Processes In Attention Deficit Hyperactivity Disorder Research Articles

P-803 - Reduced neural error signaling in left inferior prefrontal cortex in adults with ADHD

Neuroimaging studies in healthy subjects have shown that the neural network involved in inhibition of inappropriate response tendencies shares commonalities with the error processing network signalling failure of inhibition. It has also been proposed that the observed behavioral response inhibition deficits in patients with attention-deficit/hyperactivity disorder (ADHD) seem to be strongly associated with dysfunctional error processing. Most studies on error processing in ADHD have been conducted in children using electrophysiological methods, while investigations in adult patients with ADHD, and functional magnetic resonance imaging (fMRI) in particular, are sparse. Using event-related fMRI we studied 14 adults with ADHD and 12 group-matched healthy control subjects while performing a modified version of a combined Eriksen Flanker-Go/NoGo-task. The modification permitted for the distinction between congruent and incongruent Go- and NoGo-trials, with incongruent NoGo-trials representing the most demanding condition permitting a response-based analysis of the neural error processing network of failed inhibition. Behaviourally, no differences between groups were observed for reaction times or rates of incorrect NoGo-trials. Compared to healthy controls patients with ADHD demonstrated significant hypoactivation of the left inferior frontal gyrus bordering the anterior insular cortex (BA 47), when contrasting failed against successful inhibitions. The inverse group comparison (ADHD>controls) showed no difference. Our data suggest that hypoactivation in the inferior frontal cortex might represent a neuro-functional marker of altered error processing in adults with ADHD, possibly signaling dysfunctions in the neural system that operates task-set related representations and conscious evaluation of erroneous performance.

Attentional processes in children with ADHD: An event-related potential study using the attention network test

A variety of event-related potential (ERP) based studies have shown differences in neuronal processes underlying attention, inhibition and error processing in children with attention-deficit/hyperactivity disorder (ADHD) compared to controls. However, so far there are no studies that have compared children with ADHD and typically developing (TD) children regarding effects in ERP components associated with the attention network test (ANT). The ANT allows to differentiate between three particular aspects of attention: alerting, orienting, conflict. Twenty-five children with ADHD and 19 TD children (comparable with respect to age, sex, and IQ) performed the ANT while ERPs were recorded. Based on DSM-IV, the group of children with ADHD was divided in an inattentive (ADHD in, n = 10) and a combined (ADHD com, n = 15) subgroup. On the performance level, the ADHD group showed a significantly higher variability of reaction times. Concerning ERP measures, smaller cue-P3 amplitudes were found in the ADHD group indicating that children with ADHD allocate less attentional resources for cue processing. In addition, the target-P3 in ADHD showed smaller amplitudes. Subgroup analysis revealed reduced cue-P3 amplitudes in both subgroups and reduced target-P3 amplitudes in ADHD in compared to TD children. Except for a higher alerting score in ADHD after correction for cue-P3 group differences, performance data revealed no group differences specific for the three attention networks. No group differences related to the attention networks were observed at the ERP level. Our results suggest that deviant attentional processing in children with ADHD is only partly related to ANT-specific effects. Findings are compatible with the model of a suboptimal energetic state regulation in ADHD. Furthermore, our results suggest that deviant cue processing in ADHD and related differences in task modulations should be accounted for in data analysis.

Auditory conflict processing in ADHD

Impaired cognitive control has been implicated as an important developmental pathway to attention deficit/hyperactivity disorder (ADHD). Cognitive control is crucial to suppress interference resulting from conflicting information and can be measured by Stroop-like tasks. This study was conducted to gain insight into conflict processing in children with ADHD. Event-related potentials (ERPs) were recorded in an auditory Stroop task. Twenty-four children with ADHD were compared with 24 control children (aged 8-12 years). No deficit in interference control was found on the auditory Stroop task in children with ADHD. Children with ADHD responded more slowly, less accurately and more variably compared to controls. No differences between the groups occurred in the early conflict-related ERPs. However, the difference between the congruent and the incongruent condition in the 450-550 ms time window was absent in the ADHD group compared to controls. In addition, the conflict sustained potential was found frontally in the ADHD group but parietally in the control group. These ERP findings suggest that children with ADHD evaluate conflict to a lesser extent and differ in the way their brains select appropriate responses during conflict compared with controls.

Separation of Cognitive Impairments in Attention-Deficit/Hyperactivity Disorder Into 2 Familial Factors

Attention-deficit/hyperactivity disorder (ADHD) is associated with widespread cognitive impairments, but it is not known whether the apparent multiple impairments share etiological roots or separate etiological pathways exist. A better understanding of the etiological pathways is important for the development of targeted interventions and for identification of suitable intermediate phenotypes for molecular genetic investigations. To determine, by using a multivariate familial factor analysis approach, whether 1 or more familial factors underlie the slow and variable reaction times, impaired response inhibition, and choice impulsivity associated with ADHD. An ADHD and control sibling-pair design. Belgium, Germany, Ireland, Israel, Spain, Switzerland, and the United Kingdom. A total of 1265 participants, aged 6 to 18 years: 464 probands with ADHD and 456 of their siblings (524 with combined-subtype ADHD), and 345 control participants. Performance on a 4-choice reaction time task, a go/no-go inhibition task, and a choice-delay task. The final model consisted of 2 familial factors. The larger factor, reflecting 85% of the familial variance of ADHD, captured 98% to 100% of the familial influences on mean reaction time and reaction time variability. The second, smaller factor, reflecting 13% of the familial variance of ADHD, captured 62% to 82% of the familial influences on commission and omission errors on the go/no-go task. Choice impulsivity was excluded in the final model because of poor fit. The findings suggest the existence of 2 familial pathways to cognitive impairments in ADHD and indicate promising cognitive targets for future molecular genetic investigations. The familial distinction between the 2 cognitive impairments is consistent with recent theoretical models--a developmental model and an arousal-attention model--of 2 separable underlying processes in ADHD. Future research that tests the familial model within a developmental framework may inform developmentally sensitive interventions.

Alterations in theta activity associated with novelty and routinization processing in ADHD

Novelty and routinization-related information processing disturbances were examined in adolescent males with ADHD using an oddball paradigm and electrophysiological measurement of theta (4-7Hz) activity. Fifty-four unmedicated adolescent males (12-18years) with Attention Deficit Hyperactivity Disorder (ADHD) and matched controls performed an auditory oddball task. Theta activity was sub-averaged, and Fourier Integrals with simultaneous measurement of electrodermal activity (EDA) was used to index response to stimulus novelty and routinization. ADHD participants showed an overall increase in theta activity to both novel and routine stimuli relative to controls. While controls showed increased theta activity in response to novel compared to routine targets across the brain, ADHD participants did not show this novelty-related increase in theta activity in the right anterior/frontal brain. The findings of this study are consistent with disturbances in theta activity and the brain substrates of novelty relative to routinization-related processing in ADHD. These findings show that there are distinct alterations in theta activity related to stimulus novelty and routinization during an auditory oddball task in ADHD, and they highlight the value of using an event-related approach to elucidate the neural substrates of stimulus processing in ADHD.

Neural Mechanisms of Interference Control and Time Discrimination in Attention-Deficit/Hyperactivity Disorder

Both executive functions and time perception are typically impaired in subjects with attention-deficit/hyperactivity disorder (ADHD). However, the exact neural mechanisms underlying these deficits remain to be investigated. Fourteen subjects with ADHD and 14 age- and IQ-matched controls (aged 9 through 15 years) were assessed with functional magnetic resonance imaging while they performed a combined spatial stimulus-response compatibility (SRC) and time duration discrimination (TD) paradigm using identical stimuli for all experimental conditions. Children with ADHD performed less accurately in the SRC but not in the TD task compared with controls. On the brain level, subjects with ADHD showed significantly reduced neural activity in the left putamen during SRC and reduced fronto-cerebellar activation during TD when compared with the baseline conditions. Compared with subjects with ADHD, control subjects had increased activation in a left-hemispheric fronto-parietal network during the SRC task and in the right superior-frontal gyrus during the TD task. Functional connectivity analyses revealed abnormal fronto-parietal coupling during the SRC task and reduced fronto-cerebellar connectivity during the TD task in the ADHD group compared with controls. Our findings suggest specific but distinct patterns of cerebral dysfunction associated with interference control and TD processing in ADHD, characterized by both reduced neural activation in regions critical for task performance and reduced co-activation of frontal cortex. Group differences on the behavioral level were controlled by several methodological approaches. Nonetheless, given the use of a block design, we cannot rule out the possibility that between-group differences in behavior confounded the neural activation patterns.

Electrophysiological evidence for abnormal preparatory states and inhibitory processing in adult ADHD

BackgroundAttention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder that starts in childhood and frequently persists in adults. Several theories postulate deficits in ADHD that have effects across many executive functions or in more narrowly defined aspects, such as response inhibition. Electrophysiological studies on children, however, indicate that ADHD is not associated with a core deficit of response inhibition, as abnormal inhibitory processing is typically preceded or accompanied by other processing deficits. It is not yet known if this pattern of abnormal processing is evident in adult ADHD.MethodsThe objective of this paper was to investigate event-related potential indices of preparatory states and subsequent response inhibition processing in adults with ADHD. Two cued continuous performance tasks were presented to 21 adults meeting current criteria for adult ADHD and combined type ADHD in childhood, and 20 controls.ResultsThe ADHD group exhibited significantly weaker orienting attention to cues, cognitive preparation processes and inhibitory processing. In addition, we observed a strong correlation between the resources allocated to orienting to cues and the strength of the subsequent response strength control processes, suggesting that orienting deficits partly predict and determine response control deficits in ADHD.ConclusionsThese findings closely resemble those previously found in children with ADHD, which indicate that there is not a core response inhibition deficit in ADHD. These findings therefore suggest the possibility of developmental stability into adulthood of the underlying abnormal processes in ADHD.

Ventro-Striatal Reductions Underpin Symptoms of Hyperactivity and Impulsivity in Attention-Deficit/Hyperactivity Disorder

Models of attention-deficit/hyperactivity disorder (ADHD) classically emphasize the relevance of executive processes and, recently, reward circuits. The neural bases of reward processes have barely been explored in relation to this disorder, in contrast to extensive neuroimaging studies that examine executive functions in patients with ADHD. To our knowledge, no previous studies have analyzed the volume of the ventral striatum, a key region for reward processes in ADHD children. We used a manual region-of-interest approach to examine whether there were volumetric differences in the ventral striatum of ADHD children. Forty-two children/adolescents with ADHD (ages 6-18), and 42 healthy control subjects matched on age, gender, and handedness were selected for the study. The ADHD children presented significant reductions in both right and left ventro-striatal volumes (t = 3.290, p = .001; and t = 3.486, p = .001, respectively). In addition, we found that the volume of the right ventral striatum negatively correlated with maternal ratings of hyperactivity/impulsivity (r = -.503, p = .003). Our study provides neuroanatomical evidence of alterations in the ventral striatum of ADHD children. These findings coincide with previous explicative models as well as with recent reports in behavioral and functional neuroimaging studies. Furthermore, the negative correlations we observed strongly uphold the relation between the ventral striatum and symptoms of hyperactivity/impulsivity.

Age-Dependent Differences in Attentional Processes in ADHD and Disruptive Behavior Disorder

The aim of this study was to analyze age-dependent differences in attentional performance in subjects aged 8–16 years with attention deficit/hyperactivity disorder (ADHD) with or without disruptive behavior disorders (DBD). Age effects were investigated in three different groups (ADHD [N = 118], ADHD + DBD [N = 105], and controls [N = 105]) on a sustained attention and a Go-No-Go paradigm. Attentional competencies increased with age and children in the two clinical groups performed worse than control children on both tasks. However, these group differences between ADHD, ADHD + DBD, and controls decreased with increasing age. Thus, age-related differences must be considered in neuropsychological studies.

Total red blood cell concentrations of ω-3 fatty acids are associated with emotion-elicited neural activity in adolescent boys with attention-deficit hyperactivity disorder

Affective impairment is observed in children and adolescents with attention-deficit hyperactivity disorder (ADHD). Low levels of long-chain polyunsaturated fatty acids (LC-PUFA), specifically omega-3 (ω-3) fatty acids in blood measures have been linked to a range of behavioural and mood disorders including ADHD. However, nothing is known about the relationship between ω-3 and brain function in children with ADHD. In the current study, 20 adolescent boys with ADHD were assessed for total lipid fractions in red blood cells and their event-related potential (ERP) response to the presentation of facial expressions of happiness, sadness and fearfulness. The results supported the hypothesis of a positive association between eicosapentaenoic acid (EPA) and a cognitive bias in orientation to overt expressions of happiness over both sad and fearful faces as indexed by midline frontal P300 amplitude. Additional exploratory analyses revealed a positive association between levels of docosahexaenoic acid (DHA) and the right temporal N170 amplitude in response to covert expressions of fear. The arachidonic (AA)/DHA ratio was negatively associated with the right temporal N170 amplitude also to covert expressions of fear. These findings indicate that EPA and DHA may be involved in distinct aspects of affect processing in ADHD and have implications for understanding currently inconsistent findings in the literature on EFA supplementation in ADHD and depression.

The neural correlates of deficient error awareness in attention-deficit hyperactivity disorder (ADHD)

The ability to detect and correct errors is critical to adaptive control of behaviour and represents a discrete neuropsychological function. A number of studies have highlighted that attention-deficit hyperactivity disorder (ADHD) is associated with abnormalities in behavioural and neural responsiveness to performance errors. One limitation of previous work has been a failure to determine the extent to which these differences are attributable to failures of conscious error awareness, a process that is dependent on the integrity of the frontal lobes. Recent advances in electrophysiological research make it possible to distinguish unconscious and conscious aspects of error processing. This study constitutes an extensive electrophysiological investigation of error awareness and error processing in ADHD. A Go/No-Go response inhibition task specifically designed to assess error awareness was administered to a group of adults diagnosed with ADHD and a group of matched control participants. The ADHD group made significantly more errors than the control group but was less likely to consciously detect these errors. An analysis of event-related potentials elicited by errors indicated that an early performance monitoring component (early positivity) was significantly attenuated in the ADHD group as was a later component that specifically reflects conscious error processing (Pe). Dipole source modelling suggested that abnormal Pe amplitudes were attributable to decreased activation of the anterior cingulate cortex. Decreased electrodermal activity in the ADHD group also suggested a motivational insensitivity to performance errors. Our data provide evidence that neuropsychological deficits associated with ADHD can be exacerbated by error processing abnormalities. Error awareness may represent an important cognitive and physiological phenotype for ADHD.

Attention Deficit Hyperactivity Disorder

Attention deficit hyperactivity disorder (ADHD) is a behavioral diagnosis based on the presence of developmentally inappropriate levels of impulsivity, overactivity, and inattentiveness. It is a familial condition with a complex pattern of inheritance. Variation of several genes involved in the regulation of dopamine, norepinephrine, and serotonin neurotransmission is associated with ADHD. We highlight the two most prominent findings with the dopamine D4 receptor (DRD4) gene and the dopamine transporter (DAT1) gene, and their implications for the understanding of the cellular and neurobiological basis for ADHD. Cognitive and functional studies using electrophysiology and brain imaging frequently indicate altered processing in ADHD during performance on cognitive tasks hypothesized to measure a "core" deficit, such as response inhibition. Yet, children with ADHD appear to suffer from a more general deficit, including impairment in attentional alerting, orienting, response preparation, and control. Reward processes are also altered and, further, a strong association emerges with intraindividual variability, with several causal hypotheses being proposed. Task performance correlates with underactivation of, especially, frontostriatal areas of the brain, but an extended network of brain regions is also implicated. Electroencephalography studies indicate abnormalities in ADHD in relation to slow-wave activity, linked to underarousal. These advances in the areas of genetics, cognitive function, neurophysiology, and neuroanatomy of ADHD give important leads for interdisciplinary research that aims to delineate the causal pathways. Such research is only at its beginning, but is illustrated by recent findings of an association between DAT1 and increased response variability in ADHD.

The IMAGE project: methodological issues for the molecular genetic analysis of ADHD

The genetic mechanisms involved in attention deficit hyperactivity disorder (ADHD) are being studied with considerable success by several centres worldwide. These studies confirm prior hypotheses about the role of genetic variation within genes involved in the regulation of dopamine, norepinephrine and serotonin neurotransmission in susceptibility to ADHD. Despite the importance of these findings, uncertainties remain due to the very small effects sizes that are observed. We discuss possible reasons for why the true strength of the associations may have been underestimated in research to date, considering the effects of linkage disequilibrium, allelic heterogeneity, population differences and gene by environment interactions.With the identification of genes associated with ADHD, the goal of ADHD genetics is now shifting from gene discovery towards gene functionality – the study of intermediate phenotypes ('endophenotypes'). We discuss methodological issues relating to quantitative genetic data from twin and family studies on candidate endophenotypes and how such data can inform attempts to link molecular genetic data to cognitive, affective and motivational processes in ADHD.The International Multi-centre ADHD Gene (IMAGE) project exemplifies current collaborative research efforts on the genetics of ADHD. This European multi-site project is well placed to take advantage of the resources that are emerging following the sequencing of the human genome and the development of international resources for whole genome association analysis. As a result of IMAGE and other molecular genetic investigations of ADHD, we envisage a rapid increase in the number of identified genetic variants and the promise of identifying novel gene systems that we are not currently investigating, opening further doors in the study of gene functionality.

A Meta-Analysis of Working Memory Impairments in Children With Attention-Deficit/Hyperactivity Disorder

To determine the empirical evidence for deficits in working memory (WM) processes in children and adolescents with attention-deficit/hyperactivity disorder (ADHD). Exploratory meta-analytic procedures were used to investigate whether children with ADHD exhibit WM impairments. Twenty-six empirical research studies published from 1997 to December, 2003 (subsequent to a previous review) met our inclusion criteria. WM measures were categorized according to both modality (verbal, spatial) and type of processing required (storage versus storage/manipulation). Children with ADHD exhibited deficits in multiple components of WM that were independent of comorbidity with language learning disorders and weaknesses in general intellectual ability. Overall effect sizes for spatial storage (effect size = 0.85, CI = 0.62 - 1.08) and spatial central executive WM (effect size = 1.06, confidence interval = 0.72-1.39) were greater than those obtained for verbal storage (effect size = 0.47, confidence interval = 0.36-0.59) and verbal central executive WM (effect size = 0.43, confidence interval = 0.24-0.62). Evidence of WM impairments in children with ADHD supports recent theoretical models implicating WM processes in ADHD. Future research is needed to more clearly delineate the nature, severity, and specificity of the impairments to ADHD.

Cognitive Deficits in Children with Attention Deficit Hyperactivity Disorder: A Long-Term Follow-Up.

Abstract The phrase long-term follow-up in the title of this paper refers to my Presidential Address to CPA (Douglas, 1972), in which I made my first attempt to pull together my on the nature of the cognitive deficits associated with Childhood Hyperactivity, now known as Attention Deficit Hyperactivity Disorder. This paper represents a much later attempt to my thinking. The paper describes my current conceptualization of the cognitive and motor deficits of children with ADHD. It points to the self-regulatory nature of their deficits, and stresses the importance of differentiating between the attentional and inhibitory components, as opposed to the strategic or organizational components, of self-regulation. A main theme is the need for better collaboration among investigators to develop a diagnostic profile of operationally defined, laboratory-based measures that can assess specific attentional, inhibitory, and strategic deficits under clearly specified conditions. I argue that the profile should also include measures and manipulations that demonstrate the cognitive strengths of ADHD children, which are frequently masked by impaired self-regulation. I discuss the possibility of using tasks and games based on the operational definitions to try to influence the early development of cognitive and motor control processes in ADHD. I also argue that pervasive, dose-dependent stimulant effects across multiple simple and complex tasks point to action on self-regulatory processes and provide one example showing that high doses can produce overregulation. I am very grateful to have been honoured with the Lifetime Contributions award from the Canadian Psychological Association, and for the invitation to use this occasion to my thinking on the cognitive and motor deficits associated with Attention Deficit Hyperactivity Disorder (ADHD), a topic that has consumed my interest for many years. It is particularly appropriate that this event is taking place at the Annual Meeting of CPA in St. John's, Newfoundland. Some years ago, when I was President of CPA, I gave my Presidential Address at the Annual Meeting, which also was held in St. John's that year. I developed a deep affection for the town, and it is a great pleasure to be back. As you may have guessed, the talk dealt with ADHD, then known as Childhood Hyperactivity. The topic was Stop, Look, and Listen: The Problem of Sustained Attention and Impulse Control in Hyperactive and Normal Children (Douglas, 1972). Thus, you can consider this talk a long-term follow-up. Since that time, the field has experienced a mind-boggling surge of research. Theories and models attempting to establish the basic nature of the disorder have proliferated; the debate about diagnostic and treatment approaches has taken many turns; and neuroscience advances in brain imaging and the neurotransmitters have begun to show an impact. As new evidence and new theories have emerged, those of us working in the field have had to continually update our thinking. I will use this talk to give you a brief overview of my current conceptualization of the cognitive and motor deficits associated with ADHD, highlighting the research that has guided my thinking, and pointing to possible diagnostic and treatment implications. Search for the Core Deficit Attempts to characterize the cognitive deficits of children with ADHD have emphasized several key processes, including attention, inhibition, state regulation, delay aversion, and executive functions. Considerable confusion has developed, however, because investigators have differed in the priority they assign to each of these processes, arid in how they conceptualize the relationships among them. In the model proposed by Barkley (1997), a core inhibitory deficit impairs the development of several executive functions, including working memory. In contrast, Denney and Rapport (2001) proposed a model in which working memory constitutes the key causal process. …

Effect of methylphenidate on auditory event related potential in boys with attention deficit hyperactivity disorder

Event related brain potentials (ERPs) is a non-invasive technique giving knowledge about neural activity associated with sensory and cognitive information processing. The aims of the present study were to investigate amplitude and latency of P100, N200, and P300 in parietal and frontal areas in children with attention deficit hyperactivity disorder (ADHD), and in healthy children, and to determine the effect of methylphenidate (MPH) on these ERPs indices in ADHD group. ERP indices, latencies of parietal P3 (PP3L), P1 (PP1L), N2 (PN2L), and frontal P1 (FP1L), N2 (FN2L), P3 (FP3L), and amplitudes of parietal P3 (PP3A), P1 (PP1A), N2 (PN2A), and frontal P1 (FP1A), N2 (FN2A), and P3 (FP3A), using an auditory oddball paradigm were recorded before and under MPH treatment in boys with ADHD, and in 23 healthy children. Before MPH treatment, PP3L was significantly longer and PP3A, PN2A, FN2A, and FP3A smaller in children with ADHD compared to healthy children (all P values < .05). No significant difference was found in PP1L, PP1A, PN2L, FP1L, FP1A, FN2L, and FP3L between ADHD and control group (all P values > .05). MPH treatment resulted in a significant decrease in PP3L, PN2L, and FP3L, and increase in PP3A, PP1A, and FP3A (all P values < .05). There was no significant difference in PP1L, PN2A, FP1L, FP1A, FN2L, and FN2A between before MPH and under MPH treatment in ADHD subjects (all P values > .05). Under MPH treatment, PP3L, PP3A, PP1L, PP1A, PN2L, FP1L, FP1A, FN2L, FP3L, and FP3A were not significantly different between children with ADHD and healthy controls (all P values > .05). However, PN2A and FN2A were significantly smaller in ADHD subjects compared to controls (both P values < .05). This study provides indirect evidence that ADHD subjects are associated with abnormalities in signal detection (inattention) and discrimination, and information processing. In addition, present study has shown that except FN2A and PN2A, MPH normalizes ERP indices, which suggested that MPH may be effective on impaired information processing in ADHD, but not on the receiving information.

Methylphenidate Improves Visual-Spatial Memory in Children With Attention-Deficit/Hyperactivity Disorder

To investigate the effect of methylphenidate (MPH) on visual-spatial memory, as measured by subtests of the Cambridge Neuropsychological Testing Automated Battery (CANTAB), in children with attention-deficit/hyperactivity disorder (ADHD). Visual-spatial memory is a core component of working memory that has been shown to be impaired in ADHD, irrespective of comorbid reading and/or language problems. A clinic-referred sample of school-age children with a confirmed DSM-IV diagnosis of ADHD (n = 26) completed tests of visual-spatial memory, planning ability, and recognition memory in an acute, randomized, placebo-controlled, crossover trial with three single fixed doses of MPH. MPH effects on right-handed and left-handed motor control were also assessed. MPH significantly improved performance on a self-ordered, updating visual-spatial working memory task and on maintenance of visual-spatial information but had no effects on measures of visual-spatial planning ability or recognition memory. Also, MPH significantly improved left-handed motor control. Beneficial effects of MPH on visual-spatial processing in ADHD are selective and restricted to visual-spatial memory.

Covert Orienting of Visual Spatial Attention in Attention Deficit Hyperactivity Disorder: Does Comorbidity Make a Difference?

Attentional performance in children with attention deficit hyperactivity disorder (ADHD) with and without comorbid disorders was examined using the Covert Orienting of Visuospatial Attention Task (COVAT) and the Continuous Performance Task (CPT). The relationship between these two tasks was also examined. The results showed no overall differences on the attention tasks between children with ADHD alone and those with ADHD plus other disorders. Compared to non-ADHD control children, children with ADHD showed a deficit in the disengage operation of covert visuospatial attention, suggesting a difficulty in the endogenous mode of orienting. The ADHD children also showed a general performance deficit on the CPT. Although there was a general slowing on both attention tasks in the ADHD group, there was no relationship between invalid cue effect sizes on the COVAT and the CPT measures. These results indicate that these two attention tasks may be tapping both similar and independent underlying cognitive processes in ADHD.

Covert Orienting of Visual Spatial Attention in Attention Deficit Hyperactivity Disorder: Does Comorbidity Make a Difference?

Attentional performance in children with attention deficit hyperactivity disorder (ADHD) with and without comorbid disorders was examined using the Covert Orienting of Visuospatial Attention Task (COVAT) and the Continuous Performance Task (CPT). The relationship between these two tasks was also examined. The results showed no overall differences on the attention tasks between children with ADHD alone and those with ADHD plus other disorders. Compared to non-ADHD control children, children with ADHD showed a deficit in the disengage operation of covert visuospatial attention, suggesting a difficulty in the endogenous mode of orienting. The ADHD children also showed a general performance deficit on the CPT. Although there was a general slowing on both attention tasks in the ADHD group, there was no relationship between invalid cue effect sizes on the COVAT and the CPT measures. These results indicate that these two attention tasks may be tapping both similar and independent underlying cognitive processes in ADHD.

Effects of methylphenidate on complex cognitive processing in attention-deficit hyperactivity disorder.

Effects of methylphenidate on complex cognitive processing in attention-deficit hyperactivity disorder.