Event-related potentials in adults with Attention-Deficit/Hyperactivity Disorder: An investigation using an inter-modal auditory/visual oddball task

Hearing abilities in children with dyslexia and attention deficit hyperactivity disorder

BACKGROUND

auditory processing and co-occurrence of pathologies.

AIM

to investigate the performance of children with Dyslexia and attention deficit hyperactivity disorder (ADHD) in behavioral and auditory processing tests, comparing the results to a control group.

METHOD

participants of the study were 30 children, with ages between 7 and 12 years, divided into three groups: a control group of 10 children, a study group of 10 children with dyslexia and a study group of 10 children with ADHD. All participants were submitted to the following auditory processing tests: Speech in Noise, Dichotic of Digits and Frequency Pattern.

RESULTS

concerning the Speech in Noise Test, there was an interactive effect between the control group and the ADHD group (p < 0.001), with the ADHD group presenting a significantly lower performance; for the Dichotic of Digits test, there was an interactive effect between the three groups (p < 0.001), with the ADHD group presenting a lower performance, followed by the dyslexic and control groups; for the Frequency Pattern, there was a marginal effect (p = 0.056) with the ADHA group presenting a lower performance, followed by the dyslexic and control groups.

CONCLUSION

the ADHD group presented a poorer performance in all tests when compared to the dyslexic and control groups. This result suggests a relationship between attention and hearing abilities.

P300 deficits in adults with attention deficit hyperactivity disorder: a meta-analysis

BACKGROUND

The P300 (P3) event-related potential (ERP) component, a possible endophenotype for attention deficit hyperactivity disorder (ADHD), has been widely examined in children, but received little attention in adults. Our objective was to conduct a meta-analysis of P3 studies in adults with ADHD.

METHOD

We searched the Medline and PsycINFO databases for controlled studies examining both adult ADHD and matched healthy controls. Six relevant publications were identified for the meta-analysis, which had comparable data across studies with regard to the amplitude of ERP components related to target detection (P3, P3b). Pooled effect size (ES) for P3 amplitude as well as the association of the ES with age and gender were investigated using meta-regression.

RESULTS

Comparing the ADHD group versus controls, the pooled effect size for a decrease in P3 amplitude was in the medium range (Cohen's d=-0.55, p=0.0006). Additionally, meta-regression revealed that decrease in P3 amplitude significantly varied with the mean age of ADHD patients (p=0.0087), with a gradual increasing of the difference at higher ages. Results also showed a significant association between the ES and gender, indicating a more pronounced reduction of P3 amplitude in the ADHD group versus controls when females were predominantly represented in the sample.

CONCLUSIONS

To our knowledge, this is the first meta-analysis of P3 characteristics in adults with ADHD. It reveals a significantly decreased P3 amplitude during target detection. Our result that the reduction in P3 amplitude increases with age is interpreted in a neurodevelopmental context.

Impaired engagement of the ventral attentional pathway in ADHD

In the cognitive theories of Attention Deficit Hyperactivity Disorder (ADHD) impaired behavioral adjustment has been linked to a deficit in learning to detect regularities or irregularities in the environment. In the neural level, the P3 component of event-related potential (ERP) is modulated by stimulus probability and has been suggested to index activation of the ventral attention network, which constitutes the reorienting system of the human brain. To explore the cortical basis of late positive ERP components and the engagement of the ventral attentional pathway in ADHD, we used ERP recordings complemented by spatiotemporally sensitive magnetoencephalography (MEG) measurements. We followed the activation evoked by frequent Go and infrequent NoGo stimuli in 10 ADHD adults and 13 control subjects. In the ERP recordings, a prominent positive deflection was detected after the infrequent visual stimuli (late positive component, LPC) in both subject groups. In ADHD adults the difference between the responses evoked by infrequent NoGo and frequent Go stimuli was markedly reduced compared to the control group during the LPC. The MEG recordings revealed that the activation detected during the LPC was localized bilaterally in the posterior temporal cortex. Activation of the left and right temporal regions was enhanced after infrequent NoGo stimuli in both subject groups. In ADHD adults, however, the effect of stimulus frequency was less pronounced. We suggest that the activation in the superior temporal cortices during the LPC reflects the action of ventral attention network. The engagement of this stimulus-driven reorienting system is defective in ADHD.

Word recognition memory in adults with attention-deficit/hyperactivity disorder as reflected by event-related potentials

Objective: Attention-deficit/hyperactivity disorder (ADHD) is increasingly diagnosed in adults. In this study we address the question whether there are impairments in recognition memory. Methods: In the present study 13 adults diagnosed with ADHD according to DSM-IV and 13 healthy controls were examined with respect to event-related potentials (ERPs) in a visual continuous word recognition paradigm to gain information about recognition memory effects in these patients. Results: The amplitude of one attention-related ERP component, the N1, was significantly increased for the ADHD adults compared with the healthy controls in the occipital electrodes. The ERPs for the second presentation were significantly more positive than the ERPs for the first presentation. This effect did not significantly differ between groups. Conclusion: Neuronal activity related to an early attentional mechanism appears to be enhanced in ADHD patients. Concerning the early or the late part of the old/new effect ADHD patients show no difference which suggests that there are no differences with respect to recollection and familiarity-based recognition processes.

Spontaneous EEG Oscillations in Children, Adolescents, and Adults

Data are presented on EEG activity in typically developing controls, focusing on the traditional delta, theta, alpha, and beta bands through childhood, with some extensions into adolescence and adults. Both eyes-closed and eyes-open resting state data are discussed. These reflections of typical development provide a framework for illustrating EEG differences in people with attention deficit/hyperactivity disorder (AD/HD), and its main diagnostic types, from children to adults. Comorbidity effects in the EEG of children with AD/HD, particularly comorbid reading disabilities and conduct disorders, are also described. Some recent explorations of the links between arousal/activation and EEG activity may contribute to our understanding of the functional nature of brain oscillations in this context. Other aspects of oscillatory brain activity, coherence and event-related potentials, are also briefly discussed within this framework.