EEG Activity in Subtypes of Attention-Deficit/Hyperactivity Disorder

ABSTRACT

This article is a review of electroencephalography (EEG) studies of different types and subtypes of Attention-Deficit/Hyperactivity Disorder (AD/HD). The review outlines the definitional history of AD/HD, and changes that have been made to the conceptualization of the disorder as these different definitions have impacted on the EEG literature. EEG studies are examined using various models of AD/HD based on either behaviour or underlying central nervous system (CNS) abnormalities. From these studies, it appears that AD/HD children generally have increased absolute and relative power in the theta band, either at the frontal electrode sites or over the entire scalp. Reductions in absolute and relative power in the alpha and beta bands have also been found in several studies, although relative power measures appear to be more reliable than absolute power. Increased delta activity in both absolute and relative power has also been noted in several studies. These results are discussed in terms of existing CNS-based models of AD/HD, which attribute the disorder to hypoarousal or a maturational lag in CNS development. Implications of these data for clinical use and future research and development in AD/HD are considered.     

EEG Activity in Females with Attention-Deficit/Hyperactivity Disorder

Although Attention-Deficit/Hyperactivity Disorder (AD/HD) affects millions of females worldwide, our understanding of AD/HD continues to be based heavily on male-dominated research. Significant sex differences reported in the presentation and diagnosis of AD/HD can no longer be ignored; females with AD/HD are different from males with the disorder. Electroencephalography (EEG) is a valuable tool for measuring electro-cortical activity and has been found useful in AD/HD research. Preliminary studies have shown that females with AD/HD have EEG abnormalities different from those found in males with AD/HD. This article reviews the current literature on EEG activity of females with AD/HD and concludes that the lack of comprehensive research draws attention to the necessity for sex-specific EEG research within AD/HD populations.     

Changes After EEG Biofeedback and Cognitive Retraining in Adults with Mild Traumatic Brain Injury and Attention Deficit Hyperactivity Disorder

Abstract

Introduction. Adults diagnosed with mild traumatic brain injury (mTBI) or Attention Deficit Hyperactivity Disorder (ADHD) were treated with EEG Biofeedback and cognitive retraining.

Methods. Psychological and neuropsychological tests were completed at pre-treatment and post-treatment and compared to a normal control group that did not receive training, but tested on two occasions.

Results. The results found significant improvement on full scale attention and full scale response accuracy of a continuous performance task in the mTBI and ADHD groups compared to the control group. A self report showed a significant decline in symptoms in the mTBI and ADHD groups compared to the control group. Errors on a problem solving task decreased only in the mTBI group.

Discussion. The treatment model used in this study showed significant improvement in the sustained attention of individuals diagnosed with mTBI and ADHD after twenty treatment sessions.     

EEG and electrodermal activity in girls with Attention-Deficit/Hyperactivity Disorder

ObjectiveThis study investigated the Hypoarousal Model of Attention-Deficit/Hyperactivity Disorder (AD/HD) in girls.Methods40 girls with AD/HD and 40 girl controls (aged 7–12 years) had an eyes-closed resting EEG recorded from 19 electrodes and Fourier transformed. Estimates for total power, absolute and relative power in the delta, theta, alpha, beta and gamma frequency bands, and theta/beta ratio were analysed in nine cortical regions. Skin conductance level (SCL) was simultaneously recorded. Regression analyses explored relationships between symptoms and physiology.ResultsCompared with controls, girls with AD/HD had globally elevated relative delta, globally reduced absolute beta, and globally reduced absolute and relative gamma activity. Girls with AD/HD also had lower mean SCL. Inattentive symptoms were predicted by elevated frontal relative delta, reduced SCL, and reduced temporal relative gamma activity, while elevated hyperactive–impulsive symptoms correlated with elevated frontal relative delta activity in both the patient and control groups.ConclusionsThese EEG results are comparable with the limited female AD/HD literature. Girls with AD/HD are hypoaroused, indicated by reduced SCL, and appear to have an anomalous arousal mechanism. Absolute and relative gamma results are similar to previous findings in AD/HD children. Symptom correlations with physiology offer intriguing insights for future research.SignificanceThis is the first study to examine CNS arousal exclusively in girls with AD/HD.     

Resting-state EEG gamma activity in children with Attention-Deficit/Hyperactivity Disorder

Objective

Children with Attention-Deficit/Hyperactivity Disorder (AD/HD) have well-described abnormalities in the four traditional EEG bands. However, to date the gamma band has not been widely investigated. This study investigated resting-state EEG in children with AD/HD and matched controls, with a particular focus on gamma activity.

Method

Forty children with AD/HD, and 40 age- and sex-matched controls, participated. EEG was recorded from 19 sites during an eyes-closed resting condition and Fourier transformed to provide estimates for absolute and relative power in the delta, theta, alpha, beta and gamma bands.

Results

Children with AD/HD had elevated levels of absolute delta and theta power, and decreased levels of absolute beta and gamma power, compared to controls. With relative power measures, children with AD/HD showed enhanced delta and theta activity, with reduced alpha, beta and gamma activity. Inattention scores on the Conners’ Parent Rating Scale were negatively correlated with absolute gamma.

Conclusions

These patients demonstrate the typical EEG profile in the eyes-closed resting state, over the delta, theta, alpha and beta bands, associated with AD/HD. In addition, compared with controls, they demonstrate reduced absolute and relative gamma activity. These differences appear to contribute importantly to their dysfunctional stimulus processing, and impact their behavioural outcomes.

Significance

This resting-state study extends the well-established fast-wave EEG deficits in children with AD/HD to the gamma band, and links that to increased inattention, which is of special importance in understanding their cognitive-processing problems.     

Double-Blind Placebo-Controlled Randomized Clinical Trial of Neurofeedback for Attention-Deficit/Hyperactivity Disorder With 13-Month Follow-up

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Correlation Between EEG Activity and Behavior in Children with Attention-Deficit/Hyperactivity Disorder

The aim of this study was to determine whether EEG activity in specific bands correlated with the core behavioral symptoms of children with attention-deficit/hyperactivity disorder (AD/HD). Sixty boys diagnosed with AD/HD Combined type and 60 age-matched male controls participated in this study. An EEG was recorded during an eyes-closed resting condition and relative power estimates in the delta, theta, alpha, and beta bands, and the theta/beta ratio, were calculated. The EEG measures of the AD/HD group were converted to z scores relative to the controls, and these were correlated with scores on the Conners' Rating Scale obtained from a parent. The AD/HD group had global increases in theta activity and the theta/beta ratio, increased frontal delta, with reduced global alpha and frontal beta activity. Frontal theta activity correlated with inattention, the theta/beta ratio correlated with hyperactivity-impulsivity, and both measures correlated with a Combined type diagnosis. EEG power anomalies in AD/HD are associated with specific symptom clusters in the disorder.     

Clinical Utility of EEG in Attention-Deficit/Hyperactivity Disorder: A Research Update

Psychiatric research applications of electroencephalography (EEG), the earliest approach to imaging human cortical brain activity, are attracting increasing scientific and clinical interest. For more than 40 years, EEG research has attempted to characterize and quantify the neurophysiology of attention-deficit/hyperactivity disorder (ADHD), most consistently associating it with increased frontocentral theta band activity and increased theta to beta (θ/β) power ratio during rest compared to non-ADHD controls. Recent reports suggest that while these EEG measures demonstrate strong discriminant validity for ADHD, significant EEG heterogeneity also exists across ADHD-diagnosed individuals. In particular, additional studies validating the use of the θ/β power ratio measure appear to be needed before it can be used for clinical diagnosis. In recent years, the number and the scientific quality of research reports on EEG-based neurofeedback (NF) for ADHD have grown considerably, although the studies reviewed here do not yet support NF training as a first-line, stand-alone treatment modality. In particular, more research is needed comparing NF to placebo control and other effective treatments for ADHD. Currently, after a long period of relative stasis, the neurophysiological specificity of measures used in EEG research is rapidly increasing. It is likely, therefore, that new EEG studies of ADHD using higher density recordings and new measures drawn from viewing EEG as a 3-dimensional functional imaging modality, as well as intensive re-analyses of existing EEG study data, can better characterize the neurophysiological differences between and within ADHD and non-ADHD subjects, and lead to more precise diagnostic measures and effective NF approaches.     

Attention-Deficit/Hyperactivity Disorder and comorbidity in Brazil

Abstract. Objective: The aim of this study was to compare the pattern of comorbidity in referred samples of Attention-Deficit/Hyperactivity Disorder (ADHD) patients from two different geographic areas in Brazil. Methods: The diagnoses of ADHD and comorbid conditions, according to DSM-IV criteria, were achieved in both clinics through semi-structured interview methodology, complemented by clinical interviews with the children or adolescents and their parents. Results: We assessed 343 ADHD children and adolescents in Porto Alegre (capital of the southernmost state of the country) and 78 ADHD youths in Rio de Janeiro (capital of a southestern state). Although a significant difference in the prevalence of ADHD without comorbidity was detected between the two groups (p = 0.02), no significant difference was detected in the profile of comorbidities between them. Main ADHD comorbidities in both samples were: a) Oppositional Defiant Disorder (Porto Alegre = 39.1%; Rio de Janeiro = 51.3 %); b) Anxiety Disorders (Porto Alegre = 24.2%; Rio de Janeiro = 30.8 %); c) Conduct Disorder (Porto Alegre = 13.7%; Rio de Janeiro = 17.9 %); and d) Major Depression and/or Dysthymia (Porto Alegre = 11.4%; Rio de Janeiro = 10.3 %). Conclusions: Our results from clinical samples in a developing country with a diverse culture suggest the crosscultural validity of the ADHD comorbidity profile.     

Resting state EEG power research in Attention-Deficit/Hyperactivity Disorder: A review update

This article reviews the eyes-open and eyes-closed resting electroencephalogram (EEG) literature for Attention-Deficit/Hyperactivity Disorder (AD/HD) from 2002 to 2019. This time has seen substantial increase in interest in resting state EEG, with investigations moving from a comparison of an AD/HD sample to a control group, to research investigating a wide range of theoretical and clinical aspects of the disorder. This has included investigations of subgroups based on their EEG profile, sex differences in the EEG, increasing interest in the EEG of adults, and the effects of comorbid disorders on the EEG of people with AD/HD. Research has further investigated the hyper- and hypo- arousal models of AD/HD, as well as the developmental deviation model. From a clinical perspective, a growing body of literature is emerging trying to ascertain if the EEG can be used as a diagnostic test, particularly the theta/beta ratio. While these advances have been made, there is widespread use of both the eyes-open and eyes-closed resting paradigms as being interchangeable, despite the two paradigms differ on a number of important factors. There is also lack of independent replication within the literature, which is needed to consolidate many of the findings that have been published.     

Effects of Acute Exercise on Resting EEG in Children with Attention-Deficit/Hyperactivity Disorder

This two stage study examined the effects of acute exercise on resting electroencephalographic (EEG) patterns of children with attention-deficit hyperactivity disorder (ADHD). The first stage compared the neural oscillatory patterns of children with and without ADHD. Resting EEGs were recorded under an open-eyes condition from 24 boys with ADHD and 28 matched controls. The second stage of the study employed a randomized cross-over trial design. The 24 boys with ADHD engaged in a 30-min intervention that consisted of either running on a treadmill or watching a video on alternative days, with resting EEGs recorded before and after treatment. The first stage found that children with ADHD exhibited significantly higher theta/beta ratios over the midline electrodes sites than controls. The second stage further indicated that children with ADHD displayed smaller theta/beta ratios following the exercise condition compared with the video-watching condition. This finding suggests that acute exercise normalizes arousal and alertness of children with ADHD, as reflected in resting EEG readings.