Effects of stimulant medications on children with attention-deficit/hyperactivity disorder and excessive beta activity in their EEG.

OBJECTIVE: This study investigated the effects of stimulant medications on the Electroencephalography (EEG) of children with the combined type of attention-deficit/hyperactivity disorder (ADHD) together with excessive beta activity in their EEG. METHODS: Twenty ADHD and 20 control subjects participated in this study. EEG was recorded from 21 sites during an eyes-closed resting condition and Fourier transformed to provide estimates for total power and absolute and relative power in the delta, theta, alpha and beta bands, and for the theta/alpha and theta/beta ratios. Subjects were placed on a 6-month trial of a stimulant medication and a second EEG was recorded at the end of the trial. RESULTS: The unmedicated ADHD group had greater absolute and relative beta, less absolute and relative alpha, a higher theta/alpha and a lower theta/beta ratio than the control group. In the frontal regions the ADHD group had an increase in total power, absolute theta, absolute and relative beta and the theta/beta ratio, with greater relative delta, relative theta, and absolute and relative alpha in posterior regions. With medication use, absolute beta activity and frontal total power decreased, although these changes represented a reduction in power, not a normalisation. CONCLUSIONS: These results indicate that ADHD children with excessive beta activity in their EEG are probably not hypoaroused as previously suggested, and that beta activity in these children is probably only associated with the impulsivity and/or hyperactivity aspects of the disorder, but may not necessarily be associated with inattention. SIGNIFICANCE: This study is the first to investigate effects of stimulant medications on the EEG of ADHD children with excessive beta activity in their EEG.     

Age and sex effects in the EEG: development of the normal child.

OBJECTIVES: This study investigated age-related changes and sex differences in the EEGs of normal children. METHODS: Forty boys and 40 girls, between the ages of 8 and 12 years, participated in this study. The EEG was recorded during an eyes-closed resting condition and Fourier transformed to provide estimates for total power, absolute and relative power in the delta, theta, alpha and beta bands, and for theta/alpha and theta/beta ratios. RESULTS: Absolute delta activity decreased with age. Relative delta and theta decreased and alpha and beta increased with increasing age. The theta/alpha and theta/beta ratios decreased with increasing age. All of these indicated a developmental reduction in slow wave activity. Maturational differences were found in the rates of change between the midline and the two hemispheres. In the absolute delta and the theta/beta ratio, the midline and the two hemispheres became more equipotential with age. In the beta band, power increased at a greater rate than in the two hemispheres. Sex differences were found, with males having less theta and more alpha than females. CONCLUSIONS: These results indicated that maturation occurs earlier at the midline than in the two hemispheres. Females were also found to have a developmental lag in the EEG compared with males.     

Increased EEG power density in alpha and theta bands in adult ADHD patients

This study examined EEG abnormalities in adults with attention deficit hyperactivity disorder (ADHD). We investigated EEG frequencies in 34 adults with ADHD and 34 control subjects. Two EEG readings were taken over 5 min intervals during an eyes-closed resting period with 21 electrodes placed in accordance with the international 10–20 system. Fourier transformation was performed to obtain absolute power density in delta, theta, alpha and beta frequency bands. The ADHD patients showed a significant increase of absolute power density in alpha and theta bands. No differences were found for beta activity. Our findings indicate that abnormalities in the EEG power spectrum of adults with ADHD are different than those described in children. Reliable discriminators between patients and healthy subjects in adulthood could be alpha and theta power density. Based on our results, we suggest further research involving longitudinal studies in ADHD patients to investigate the changes of EEG abnormalities with age.     

Changes in absolute power values of EEG spectra in the follow-up of Alzheimer's disease

We have studied the absolute and relative power and amplitude of EEG spectra (T6–02) of 24 patients with "probable" Alzheimer's disease at the early stage of the disease and 1 year later and also compared the values to those of normal elderly controls. A remarkable variability of the absolute values was evident both for the patients and for the controls. The AD patients had significantly higher absolute theta amplitude and power and the absolute beta values tended to decrease compared to controls. Absolute delta and alpha values did not differ from those of the controls. The relative delta, theta and alpha power and amplitude, and beta amplitude showed significant changes in AD patients, whereas the relative beta power was unchanged. In the follow-up of AD patients at 1 year, absolute alpha values decreased and delta values tended to increase. As to relative values, both the alpha and the delta significantly changed but the theta and the beta were unaltered. We conclude that both absolute and relative power and amplitude values should be considered in EEG studies of dementia patients. Absolute values are especially useful in follow-up.     

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.     

Individual analysis of EEG background-activity within school age: impact of age and sex within a longitudinal data set

Objectives

Quantitative EEG can monitor changes in brain function during development and may help to understand developmental disorders. However, current EEG-databases are primarily based on standardized frequency bands which disregard age-related changes in alpha peak frequency (PF) and therefore complicate the interpretation of spectral estimates in the theta and alpha range.

Methods

We used a two point longitudinal design in order to analyze intraindividual changes in 40 healthy children and adolescents with age (T₁: 6-18 years; interval approximately 4 years). Using a 64-channel eyes closed resting EEG we calculated absolute/relative power in individualized frequency bands (IFB: delta, theta, alpha_1/2 and beta) based on PF.

Results

PF increased with age, with changes being larger for children than adolescents. Controlling for changes in PF, changes in absolute/relative alpha_1/2 power and in absolute beta power were minor. Relative beta power, however, increased while absolute/relative delta and theta power decreased massively.Sex-differences in PF did not reach significance. However, boys exhibited larger changes during adolescence than girls for all absolute power measures except alpha.

Conclusion

Normal EEG development during school-age is mainly based on an absolute decrease of slow frequency activity and increases of PF which may be interpreted in terms of a reorganization of the EEG towards a higher frequency oscillatory scale rather than a maturation of the theta-alpha_1/2 band power sequence. Age-related changes differed between boys and girls suggesting a different developmental timing for the sexes. In future studies a combined analysis of PF and IFB may help to specify deviations in developmental disorders.     

EEG differences between eyes-closed and eyes-open resting conditions

OBJECTIVE: Recent work has attempted to clarify the energetics of physiological responding and behaviour by refining and separating the operational definitions of "arousal" and "activation", which have different effects on physiological responding and behaviour. At the EEG level, we relate the former to widespread activity, and the latter to task-specific topographically-focussed activity reflecting regional processing. This study aimed to investigate this further in terms of differences in EEG activity between eyes-closed and eyes-open resting conditions. METHODS: EEG activity was recorded from 28 university students during both eyes-closed and eyes-open resting conditions, Fourier transformed to provide estimates for absolute power in the delta, theta, alpha and beta bands, and analysed in 9 regions across the scalp. Skin conductance level was also measured as an indicator of arousal level. RESULTS: Across the eyes-closed conditions, skin conductance levels were negatively correlated with mean alpha levels. Skin conductance levels increased significantly from eyes-closed to eyes-open conditions. Reductions were found in across-scalp mean absolute delta, theta, alpha and beta from the eyes-closed to eyes-open condition. Topographic changes were also evident in all bands except for alpha, with reduced lateral frontal delta and posterior theta, and decreased posterior/increased frontal beta in the eyes-open condition. In particular, the topographic beta effects indicate that the across-scalp reduction arose from focal reductions rather than global changes. CONCLUSIONS: The obtained results confirm the use of mean alpha level as a measure of resting-state arousal under eyes-closed and eyes-open conditions. The focal nature of EEG effects in the other bands suggests that these reflect cortical processing of visual input, producing differences in activation between eyes-closed and eyes-open resting conditions, rather than just the simple increase in arousal level shown in alpha. SIGNIFICANCE: This study demonstrates that the eyes-closed and eyes-open conditions provide EEG measures differing in topography as well as power levels. These differences should be recognised when evaluating EEG research, and considered when choosing eyes-open or eyes-closed baseline conditions for different paradigms.     

Quantified EEG and psychometric effects of 3 doses of dexfenfluramine in the young adult

In an acute, double-blind placebo-controlled study, three groups of nine healthy subjects were included. Each group received, in randomized and weekly intervals, a single oral dose of dexfenfluramine (15 mg, 30 mg or 60 mg) or placebo. Psychometric and EEG studies were carried out before as well as 1, 2, 3, 4, 5 and 6 h after drug administration. Changes from predrug to postdrug conditions for each time were determined by the ratio of absolute spectral power and compared to the evolution of power spectra under placebo conditions. Statistical evaluation was done with ANOVA. Dexfenfluramine induced a dose-dependent decrease of power spectra for theta and alpha 1 bands and an increase for the beta band. Topographic brain mapping of these significant changes displayed a central and posterior decrease for theta and alpha 1 bands, and a temporal localization for the beta-power. Maps of relative power-enhanced changes were seen in absolute power and provided false displays. Psychometric evaluation of dexfenfluramine effects only showed trends to extraversion and increased mood scores but no statistical significance was found. Arousal and performance tests were unchanged. These results suggest that qEEG variations are more sensitive to serotonergic drug effects than psychometric investigations. It appears that spontaneous EEG power spectra variations with time must be accounted for by drug evaluation. Absolute power variations are more reliable than relative power. Methodological implications are discussed.     

EEG abnormalities in adolescent males with AD/HD.

OBJECTIVE: This study investigated EEG abnormalities in adolescents with attention-deficit/hyperactivity disorder (AD/HD). METHODS: Fifteen AD/HD subjects and 15 control subjects participated in this study. All subjects were between 14 and 17 years of age. The EEG was recorded from 19 electrode sites and was analysed to provide estimates of both absolute and relative power in the delta, theta, alpha and beta bands. Theta/alpha and theta/beta ratio coefficients were also calculated. RESULTS: Across the scalp, AD/HD subjects were characterised by greater absolute delta and theta activity, and an increased theta/beta ratio compared to controls. No group differences were found for either absolute or relative alpha, or absolute beta. However, AD/HD subjects demonstrated a reduction in relative beta activity in the posterior regions. CONCLUSIONS: The AD/HD group showed significant deviations from normal CNS development, in particular in posterior regions. This supports previous suggestions that individuals with an EEG profile that is not indicative of a maturational lag are more likely to have AD/HD during adolescence. SIGNIFICANCE: This is the first study to investigate EEG abnormalities in adolescents with AD/HD during an eyes-closed resting condition.     

EEG and behavioral changes following neurofeedback treatment in learning disabled children.

Neurofeedback (NFB) is an operant conditioning procedure, by which the subject learns to control his/her EEG activity. On one hand, Learning Disabled (LD) children have higher values of theta EEG absolute and relative power than normal children, and on the other hand, it has been shown that minimum alpha absolute power is necessary for adequate performance. Ten LD children were selected with higher than normal ratios of theta to alpha absolute power (theta/alpha). The Test Of Variables of Attention (TOVA) was applied. Children were divided into two groups in order to maintain similar IQ values, TOVA values, socioeconomical status, and gender for each group. In the experimental group, NFB was applied in the region with highest ratio, triggering a sound each time the ratio fell below a threshold value. Noncontingent reinforcement was given to the other group. Twenty half-hour sessions were applied, at a rate of 2 per week. At the end of the 20 sessions, TOVA, WISC and EEG were obtained. There was significant improvement in WISC performance in the experimental group that was not observed in the control group. EEG absolute power decreased in delta, theta, alpha and beta bands in the experimental group. Control children only showed a decrease in relative power in the delta band. All changes observed in the experimental group and not observed in the control group indicate better cognitive performance and the presence of greater EEG maturation in the experimental group, which suggests that changes were due not only to development but also to NFB treatment.     

Blinded, prospective, and serial evaluation by quantitative-EEG in interferon-alpha-treated hepatitis-C

OBJECTIVES: To estimate the effect of brain function due to IFN-alpha in chronic hepatitis C patients by the quantitative EEG. METHODS: 56 chronic hepatitis C patients were administered IFN-alpha intramuscularly at 9x10(6) IU daily for the first 4 weeks and then 3 times/week for the next 20 weeks. Serial EEGs were obtained in each subject before, at 2 and 4 weeks, and after completing the treatment. Resting EEG without artifacts was selected for quantitative EEG analysis, which was performed blindly. The frequency range was divided into delta to beta. The absolute and relative powers of each frequency band in each subject were calculated and the differences of these powers at different stages were analyzed statistically. RESULTS: The absolute powers of slow waves (delta, theta 1, and theta 2) increased while alpha 2 and fast wave (beta) decreased significantly at all locations during IFN-alpha administration. The total power and alpha 1 values revealed no significant alterations. The relative power revealed the same alteration during treatment. These changes disappeared following the treatment. Such diffuse slowing in the EEG was revealed by the total change in the whole subjects. CONCLUSIONS: Diffuse slowing in the EEG was induced by IFN-alpha, was reversible, and was evident as the total change in the subjects. These findings suggested mild IFN-alpha-induced encephalopathy.     

Quantitative EEG in schizophrenia and in response to acute and chronic clozapine treatment

Topographic quantitative electroencephalographic (EEG) power and frequency indices were collected in 17 treatment refractory, DSM-III diagnosed schizophrenic patients, before and after acute (single dose) and chronic (six weeks) clozapine treatment, as well as in 17 healthy volunteers. Prior to treatment, patients exhibited greater overall absolute theta power, slower mean alpha frequency and elevated absolute delta and total power in anterior regions. Acute dosing increased total spectrum power globally, slow wave power posteriorally, mean alpha frequency and beta power anteriorally and decreased alpha power posteriorally. Six weeks of clozapine treatment significantly reduced clinical ratings of positive and negative symptoms as well as symptoms of global psychopathology. Chronic treatment resulted in EEG slowing as shown by decreases in relative alpha power, mean beta/total spectrum frequency and by widespread increases in absolute total and delta/theta power. The preliminary findings suggest that brain electric profiling may be a promising tool for assessing and understanding the central impact of pharmacotherapeutic interventions in schizophrenia.     

EEG background activity in patients with dementia of the Alzheimer type--with special reference to analysis by t-statistic significance probability mapping (SPM) in Alzheimer's disease and senile dementia

EEG power amplitude and power ratio data obtained from 15 (3 men and 12 women) patients with Alzheimer's disease (AD) and 8 (2 men and 6 women) with senile dementia of Alzheimer type (SDAT) were compared with similar data from 40 age- and sex-matched normal controls. Compared with the healthy controls, both patient groups demonstrated increased EEG background slowing, and it indicated more slower in AD than in SDAT. Moreover, both groups showed characteristic findings respectively on EEG topography and t-statistic significance probability mapping (SPM). The differences between AD and their controls indicated high slowing with reductions in alpha 2, beta 1 and beta 2 activity. The SPMs of power ratio in theta and alpha 2 bands showed most prominent significance in the right posterior-temporal region and delta and beta bands did in the frontal region. Severe AD indicated only frontal delta slowing compared to mild AD. The differences between SDAT and their controls indicated only mild slowing in delta and theta bands. The SPM of power amplitude showed occipital slowing, whereas the SPM of power ratio showed the slowing in the frontal region. Judging from both topographic findings, these were considered to denote diffuse slow tendency. In summary, these results presumed that in AD, cortical damages followed by EEG slowing with reductions of alpha 2 and beta bands originated rapidly and thereafter developed subcortical (non-specific area in thalamus) changes with frontal delta activity on SPM. On the other hand, in SDAT, diffuse cortico-subcortical damages with diffuse slowing on EEG topography were caused gradually.     

Computerized electroencephalographic assessment of congenital brain infarction

We studied 12 children (8 female and 4 male) aged 2.2–14.3 years, whose computed tomographic (CT) examination had shown evidence of malacic and/or porencephalic outcomes of early vascular brain infarction. Topographic spectral electroencephalographic (EEG) analysis was performed in all patients in the awake state. The following spectral EEG variables were studied: topography, absolute and relative power of delta, theta, alpha, beta bands, overall power, and peak alpha frequency asymmetries. The results of topographic spectral EEG analysis were compared with the localization and nature of lesions as detected by CT scans. Depending on the nature of the lesions, we were able to identify two different spectral patterns. Porencephalic cysts were characterized by an increase in delta and theta bands in the areas surrounding the lesion sites, as identified by CT. Spectral EEG patterns of malacic outcomes resulted in a focal increase in theta and delta band power, corresponding to the topography of lesions. Moreover, in 9/12 subjects an asymmetry of alpha rhythm in occipital leads was found homolaterally to the lesion sites, associated with a decrease in power, without any CT evidence of an occipital lesion.     

Variation in power spectral analysis of the EEG with gestational age

Power spectral analysis (PSA) of the EEG was studied in healthy term and preterm neonates to establish the normal range with gestational age. Sixty healthy newborn infants from 26 to 41 weeks' gestation had PSA performed at 3 days of age. Five main frequency bands were studied: delta 1 (1 Hz or less), delta 2 (2-3 Hz), theta, alpha, and beta. A significant correlation was shown between absolute power in delta 1 and delta 2 with gestational age. Relative power of each frequency band, calculated as a percentage of the total power in each channel, also correlated with gestational age. A significant quadratic relationship between absolute power in the beta range and gestational age is described for the first time.     

Short-term variability in EEG frequency analysis

Knowledge of short-term EEG variability in computerized analysis is important before interpreting spectral EEGs or assessing changes that may be due to inherent variability and not necessarily related to a task (e.g., listening to a story), therapy or changes in underlying disease. Eighty to 120 sec of 14-channel, edited, bipolar EEG were recorded in normal subjects and analyzed using an FFT. Absolute and relative power in 5 standard frequency bands, and median and peak power frequencies were obtained for each 4 sec epoch, and the mean and standard deviation calculated for each parameter. The average variation of the mean power, absolute and relative, in the frequency bands was less than 10% although some parameters varied by up to 50% in an individual subject. Median and peak power had the least variability, about 3%. Changes in total power correlated positively with relative alpha power, but negatively or not at all with the other relative power measures. This suggests that interpretation of relative measures of delta, theta and beta in individual spectra may be dependent on total power or absolute alpha power. In addition, mathematical transformations were necessary to normalize the epoch data, suggesting that the mean and standard deviation of data from a series of epochs may not have maximal value unless a transformation is used. These results also indicate that caution is needed in interpreting changes in EEG frequency analysis data that are of the same magnitude as spontaneous EEG variability.     

Determinants of quantitative spectral electroencephalography in early Alzheimer's disease: cognitive function, regional cerebral blood flow, and computed tomography

Electroencephalography (EEG) bands may have different clinical or physiological correlates at initial diagnosis of Alzheimer's disease (AD). We studied 163 consecutive patients with probable (n = 105) and possible (n = 58) AD with measurements of cognitive function (CAMCOG), regional cerebral blood flow (rCBF) with single photon emission computed tomography using technetium-99m-labeled hexamethylpropylene amine oxime, and computed tomography (CT). Lower CAMCOG scores were significantly and most strongly associated with lower parieto-occipital and fronto-central alpha power. In a separate analysis of cognitive domains, disturbances in language, praxis, attention, and abstraction were also significantly and most consistently related to decrease in alpha power. Presence of cortical atrophy as measured on CT showed some statistically significant relations with EEG bands, but these associations were not consistent. Lower temporal and parietal rCBF were significantly related to lower parieto-occipital alpha activity. Presence of leukoaraiosis was significantly associated with lower beta values, but also with higher absolute theta and delta activity. The results suggest that alpha on EEG is most closely linked to cognitive function and rCBF, while beta and theta activity more likely reflect lower cortical or subcortical changes. Our study thus provides evidence that the EEG bands reflect differential pathophysiologic changes in AD.     

Age and sex effects in the EEG: differences in two subtypes of attention-deficit/hyperactivity disorder.

OBJECTIVES: This study investigated age-related changes and sex differences in the EEGs of two groups of children with attention-deficit/hyperactivity disorder (ADHD) combined type and ADHD predominantly inattentive type, in comparison with a control group of normal children. METHODS: Forty boys and forty girls were included in each group. The EEG was recorded during an eyes-closed resting condition and Fourier transformed to provide estimates for total power, absolute and relative power in the delta, theta, alpha and beta bands, and for theta/alpha and theta/beta ratios. RESULTS: Total power, relative alpha, and the theta/alpha and theta/beta ratios were differentiated between all 3 groups. Sex differences between the ADHD subjects and the control group were greater in males than females and matured faster in males. With increasing age, the EEG of the ADHD inattentive group was found to change at a similar rate to the changes found in the normal group, with the differences in power levels remaining constant. In the ADHD combined group, the power was found to change at a greater rate than in the ADHD inattentive group, with power levels of the two ADHD groups becoming similar with age. CONCLUSIONS: These results are supportive of a two-component model of ADHD, with the hyperactive/impulsive component maturing with age and the inattentive component remaining more stable.     

Analysis of background EEG activity in patients with juvenile myoclonic epilepsy

PURPOSE: To analyze background EEG activity of patients with juvenile myoclonic epilepsy (JME) with and without antiepileptic drugs. METHODS: We studied the background EEG activity in 18 patients with JME. The qEEG analysis included absolute power (AP), relative power (RP) and mean frequency (MF) of delta, theta, alpha and beta bands. The Z scores were calculated by comparison with population parameters based on the age-dependent regression function. Seven patients were unmedicated (UM) and eleven medicated (M). RESULTS: The UM group presented 69 (4.32%) abnormal Z scores and 227 (9.05%) in the M group (P<0.001). In the UM group, AP delta abnormal Z scores were identified in frontotemporal and occipital leads. In AP alpha and beta bands an increase in Z scores was encountered in frontoparietal leads in three patients. In addition, in three patients, the AP theta Z scores were below -1.96 and distributed in all regions. In the M group, AP beta Z scores were above 1.96 in frontoparietal leads in 7 of 11 patients. The AP delta increased above 1.96 in frontotemporal and occipital leads in 6 patients of 11. The AP alpha showed an abnormal decrease in Z scores in 5 of 11 patients, whereas other 5 patients presented normal scores. The AP theta presented 7 normal Z scores out of 11; this band exhibited the lowest number of abnormalities of the 4. CONCLUSION: Patients with JME have an increase in AP delta, alpha and beta bands, which is more evident in frontoparietal regions.     

EEG development in Attention Deficit Hyperactivity Disorder: From child to adult

ObjectiveAttention Deficit Hyperactivity Disorder (ADHD) is one of the most common psychiatric disorders found in children. While an extensive literature has documented the EEG in this clinical population, few studies have investigated EEG throughout the lifespan in ADHD. This study aimed to investigate EEG maturational changes, in subjects with ADHD combined type, that spanned from childhood into adulthood.MethodTwenty five male adults with ADHD were assessed between the ages of 8–12 years and again as adults. At both ages, an EEG was recorded during an eyes-closed resting period, and power estimates were calculated for relative delta, theta, alpha and beta.ResultsAt the childhood assessment, the ADHD subjects had elevated posterior delta. Relative theta was elevated, with diminished alpha activity across all sites. Significant maturational changes were observed, with reductions in the delta and theta bands, and increases in the alpha and beta bands across all electrodes. In adulthood, relative to controls, diminished frontal delta and elevated global theta activity were apparent.ConclusionsSubstantial developmental changes occurred in the EEG of these subjects. These results identify important issues when using EEG as part of the diagnosis for ADHD.SignificanceThis study is the first to explore EEG changes from childhood to adulthood over an 11 year period in the same subjects with ADHD.