Neurophysiological and neuropsychological aspects of time processing in children und adults with and without ADHD

Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common mental disorders of children and adolescents, and a sizable number of ADHD patients continue to be impaired in later life. Developmental changes of cardinal symptoms of ADHD and their possible overlap with other deficits as well as influences of compensatory mechanisms in adult age make direct comparisons of children and adults with ADHD difficult. In this work, neurophysiological and neuropsychological markers of ADHD are investigated in order to better compare different attention aspects of children and adults with ADHD. A central aim of this piece of work was to compare children's’ and adults’ performances on different tasks, exploring either classical executive functions like inhibition and attention or probing more basal functions like alertness and temporal processing. The main focus was on aspects of temporal processing, though. In study A, event-related potentials (CNV and Nogo P300) during cued continuous performance tasks were used to compare ADHD-related temporal processing (CNV) and response inhibition (Nogo P300) deficits in children (32 with ADHD, mean age 11.2 years, and 31 controls, mean age 11.1 years) and adults (22 with ADHD, mean age 42.7 years, and 22 controls, mean age 44.0 years). In study B, children and adults with ADHD were compared to controls on two-time processing tasks containing time reproduction (in the seconds time range) and time discrimination (in the milliseconds time range). Developmental, as well as ADHD-related effects, could be found in both studies. The results show that there exist differences between both children and adults with ADHD compared to their matched controls. However, the pattern of differences is not the same for children and adults. This leads to the conclusion that ADHD- related deficits concerning temporal processing and inhibition persist into adulthood despite alterations of their qualitative aspects during development. Die Aufmerksamkeits- und Hyperaktivitätsstörung (ADHS) ist eine der häufigsten psychischen Erkrankungen im Kindes- und Jugendalter. Viele Betroffene sind auch im Er- wachsenenalter beeinträchtigt. Entwicklungsbedingte Veränderungen der Hauptsymptome, ihre mögliche Überlappung mit anderen Defiziten sowie Einflüsse von Kompensationsmechanismen im Erwachsenenalter erschweren den direkten Vergleich zwischen Kindern und Erwachsenen mit ADHS. Um verschiedene Aufmerksamkeit-bezogene Aspekte zwischen betroffenen Kindern und Erwachsenen besser vergleichen zu können, wurden hier neurophysiologische und neu- ropsychologische ADHS-Marker untersucht. Eines der zentralen Ziele dieser Arbeit war es, die Leistungen der Kinder und Erwachsenen in verschiedenen Aufgaben hinsichtlich klassischer Exekutivfunktionen wie Inhibition und Aufmerksamkeit zum einen und grundlegender Funktionen wie Alertness und Zeitverarbeitung zum anderen zu vergleichen. Der Schwerpunkt wurde dabei auf Aspekte der Zeitverarbeitung gelegt. In Studie A wurden Ereignisbezogene Potentiale (CNV und Nogo P300) während ei- nes Daueraufmerksamkeitstests erhoben, um somit ADHS-bezogene Defizite in der Zeit- verarbeitung (CNV) und Antwortinhibition (Nogo P300) zwischen Kindern (32 mit ADHS, Durchschnittsalter [DA] 11.2 Jahre und 31 Kontrollkindern ohne ADHS, DA 11.1 Jahre) und Erwachsenen (22 mit ADHS, DA 42.7 Jahre und 22 Kontrollerwachsene ohne ADHS, DA 44.0 Jahre) zu vergleichen. In Studie B erfolgte der Vergleich der betroffenen Kinder und Erwachsenen mit den Kontrollen bezüglich zweier verschiedener Zeitverarbeitungsaufgaben: einer Reprodukti- onsaufgabe im Sekundenbereich und einer Diskriminationsaufgabe im Millisekundenbereich. Die Resultate beider Studien zeigen, dass sich sowohl Kinder als auch Erwachsene mit ADHS von ihren jeweiligen Vergleichsgruppen unterscheiden. Das Muster der Unterschiede ist jedoch bei Kindern anders als bei Erwachsenen. Dies führt zur Hypothese, dass ADHS-bezogene Defizite bezüglich Zeitverarbeitung und Inhibition bis ins Erwachsenenalter erhalten bleiben, dass sie sich in ihren qualitativen Aspekten aber über die Entwicklung hinweg verändern

The behavioural profile of children with attention-deficit/hyperactivity disorder and of their siblings

The behavioural profiles in N=69 index children with attention-deficit/hyperactivity disorder (ADHD), N=32 siblings with ADHD, N=35 siblings without ADHD, and N=36 normal controls were compared by the use of standardized parent and teacher rating scales. The four groups were matched by age and IQ. The behavioural profiles of the two ADHD groups were very similar not only in the behavioural domains of ADHD, but also in scales measuring emotional and conduct problems. Siblings without ADHD shared more similarities with normal controls except for more emotional problems. These general trends were stronger in the parent compared to the teacher ratings. These findings indicate that not only ADHD-related but also other behaviours show a strong family aggregation. The informant differences may reflect context dependent differences in child behaviour and contrast effects particularly in parental rating

Neural correlate of spatial presence in an arousing and noninteractive virtual reality: an EEG and psychophysiology study

Using electroencephalography (EEG), psychophysiology, and psychometric measures, this is the first study which investigated the neurophysiological underpinnings of spatial presence. Spatial presence is considered a sense of being physically situated within a spatial environment portrayed by a medium (e.g., television, virtual reality). Twelve healthy children and 11 healthy adolescents were watching different virtual roller coaster scenarios. During a control session, the roller coaster cab drove through a horizontal roundabout track. The following realistic roller coaster rides consisted of spectacular ups, downs, and loops. Low-resolution brain electromagnetic tomography (LORETA) and event-related desynchronization (ERD) were used to analyze the EEG data. As expected, we found that, compared to the control condition, experiencing a virtual roller coaster ride evoked in both groups strong SP experiences, increased electrodermal reactions, and activations in parietal brain areas known to be involved in spatial navigation. In addition, brain areas that receive homeostatic afferents from somatic and visceral sensations of the body were strongly activated. Most interesting, children (as compared to adolescents) reported higher spatial presence experiences and demonstrated a different frontal activation pattern. While adolescents showed increased activation in prefrontal areas known to be involved in the control of executive functions, children demonstrated a decreased activity in these brain regions. Interestingly, recent neuroanatomical and neurophysiological studies have shown that the frontal brain continues to develop to adult status well into adolescence. Thus, the result of our study implies that the increased spatial presence experience in children may result from the not fully developed control functions of the frontal cortex

Time processing in children and adults with ADHD

A time-processing deficit has been proposed as a neuropsychological candidate endophenotype for Attention Deficit Hyperactivity Disorder (ADHD), but its developmental trajectory still needs to be explored. In the present study, children (N=33) and adults (N=22) with ADHD were compared to normal controls on two time-processing tasks. For time reproduction, ADHD-related impairment was found in the full group, but not when adults were analyzed separately. For the discrimination of brief intervals, children and adults with ADHD showed different patterns of deficit. We conclude that in ADHD some time-processing deficits are still present in adults, but may take on age-related different form

Diagnostic Value of Resting Electroencephalogram in Attention-Deficit/Hyperactivity Disorder Across the Lifespan

The resting electroencephalogram (EEG) reflects development and arousal, but whether it can support clinical diagnosis of attention-deficit/hyperactivity disorder (ADHD) remains controversial. Here we examined whether theta power and theta/beta ratio are consistently elevated in ADHD and younger age as proposed. Topographic 48-channel EEG from 32 children (8-16years) and 22 adults (32-55years) with ADHD and matched healthy controls (n=30 children/21 adults) was compared. Following advanced artefact correction, resting EEG was tested for increased theta and theta/beta activity due to ADHD and due to normal immaturity. Discriminant analyses tested classification performance by ADHD and age using these EEG markers as well as EEG artefacts and deviant attentional event-related potentials (ERPs). No consistent theta or theta/beta increases were found with ADHD. Even multivariate analyses indicated only marginal EEG power increases in children with ADHD. Instead, consistent developmental theta decreases were observed, indicating that maturational lags of fewer than 3years would have been detected in children. Discriminant analysis based on proposed simple spectral resting EEG markers was successful for age but not for ADHD (81 vs. 53% accuracy). Including ERP markers and EEG artefacts improved discrimination, although not to diagnostically useful levels. The lack of consistent spectral resting EEG abnormalities in ADHD despite consistent developmental effects casts doubt upon conventional neurometric approaches towards EEG-based ADHD diagnosis, but is consistent with evidence that ADHD is a heterogeneous disorder, where the resting state is not consistently characterised by maturational la

Noninteractive Virtual Reality: An EEG and Psychophysiology Study

Using electroencephalography (EEG), psychophysiology, and psychometric measures, this is the first study which investigated the neurophysiological underpinnings of spatial presence. Spatial presence is considered a sense of being physically situated within a spatial environment portrayed by a medium (e.g., television, virtual reality). Twelve healthy children and 11 healthy adolescents were watching different virtual roller coaster scenarios. During a control session, the roller coaster cab drove through a horizontal roundabout track. The following realistic roller coaster rides consisted of spectacular ups, downs, and loops. Low-resolution brain electromagnetic tomography (LORETA) and event-related desynchronization (ERD) were used to analyze the EEG data. As expected, we found that, compared to the control condition, experiencing a virtual roller coaster ride evoked in both groups strong SP experiences, increased electrodermal reactions, and activations in parietal brain areas known to be involved in spatial navigation. In addition, brain areas that receive homeostatic afferents from somatic and visceral sensations of the body were strongly activated. Most interesting, children (as compared to adolescents) reported higher spatial presence experiences and demonstrated a different frontal activation pattern. While adolescents showed increased activation in prefrontal areas known to be involved in the control of executive functions, children demonstrated a decreased activity in these brain regions. Interestingly, recent neuroanatomical and neurophysiological studies have shown that the frontal brain continues to develop to adult status well into adolescence. Thus, the result of our study implies that the increased spatial presence experience in children may result from the not fully developed control functions of the frontal cortex

The behavioural profile of children with attention-deficit/hyperactivity disorder and of their siblings

The behavioural profiles in N = 69 index children with attention-deficit/hyperactivity disorder (ADHD), N = 32 siblings with ADHD, N = 35 siblings without ADHD, and N = 36 normal controls were compared by the use of standardized parent and teacher rating scales. The four groups were matched by age and IQ. The behavioural profiles of the two ADHD groups were very similar not only in the behavioural domains of ADHD, but also in scales measuring emotional and conduct problems. Siblings without ADHD shared more similarities with normal controls except for more emotional problems. These general trends were stronger in the parent compared to the teacher ratings. These findings indicate that not only ADHD-related but also other behaviours show a strong family aggregation. The informant differences may reflect context dependent differences in child behaviour and contrast effects particularly in parental ratings

Genetics of preparation and response control in ADHD: the role of DRD4 and DAT1

BACKGROUND Difficulties with performance and brain activity related to attentional orienting (Cue-P3), cognitive or response preparation (Cue-CNV) and inhibitory response control (Nogo-P3) during tasks tapping executive functions are familial in ADHD and may represent endophenotypes. The aim of this study was to clarify the impact of dopamine receptor D4 (DRD4) and dopamine transporter (DAT1) gene polymorphisms on these processes in ADHD and control children. METHODS Behavioural and electrophysiological parameters from cued continuous performance tests with low and high attentional load were assessed in boys with ADHD combined type (N = 94) and controls without family history of ADHD (N = 31). Both groups were split for the presence of at least one DRD4 7-repeat allele and the DAT1 10-6 haplotype. RESULTS Children with ADHD showed diminished performance and lower Cue-P3, CNV and Nogo-P3 amplitudes. Children with DRD4 7R showed similar performance problems and lower Cue-P3 and CNV, but Nogo-P3 was not reduced. Children with the DAT1 10-6 haplotype had no difficulties with performance or Cue-P3 and CNV, but contrary to expectations increased Nogo-P3. There were no Genotype by ADHD interactions. CONCLUSIONS This study detected specific effects of DRD4 7R on performance and brain activity related to attentional orienting and response preparation, while DAT1 10-6 was associated with elevated brain activity related to inhibitory response control, which potentially compensates increased impulsivity. As these genotype effects were additive to the impact of ADHD, the current results indicate that DRD4 and DAT1 polymorphisms are functionally relevant risk factors for ADHD and presumably other disorders sharing these endophenotypes