Browsing by Author "Albrecht, B."

Background: To evaluate the impact of psychopathological comorbidity with oppositional defiant/conduct disorder (ODD/CD) on brain electrical correlates in children with attention deficit hyperactivity disorder (ADHD) and to study the pathophysiological background of comorbidity of ADHD+ODD/CD. Method: Event-related potentials (ERPs) were recorded during a cued continuous performance test (CPT-A-X) in children (aged 8 to 14 years) with ICD-10 diagnoses of either hyperkinetic disorder (HD; n = 15), hyperkinetic conduct disorder (HCD; n = 16), or ODD/CD (n = 15) and normal children (n 18). HD/HCD diagnoses in all children were fully concordant with the DSM-IV diagnosis of ADHD-combined type. ERP-microstates, i.e., time segments with stable brain electrical map topography were identified by adaptive segmentation. Their characteristic parameters and behavioral measures were further analyzed. Results: Children with HD but not comorbid children showed slower and more variable reaction times compared to control children. Children with HD and ODD/CD-only but not comorbid children displayed reduced P3a amplitudes to cues and certain distractors (distractor-X) linked to attentional orienting. Correspondingly, global field power of the cue-CNV microstate related to anticipation and preparation was reduced in HD but not in HCD. Topographical alterations of the HD occurred already in the cue-P2/N2 microstate. In sum, the comorbid group was less deviant than both the HD-group and the ODD/CD-group. Conclusions: The findings suggest that HD children (ADHD-combined type without ODD/CD) suffer from a more general deficit (e.g., suboptimal energetical state regulation) including deficits of attentional orienting and response preparation than just a response inhibitory deficit, backing the hypothesis of an involvement of a dysregulation of the central noradrenergic networks. The results contradict the hypothesis that ADHD+ODD/CD represents an additive co-occurrence of ADHD and ODD/CD and strongly suggest that it represents a separate pathological entity as considered in the ICD-10 classification system, which differs from both HD and ODD/CD-only.

Preliminary findings suggest that color perception, particularly of blue-yellow stimuli, is impaired in attention-deficit/hyperactivity disorder (ADHD) as well as in chronic tic disorders (CTD). However, these findings have been not replicated and it is unclear what these deficits mean for the comorbidity of ADHD + CTD. Four groups (ADHD, CTD, ADHD + CTD, controls) of children with similar age, IQ and gender distribution were investigated with the Farnsworth-Munsell 100 Hue Test (FMT) and the Stroop-Color-Word Task using a factorial design. Color perception deficits, as indexed by the FMT, were found for both main factors (ADHD and CTD), but there were no interaction effects. A preponderance of deficits on the blue-yellow compared to the red-green axis was detected for ADHD. In the Stroop task only the 'pure' ADHD group showed impairments in interference control and other parameters of Stroop performance. No significant correlations between any FMT parameter and color naming in the Stroop task were found. Basic color perception deficits in both ADHD and CTD could be found. Beyond that, it could be shown that these deficits are additive in the case of comorbidity (ADHD + CTD). Performance deficits on the Stroop task were present only in the 'pure' ADHD group. Hence, the latter may be compensated in the comorbid group by good prefrontal capabilities of CTD. The influence of color perception deficits on Stroop task performance might be negligible.

Attention-deficit/hyperactivity disorder (ADHD) is associated with unexplained impairments on speeded naming of coloured stimuli. These deficits may reflect hypofunctioning retinal dopaminergic mechanisms impairing particularly blue-yellow colour discrimination. Colour perception and rapid colour naming ability were investigated in 14 children with ADHD and 13 healthy peers matched for age, gender, and IQ, using the Farnsworth-Munsell 100 Hue Test (FMT) and the Stroop-Colour-Word test. Children with ADHD committed more errors on the FMT, particularly on discrimination of colours along the blue-yellow axis, and were slower on Stroop subtests involving colour naming. However, the latter deficit was accounted for similarly by blue-yellow and red-green discrimination abilities. Blue-yellow colour perception problems in ADHD contribute to but do not fully explain the observed slowed colour naming.

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.

Background. Patients with attention deficit-hyperactivity disorder (ADHD) exhibit difficulties in multiple attentional functions. Although high heritability rates suggest a strong genetic impact, aetiological pathways from genes and environmental factors to the ADHD phenotype are not well understood. Tracking the time course of deviant task processing using event-related electrophysiological brain activity should characterize the impact of familiality on the sequence of cognitive functions from preparation to response control in ADHD. Method. Preparation and response control were assessed using behavioural and electrophysiological parameters of two versions of a cued continuous performance test with varying attentional load in boys with ADHD combined type (n = 97), their non-affected siblings (n = 27) and control children without a family history of ADHD (n = 43). Results. Children with ADHD and non-affected siblings showed more variable performance and made more omission errors than controls. The preparatory Cue-P3 and contingent negative variation (CNV) following cues were reduced in both ADHD children and their non-affected siblings compared with controls. The NoGo-P3 was diminished in ADHD compared with controls whilst non-affected siblings were located intermediate but did not differ from both other groups. No clear familiality effects were found for the Go-P3. Better task performance was further associated with higher CNV and P3 amplitudes. Conclusions. Impairments in performance and electrophysiological parameters reflecting preparatory processes and to some extend also for inhibitory response control, especially under high attentional load, appeared to be familially driven in ADHD and may thus constitute functionally relevant endophenotypes for the disorder.

To define the range of phenotypic expression in Treacher Collins syndrome (TCS; Franceschetti-Klein syndrome), we performed mutation analysis in the TCOF1 gene in 46 patients with tentative diagnosis of TCS and evaluated the clinical data, including a scoring system. A total of 27 coding exons of TCOF1 and adjacent splice junctions were analysed by direct sequencing. In 36 patients with a clinically unequivocal diagnosis of TCS, we detected 28 pathogenic mutations, including 25 novel alterations. No mutation was identified in the remaining eight patients with unequivocal diagnosis of TCS and 10 further patients, in whom the referring diagnosis of TCS was clinically doubtful. There is no overt genotype-phenotype correlation except that conductive deafness is significantly less frequent in patients with mutations in the 30 part of the open reading frame. Inter- and intrafamilial variation is wide. Some mutation carriers, parents of typically affected patients, are so mildly affected that the diagnosis might be overlooked clinically. This suggests that modifying factors are important for phenotypic expression. Based on these findings, minimal diagnostic criteria were defined: downward slanting palpebral fissures and hypoplasia of the zygomatic arch. The difficulties in genetic counselling, especially diagnosis of family members with a mild phenotype, are described.

Deficits in interference control are ascribed to patients suffering from ADHD by a number of cognitive theories. However, previous research using the Stroop Colour Word Interference Task has demonstrated mixed results that may be explained by methodological issues (e.g., possible impact of colour perception abilities on interference liability, different approaches to calculate interference scores, conflation of speed and accuracy factors). Hence, this study included two computerized versions of the Stroop (Colour-Stroop, Counting Stroop) which allowed to calculate separate measures of speed and accuracy, provided a more rigorous approach to calculate interference, and permitted to investigate the effects of stimulus properties on interference. Participants were 14 children with a DSM-IV diagnosis of ADHD combined type and 15 matched controls. Children completed a traditional Stroop as well as both a computerized Colour- and Counting-Stroop. Results indicated that the ADHD group showed higher interference scores than controls in the Colour-Stroop, but not in the Counting-Stroop. Thus, interference control may be not generally impaired in ADHD, and examinations with the Colour Stroop should be interpreted with care.

Out-of-hospital (OOH) pediatric emergencies have a relatively low prevalence. In Germany the vast majority of cases are attended by non-specialized emergency physicians (EPs) for whom these are not routine procedures. This may lead to insecurity and fear. However, it is unknown how EPs perceive and assess pediatric emergencies and how they could be better prepared for them. All active EPs (n=50) of the Department of Anaesthesiology, Emergency and Intensive Care Medicine at the University Medical Centre of Gottingen were presented with a structured questionnaire in order to evaluate their perception and assessment of OOH pediatric emergencies. The 43 participating EPs made highly detailed statements on the expected characteristics of OOH pediatric emergencies. Their confidence level grew with the children's age (p < 0.03) and with their own experience (p < 0.01). The EPs felt particular deficits in the fields of cardiopulmonary resuscitation (n=18) and trauma management (n=8). The preferred educational strategies included simulator-based training (n=24) as well as more exposure to pediatric intensive care and pediatric anesthesia (n=12). Despite their own limited experience EPs can realistically assess the incidence and severity of pediatric emergencies. They felt the greatest deficits were in the care of infrequent but life-threatening emergencies. Three educational groups can be differentiated: knowledge and skills to be gained with children in hospital, clinical experience from adult care also applicable in children and rare diagnoses and interventions to be trained with manikins or simulators.

Objective: To investigate motor response control during a cued continuous performance test (CPT-A-X) by performance and ERP parameters in children with hyperkinetic disorder (HD), hyperkinetic conduct disorder (HCD) or oppositional deviant/conduct disorder (ODD/CD), to examine the evidence for an inhibition-specific deficit as indicated by these parameters, and to analyze whether possible deviations are specific for HD/HCD. Method: Behavioral parameters and event-related potentials (ERPs) were recorded during a CPT-A-X-task in children (aged 8 to 14 years) with either HD (n=15), HCD (n=16), or ODD/CD (n=15) and normal children (n=18) and analysed. ICD-10 diagnoses of HD/HCD diagnoses in all children were fully concordant with the DSM-IV diagnosis of ADHD-combined type. Results: Children with HCD committed more dyscontrol errors and differed most from normal children on ERP measures of motor response control, while children with HD-only were more impaired during processing of the warning stimuli for motor preparation. ERP measures specific for response inhibition were not different between the groups. Conclusions: The results show that ADHD cannot be fully explained by an inhibition-specific deficit and implicate impaired response execution processes as well. This indicates that comorbid children suffer from a reduced ability to control their prepared motor responses. Further, they seem to have difficulties in timely switching attention from monitoring the sensory input stream to the monitoring of own responses and actions.

Aim: To investigate (1) whether and how local stimulus context variation may modify behavioural and preparatory motor processes in children, and (2) if these effects differ between healthy children and children with attention-deficit/hyperactivity disorder (ADHD) aged 9-12 years. Methods: Behavioural parameters and contingent negative variation (CNV) at conical motor electrodes were recorded during a cued continuous performance task (AX-CPT) in three stimulus context conditions (Go, NoGo, neutral). Stimulus context was varied on the basis of stimulus types preceding the cue letter A. Results: In all children, responses were slowed in both the NoGo- and Go-conditions relative to the neutral condition. Stimulus context affected preparatory motor processes in both groups but differentially. ADHD children showed smaller CNV potentials and a functionally irrelevant over-activation of the ipsilateral motor area. Conclusions: Local stimulus context may modify behavioural and preparatory motor processes in children. In ADHD, local context variations may disrupt behaviour due to inefficient regulation of supervisory higher control systems. (C) 2007 Elsevier B.V. All rights reserved.

Background. Twin and sibling studies have identified specific cognitive phenotypes that may mediate the association between genes and the clinical symptoms of attention deficit hyperactivity disorder (ADHD). ADHD is also associated with lower IQ scores. We aimed to investigate whether the familial association between measures of cognitive performance and the clinical diagnosis of ADHD is mediated through shared familial influences with IQ. Method. Multivariate familial models were run on data from 1265 individuals aged 6-18 years, comprising 920 participants from ADHD sibling pairs and 345 control participants. Cognitive assessments included a four-choice reaction time (RT) task, a go/no-go task, a choice-delay task and an IQ assessment. The analyses focused on the cognitive variables of mean RT (MRT), RT variability (RTV), commission errors (CE), omission errors (OE) and choice impulsivity (CI). Results. Significant familial association (rF) was confirmed between cognitive performance and both ADHD (rF = 0.41-0.71) and IQ (rF = -0.25 to -0.49). The association between ADHD and cognitive performance was largely independent (80-87%) of any contribution from etiological factors shared with IQ. The exception was for CI, where 49% of the overlap could be accounted for by the familial variance underlying IQ. Conclusions. The aetiological factors underlying lower IQ in ADHD seem to be distinct from those between ADHD and RT/error measures. This suggests that lower IQ does not account for the key cognitive impairments observed in ADHD. The results have implications for molecular genetic studies designed to identify genes involved in ADHD.

Electrophysiologically, Tourette syndrome (TS) is characterized by shortened cortical silent period (CSP), reflecting decreased motor inhibition. However, voluntary versus involuntary aspects of inhibitory functions in TS are not well understood. Hence, investigating voluntary motor drive (VMD) could help to elucidate this issue. A group of 14 healthy adolescents was compared with subjects of same age suffering from TS with (N = 6) and without (N = 6) presence of distal tics. Basic resting and active motor thresholds (RMT and AMT, respectively) as well as suprathreshold transcranial magnetic stimulation-conditioned RMT and AMT were determined during the CSP. The difference between AMT and RMT was considered as VMD quantum. No group-differences were found in RMT or AMT. Subjects with distal tics showed reduced VMD compared to healthy controls while patients without distal tics did not differ from controls. In the second half of CSP, patients with distal tics showed also diminished VMD compared to tic-patients without distal tics. The findings support the notion, that TS shows possible reduction of VMD and is associated with central motor threshold alterations confined to the very motor networks related to the tics observed.