develop shared understandings of community participation. Analysis of their narratives suggests that spatial indices of inclusion are quiet in potentially oppressive ways about the ways mainstream settings can be experienced by people with disabilities and quiet too about the alternative, less well sanctioned communities to which people with disabilities have always belonged. Participants identified five key attributes of place as important qualitative antecedents to a sense of community belonging. The potential of these attributes and other self-authored approaches to inclusion are explored as ways that people with disabilities can support the policy objective of effecting a transformation from disabling to inclusive communities.

Inflammatory mediators in bronchoalveolar lavage samples from children with and without asthma

Background: We investigated whether eosinophils and mast cells, found in the airways of children with wheeze, were activated during relatively asymptomatic periods.
Methods: A nonbronchoscopic bronchoalveolar lavage (BAL) procedure was performed on children presenting for an elective surgical procedure. Eosinophil-derived (eosinophil cationic protein, ECP) and mast cell-derived (histamine/tryptase) mediator concentrations were measured in the BAL fluid. A detailed history and serum immunoglobulin E were used to classify the children into four groups: atopic with and without asthma, viral-associated wheeze and normal controls.
Results: The ECP concentrations in BAL from atopic asthmatic subjects were significantly higher than those measured in BAL from normal controls (P < 0.01), no other groups differed significantly. Histamine concentrations were elevated in both the atopic asthmatic and viral-associated wheeze groups compared with controls (P < 0.02) and additionally higher concentrations were obtained in atopics with asthma compared with atopics without asthma (P < 0.03). Tryptase concentrations did not differ between groups, although the tryptase and histamine concentrations correlated significantly (r = 0.78, P < 0.0001).
Conclusions: Elevated histamine concentrations were found in children with wheeze regardless of the aetiology, whereas ECP was only elevated in those asthmatics with atopy. This suggests that even in relatively quiescent periods, there is some on going activation of airway eosinophils in children with atopic asthma.