Original Article

Yonago Acta medica 2016;59:169–173

EEG Power Spectrum Analysis in Children with ADHD
Akira Kamida,* Kenta Shimabayashi,* Masayoshi Oguri,† Toshihiro Takamori,† Naoyuki Ueda,* Yuki
Koyanagi,* Naoko Sannomiya,* Haruki Nagira,* Saeko Ikunishi,* Yuiko Hattori,* Kengo Sato,* Chisako
Fukuda,* Yasuaki Hirooka* and Yoshihiro Maegaki‡*Department of Pathobiological Science and Technology, School of Health Science, Tottori University Faculty of Medicine, Yonago 6838503, Japan, †Division of Clinical Laboratory, Tottori University Hospital, Yonago, 683-8504, Japan and ‡Department of Child Neurology, Institute of Neurological Sciences, Tottori University Faculty of Medicine, Yonago, 683-8503, Japanfrequently treated with drugs such as methylphenidate
and atomoxetine. The prevalence of ADHD among children is 5%, with a higher occurrence rate among boys.1
The initiation of treatment is often delayed because
hyperactive children are regularly considered healthy
active children in kindergarten and nursery settings.
The ADHD Rating Scale (ADHD-RS), which isused in the diagnosis of ADHD, is essentially a tool inwhich parents or teachers assess the behavior of children. However, this assessment tool involves a degreeof subjectivity, thus encouraging the development of
more objective assessment methods. As the symptomsof ADHD persist into adulthood in half of children with
ADHD,1 the early detection of ADHD is necessary to
prevent social maladaptation. However, neurophysiological function in individuals with ADHD is poorly
understood. In an electrophysiological study of children
with ADHD, Puente et al. reported latency prolongation in waves I and III and a prolonged I–III and I–
V interwave interval in auditory brainstem responses(ABR).2 In a study conducted by Miyazaki et al., sevenof 18 children with ADHD had abnormal somatosensory evoked potentials (SEP), with giant SEPs in threeof the children.3 In addition, several studies have examined electroencephalograms (EEG) in individuals with
ADHD. For example, Kanazawa et al. observed epileptiform discharge and slow alpha in 22.1% and 18.6%
of ADHD patients, respectively.4 In addition, basedon EEG findings, Clarke et al. classified children with
ADHD into: i) a maturational lag group, characterized
by increased slow waves and decreased fast waves; ii) a
cortical hypoarousal group, characterized by increased
high amplitude theta waves and decreased beta waves;

ABSTRACT

Attention deficit disorder/hyperactivity
disorder (ADHD) is a pathological condition that is not
fully understood. In this study, we investigated electroencephalographic (EEG) power differences between
children with ADHD and healthy control children.
Methods EEGs were recorded as part of routine
medical care received by 80 children with ADHD aged
4–15 years at the Department of Pediatric Neurology in
Tottori University Hospital. Additionally, we recorded
in 59 control children aged 4–15 years after obtaining
informed consent. Specifically, awake EEG signals wererecorded from each child using the international 10–20
system, and we used ten 3-s epochs on the EEG power
spectrum to calculate the powers of individual EEG frequency bands.
Results The powers of different EEG bands were significantly higher in the frontal brain region of those in
the ADHD group compared with the control group. In
addition, the power of the beta band in the ADHD groupwas significantly higher in all brain regions, except forthe occipital region, compared with control children.
With regard to developmental changes, the power of thealpha band in the occipital region showed an age-dependent decrease in both groups, with slightly lower
power in the ADHD group. Additionally, the intergroupdifference decreased in children aged 11 years or older.
As with the alpha band in the occipital region, the beta
band in the frontal region showed an age-dependent decrease in both groups. Unlike the alpha band, the powerof the beta band was higher in the ADHD group than in
the control group for children of all ages.
Conclusion The observed intergroup differences in
EEG power may provide insight into the brain functionof children with ADHD.
Background

Corresponding author: Yasuaki Hirooka, MD, PhD
yhirooka@med.tottori-u.ac.jp
Received 2016 March 11
Accepted 2016 May 8
Abbreviations: ABR, auditory brainstem response; ADHD, attention deficit disorder/hyperactivity disorder; ADHD-RS, ADHD
Rating Scale; DSM, Diagnostic and Statistical Manual of Mental
Disorders; EEG, electroencephalogram; fMRI, functional magnetic
resonance imaging; MRI, magnetic resonance imaging; SEP, somatosensory evoked potential

Key words attention deficit disorder/hyperactivity dis-order (ADHD); electroencephalography (EEG)

Attention deficit disorder/hyperactivity disorder(ADHD) is a developmental disorder characterized byinattention, hyperactivity, and impulsivity.1 ADHD is169

A. Kamida et al.

or iii) an over-aroused group, characterized by excess
beta activity.5
In this study, we examined differences in central
nervous system function in terms of EEG power between control children and children with ADHD whowere awake, resting, and had their eyes closed.

ten 3-s epochs that were on the power spectrum of EEG
with no paroxysmal waves and few artifacts.
The head was divided into the frontal (Fp1-F3,
Fp2-F4), central (F3-C3, F4-C4), parietal (C3-P3, C4P4), and occipital (P3-O1, P4-O2) regions, and bipolar
leads were used to record the delta (0–4 Hz), theta (4–8
Hz), alpha (8–13 Hz), beta (13–20 Hz), and gamma(20–40 Hz) waves in each brain region. We compared
the powers of the above frequency bands between
ADHD and control children. However, the gamma band
was difficult to discern, and so we only compared thisvariable between 41 ADHD and 49 control children who
had less electromyographic noise in their EEGs. Before
comparing the powers between the control and ADHD
groups, we compared the powers between children with
ADHD who had or did not have epileptic paroxysmal
waves in their EEGs.
We averaged the power of the alpha band in the left
and right occipital (P-O) regions and that of the beta
band in the left and right frontal (Fp-F) regions, andthen compared the mean powers between the ADHD
and control groups.
Statistical analyses were performed using the SPSS
Statistics 21 software (IBM, Tokyo, Japan). We used theMann–Whitney U test with the significance set at P <0.05.

SUBJECTS AND METHODS
Subjects were 80 children (58 boys, 22 girls) aged 4–15
years who had been diagnosed with ADHD in accordance with the Diagnostic and Statistical Manual of
Mental Disorders (DSM) at the Department of Pediatric Neurology in Tottori University Hospital between
December 1993 and March 2007. We analyzed EEGs
recorded prior to treatment with methylphenidate or
atomoxetine. We included 23 children with ADHD who
had EEG signals characterized by epileptic paroxysmal
waves. For these children, we analyzed sections of EEG
data without epileptic paroxysmal waves. In addition, 59
healthy children (31 boys, 28 girls) aged 4–15 years volunteered to participate in this study as control subjects.
The control subjects and their parents were fully educated regarding the study objectives and they provided
informed consent. To elucidate age-related changes, theADHD and control subjects were divided into different
age groups as follows: 4–6, 7–8, 9–10, 11–12, and 13–15
years (Table 1) and the powers were compared in eachage group. This study was approved by the Ethics Committee of Tottori University School of Medicine (approval
number 2494).
We recorded EEGs using the Neurofax EEG-1200
monitoring system (Nihon Kohden, Tokyo, Japan) withthe time constant set at 0.3 sec, high cut filter at 60 Hz,
sensitivity at 10 μV/mm, and sampling frequency at 200
Hz. In accordance with the international 10–20 system,disc electrodes were placed on the head of each subject,
who was asked to rest in a supine position with theireyes closed. Contact impedance was set below 20 kΩ.
We used MATLAB 8.1.0.604 software to analyze thespectra offline, and we calculated the mean power fromRESULTSWe did not observe any significant differences between
the ADHD group with epileptic paroxysmal waves andthe ADHD group without epileptic paroxysmal waves,for all regions and frequency bands (P > 0.05). Therefore, children with ADHD with epileptic paroxysmal
waves were included as ADHD subjects in this study.
Compared with the control group, the ADHD group
had significantly higher mean delta (Fig. 1A) and theta(Fig. 1B) powers in the frontal and parietal regions.
Children with ADHD also had significantly higher beta
power (Fig. 1D) in all regions except for the occipital region, while alpha (Fig. 1C) and gamma (Fig. 1E) powers

Table 1. Proﬁles of study subjects
Age group (year)

Control

ADHD

NumberMale : Female

Average age (year)

Number [EPW+]

Male : Female

Average age (year)

Total

59

31:28

8.7

80 [23]

58:22

8.3

4–6

14

8:6

5.1

14 [4]

10:4

5.5

7–8

12

2:10

7.4

37 [9]

27:10

7.5

9–10

17

10:7

9.3

18 [6]

12:6

9.4

11–12

10

7:3

11.3

6 [3]

6:0

11.5

13–15

6

4:2

13.8

5 [1]

3:2

13.6

ADHD, attention deficit disorder/hyperactivity disorder; EPW, epileptic paroxysmal wave.

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A. Kamida et al., P. 19

Fig. 1.
FA
ig. 1.
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EEG power in children withB
ADHD

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µV2

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10000

µμV
V 22

100000

10000

1000

1000

100

100

C

B

** *
** *

** *
** *

**
**

D

µμV
V 22

µ
μVV2 2C
100000
µV2

10000

1000

***
* *D*
*
µV2
***
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*

1000

***
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**
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100

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100

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1000

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10

100

µ V2 2μV
E*

Fig. 1. Mean powers in different brain regions. ○, healthy children; ●,children with ADHD. *P < 0.05, **P < 0.01, ***P < 0.001.
A: Comparison of delta power in different brain regions between the
ADHD and control groups. The power of the delta band was significantly higher in the frontal (Fp1-F3, Fp2-F4) and parietal (C3-P3, C4-P4)
regions in the ADHD group compared with the control group.
B: Comparison of theta power in different brain regions between the
ADHD and control groups. The power of the theta band was significantly higher in the frontal (Fp1-F3, Fp2-F4), right central (F4-C4) andparietal (C3-P3, C4-P4) regions in the ADHD group compared with thecontrol group.
C: Comparison of alpha power in different brain regions between the
ADHD and control groups. The power of the alpha band was significantly higher in the frontal (Fp1-F3, Fp2-F4) and right parietal (C4-P4)
regions in the ADHD group compared with the control group.
D: Comparison of beta power in different brain regions between the
ADHD and control groups. The power of the beta band was significantly higher in the frontal (Fp1-F3, Fp2-F4), central (F3-C3, F4-C4) andparietal (C3-P3, C4-P4) regions in the ADHD group compared with thecontrol group.
E: Comparison of gamma power in different brain regions between the
ADHD and control groups. The power of the gamma band was significantly higher in the frontal (Fp1-F3, Fp2-F4) regions in the ADHD groupcompared with the control group.
ADHD, attention deficit disorder/hyperactivity disorder.

171

A. Kamida et al.

μV2

μV2

Fig. 2. Mean power in different age groups.
, control group;, ADHD group. *P < 0.05.
A: Age-related changes in occipital alpha power. The power of the alpha band in the occipital region decreased age-dependently in both
the ADHD and control groups. Although occipital alpha power was lower (although this was not significant) in the ADHD group during
early development, this difference decreased after the age of 11–12 years.
B: Age-related changes in frontal beta power. The power of the beta band in the frontal region decreased age-dependently in both the
ADHD and control groups. For all age groups, children with ADHD exhibited higher power compared with the control group.
ADHD, attention deficit disorder/hyperactivity disorder; y, year(s).

were significantly higher in an area that encompassed
the frontal region. We observed significant group differences for the central theta and parietal alpha bands inthe right hemisphere only.
To clarify developmental changes in background
EEG activity, we analyzed the mean power of the alphaband in the occipital region (Fig. 2A) in all age groups.
The results revealed an age-dependent decrease in
occipital alpha power in both the ADHD and control
groups. This power was lower in children aged ≤ 10
years in the ADHD group compared with those in thecontrol group, although this finding was insignificant.
The intergroup difference diminished in older age
groups. As with the occipital alpha band, the beta power in the frontal region (Fig. 2B), where the intergroupdifference was prominent, decreased with age in bothgroups. However, unlike the occipital alpha band, theintergroup differences among children with ADHD
were higher in all age groups, and we observed significant differences in the 4–6 and 9–10 years groups.

found no significant differences in EEG power between
children with ADHD with and without epileptic paroxysmal waves. This was the case when comparing byregion and frequency band.
Comparison by region revealed that the powersof all frequency bands in the frontal region were significantly higher in children with ADHD comparedwith control children. This indicates the presence of afunctional abnormality in the frontal brain area of children with ADHD. Shaw et al. conducted a magnetic
resonance imaging (MRI) study and reported that thematurity of the prefrontal lobe in children with ADHD
lags by up to 5 years.6 Decreased blood flow during acontinuous performance test7 and decreased activity inthe prefrontal lobe during the stop and delay task8 havealso been reported in children with ADHD.
In terms of the parietal region, we found significantly higher delta, theta, alpha, and beta band power inthe ADHD group compared with the control group. In
a study conducted by Booth et al., functional magnetic
resonance imaging (fMRI) revealed reduced brain activity in the parietal lobe among children with ADHD.9
This may reflect a functional abnormality in the parietal
lobe in children with ADHD.
Comparisons by hemisphere revealed significant
intergroup differences in central theta and parietal alpha power in the right hemisphere only. Consistent with
this, cortical thinning in the right dorsolateral prefrontal

DISCUSSION
Epileptic paroxysmal waves are known to be more frequently in children with ADHD compared with healthy
children.3 In this study, we observed epileptic paroxysmal waves in 23 of the 80 children with ADHD. We
decided to include children with ADHD who had EEG
epileptic paroxysmal waves in our analysis because we
172

EEG power in children with ADHD

cortex10 and a volume reduction in the right striatum11
have been reported in autopsy studies of children withADHD.
As in the present study, many previous studies
have reported global high theta wave power in children
with ADHD.12–17 Elevated theta power in individuals
with ADHD may reflect the maturational delay of the
ADHD brain.18 Furthermore, our study revealed that thebeta power was higher in the ADHD group in all brain
regions except for the occipital region. It is generally
known that mental excitability and tension increases
the beta power. For example, Clarke et al. reported thatmoody children had increased beta wave activity.19 The
increased beta power found in this study suggests afunctional relationship between beta power and mental
state in individuals with ADHD.
We compared developmental findings in different
age groups. An intergroup difference in occipital alphapower was apparent in children aged ≤ 10 years, but not≥ 11 years. This may be consistent with the Maturation
Lag Model, which proposes that ADHD is caused bya maturational delay of the central nervous system.20
Conversely, frontal beta power was higher in children
with ADHD compared with control children in all age
groups. This may reflect the Developmental Deviation
Model, which proposes that ADHD is caused by a functional abnormality in the central nervous system.20 Additionally, these findings suggest that occipital alpha power
may reflect the hyperactivity characteristic of ADHD, as
this generally decreases to normal levels during development, while frontal beta power may reflect an attention
deficit, which seldom changes during development.

6 Shaw P, Eckstrand K, Sharp W, Blumenthal J, Lerch JP,
Greenstein D, et al. Attention-deficit/hyperactivity disorderis characterized by a delay in cortical maturation. Proc Natl
Acad Sci U S A. 2007;104:19649-54. PMID: 18024590.
7 Amen DG, Carmichael BD. High-resolution brain SPECT
imaging in ADHD. Ann Clin Psychiatry. 1997;9:81-6. PMID:
9242893.
8 Rubia K, Overmeyer S, Taylor E, Brammer M, Williams SC,
Simmons A, et al. Hypofrontality in attention deficit hyperactivity disorder during higher-order motor control: a study withfunctional MRI. Am J Psychiatry. 1999;156:891-6. PMID:
10360128.
9 Booth JR, Burman DD, Meyer JR, Lei Z, Trommer BL,
Davenport ND, et al. Larger deficits in brain networks forresponse inhibition than for visual selective attention in attention deficit hyperactivity disorder (ADHD). J Child Psychol
Psychiatry. 2005;46:94-111. PMID: 15660647.
10 Makris N, Biederman J, Valera EM, Bush G, Kaiser J,
Kennedy DN, et al. Cortical thinning of the attention andexecutive function networks in adults with attention-deficit/
hyperactivity disorder. Cereb Cortex. 2007;17:1364-75. PMID:
16920883.
11 Nakao T, Radua J, Rubia K, Mataix-Cols D. Gray mattervolume abnormalities in ADHD: voxel-based meta-analysis
exploring the effects of age and stimulant medication. Am J
Psychiatry. 2011;168:1154-63. PMID: 21865529.
12 Dupuy FE, Barry RJ, Clarke AR, McCarthy R, Selikowitz M.
Sex differences between the combined and inattentive types ofattention-deficit/hyperactivity disorder: an EEG perspective.
Int J Psychophysiol. 2013;89:320-7. PMID: 23603052.
13 Clarke AR, Barry RJ, McCarthy R, Selikowitz M, Magee CA,
Johnstone SJ, et al. Quantitative EEG in low-IQ children withattention-deficit/hyperactivity disorder. Clin Neurophysiol.
2006;117:1708-14. PMID: 16793337.
14 Barry RJ, Clarke AR, Hajos M, McCarthy R, Selikowitz M,
Dupuy FE. Resting-state EEG gamma activity in children
with attention-deficit/hyperactivity disorder. Clin Neurophysiol. 2010;121:1871-7. PMID: 20483659.
15 Clarke AR, Barry RJ, McCarthy R, Selikowitz M. Ageand sex effects in the EEG: differences in two subtypes ofattention-deficit/hyperactivity disorder. Clin Neurophysiol.
2001;112:815-26. PMID: 11336897.
16 Clarke AR, Barry RJ, Dupuy FE, McCarthy R, Selikowitz M,
Heaven PC. Childhood EEG as a predictor of adult attention-deficit/hyperactivity disorder. Clin Neurophysiol.
2011;122:73-80. PMID: 20598939.
17 Cla rke AR, Ba r r y R J, McCa r thy R, Selikowitz M,
Brown CR, Croft RJ. Effects of stimulant medications on
the EEG of children with Attention-Deficit/Hyperactivity
Disorder Predominantly Inattentive type. Int J Psychophysiol.
2003;47:129-37. PMID: 12568943.
18 Clarke AR, Barry RJ, McCarthy R, Selikowitz M. Age andsex effects in the EEG: development of the normal child. Clin
Neurophysiol. 2001;112:806-14. PMID: 11336896.
19 Clarke AR, Barry RJ, McCarthy R, Selikowitz M. Excess
beta activity in children with attention-deficit/hyperactivity
disorder: an atypical electrophysiological group. Psychiatry
Res. 2001;103:205-18. PMID: 11549408.
20 Barry RJ, Clarke AR, Johnstone SJ. A review of electrophysiology in attention-deficit/hyperactivity disorder: I. Qualitativeand quantitative electroencephalography. Clin Neurophysiol.
2003;114:171-83. PMID: 12559224.

The authors declare no conflict of interest.

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