Department of Psychiatry, Brain Research Laboratories, New York University School of Medicine,
462 First Avenue, OBVRoom 884, New York, NY 10016, USA
bDepartment of Neuroscience, Tor Vergata University, IRCSS, 00133 Rome, St. Lucia, Italy
cNathan Kline Institute for Psychiatric Research, Orangeberg, NY 10962, USA
This article focuses on computerized methods of quantifying electroencephalography
(EEG) and the clinical use of comparing EEG features obtained from
specific patients with psychiatric and neurologic disorders to values obtained
from a population of normal individuals. The current status of quantitative EEG
(qEEG) studies is reviewed with the goal of extracting information that would be
useful to the practicing clinician. Although the major focus of this article is the
use of qEEG in child and adolescent psychiatric disorders, preliminary sections of
this article summarize qEEG findings from relevant adult psychiatric and
neurologic disorders. The qEEG studies that involved children and adolescents
have been, with a few exceptions, limited to individuals with attention or learning
problems. Many qEEG studies of adult psychiatric populations have
implications that can impact on our knowledge of childhood disorders and are
summarized. Initial sections also present a discussion of the development of
qEEG, controversial issues surrounding its clinical usage, and a summary of
important methodologic issues.
The clinical uses of qEEG were described in a position paper of the American
Medical Electroencephalographic Society . These uses include the detection of
an organic disorder as the underlying cause of brain dysfunction, roles in making
1056-4993/05/$ see front matter D 2004 Elsevier Inc. All rights reserved.
* Corresponding author.
E-mail address: Robert.email@example.com (R.J. Chabot).
Child Adolesc Psychiatric Clin N Am
14 (2005) 21 53
differential diagnosis, and epileptic source localization. We add possible roles in
determining appropriate medication selection, following treatment response, and
delineating the underlying cause of specific psychiatric disorders. Sections of this
article examine the current status of qEEG and how it can impact on these
The greatest body of evidence regarding replicable neurophysiologic indices
of psychiatric and developmental disorders has been provided by qEEG studies.
Electrophysiologic assessment is also the most practical and economic neuroimaging
method, because it uses relatively simple, inexpensive equipment that
can be used in space readily available in clinics, hospitals or private offices.
Special purpose qEEG analytic algorithms are widely available from commercial
sources, training workshops with continuing medical education accreditation in
collection, analysis, and interpretation of data are regularly presented by
professional societies and equipment manufacturers, and certification examinations
are administered by the American Medical EEG Association and the
American Board of Clinical Neurophysiology.
Important technical terms are defined as follows:
! The four commonly used EEG frequency bands used include (1) delta (1.5
3.5 Hz), (2) theta (3.5 7.5 Hz), (3) alpha (7.512.5 Hz), and (4) beta (12.5
25 Hz). Total power represents the frequency range of 1.5 to 25 Hz.
! Absolute power: The average amount of power (mV2 ) in each frequency
band and in the total frequency spectrum of the EEG recorded from each
! Relative power: The percentage of the total power contributed by each
frequency band in the spectrum from each electrode site. These features
define the frequency composition of the electrical signal independent of its
total power. For example, relative alpha power is the ratio of total alpha
power/total power at each electrode site.
! Power asymmetry: Interhemispheric: The ratio of absolute power between
corresponding (homologous) regions of the two hemispheres in each frequency
band and for the total power across all frequency bands. Intrahemispheric:
The ratio of absolute power between regions within a hemisphere in
each frequency band and for the total power. This addresses the question,
How similar is the observed activity between/or within hemispheres?
! Coherence: Interhemispheric: The amount of synchronization of electrical
events in corresponding brain regions, separately for each frequency band
and for the entire frequency spectrum. Intrahemispheric: The amount of
synchronization of electrical events between regions within a hemisphere in
each frequency band and for the entire frequency spectrum. This addresses
the question, How synchronized is the observed activity?
! Mean frequency: The frequency within each band, or for the entire spectrum,
above and below which there is the same amount of power. This
addresses the question, Where in each frequency bandor in the entire
frequency spectrumis the concentration of power?
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 22
Historical perspective: origins of the electroencephalogram
Research about the origins of the various EEG frequency bands makes it clear
that anatomically complex regulatory systems are involved in the generation of
the EEG power spectrum. Brain stem, thalamic, and cortical processes mediate
this regulation using all the major neurotransmitters . The EEG power
spectrum can be argued to be characteristic for human beings, resulting from the
coordination of brain processes normally produced in healthy individuals. These
facts suggest that EEG frequency measures can be sensitive to brain dysfunctions
believed to be abnormal in psychiatric disorders. Numerous twin and family
studies have been conducted on normal variation in the human EEG. A recent
review concluded that most EEG parameters are to a large extent genetically
determined . The effect size of genetic determination is between 76% and 89%
for the four EEG frequency bands , and about 60% of the variance in theta,
alpha, and beta coherence was explained by genetic factors. Environmental
factors did not influence variation in coherence .
Initial qEEG studies showed systematic changes with maturation from birth to
adulthood in the average power in the delta, theta, alpha, and beta frequency
bands . Replication studies not only confirmed these systematic changes with
age but they also found no significant differences between the EEGs of normally
functioning Swedish children and white or black US children . Cultural
independence and replication of qEEG findings has been extended to studies from
Barbados, China, Cuba, Germany, Holland, Japan, Korea, Mexico, Netherlands,
Sweden, United States, and Venezuela .
The independence from cultural and ethnic factors of normative qEEG
descriptors makes possible objective assessment of brain integrity in persons of
any age, origin, or background. The incidence of positive findings different from
the normative database in healthy, normally functioning individuals repeatedly
has been shown to be within the chance levels, with high test-retest reliability.
Normative data have been extended to cover the age range from 1 to 95 years of
age for each of the electrode positions in the standardized international 10/20
system and broadened to include measures of absolute power, relative power,
mean frequency, coherence, and symmetry .
The limited acceptance of qEEG in US psychiatry can be attributed largely to
two major factors. First, most papers that report the results of qEEG studies of
psychiatric patients have not appeared in journals widely read by psychiatrists but
rather in specialized electrophysiologic or brain research publications. Reports of
qEEG abnormalities in psychiatric patients have been regarded as nonspecific
and are not included in the curriculum of medical students or psychiatric residents.
Second, since 1989, skeptical statements about the use of qEEG in
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 23
psychiatry have appeared in professional journals  and in position statements
by committees from some professional organizations, such as the American EEG
Society, the American Academy of Neurology, and the American Psychiatric
Association. These position statements indicated that published qEEG findings
were promising but required further research before clinical use could be established.
These negative conclusions were repeated in a report by subcommittees of
the American Academy of Neurology, the American Clinical Neurophysiology
Society, and a panel of experts .
Findings from a large number of excellent studies not reviewed by these
committees and from numerous studies completed since the time of most of these
reviews provide substantial additional support for the validity and clinical use of
qEEG in several areas of child psychiatry, however. The American Medical EEG
Association recently issued a positive position statement about the clinical value
of qEEG in psychiatry , and the American Psychiatric Electrophysiological
Association established a committee to assess the current use of qEEG examinations
in the management of various psychiatric disorders. After a thorough
review of more than 500 qEEG and conventional EEG studies of psychiatric
patients published in the last 20 years, this positive report was adopted by the
Steering Committee of the American Psychiatric Electrophysiological Association
in May 1996.
The specificity of qEEG findings recently was questioned in a study that
compared the EEGs of 100 normal controls with those obtained from an independent
sample of 67 controls and 340 patients with 22 different psychiatric or
neurological diagnosis . The authors conclude that while decreases in delta
and theta absolute and relative power are specific signs of brain dysfunction that
correlate with cortical atrophy, no specific qEEG patterns could be found that
were pathognomonic for any specific disorder. While this is an interesting study,
there is a fatal flaw that invalidates their conclusion. The group sizes for any
specific disorder were highly limited, with the largest group at 57 patients and
with nine of the disorders having less than 10 patients. Clearly these numbers are
too small to expect anything but non-specific findings. Interestingly, abnormal
qEEG findings were reported in 11.9% of their normal controls, suggesting the
inadequate number of individuals in their normal database. Furthermore, an
editorial appeared in the same journal issue in support of their findings . This
editorial made general statements that reiterated potential problems with qEEG
research. These included problems with EEG filter settings, artifact inclusion or
exclusion, drowsiness, age effects, medication effects, and statistical problems
due to the large number of qEEG variables often available for study compared to
the size of the patient populations under study. It is interesting that this editorial
praises the described study since it suffers from a major problem of small sample
sizes. In the following methodological section of this article we address each of
these criticisms. We also argue that the use of an appropriate normal database and
method of collecting and analyzing qEEG can effectively make such criticism
a non-issue. The present article reassess the current status of qEEG research
findings in lieu of the criticisms described above.
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 24
It is the goal of this article to provide an up-to-date and comprehensive review
of all of the relevant research published to date to allow for an informed
consideration of the scientific knowledge base on the clinical value of qEEG in
child and adolescent psychiatry.
Quantitative electroencephalographic methodologic issues
A brief description of the development, replication, validation, and sensitivity
of the neurometric qEEG methodology follows. The neurometric qEEG
normative database has been published, and findings using this technique have
been replicated widely. Neurometrics is the only qEEG technology that has
published normative data and been approved by the US Food and Drug
Administration. Complete details have been published elsewhere [11,25,26,32].
The neurometric analytic method enables objective evaluation of brain function
based on qEEG. Its initial development was supported by program grants from
the Research Applied to National Needs Program of the National Science
Foundation and the Bureau of Educational Handicapped of the US Office of
Education. An understanding of the important methodologic issues that follow is
necessary to offset the criticisms of qEEG that were described previously.
The neurometric normative database contains the EEG records and features
derived from 650 individuals, aged 6 to 90 years, with function confirmed
as normal by multidisciplinary examinations . The number of subjects
required for reliability at each age was statistically determined and increased until
consistent split half replications were obtained. This sample requirement was
dynamic in that different ages required different Ns. For example, in the ages
from 6 to 13, in which brain maturation changes are rapid, the Ns were greater,
as were those in later adolescence, in which findings indicated that the frontal
regions of the brain were maturing to adult levels .
Quantitative features were extracted from artifact-free data by spectral analysis
of the EEG (qEEG), log transformed to obtain normal (Gaussian) distributions,
age regressed, and evaluated statistically relative to the distributions of every
feature in the qEEG database [27,34]. Great care was taken to include only
artifact-free EEG and guard against changes in patient state, such as drowsiness.
All features were transformed to Z scores and expressed in standard deviations
from the normative values. This allows objective assessment of the statistical
probability that the measurements obtained from an individual lie outside the
normal limits for his or her age. The importance of selecting artifact-free EEG
segments for analysis and the use of log transformation must be stressed, because
the failure to follow these procedures validates the criticisms described
previously. For example, qEEG normal control groups often rely on a reference
sample of data obtained from individuals whose ages span one or several
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 25
decades. In neurometrics, the use of age-regression techniques yields an estimate
of the range expected from persons exactly the same age as the subject.
Computation of the Z score for the difference between the predicted normative
value and the value obtained from the individual estimates the probability that
such a value might be obtained by chance from a healthy peer. Using only
significant Z values in feature selection for further statistical analyses acts as a
preliminary step in data reduction. Test-retest reliability of neurometric qEEG has
been confirmed by intensive short- and long-term follow-up studies in a large
sample . Although concern about normative databases can be valid, the
widespread independent replications described previously provide confidence in
the use of the neurometric normative database. Statistical evaluation of
distributions of features by gender revealed small differences within the normal
population compared with between-population variance (eg, normal versus
abnormal). Neurometric qEEG contains combined gender norms, considered to
be a more conservative approach.
Distinctive patterns of qEEG abnormalities have been described in diverse
psychiatric disorders (eg, depression, schizophrenia, dementia, and attention
deficit hyperactivity disorder [ADHD]). This allows differentiation of these
disorders from normal and, where appropriate, from each other . A large body
of peer-reviewed published data from independent laboratories reports the
sensitivity of neurometrics in varied clinical populations, including head injury
, stroke and transient ischemic attack [13,38], schizophrenia , depression
, marijuana abuse , and ADHD [42,43].
Importance of reduction of quantitative electroencephalographic feature set
Criticisms of qEEG studies often focus on the abundance of qEEG features
available for study, which can lead to spurious findings if appropriate measures
are not undertaken. Statistically guided data reduction is fundamental. Conventional
methods of data reduction, such as feature selection from t-tests and
analysis of variance (ANOVAs), used to identify variables significantly related to
dependent variables of interest, should be used [44,45]. Variables should be
selected that maximize adjusted multiple correlation coefficients between qEEG
and dependent variables, minimizing the residual sum of squares with each
feature set considered independently and appropriate corrections for multiple
tests applied (eg, Bonferroni, Tukey, or Greenhouse-Geisser). In parallel, factor
and discriminant analysis can be used to reduce the dimensionality of the variable
set to better address specific hypotheses. Selected qEEG features can be pruned
further by using stepwise procedures and split-half or jackknifed replications,
always maintaining the conservative rule of 10:1 subject-to-variable ratios. These
methods allow one to identify variables that independently account for the
maximum variance in the model under study. In this way, the likelihood of
spurious findings can be minimized and the sensitivity and specificity of qEEG
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 26
Quantitative electroencephalographic source localization
Knowledge about the neuroanatomic generators of EEG frequency components
has important implications for the generation of models of the neurophysiology
of the EEG and the neuropathology of psychiatric disorders. For
reviews of this literature, see Hughes and John  and Alper et al . The
major qEEG source localizations method currently available is variable resolution
electromagnetic tomography (VARETA) . Correlations of VARETA maps of
broadband spectral parameters with radiologic studies in patients with spaceoccupying
lesions have shown that EEG delta power is correlated with the
volume of the lesion and EEG theta power is correlated with the volume of
edema surrounding such lesions . Recent research has further tested the
accuracy of VARETA in a group of patients with various space-occupying lesions,
evaluating the Z correspondence of VARETA solutions in the delta and
theta frequency domains to the volume of brain edema and the centroid of the
mass . The authors concluded that VARETA achieved accurate location of
brain lesions. Using LORETA analyses (a source localization algorithm mathematically
akin to VARETA), Pascual-Marqui  reported further validation of
such methods by demonstrating low error of sources and correct localization of
primary sensory cortices of evoked potential data. In a recent study using
LORETA, Saletu et al  found different representative drugs to induce
different changes in different brain regions, which they interpreted as supporting
the use of such methods for studying the mode of action of psychotropic drugs.
Differences between specific drug-free patient groups and normal individuals
were found to be opposite to the observed changes induced by the respective
drugs. In a subsequent section of this article we demonstrate how VARETA can
be used in the development of a neuroanatomic model of attention deficit disorder
(ADD) in children and adolescents.
Relevant quantitative electroencephalographic studies in adult psychiatric
Studies that use qEEG in dementia patients are in agreement with conventional
EEG findings and report increased delta or theta power , decreased
mean frequency [68,7173], decreased beta power [74,75], and decreased
occipital dominant frequency [60,65]. Many studies regard increased slow
activity before reduction of alpha power as the earliest electrophysiologic indicator
that appears in Alzheimers disease [57,65,69,70,76,77]. The amount of
theta activity shows the best correlation with cognitive deterioration [70,78,79]
and clinical outcome in longitudinal follow-up [66,69,70,76,80]. Increased delta
seems to be a correlate of severe advanced dementia, subsequent to increased
theta [67,70,80,81]. Multiple studies report accurate discrimination of patients
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 27
with Alzheimers disease from depressed patients and normal controls using
qEEG measures of slow activity [26,56,71,82]. Several qEEG studies of dementia
patients report high correlations between the severity of cognitive impairment and
amount of EEG slowing. These features are absent in depression and are localized
in multi-infarct dementia, which enables these disorders to be differentiated from
Alcohol and substance abuse
Several recent studies of substance abuse have used qEEG. Replicated reports
have appeared of increased beta relative power in alcohol dependence [26,83
86]. Increased alpha power, especially in anterior regions, has been reported in
withdrawal and after acute exposure to cannabis [41,87]. Increased alpha and
decreased delta and theta have been reported in crack cocaine users in withdrawal
. Use of qEEG reveals marked abnormalities in alcohol and substance
abuse. The effects vary depending on the drug. Either increased slow activity
with lower alpha and beta or the converse has been reported, which reflects
diversity of substances studied and the differences in anatomic regions or states
focused on. There is a consensus regarding increased beta relative power in
alcoholism and increased alpha in chronic cannabis or crack cocaine users.
In studies from our laboratory , a chronic crack cocainedependent
population was divided by age of first use (age b20 or _20 years) (young onset,
n = 52; adult onset, n = 48) to explore the consequences of use during adolescence.
The qEEGs contained significantly more theta excess in individuals who
started using as adolescents, which suggests enhanced vulnerability for such
effects on brain function. Of note, theta excess characterized the group of cocaine
abusers who relapsed most quickly . A significantly larger (Pb0.04)
proportion of the group who began using as adolescents was found to have a
history or current signs of ADHD. Clear differences were reported between crack
cocainedependent subjects who began using as adolescents and subjects who
began using as adults.
Numerous qEEG studies have been performed on carefully evaluated groups
of patients with schizophrenia. A deficit in alpha power is consistently reported
[26,95100] with altered alpha mean frequency or diminished alpha responsiveness
. Numerous studies have reported increased beta activity in
schizophrenia [98,104107]. Neuroleptic medication typically increases alpha
power  and reduces beta power [110,111], which suggests possible
normalization of deviant features by medication. Increased delta or theta activity
also has been reported in a large number of studies [95,98,99,106,112119].
Increased slow activity apparently can result from long-term neuroleptic
treatment [120,121], although there are reports of increased delta in patients
off medication for several weeks [86,95,98] and reduction of delta or theta after
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 28
resumption of medication [108,118,122]. Patients with schizophrenia can be
discriminated from controls by the presence of increased amounts of delta activity
in the left anterior temporal area .
Heterogeneity within schizophrenia has been documented in a large sample of
medicated, nonmedicated, and never-medicated persons with schizophrenia using
cluster analysis based on qEEG variables. Five subtypes were described, with
qEEG profiles characterized by (1) delta plus theta excess, (2) theta excess with
decreased alpha and beta, (3) theta plus alpha excess with beta deficit, (4) alpha
excess with decreases in delta, theta, and beta, and (5) beta excess . Patients
who were never medicated were classified into three of these subtypes.
Individuals with schizophrenia with qEEG profiles that corresponded to some
of the groups identified by this cluster analysis have been reported to display
differential responses to treatment with haloperidol  or risperidone .
Heterogeneity in the schizophrenic population has been presented in other qEEG
studies [126,127]. In the cluster analysis just cited, qEEG asymmetry was found
in every frequency band for all five subtypes . Increased coherence within
cerebral hemispheres in anterior regions also has been consistently reported
Numerous qEEG studies have found increased alpha or theta power in
depressed patients [26,71,131137]. Asymmetry within cerebral hemispheres,
especially in anterior regions, has been reported repeatedly , as
has decreased coherence [26,115,143]. In bipolar illness, in contrast to unipolar
depression, alpha activity is reduced [135,144] and beta activity increased
[26,145]. This difference may serve to separate unipolar from bipolar patients
who are evaluated while in a state of depression without prior history of mania
Available qEEG studies suggest a high incidence of abnormalities in patients
with anxiety, panic, and obsessive-compulsive disorder . Diminished
alpha activity has been found in anxiety disorder [151,152], and increased theta
activity has been reported in obsessive-compulsive disorder [153,154]. Two
subtypes of patients with obsessive-compulsive disorder have been described.
One, with increased alpha relative power, responded positively (82%) to serotonergic
antidepressants, whereas the second, with increased theta relative power,
failed to improve (80%) . Recent reports stated that a qEEG measure called
cordance may play a role in predicting clinical response to different antidepressants
. A qEEG was obtained before treatment and 48 hours
and 1 week after initiation of treatment with fluoxetine, venlafaxine, or placebo,
with treatment response evaluated out to 8 weeks. No baseline qEEG differences
were noted, whereas responders to placebo showed increased prefrontal cordance
and medication responders showed decreased prefrontal cordance within 48 hours
of treatment initiation. Nonresponders showed no change in cordance values.
These results may indicate a role for the prefrontal cortex in mediating treatment
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 29
response, with changes in cordance values preceding favorable behavioral
response. Currently, this research has not been replicated beyond this group of
Mild head injury or concussion syndrome
Patients with complaints of cognitive, memory, or attention deficit after mild
head injury without loss of consciousness frequently present for psychiatric
evaluation for workers compensation and disability benefits. Objective evidence
of brain dysfunction in such cases is critical. Numerous qEEG studies of severe
(Glasgow Coma Scale 48) and moderate head injury (Glasgow Coma Scale
912) have agreed that increased theta and decreased alpha power or decreased
coherence and increased asymmetry are found in such patients. Changes in these
measures provide the best predictors of long-term outcome . The qEEG
abnormalities that persist after mild or moderate head injury are similar in type to
those found after severe head injury, namely increased power in the theta band,
decreased alpha, low coherence, and increased asymmetry. It is noteworthy that
similar EEG abnormalities have been reported in boxers  and professional
soccer players who were headers . There is a broad consensus that
increased focal or diffuse theta, decreased alpha, decreased coherence, and
increased asymmetry are common EEG indicators of postconcussion syndrome.
There are multiple reports of discriminant functions based on qEEG variables that
successfully separated normal individuals from patients with a history of mild to
moderate head injury years after apparent clinical recovery [37,165]. Thatcher
et al  argued that qEEG findings meet all criteria for admissibility into the
federal court system.
Quantitative electroencephalography in adult attention deficit hyperactivity
A single qEEG study compared qEEG findings among normal controls, adults
with ADD, and adults with attention problems that do not reach criteria for
ADHD . Results indicated that adults with ADHD show increased theta
absolute and relative power in comparison to both control groups. This finding is
consistent with that described later in children and adolescents with ADHD.
Adults with attention problems but not ADHD showed reduced relative theta
and increased relative beta power in comparisons to normal controls and adults
Quantitative electroencephalography: sensitivity to signs of cortical dysfunction
We have published several qEEG studies that attest to the sensitivity of qEEG
in the documentation of signs of cortical dysfunction in various disorders. These
studies attest to the use of qEEG to document brain dysfunction and evaluate the
effectiveness of treatment of these abnormalities.
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 30
The use of qEEG was found to be a sensitive indicator of brain dysfunction in
patients with systemic lupus erythematosus who present with or without
neuropsychiatric manifestations of their illness . In a sample of 52 such
patients, qEEG was found to have a sensitivity of 87% and a specificity of 75% in
documenting a neurophysiologic disorder. The qEEG profiles described varied
with the severity and type of neuropsychiatric problem manifested. Patients with
signs of memory and cognitive problems showed qEEG profiles similar to that
described in dementia, whereas patients with clinical signs of depression showed
qEEG findings similar to that seen in mood disorders. In 6 patients tested before
and after treatment, qEEG changes mirrored changes in clinical state. The qEEG
also was found to be useful in documenting the effects of Lyme disease on brain
function . Abnormal qEEG was seen in 75% of patients with active Lyme
disease and was found to normalize after successful treatment. Use of qEEG also
has been shown to be a sensitive indicator of cortical dysfunction caused by
cerebral ischemia [169,170]. Signs of pre-existing cortical dysfunction were
noted in 40% of 38 patients before undergoing cardiopulmonary bypass surgery,
with the degree of abnormality predictive of the development of postoperative
neuropsychological test performance deficits. A comparison of preoperative and
1-week postoperative qEEG showed a positive correlation with neuropsychological
function 3 months after surgery. These resultsin addition to the qEEG
findings reported in mild head injuryare compatible with the notion that qEEG
could provide useful information about brain function in situations in which
unexplained changes in cognitive function occur in children and adolescents.
Quantitative electroencephalographic studies in childhood and adolescent
Several studies have used varying types and degrees of EEG quantification to
describe differences between autistic children and matched normal controls .
Studies that used different EEG recording conditions (normal waking, stage II
sleep, and during cognitive activation) reported findings of hemispheric differences
in normal controls and a lack of hemispheric differences in autism [172
174]. The largest such study examined qEEG in autistic children, normal
controls, mental age-matched toddlers, and age-matched mentally handicapped
individuals . The autistic children showed increased frontal/temporal and
left temporal total power and decreased power asymmetry when compared with
normal or mentally handicapped controls. The autistic children and mental agematched
toddlers showed greater within-and-between cerebral hemispheric EEG
coherence than the other two groups. The autistic childrens EEG findings
indicated decreased cerebral hemispheric and topographic differentiation, which
suggested a severe maturational lag . No qEEG studies that compared large
numbers of autistic children with children with other psychiatric disorders have
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 31
been published. The qEEG measurements of the degree of maturational lag and
amount of EEG slowing in individual autistic children might prove useful in the
development of educational intervention strategies .
Quantitative electroencephalography in children and adolescents with diabetes
Three qEEG studies of the effects of diabetes and hypoglycemia on brain
function have been conducted. The first study examined qEEG in 44 persons with
insulin-dependent diabetes and age-matched controls. A significant correlation
was found between hemoglobin A1c concentrations and decreased alpha relative
power. A positive history of ketoacidotic episodes was associated with increased
delta-theta and decreased alpha relative power . An examination of qEEG in
28 children with type 1 diabetes and 28 age- and sex-matched controls revealed
a relationship between severe hypoglycemic episodes and increased theta in
frontal/central regions and increased delta in occipital regions. Nonlocalized
decreases in alpha power also were found . A recent study examined the
effects of a controlled reduction in plasma glucose concentration in 19 children
with diabetes and 17 children without. Decreased glucose was associated with
increased delta and theta activity in both groups but was more pronounced in the
children with diabetes . The authors concluded that improvement in glucose
metabolism is an important factor in preventing the development of qEEG
abnormality in children with diabetes.
Specific developmental disorders
The qEEG studies of eyes-closed resting EEG in dyslexia have resulted in
inconsistent findings, including decreased and elevated alpha or beta power and
increased theta power . These inconsistencies most likely reflect small
sample sizes, varying methods of defining dyslexia, and differences in qEEG
recording and analysis techniques. For example, no differences were reported
between normal controls and a highly screened sample of boys with pure dyslexia
Several studies documented qEEG abnormalities in less selective samples of
children with learning disorders (LDs). Children with severe spelling disorders
showed decreased alpha and beta absolute and relative power in parietal and
occipital regions and increased temporal-parietal/occipital power ratiosboth
signs of decreased topographic cortical differentiation . Data that suggested
that the nature of qEEG abnormalities in LDs may change with age also have
been published . Although 8- and 9-year-old children showed decreased
alpha, the topographic distribution was different, and 10-year-old children
showed focal theta excess. This age effect has not been replicated. The work of
John et al  would suggest that when age-regression qEEG equations are used
to compare normal children and children with LD, age effects disappear. The
finding of increased theta and decreased alpha in children with LD has been
replicated. Children with LDs without hyperactivity but with attention problems
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 32
showed increased theta and low alpha power . Hyperactive children and
children with learning disorders have been shown to have decreased alpha and
beta power in comparison to normal controls . The discrepant results of
these studies most likely reflect differences in patient selection criteria and the
location of recording electrodes. An examination of qEEG abnormalities across a
wide topographic distribution of recording sites and a large sample of children
with LDs reveal most of the qEEG abnormalities described previously are an
indication of the heterogeneity of LDs .
John  used the neurometric approach to qEEG to examine children with
LDs. Samples of 155 children with generalized LD and 155 children with specific
LD (SLD) had their qEEGs compared with the neurometric normal database.
Abnormal qEEGs were found in 32.7% of the children with SLD and 38.1% of
the children with LD, whereas only 5.5% of an independent sample of normal
children had abnormal qEEGs. The percentage of children who showed various
types of qEEG frequency abnormality also was presented and included increased
delta or theta and decreased alpha relative power. A discriminant function that
compared these groups of children to each other achieved sensitivity and specificity
levels that were well above chance levels .
Using qEEG techniques similar to those just described, Harmony and
associates [177,187] elucidated the nature of neurophysiologic abnormalities in
children with documented LDs. Children with LDs were shown to have different
patterns of brain maturation than normal controls. Within normal controls, there
was an increase of posterior/vertex EEG coherence and a decrease in coherence
among frontal recordings with increased age, which indicated increased differentiation
of frontal cortical regions and increased communication across basic
sensory and association cortex. These changes were not seen in children with
LDs. Instead, these children showed no change in posterior/vertex coherence with
age, and levels of frontal coherence remained high across all ages. Brain
maturation as indexed by changes in EEG coherence indicated a developmental
deviation in children with learning problems . This finding was replicated
using different but converging qEEG feature sets. Decreased spatial differentiation
of the EEG was reported in children with spelling problems , and
the structure of the parietal/temporal and occipital EEG could be explained by a
single factor in children with specific reading disorders, whereas three factors
were required in normal controls . VARETA images of the qEEG of
46 children with LD and 25 control children showed increased theta in the frontal
lobes of the children with LD and more alpha activity in the occipital lobes of
the controls . Coherence differences also were reported between children
with dyslexia and a control population. Coherence between cerebral hemispheres
was greater in the control children, which indicated a greater disconnection of
cerebral hemispheres in the children with dyslexia .
The qEEG findings presented herein and our own research indicates that
children with LDs represent a heterogeneous population. Harmony et al 
showed that the nature of the qEEG abnormality present was directly related to
academic performance in reading and writing. Increased power in delta or
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 33
decreased alpha power was associated with a poor educational evaluation,
increased theta or decreased alpha was associated with mildly abnormal
evaluations, and increased alpha and decreased theta were associated with good
evaluations. Theta excess with alpha deficit was described as reflecting
maturational lag, whereas delta excess indicated cerebral dysfunction. qEEG
can be used to indicate which children with learning problems present with an
underlying neurophysiologic dysfunction. This information may be useful for
determining resource allocation and designing remediation programs.
The role that environmental and cultural factors may play in brain development
recently was examined . A comparison was made between the qEEGs
of children at high and low risk of developing learning problems caused by
residing in economically, socially, and culturally disadvantaged environments.
These children were tested at 18 to 30 months, 4 years, and 5 to 6 years of age.
High-risk children were found to have increased delta and theta in frontal regions
and decreased alpha in posterior regions. Although these qEEG differences
decreased with age, frontal theta excess and posterior alpha deficits persisted.
This study indicates that sociocultural effects contribute to EEG maturation.
Likewise, Ito et al  reported that severely abused children have EEGs
characterized by increased interhemispheric coherence, which indicates delayed
Quantitative electroencephalographic studies of attention deficit disorders
The greatest amount of qEEG information available in children and
adolescents involves those with ADD and ADHD. We examine this information
in detail and conclude with a neurophysiologic model of these disorders. Many
early studies conducted in children with attention deficit disorder had small
samples of children with ADD or ADHD with recordings of eyes-open EEG from
2 to 3 leads within the central, parietal, or occipital regions. The results from
these studies were relatively consistent despite these shortcomings. Hyperactive
children were reported to show decreased alpha activity and increased intrahemisphere
coherence , decreased alpha and beta activity , and
decreased alpha and beta absolute power . These studies suggested that
central and parietal/occipital deficits of alpha and beta may characterize the eyesopen
EEG of hyperactive children.
When the number of recording channels is increased or larger samples of
children are tested, more consistent patterns of qEEG abnormality emerge.
Samples of 21 Japanese, 41 Chinese, and 29 Korean children with ADHD were
found to have eyes-closed resting EEGs characterized by increased delta and fast
theta with decreased alpha activity over left central or occipital regions when
compared with age-matched normal controls and children with conduct disorders
. Regional differences in ADHD/normal qEEG findings also have been
reported . Eyes-open resting EEG was recorded from 16 channels in 25 boys
with ADD without hyperactivity or concomitant learning problems and 25 agematched
normal controls. The qEEG of these boys with ADD was characterized
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 34
by generalized theta excess and beta deficit, with the theta excess greater in
frontal/temporal regions and the beta deficit greatest in temporal and posterior
regions. The size of these differences increased when the EEG was recorded
while reading or drawing. Similarly, El-Sayed reported that the amount of qEEG
slowing in frontal regions and the degree of beta deficit increased in children with
attention problems as the amount of attention load was increased while EEG was
recorded during performance of a continuous performance task .
Several recently published studies examined qEEG in various subgroups of
Australian children and adolescents with attention problems. A review of these
and other relevant findings also was published . Their initial study examined
eyes-closed resting qEEG in 8- to 12-year-old children with ADHD and children
with ADHD of predominantly inattentive type. Although both groups showed
increased theta and decreased alpha and beta, the inattentive subgroup results
were less severe . The qEEG coherence differences were then examined
between these subgroups of children with ADHD and normal controls. At shorter
electrode distances, children with ADHD had increased intrahemispheric theta
coherence and decreased lateral coherence differences. At longer distances,
children with ADHD showed decreased alpha intrahemispheric coherence,
whereas in frontal regions they showed increased theta and delta and decreased
alpha interhemispheric coherence. Children of the inattentive subgroup with
ADHD had less severe abnormality than those in the ADHD hyperactivity
subgroup . The authors concluded that these findings indicated reduced
cortical differentiation and specialization in ADHD. Clarke et al  used
cluster analysis of qEEG to document the existence of three ADHD subtypes in a
sample of 184 boys with ADHD and 40 age- and gender-matched controls.
Subtype 1 showed increased total power, increased relative theta, and decreased
relative delta and beta waves; type 2 showed increased relative theta and decreased
relative alpha and increased central/posterior relative delta. Subtype 3
showed increased relative beta and decreased relative alpha activity. Gender
differences also were examined. They used cluster analysis to examine the
qEEGs of 100 girls with ADHD and 40 age- and gender-matched controls .
Two clusters were identified. The largest subtype showed increased total power
and increased relative theta and decreased relative delta and beta power in
comparison to the control population. The second subtype showed increased high
amplitude theta and decreases in delta, alpha, and beta. The relatively small
number of normal controls may have influenced these results (see later
discussions regarding our ADHD research).
The clinical use of qEEG as a possible diagnostic tool for ADHD has been
examined using discriminant analyses techniques. A discriminant function was
developed that correctly classified 80% of 25 children with ADHD and 74% of
27 normal controls . These discriminant results were similar to those
reported by Lubar et al [184,200] in children with ADD without hyperactivity but
with reading disorders. The eyes-open resting EEG of this sample of children was
characterized by an increased theta-beta power ratio, especially in frontal/
temporal regions, with 79.2% correct identification of 69 children with ADD
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 35
against 34 normal controls. More recently, Monastra et al [201,202] recorded
eyes-open qEEG and used the theta-beta power ratio from the midline central
region to distinguish 176 children, adolescents, and young adults with ADD and
221 children adolescents, and young adults with ADHD from 85 normal controls.
They reported sensitivity rates from 86% to 90% and specificity rates between
94% and 98%.
Studies of medication effects in children with attention deficit hyperactivity
Several studies have examined the relationships between pretreatment EEG
and treatment response to methylphenidate or d-amphetamine. In an early study,
it was reported that 6- to 9-year-old boys with minimal brain dysfunction were
more likely to respond to methylphenidate if abnormal conventional EEG and
neurologic soft signs were present versus if they were absent . These
findings have not been replicated. Halperin et al  reported that the presence
or absence of conventional EEG abnormalities did not predict response to
methylphenidate. The qEEG differences have been reported between ADHD
responders and nonresponders to stimulants. Responders to d- or l-amphetamine
showed predrug qEEGs characterized by increased predominant peak beta
frequency and nonsignificant increases in theta and alpha power when compared
with nonresponders. Increased visual evoked potential values of N220 more than
250 msec and increased average beta frequency more than 13 Hz correctly
identified 100% of responders and 70% of nonresponders . Age-regressed
qEEG features extracted from eyes-closed resting EEG collected before
medication with methylphenidate were used to develop a discriminant function
to distinguish 16 responding from 12 nonresponding boys with ADHD.
Responders were correctly identified 81% of the time and nonresponders were
identified 83% of the time. Responders qEEGs were characterized by significant
developmental deviation (qEEG findings abnormal at any age), whereas
nonresponders were characterized by significant maturational lag (qEEG findings
normal at a younger age) . These findings increase the accuracy of the
discriminant results over those found by Steinhausen et al , who correctly
predicted methylphenidate response in 73.3% using qEEG features that had not
been age regressed. Children with ADHD who responded to methylphenidate
(n = 10) were reported to have less frontal theta and alpha and more frontal
beta activity than nonresponders .
Three reports suggest that methylphenidate or d-amphetamine leads to a
normalization of the qEEG of boys with ADHD who respond to treatment
[199,209,210]. In a second study, however, Clarke et al  found that stimulant
medication did not lead to a normalization of the qEEGs of boys with ADHD
whose qEEG was characterized by beta excess. In each of these studies, the
sample sizes involved were small (nb 25), which makes these conclusions
premature. Suffin and Emory  examined qEEG in 100 patients diagnosed
with either attention or affective disorders. They reported that 13 of 15 patients
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 36
with attention disorder and 9of 10 patients with affective disorder with a frontal
alpha excess responded to antidepressants; 7of 7 patients with attention disorder
with a frontal theta excess responded to stimulants; 17of 20 patients with
affective disorder and 5 of 5 patients with attention disorder with frontal alpha
excess plus frontal hypercoherence responded to an anticonvulsant plus lithium,
and 2 of 2 patients with affective disorder and 2 of 3 patients with attention
disorder with a frontal theta excess plus hypercoherence responded to an
anticonvulsant. Although interesting, these results are based on small samples,
diagnostic criteria are not presented, and the results have yet to be replicated and
are not in agreement with our studies (described later), which show that theta
and alpha excess subtypes may respond to stimulant medication.
Neurometric quantitative electroencephalography in learning and attention
Most studies cited previously indicated that qEEG can play a significant role
in the diagnosis and evaluation of children with learning and attention problems.
Despite this evidence, the clinical use of qEEG has been questioned for want of
knowledge of the sensitivity and specificity of qEEG measures in mixed clinical
populations [212,213]. It is the purpose of this section to provide this information
using the child psychiatric qEEG database developed at the Brain Research
Laboratories over the past 25 years. Within this section we review the study of
John et al , who used qEEG to evaluate brain function in children with LDs,
review our recent studies of qEEG in children with ADD and ADHD ,
and present a comparison of the normal children and children with LD and ADD/
ADHD from these two studies . We also present evidence that qEEG can be
useful for optimizing medication selection during pharmacologic intervention in
ADD and ADHD. We propose that this information and the cited research are
sufficient to justify the routine clinical use of qEEG in the diagnosis and
treatment of learning and attention disorders.
All children with ADD and ADHD were referred to the Developmental
Pediatrics and Learning Disorders Clinic in Sydney, Australia. A sample of 407
children was evaluated between June 1991 and December 1992. All children
were examined by a pediatric neurologist and had neuropsychological and qEEG
evaluations. None of the children received medication at the time of testing.
Children with histories of epilepsy, drug abuse, head injury, or psychotic disorders
were excluded. Diagnostic and Statistical Manual-III criteria were used
for clinical classification . This sample included children from the ages of
6 to 17 years (mean age, 10.8 years), with 78% having normal IQ scores. Within
this sample, 43.9% had ADHD, 40.5% had ADD, and 15.6% did not reach
criteria for ADD. This later group rated high in attention problems but showed no
impulsivity or hyperactivity and is called the attention subgroup-ATT. A reading
disorder was present in 58% of the entire sample.
Treatment response data were available on 152 of these children, with 42.8%
showing a positive response to dexamphetamine, 53.3% to methylphenidate, and
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 37
3.9% to thioridazine. The choice of medication was based on the clinical
presentation of the child and a challenge paired-associate learning task given
before medication at the time of initial evaluation and repeated after a trial dose of
dexamphetamine or methylphenidate. An adverse reaction (decreased memory
performance) resulted in new testing and placement on the other medication in
13 children initially tested on methylphenidate and 18 initially tested on
dexamphetamine. All 6 children who responded to thioridazine had either
adverse reaction or no change in paired-associate performance to dexamphetamine
and methylphenidate. Treatment response was evaluated 6 months after
treatment initiation. This evaluation included parent and teacher ratings of
changes in learning or in behavior and parent/teacher ratings on the Connors and
Diagnostic and Statistical Manual-III rating scales.
The populations with LD included 127 children with SLD (mean age,
11.4 years) whose LD occurred in only one academic area and who had normal
full-scale IQ scores and 115 children with LD (mean age, 11.8 years) whose LD
spanned two or more academic areas and who had full-scale IQ scores between
65 and 84 . Although these children with LD and SLD were not specifically
screened for ADD or ADHD, children with hyperactivity were excluded, and all
had been selected by their respective school systems because of learning
problems. No known neurologic disorder was noted in these children.
The normal controls included 310 children between the ages of 6 and 17 years.
Details concerning the collection and validation of this normal sample have been
published . Statements about the reliability and validity of these normal
databases were described in initial sections of this article.
The following section represents a summary of our previously published
research involving children with attention and learning problems [42,214216].
Most children with ADHD and ADD in the normal and low IQ groups showed
qEEG abnormalities when compared with the normal database. The qEEG
frequency abnormality occurred in more than 80% of the 407 children in this
population, with theta and alpha excess the most prevalent abnormal finding.
Frontal and central regions were the most likely to be involved, and when the
abnormality was generalized, its magnitude was usually greatest in these regions.
Inter- and intrahemispheric abnormality was present in approximately 35% and
included (1) increased coherence of theta or alpha activity between left and right
frontal recordings and between frontal and temporal recordings within each
hemisphere, (2) decreased coherence between left and right posterior temporal
and parietal regions, (3) frontal/posterior power asymmetry within each hemisphere
reflecting increased frontal power, and (4) left/right hemisphere power
asymmetry in posterior temporal and parietal regions, with the right hemisphere
most likely to show a power excess. Two major subtypes of qEEG abnormality
were identified that involved theta or alpha excess accompanied by either normal
or decreased alpha mean frequency. Beta excess was present in approximately
10% of these children.
Stepwise multivariate discriminant procedures were used to examine the
sensitivity and specificity of several two-way comparisons. Normal controls were
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 38
distinguished from children with ADHD/ADD with a sensitivity of 93.7% and a
specificity of 88.0%. The qEEG differences between the normal children and
children with low IQ and ADHD or ADD and between the children with ADHD
and ADD were present but minimal in comparison to the differences between the
normal population and population with ADD or ADHD. The presence or absence
of a secondary LD did not contribute to any of the qEEG differences observed.
When the population with ADHD or ADD was compared with the population of
children with LDs not secondary to an attention problem, qEEG differences were
observed. Children with ADHD or ADD could be distinguished from children
with LDs with a sensitivity of 97% and a specificity of 84.2%.
A qEEG also proved useful in the management of treatment response to
stimulant medication. The qEEG differences were found between individuals
who showed a short-term (initial response to one dose) positive response to
treatment with dextroamphetamine or methylphenidate and individuals who did
not benefit. Although the sensitivity and specificity levels of this discriminant
function were modest (68.7% and 67.5%, respectively), the function was accurate
(84.8%) in classifying children who had initially shown a negative response to
either dextroamphetamine or methylphenidate. Pretreatment qEEG and behavioral
measures showed a sensitivity of 83.1% and a specificity of 88.2% in
predicting long-term treatment response to either dextroamphetamine or
methylphenidate. Within the population with ADHD, 93.7% of the alpha excess
(n = 16), 83.3% of the beta excess (n = 6), and 75% of the theta excess (n = 40)
children showed a positive long-term response to stimulants. None of the children
with ADHD with an alpha or beta excess showed a negative response to either
stimulant, whereas 17.5% of the children with a theta excess showed a negative
response to treatment with dextroamphetamine. Within the population of children
with ADD, 66.7% of the beta excess (n = 6), 54.5% of the alpha excess (n = 11),
and 33.3% of the theta excess (n = 27) children showed a positive response to
stimulant therapy. None of the children with ADD with beta excess showed a
negative response to either stimulant. One of eight children with an alpha excess
treated with methylphenidate showed a negative long-term response. In contrast,
the likelihood of a negative response to either dextroamphetamine or
methylphenidate reached 30% for the children with theta excess.
Attention deficit hyperactivity disorder and attention deficit disorder:
maturational lag or developmental deviation?
The neurometric qEEG features of maturational lag (qEEG normal at a
younger age) and developmental deviation (qEEG abnormal at any age) indicated
that a developmental deviation was present in 35% of our sample localized
mainly to frontal and central regions, with signs of maturational lag mainly in
posterior regions present in 7%. To seek further evidence of maturational lag as
the underlying neurophysiologic mechanism involved in ADHD and ADD, the
qEEGs of our population with ADHD or ADD were assessed as a function of
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 39
age. Multiple ANOVAs were used to compare relative power, absolute power,
mean frequency, power asymmetry, and coherence values across four age ranges
(57, 810, 1113, and 1417 years). The degree of qEEG abnormality remained
stable, with no significant systematic decreases in the degree of abnormality
occurring across this age span. When qEEG values are age regressed, the pattern
of normal ADHD and ADD differences remains constant from the early school
years into late adolescence. The elevated frontal theta activity seen in children
with ADHD also has been reported in adults with ADHD, although the beta
deficit has been found to decrease with age [167,217].
Neurophysiologic subtypes in attention deficit hyperactivity disorder and
attention deficit disorder and learning disability
Cluster analyses procedures were used to identify the major neurophysiologic
subtypes within samples of 344 children with ADHD or ADD and 245 children
with LD or SLD. To comply with the statistical assumptions underlying cluster
analyses, we preselected qEEG features and limited the number entered into the
analyses in a systematic fashion. The qEEG variables chosen were those for
which the highest ANOVA values were obtained when comparing the children
with ADHD and ADD to normals, the children with LD and SLD to normals, and
the children with ADHD or ADD to the children with LD or SLD. We selected
variables that showed the greatest variance across the entire population of
children. Cluster analyses were performed using 35 qEEG variables that met
these criteria. An iterative approach was taken as we examined cluster solutions
starting at three clusters and progressing until the next new cluster solution failed
to further subdivide the population into clusters with more than ten members. The
five-cluster solution showed the most clearly defined cluster structure. The cluster
analyses were performed on split-half replications of our database and the entire
database. The split-half results were optimal for five clusters and replicated
Cluster one was characterized by generalized excess of alpha and deficit of
delta absolute and relative power, increased frontal theta coherence and alpha
coherence, and parietal and posterior temporal power asymmetry. Cluster two
was characterized by generalized excess of theta absolute and relative power,
decreased alpha mean frequency, and increased frontal theta coherence. Cluster
three was characterized by a generalized deficit of theta, alpha, and beta absolute
power, a generalized excess of delta and deficit of alpha relative power, and
decreased frontal alpha coherence. Cluster four was characterized by excess
frontal/central delta and theta, a generalized deficit of alpha absolute power,
generalized delta and theta excess and alpha deficit of relative power, decreased
theta and alpha mean frequency, decreased frontal and central alpha coherence,
and frontal, central, and temporal power asymmetry. Cluster five was
characterized by essentially normal qEEG findings. In this five-cluster solution,
more than 98% of the children with ADHD or ADD were placed into clusters one
or two. The children with LDs were evenly distributed among the five clusters.
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 40
Long-term stimulant treatment response data were available on 49 children with
ADD or ADHD from cluster one and 59 children with ADD or ADHD from
cluster two. Within cluster one, 75.5% showed a positive response to stimulants,
18.4% showed no measurable change, and 6.1% showed a negative response.
Within cluster two, 50.8% showed a positive response to stimulants, 33.9%
showed no change, and 15.2% showed a negative response.
VARETA images were calculated for the five patients with ADHD or ADD
closest to the centroid of clusters 1 and 2. Currently, technical problems prevent
us from examining the VARETA results for the children with LD or SLD. The
VARETA images associated with cluster one (alpha excess) at 11 Hz show
primarily cortical abnormalities that are maximal and seem to originate in right
parietal cortical regions. VARETA images of cluster two (theta excess at 5.4 Hz)
show primarily temporal cortical and hippocampal abnormalities. VARETA
images at the 5.4-Hz band for cluster one and at the 11-Hz band for cluster two
were within normal limits.
Proposed neurophysiologic model of attention deficit hyperactivity
disorder/attention deficit disorder
The results of the cluster analyses described previously indicate that the major
qEEG frequency abnormalities seen in ADHD and ADD involve excess of theta
or alpha absolute or relative power . Evidence exists that two different
but interconnected neural systems are involved in the generation of EEG within
the theta and alpha frequency bands [3,5]. Theta seems to be generated within the
septal-hippocampal pathway, whereas the alpha frequency involves thalamocortical
and cortical-cortical circuitry. Within the theta-generating septal-hippocampal
pathway, the septal nucleus and the nucleus accumbens receive inhibitory
modulation through dopaminergic innervation from the ventral tegmental area via
D2 receptors [221,222]. Cholinergic efferents modulate hippocampal and
cingulate cortex, with these hippocampal pathways acting to regulate the septal
nucleus. Theta excess can occur with overactivation of the septal-hippocampal
pathway or secondary via disinhibition from negative dopaminergic regulation
Several different alterations in the thalamocortical alpha-generating pathway
can result in alpha excess. The thalamic pathway receives positive modulation
from the midbrain reticular formation via acetylcholine and negative regulation
through nucleus reticularis of the thalamus via gamma-aminobutyric-acid with
further modulation via the dopaminergic striatal/nigral system. Alterations in the
regulation of this system can lead to alpha excess by overactivation of the
thalamus that may be caused by decreased modulation via the dopaminergic
nigral system or underactivation of the prefrontal cortex and a resulting disinhibition
from nucleus reticularis. A theta or alpha excess might result from low
dopamine levels, and our qEEG findings are in agreement with the dopaminergic
theory of ADHD expressed by Levy , which conceptualizes ADHD as a
R.J. Chabot et al / Child Adolesc Psychiatric Clin N Am 14 (2005) 2153 41
disorder of the polysynaptic dopaminergic circuits between prefrontal and striatal
centers of activity. These findings are also compatible with the neurophysiologic
model of ADHD proposed by Niedermeyer and Naidu , which also
emphasizes prefrontal, frontal and striatal, and thalamic interconnections. The
previously mentioned model also is supported by MRI and positron emission
tomographic imaging studies and by behavioral, pharmacologic, and neuroanatomic
studies on the nature of cortical and subcortical disturbances in function
that characterizes children with attention and learning problems .
In our opinion, ADD cannot be conceptualized as a single disease entity with a
narrow phenotype and a distinct cause. Rather, ADD represents a spectrum of
disorders that may be represented by different neurophysiologic subtypes present
within the population of children with attention and learning problems. qEEG
may prove to be the most clinically relevant imaging technique for use in children
with attention and learning problems. Of all neuroimaging techniques, qEEG is
less expensive, less invasive, and easier to perform and has the largest patient
database, which indicates the presence of different subtypes of attention and LDs
that may be differentially amenable to various treatment approaches. The
emergence of EEG biofeedback treatment techniques offers a direct application of
qEEG for determining qEEG biofeedback treatment parameters and may offer
effective treatment that is not medication oriented.
We believe that these findings justify the clinical use of qEEG in the initial
screening and treatment evaluation stages of children with ADD, ADHD, and
LD. A qEEG can act as an adjunct to clinical evaluation and behavioral
testing and play several of the roles set forth in the introduction to this article. A
qEEG can aid in the detection of organicity as the cause of brain dysfunction
in children who present with learning and attention problems. It also can aid
in the differential diagnosis of ADD or ADHD and LD. A qEEG can play a
role in optimizing pharmacologic, remediation, or psychological intervention.
Finally, qEEG-based models may help explain the pathophysiology of
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