Children with oppositional-defiant disorder display deviant attentional processing independent of ADHD symptoms

Summary. Objective: To examine neurophysiological correlates of attentional processing in children with oppositional-defiant disorder (ODD) independent of ADHD symptoms. Method: Thirteen children with oppositional-defiant disorder without comorbid ADHD symptoms and 13 healthy control children (all 11 years) performed a cued Continuous Performance Test (CPT-AX). Event-related potentials (ERP) to cue and target stimuli were examined for group differences. Results: Children with ODD showed significantly reduced parietal P3a and P3b amplitudes to cues and to targets, compared with healthy controls. ERP amplitudes correlated with oppositional and aggressive behavior scores. Conclusions: Event-related potentials revealed reduced orienting to cues and reduced executive target processing in children with ODD. These findings indicate that ODD children show neurophysiological deviances independent of ADHD comorbidity.     

Auditory selective attention and processing in children with attention-deficit/hyperactivity disorder

ObjectiveThis study sought to better characterize the contributions of deficits in attention allocation and distracter inhibition to the poor performance on attention tasks often seen in children with ADHD.MethodsElectrophysiological (Nd, P3b) and behavioral measures (speed and accuracy) were examined during an auditory selective attention task in children with ADHD, children with typical development (TD), and adults. Thirty children (15 ADHD; 13 females) between the ages of 7 and 13 and 16 adults (8 females) participated.ResultsNd waveforms were elicited from adults and children with TD, but not from children with ADHD. Further, those with ADHD exhibited significantly smaller auditory responses at 100 ms (Ta). P3bs were elicited in all three groups by targets but not by unattended deviants. Performance was significantly poorer in children with ADHD than TD and RTs were more variable.ConclusionsChildren with ADHD evidenced poorer attention allocation, as measured by Nd and hits, but were not more distracted by unattended deviants, as measured by P3b and false alarms, than children with TD.SignificanceFindings for Nd, P3b, and Ta considered together suggest that deficits in auditory selective attention in children with ADHD may be attributable to reduced information early in the processing stream.     

Preparatory slow potentials and event-related potentials in an auditory cued attention task.

OBJECTIVES: To examine reaction times and event-related potentials (ERPs) in an auditory cued attention task varying motor requirements, cue validity, and cue location.METHODS: Subjects (n=13) listened to cue-target stimulus pairs. Verbal cues (monaural, binaural) indicated the ear to receive a target tone 1.5s later. Cues correctly (valid) or incorrectly (invalid) predicted target ear, or were uninformative (neutral). In separate conditions subjects either responded by pressing one of two buttons, or did not respond to targets. ERPs for cues and targets (P50, N100, P200, late slow wave), and negative slow potentials between cues and targets were assessed.RESULTS: Target reaction times for valid cues were significantly shorter than for invalid cues, with intermediate values for neutral cues. When no motor response was required larger ERPs were seen to both cues and targets. Negative slow potentials had larger amplitudes before target presentation when subjects responded to targets; and were larger following neutral, vs. valid/invalid, cues. ERPs (N100, P200) to invalidly cued targets were significantly larger and a subsequent late slow wave was more positive, relative to validly cued targets.CONCLUSIONS: Expectancy for targets begins shortly after cue presentation, and is affected by both motor requirements and the information content of the cue. ERP amplitudes to targets are modulated by the correspondence between cue information and actual target location.     

Orbitofrontal cortex biases attention to emotional events

We examined the role of orbitofrontal (OF) cortex in regulating emotion-attention interaction and the balance between involuntary and voluntary attention allocation. We studied patients with OF lesion applying reaction time (RT) and event-related potential (ERP) measures in a lateralized visual discrimination task with novel task-irrelevant affective pictures (unpleasant, pleasant, or neutral) preceding a neutral target. This allowed for comparing the effects of automatic attention allocation to emotional versus neutral stimuli on subsequent voluntary attention allocation to target stimuli. N2-P3a and N2-P3b ERP components served as measures of involuntary and voluntary attention allocation correspondingly. Enhanced N2-P3a amplitudes to emotional distractors and reduced N2-P3b amplitudes to targets preceded by emotional distractors were observed in healthy subjects, suggesting automatic emotional orienting interfered with subsequent voluntary orienting. OF patients showed an opposite pattern with tendency towards reduced N2-P3a responses to emotional distractors, suggesting impaired automatic orienting to emotional stimuli due to orbitofrontal damage. Enhanced N2-P3b responses to targets preceded by any affective distractor were observed in OF patients, suggesting bias towards voluntary target-related attention allocation due to orbitofrontal lesion. Behavioral evidence indicated that left visual field (LVF) attention performance was modulated by emotional stimuli. Specifically, OF patients responded faster to LVF targets subsequent to pleasant emotional distractors. We suggest that damage to the orbitofrontal circuitry leads to dysbalance between voluntary and involuntary attention allocation in the context of affective distractors with predisposition to posterior target-related processing over frontal novelty and affect-related processing. Furthermore, we suggest that orbitofrontal influence on emotion-attention interaction is valence and hemisphere dependent.     

Response inhibition and attention processing in 5- to 7-year-old children with and without symptoms of ADHD: An ERP study

ObjectiveResponse inhibition and attention processing in 5- to 7-year-old children with or without symptoms of attention-deficit hyperactivity disorder (ADHD) were examined.MethodsTwelve children with ADHD symptoms and 15 control children performed a CPT-AX task. Behavioral measures of inattention and impulsivity and ERP measures of conflict monitoring and inhibition (Nogo-N2 and Nogo-P3), cue-orientation and prestimulus target expectation (Cue-P2 and P3) and response preparation (CNV) were collected.ResultsADHD children detected fewer targets and had higher Inattention scores accompanied by reduced centro-parietal Cue- and Go-P3 activity. Occipital CNV amplitude was larger in ADHD children. At fronto-central leads, strong and comparable fronto-parietal Nogo-N2 effects were found in both groups, whereas the Nogo-P3 was only marginally significant in both groups.ConclusionsThe attenuated Cue- and Go-P3 effects in the ADHD-symptom group are interpreted as early signs of delayed attention development, resulting in less preparation and less alertness to detect significant events. Whereas the Nogo-N2 effects were interpreted as signs of comparable levels of conflict processing in both groups, the small Nogo-P3 suggests that inhibitory processing is still immature at this age.SignificanceThe present study shows that specific attention problems can already be detected in the behavior and brain activity of 5- to 7-year-old children with symptoms of ADHD performing a CPT-AX task, and might be better indicators for the risk of developing ADHD than impulsivity measures.     

Event-related potentials associated with covert orientation of visual attention in Parkinson''s disease

Event-related potentials (ERPs) were measured in a group of patients with idiopathic Parkinson's disease and compared with a matched control group during a task involving covert orientation of visual attention. Central warning cues directed attention to the probable location of a lateralized signal that required a button-press response. Parkinson patients had enhanced post-cue P1 (at Oz) and P2 (at Cz) amplitudes, delayed N1 (at Oz) latencies, and diminished CNV amplitudes. Post-target amplitudes were similar to controls, except for an enhancedP1 to invalidly cued targets, and delayed N1 and P3 target latencies. These results indicate that Parkinson patients, in addition to their motor deficits, process spatial cues more effortfully and slowly, have impaired response preparation, and process imperative stimuli more slowly.     

Brain mapping of bilateral interactions in attention deficit hyperactivity disorder and control boys.

OBJECTIVES: Children with attention deficit hyperactivity disorder (ADHD) are thought to have deficits in attentional control, whereas the status of deficits at visual and pre-motor processing stages is unclear. METHODS: The timing of such deficits was examined with event-related potential (ERP) microstates (stimulus- and response-related) and continuous force recordings in 15 ADHD and 16 control boys in a choice reaction time task. Unilateral and bilateral stimulus and response conditions were used to assess bilateral interactions at visual, central, and pre-motor stages. RESULTS: ADHD boys showed poorer performance, particularly in the bilateral conditions. In the visual P1 microstates, they exhibited less suppression of visual evoked potential (VEP) amplitudes but similar speeding of VEP latencies in the bilateral compared to the summed unilateral condition. The central P3 and pre-/post-response microstates were attenuated and topographically altered in ADHD boys. The attenuation was most pronounced in the bilateral condition and was similar for stimulus- and response-related averages. The lateralized readiness potential was also reduced in ADHD boys; this was most pronounced for the left hand responses.CONCLUSIONS: Brain mapping during uni- and bilateral stimulus and response conditions thus indicates multilevel deficits in ADHD boys affecting visuo-attentional, central, and pre-motor processes.     

Neurophysiological differences in inhibitory control between adults with ADHD and their peers

Inhibitory control allows individuals to suppress prepotent responses and resist irrelevant stimuli, and is thought to be a core deficit in Attention-deficit/hyperactivity disorder (ADHD). Whereas numerous studies have investigated neural mechanisms underlying inhibitory control deficits in children with ADHD, less is known about underlying mechanisms in young adults with ADHD. This study explores the neural correlates of inhibitory control in college students with ADHD—a population that, despite comparatively high educational attainment, still shows marked functional impairments in academic, social, and occupational functioning. Participants were 54 college students with ADHD and 29 typically developing peers. Specifically the fronto-centrally located N2 and the centro-parietal P3 event-related potential (ERP) components were hypothesized to show decreased amplitudes for the ADHD group due to their known association with inhibitory control. Dense array electroencephalography (EEG) data was collected during a Go/nogo task. Results show lower accuracy rates for the ADHD group and significant reductions in P3 amplitude as well as a trend for reduced N2 amplitude in nogo trials where subjects successfully inhibited a response. Notably, nogo N2 and P3 amplitudes correlated with the number of ADHD symptoms: namely, smaller amplitudes were associated with more symptoms. We conclude that when compared to their typically developing peers, relatively high functioning adults with ADHD still show a deviant neural signature. These results contribute to the growing literature of adult ADHD and increase our understanding of the neural correlates of inhibitory control associated with ADHD.     

How disgust facilitates avoidance: an ERP study on attention modulation by threats

This study investigated the attention modulation of disgust in comparison with anger in a dot-probe task. Results indicated a two-stage processing of attention modulation by threats. When participants viewed the cues that were represented by Chinese faces (i.e. the in-group condition), it was found at the early processing stage that an angry face elicited a larger occipital P1 component whereas a disgusted face elicited a smaller P1 for validly than for invalidly cued targets. However, the result pattern was reversed at the later processing stage: the P3 amplitudes were larger for valid disgust cues but were smaller for valid angry cues, when both were compared with invalid cue conditions. In addition, when participants viewed the cues that were represented by foreign faces (i.e. the out-group condition), the attention modulation of disgust/anger diminished at the early stage, whereas enhanced P3 amplitudes were observed in response to validly cued targets in both disgusting and angry conditions at the later stage. The current result implied that although people can perceptually differentiate the emotional categories of out-group faces as accurately as in-group faces, they may still be not able to psychologically understand the subtle differences behind different categories of out-group facial expressions.     

Age-related differences in auditory event-related potentials during a cued attention task.

OBJECTIVE: To determine if aging is associated with differences in attentional regulation using behavioral and event-related potential (ERP) measures. METHODS: Younger (n=13;M=20 years) and older (n=12;M=76 years) subjects performed an auditory cued attention task. Verbal cues correctly (valid) or incorrectly (invalid) predicted the ear receiving a target tone 1.5 s later, or were uninformative (neutral). Targets were either 'high' (2000 Hz) or 'low' (1000 Hz) pitch monaural tones. Subjects pressed one of 4 buttons to indicate target ear and pitch. ERPs following cues and targets (P50, N100, P200, slow waves), and negative slow potentials (CNV) between cues and targets were assessed. RESULTS: Cue information had significant effects on reaction time for both groups (validvalid) but not older subjects. Target slow waves were also affected by cue information (invalid>valid), and the difference was larger and lasted longer in older subjects. Slow waves following cues were significantly larger in older subjects, but the subsequent CNV amplitudes were comparable among groups. CONCLUSIONS: When performing a cued attention task, age differences are present in transient ERPs following cues and targets. SIGNIFICANCE: Age differences in ERPs associated with attentional regulation support the hypothesis that attentional changes contribute to cognitive aging.     

Callous-unemotional traits moderate executive function in children with ASD and ADHD: A pilot event-related potential study

Attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD) are associated with varied executive function (EF) difficulties. Callous-unemotional (CU) traits, a proposed antecedent of adult psychopathy, are often associated with intact or enhanced EF. Here we test whether CU traits may therefore modulate EF in ASD and ADHD, in which EF is typically impaired. We collected CU traits and measured event-related potentials (ERPs) that index EF during a cued-continuous performance test (CPT-OX) in boys with ASD, ADHD, comorbid ASD + ADHD and typical controls. We examined attentional orienting at cues (Cue-P3), inhibitory processing at non-targets (NoGo-P3) and conflict monitoring between target and non-target trials (Go-N2 vs. NoGo-N2). In children with ASD, higher CU traits were associated with an enhanced increase in N2 amplitude in NoGo trials compared to Go trials, which suggests relatively superior conflict monitoring and a potential cognitive strength associated with CU traits. The results emphasise the importance of considering the effects of co-occurring traits in the assessment of heterogeneity of EF profiles in neurodevelopmental disorders.     

Abnormal alpha modulation in response to human eye gaze predicts inattention severity in children with ADHD

Attention-deficit/hyperactivity disorder (ADHD) is characterized by problems in directing and sustaining attention. Recent behavioral studies indicated that children with ADHD are more likely to fail to show the orienting effect in response to human eye gaze. The present study aimed to identify the neurophysiological bases of attention deficits directed by social human eye gaze in children with ADHD, focusing on the relationship between alpha modulations and ADHD symptoms. The electroencephalography data were recorded from 8–13-year-old children (typically developing (TD): n = 24; ADHD: n = 21) while they performed a cued visuospatial covert attention task. The cues were designed as human eyes that might gaze to the left or right visual field. The results revealed that TD children showed a significant alpha lateralization in response to the gaze of human eyes, whereas children with ADHD showed an inverse pattern of alpha modulation in the left parieto-occipital area. Importantly, the abnormal alpha modulation in the left hemisphere predicted inattentive symptom severity and behavioral accuracy in children with ADHD. These results suggest that the dysfunction of alpha modulation in the left hemisphere in response to social cues might be a potential neurophysiologic marker of attention deficit in children with ADHD.     

Cognitive remediation in ADHD: effects of periodic non-contingent alerts on sustained attention to response

Few studies have attempted direct cognitive remediation of attention deficits in attention-deficit hyperactivity disorder (ADHD). The present study investigated the efficacy of periodic non-informative alerting cues for improving sustaining attention in ADHD. This technique is known to improve sustained attention in right frontal injury patients and may be effective in ADHD, given that this disorder has also been linked with right frontal dysfunction. Fifteen children with ADHD and 15 matched controls completed four blocks of a modified version of the Sustained Attention to Response Task (SART). Eight random non-contingent alerts were introduced on two of these blocks as a cue for participants to adopt a more supervisory stance to their performance. While the alerting cues did not alter the total number of commission errors committed by ADHD children over a task block, they did produce a significant short-term reduction in commission errors in the period immediately following an alerting cue. Our data demonstrate that sustained attention performance can be enhanced in children with ADHD using a simple cognitive training strategy. Methods from the field of cognitive rehabilitation may be viably applied to the remediation of attention deficits in ADHD.     

Somatosensory functioning in children with attention deficit hyperactivity disorder

In older to test the hypothesis that attention deficit hyperactivity disorder (ADHD) is related to deficits in somatosensory processing, 49 ADHD male children and 49 matched controls were tested on a wide range of tactile tasks, and somatosensory evoked potentials (SEP) were also recorded. In addition, parents' and teachers' ratings on the children's typical responses to tactile stimuli were obtained. The results show that the ADHD children were less skilled on suprathreshold, but not on threshold tasks than were the controls. Further, a larger percentage of ADHD children were 'tactile defensive'. Finally, the ADHD children showed Iarger-than-normal amplitudes of late, but not early components of the SEP. These data suggest that some aspects of somatosensory processing by ADHD children are deficient.     

Cognitive remediation in ADHD: Effects of periodic non-contingent alerts on sustained attention to response

Few studies have attempted direct cognitive remediation of attention deficits in attention-deficit hyperactivity disorder (ADHD). The present study investigated the efficacy of periodic non-informative alerting cues for improving sustaining attention in ADHD. This technique is known to improve sustained attention in right frontal injury patients and may be effective in ADHD, given that this disorder has also been linked with right frontal dysfunction. Fifteen children with ADHD and 15 matched controls completed four blocks of a modified version of the Sustained Attention to Response Task (SART). Eight random non-contingent alerts were introduced on two of these blocks as a cue for participants to adopt a more supervisory stance to their performance. While the alerting cues did not alter the total number of commission errors committed by ADHD children over a task block, they did produce a significant short-term reduction in commission errors in the period immediately following an alerting cue. Our data demonstrate that sustained attention performance can be enhanced in children with ADHD using a simple cognitive training strategy. Methods from the field of cognitive rehabilitation may be viably applied to the remediation of attention deficits in ADHD.     

Attention shifts and anticipatory mechanisms in hyperactive children: an ERP study using the Posner paradigm.

BACKGROUND: The aim of this study was to assess attentional, decisional, and motor processing stages during the performance of an attention shifting paradigm, both in normal children and children with attention-deficit/hyperactivity disorder (ADHD). METHODS: We recorded event-related potentials (ERPs) and performance measures during a variant of the Posner paradigm in 13 control subjects and 24 ADHD children. Subjects responded with a spatially concordant motor response to left or right visual targets, which could be either preceded by a spatial cue ("valid" = same side; "invalid" = opposite side) or presented uncued. RESULTS: Patients made significantly more errors than control subjects, with predominance of the anticipatory type. As compared to control subjects, ADHD children had faster reaction times, as well as a shortened interval between the N2 and P3 ERPs and the motor response. Patients also showed a decreased attentional priming effect on early sensory responses (P1). Finally, the slow negativity (contingent negative variation/readiness potential) that preceded the target in the "no cue" condition was absent in ADHD patients. CONCLUSIONS: The combined analysis of electrophysiological and behavioral data suggest a characteristic mode of response of ADHD in attention shifting tasks, characterized by "motor impulsivity" with release of motor responses before stimulus processing is adequately completed, as well as a lack of strategic planning/anticipatory mechanisms in the absence of warning stimulus. These deficits may be partly attributed to dysmaturation of executive frontal functions. In addition, a minor deficit in early attentional priming was also observed in ERPs, with no apparent behavioral counterparts.     

Orienting of spatial attention in Huntington's Disease

To explore the functioning of spatial attention in Huntington's Disease (HD), 14 HD patients and 14 age-matched controls performed a cued response time (RT) task with peripheral cues. In Experiment 1, cues were not informative about the future target location, thus eliciting a purely exogenous orienting of attention. At short stimulus-onset asynchrony (SOA), controls showed an initial facilitation for cued locations, later replaced by a cost (inhibition of return, IOR). Patients had a larger and more persistent validity effect, with delayed IOR, resulting from a larger cost for uncued targets. This suggests an impairment of attentional disengaging from cued locations. In Experiment 2, 80% of the cues were valid, thus inducing an initially exogenous, and later endogenous, attentional shift towards the cued box. The validity effect was larger in patients than in controls, again as a result of a disproportionate cost for uncued targets. In Experiment 3, 80% of the cues were invalid, thus inviting participants to endogenously re-orient attention towards the uncued box. Patients could take advantage of invalid cues to re-orient their attention towards the uncued targets but at a longer SOA than controls, thus suggesting that endogenous orienting is preserved in HD, but slowed down by the disengage deficit. The disengage deficit correlated with several radiological and biological markers of HD, thus suggesting a causal relationship between HD and attentional impairments. Cued RT tasks are promising tools for the clinical monitoring of HD and of its potential treatments.     

Potential effects of zinc on information processing in boys with attention deficit hyperactivity disorder

PURPOSE: The aims of the present study were to investigate the relationship between plasma zinc levels and amplitudes and latencies of P1, N2, and P3 in parietal and frontal areas in children with ADHD, and to compare these zinc levels and event-related potentials (ERPs) indices with controls. METHODS: 28 boys with ADHD were divided into two groups according to plasma zinc levels: low zinc group (N=13, zinc level <80 microg/dL) and zinc non-deficient group (N=15, zinc level >or=80 microg/dL). ERP indices from parietal and frontal brain regions were recorded in children with ADHD and in 24 normal boys by using an auditory oddball paradigm. Plasma zinc levels were measured by an atomic absorption spectrophotometer. RESULTS: The plasma zinc levels were significantly lower in both ADHD groups (means are 65.8 microg/dL in low zinc group and 89.5 microg/dL in zinc non-deficient group) than controls (mean: 107.8 microg/dL; both p values <0.017). In ADHD compared to controls, the amplitudes of P3 in frontal and parietal regions were significantly lower, and the latency of P3 in parietal region was significantly longer (all p values <0.017). In low zinc ADHD group compared to zinc non-deficient ADHD group, the latencies of N2 in frontal and parietal region were significantly shorter (all p values <0.017). In addition, there was a medium but significant positive correlation between plasma zinc levels and amplitude and latency of frontal N2 wave in ADHD. CONCLUSIONS: These results can suggest that plasma zinc levels might have an effect on information processing in ADHD children, and lower zinc levels seem to affect N2 wave. Since N2 wave changes may reflect a different inhibition process, further studies are warranted to investigate the effect of zinc on inhibitory process in children with ADHD, and in low zinc and non-deficient ADHD groups.     

Differences in attention, executive functioning, and memory in children with and without ADHD after severe traumatic brain injury.

Although the development of Attention Deficit Hyperactivity Disorder (ADHD) after traumatic brain injury (TBI) has been described, it is unknown whether children with TBI and ADHD have greater neuropsychological impairments than children with TBI alone. This study examines attention, executive functioning, and memory in children with TBI-only and TBI + ADHD. Caregivers of 82 children with severe TBI completed structured psychiatric interviews at enrollment to diagnose premorbid ADHD and one-year after injury to diagnose post-injury ADHD. Children underwent neuropsychological testing one year after injury. One memory measure significantly differentiated children with TBI-only from children with newly developed ADHD [secondary ADHD (S-ADHD)] and those with premorbid ADHD that persisted after injury [persisting ADHD (P-ADHD)]. Compared with the TBI-only group, children with TBI + ADHD had worse performance on measures of attention, executive functioning, and memory. Results reveal that in children with severe TBI, the behavioral diagnosis of ADHD is associated with more difficulty in attention, executive functioning, and memory. Additionally, results suggest greater deficits in memory skills in the S-ADHD group compared with the P-ADHD group. Although findings provide preliminary support for distinguishing P-ADHD from S-ADHD, further research is needed to investigate neuropsychological differences between these subgroups of children with severe TBI.     

An electrophysiological investigation of reinforcement effects in attention deficit/hyperactivity disorder: Dissociating cue sensitivity from down-stream effects on target engagement and performance

ObjectiveNeural hypo-sensitivity to cues predicting positive reinforcement has been observed in ADHD using the Monetary Incentive Delay (MID) task. Here we report the first study using an electrophysiological analogue of this task to distinguish between (i) cue related anticipation of reinforcement and downstream effects on (ii) target engagement and (iii) performance in a clinical sample of adolescents with ADHD and controls.MethodsThirty-one controls and 32 adolescents with ADHD aged 10–16 years performed the electrophysiological (e)-MID task − in which preparatory cues signal whether a response to an upcoming target will be reinforced or not − under three conditions; positive reinforcement, negative reinforcement (response cost) and no consequence (neutral). We extracted values for both cue-related potentials known to be, both, associated with response preparation and modulated by reinforcement (Cue P3 and Cue CNV) and target-related potentials (target P3) and compared these between ADHD and controls.ResultsADHD and controls did not differ on cue-related components on neutral trials. Against expectation, adolescents with ADHD displayed Cue P3 and Cue CNV reinforcement-related enhancement (versus neutral trials) compared to controls. ADHD individuals displayed smaller target P3 amplitudes and slower and more variable performance − but effects were not modulated by reinforcement contingencies. When age, IQ and conduct problems were controlled effects were marginally significant but the pattern of results did not change.DiscussionADHD was associated with hypersensitivity to positive (and marginally negative) reinforcement reflected on components often thought to be associated with response preparation − however these did not translate into improved attention to targets. In the case of ADHD, upregulated CNV may be a specific marker of hyper-arousal rather than an enhancement of anticipatory attention to upcoming targets. Future studies should examine the effects of age, IQ and conduct problems on reinforcement sensitivity in ADHD.