Comparison of Quantitative Electroencephalography (qEEG) Indices in Children with Attention Deficit- Hyperactivity Disorder and Healthy Childrens

  

    
Waves 
    
Control (n=30)
      
Mean ± SE 
    
ADHD 
      
  (n=30)
      
Mean ± SE
    
P-Value 
  
  

    
Delta O1    Closed eye
      
High Beta C3    Closed eye
      
High Beta C3    open eye
      
High Beta C4    Closed eye
      
High Beta C4    open eye
      
High Beta Cz    Closed eye
      
High Beta F7    Closed eye
      
High Beta C7    open eye
      
High Beta F8    Closed eye
      
High Beta F8    open eye
      
High Beta Fz    Closed eye
      
High Beta Fz    open eye
      
High Beta O1    Closed eye
      
High Beta O1    open eye
      
High Beta O2    Closed eye
      
High Beta P4    Closed eye
      
High Beta P4    open eye
      
High Beta T6    Closed eye
      
High Beta T6    open eye
    
25.2± 1.7
      
2.7 ± 0.3
      
2.8 ± 0.3
      
2.7 ± 0.3
      
2.9 ± 0.3
      
2.1 ± 0.2
      
2.1 ± 0.1
      
2.5 ± 0.2
      
2.1 ± 0.2
      
2.5 ± 0.2
      
2.1 ± 0.3
      
2 ± 0.2
      
1 ± 0.1
      
1.3 ± 0.1
      
1.1 ± 0.1
      
1.7 ± 0.2
      
2 ± 0.3
      
2 ± 0.3
      
2.7 ± 0.3
    
20.8 ± 1.4
      
1.9 ± 0.1
      
2.1±  0.1
      
1.9 ± 0.1
      
2 ± 0.1
      
1.6 ± 0.1
      
1.7 ± 0.1
      
2 ± 0.1
      
1.6 ± 0.1
      
1.8 ± 0.1
      
1.4 ± 0.1
      
1.5 ± 0.1
      
0.7 ± 0.1
      
1.1 ± 0.1
      
0.8 ± 0.1
      
1.2 ± 0.1
      
1.4 ± 0.1
      
1.3 ± 0.1
      
1.9 ± 0.1
    
0.048
      
0.031
      
0.04
      
0.026
      
0.027
      
0.044
      
0.024
      
0.025
      
0.018
      
0.017
      
0.012
      
0.014
      
0.009
      
0.034
      
0.018
      
0.029
      
0.032
      
0.017
      
0.026
  

Table 3: QEEG analyses for relative power of waves (included only those with
statistically significant differences between the two groups).

Comparing waves in terms of the location where recording took place, the mean absolute power of high beta waves, alpha to delta and delta to theta mean power ratios, and the mean relative power of high beta waves in the central region were higher in the control group than the case group. The mean power ratios of beta to high beta and theta to high beta waves in the central region were higher in the case group compared to the control group.

The mean absolute power of beta waves in the frontal lobe was higher in the control group than the mean absolute power of delta waves. Power ratios of alpha to high beta, beta to high beta, delta to beta, delta to high beta, delta to theta, theta to high beta were higher in the case group compared to the control group in the frontal lobe.

In the occipital lobe, the mean relative powers of high beta and delta waves were higher in the control group compared to the case group. On the other hand, in the occipital lobe, the mean power ratios of alpha to high beta, beta to high beta, and theta to high beta, and the mean relative power of high beta were higher in the case group compared to the control group.

In the temporal lobe, the mean relative power of high beta was higher in the control group compared to the case group and the mean absolute power of beta waves was higher in the case group compared to the control group.

Discussion

In the present study we investigated the quantitative EEG findings in children with ADHD compared to healthy children. The results showed that the mean absolute power of high beta waves is significantly lower in ADHD children. In terms of location, the recorded waves from the frontal, parietal and occipital lobes, with different absolute power between the two groups, were demonstrated to have a significant preponderance in children with ADHD. This preponderance was in favor of the control group in the temporal lobe. There was not a significant preponderance in central region between the two groups in this regard. These results could help clinicians making definite diagnosis in complicated patients and might be an objective measure for controlling the course of disorder as well as response to treatment.

Despite the numerous studies conducted in the field of EEG on children with ADHD, the reported results vary. The number of QEEG studies in this field is limited. Dykman et al. investigated the electrocortical frequencies in hyperactive, learning-disabled, mixed, and normal children. They could specify a multi-frequency component with highest loadings in frequencies from 16 to 20 Hz as well as 7 to 10 Hz to be sensitive to children with hyperactivity symptoms and learning disability [9]. Callaway et al. investigated the differences in EEG findings of 18 children with ADHD and 18 normal children. In this research, the power of beta was reported to be lower in hyperactive children compared to the control group [10]. Chabot and Serfontein reported differences in EEG findings among 407 children with ADHD compared to the control group. In children with ADHD the power of Theta wave was increased. Their records could distinguish normal children from those with ADHD with a high sensitivity and specificity. Both patterns of EEG slowing and an increase in EEG activity were noted in these children [11]. In another study, Lazzaro et al. investigated 54 male adolescents with ADHD and the same number of healthy adolescents. It was shown that the relative and absolute activity of alpha and theta increased and the relative activity of beta decreased [12]. Lazzaro et al. again reported an increase of theta activity in children with ADHD [13]. The result of our study on the decrease of power of high-beta waves in ADHD children was consistent with the above-mentioned studies. In this context, via considering the absolute power of the other waves, there were no significant differences between the two groups. The differences in the power ratio of waves (including the increased ratio of alpha, beta, delta, and theta to high beta in the case group) can be accounted for by considering the decreased power of high beta waves in the ratio denominator. Lazzaro et al. (1998) investigated differences in EEG findings between 26 teenage boys diagnosed with ADHD and the control group. The results indicated an increase in the power of theta and alpha waves in the frontal region and a decrease in the relative power of beta waves in the occipital region [14]. Considering the increase in the power of waves in the frontal lobe, the results of the stated study are consistent with the findings of the present study and can be an objective guide for clinical diagnosis, especially in presence of other comorbidities. However, we also showed the increase of the relative power of waves in the occipital region of patients. Clarke et al. studied the EEG differences between 20 children with ADHD, 20 children with ADHD and learning disability, and 20 healthy children. Results indicated that among the clinical groups, in comparison with the control group, the absolute and relative powers of alpha and beta waves were lower and the relative powers of delta and theta waves were higher. The group of patients in the posterior region had decreased absolute power of alpha and beta, and decreased relative power of delta, theta, and alpha waves. They also had a lower relative power of beta in the frontal region.

According to the results of this study, the ratios of theta/alpha, and theta/beta were able to differentiate case and control groups from each other [15]. Lubar calculated the ratio of theta/beta in 25 children with ADHD and 27 healthy children during the act of painting. In children with ADHD this ratio was higher than healthy children, but most of the differences were seen in the frontal lobe [16]. Ucles and Lorente reported that children with ADHD had a lower alpha/theta ratio than normal children in the occipital region [17].

As mentioned earlier, the results of the various studies in the field of QEEG findings in ADHD are highly varied. In summing up the results of various studies in this field, increased activity of the slow waves in the frontal region, increased power of the theta and delta waves and decreased power of alpha and beta waves in ADHD children and in comparison with healthy children are notable [18- 24]. The results of the present study are also similar, in some aspects, to those reported above. However, we need to take into account that the status of the patients at the time of study in different studies can have a significant effect on the obtained results. Snyder and Hall conducted a meta-analysis, including the results of 9 studies of the quantitative EEG in 1498 ADHD children. They concluded that many of these studies have variable and unreliable results due to flaws in methodology (for example in retrospective studies) [25]. According to Clarke et al. many of the findings of QEEG in ADHD children are influenced by the concurrent brain pathological conditions. However, in their study the increase in the power of beta waves has been emphasized and dysfunction in the frontal lobe has been attributed for this [26].

Moreover, it has been previously shown that the results of EEG will vary according to the patients’ eyes being open or closed [27]. In the present study, the results of EEG were recorded in both open and closed eyes. Moreover, the other reason for failure to achieve definite results in the area of QEEG findings in ADHD may be the nature of the ADHD itself and indeed its different subtypes [18]. According to Bresnahan et al. the predominant symptoms of ADHD may be related to the findings of the EEG, so that in the more hyperactive children the power of the beta is decreased; whereas in the more impulsive children the power of the theta is increased. Furthermore, they have raised the role of increasing age in QEEG findings in ADHD and showed a decrease in the extent of the reduction in relative beta activity in the ADHD groups [28].

There have been some limitations in the present study, including the lack of determining the differentiating cut-off points between the ADHD and healthy children groups due to the small sample size, not including female subjects, and not considering the role of different sub-types of ADHD on the results of the study.

Conclusion

According to our results, generalized decrease in absolute power of “high-beta” waves was a constant finding in ADHD children. These findings may be employed as a reference for future studies, determining factors for prognosis or for the treatment of ADHD.

Determining the appropriate cut-off points based on a careful distinction between different significant parameters among patients and healthy subjects with larger sample size is recommended. Also, similar studies are recommended for female children and different ADHD subtypes.

Acknowledgement

The authors are thankful to all parents and children participating in this study. The paper was adopted from doctoral dissertation of Dr Mahmoud Nasiri with the Reg. No. of 87/3-6/13 from Tabriz University of Medical Sciences.

References

1. Psychiatry. 8th ed. Lippincott Williams & Wilkins. Philadelphia. 145; 791-793: 2697-2680.
2. American Psychiatric Association. Diagnostic and statistical Manual of mental disorders, 4th ed. American Psychiatric Association, Washington DC. 1995; 25.
3. Barry R, Clarke A, Johnstone S. A review of electrophysiology in attention- deficit/hyperactivity disorder: I: Qualitative and quantitative electroencephalography. Clinical Neurophsiology. 2003; 114: 171-183.
4. Clarke A, Barry R, McCarthy R, Selikowitz M, Clarke D, Croft R. EEG activity in girls with attention-deficit/hyperactivity disorder. Clinical Neurophysiology. 2003; 114: 319-328.
5. Clarke R, Barry R, McCarthy R, Selikowitz M, Brown C. EEG evidence for a new conceptualization of attention- deficit hyperactivity disorder. Clinical Neurophysiolosy. 2002; 113: 1036-1044.
6. Clarke A, Barry R, McCarthy R, Selikowitz M. EEG differences between good and poor responders to methylplenidate and dexamphetamine in children with attention deficit hyperactivity disorder. Clinical Neurophysiolosy. 2002; 113: 194-205.
7. Clarke A, Barry R, McCarthy R, Selikowitz M, Croft R. EEG differences between good and poor responders to methylplenidate in boys with the inattentive type of attention-defiant hyperactivity disorder. Clinical Neurophysiolosy. 2002; 113: 1191-1198.
8. Ghanizadeh A, Mohammadi MR, Yazdanshenas A. Psychometric properties of the Farsi translation of the Kiddie Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version. BMC Psychiatry. 2006; 6: 10.
9. Dykman RA, Holcomb PJ, Oglesby DM, Ackerman PT. Electrocortical frequencies in hyperactive, learning-disabled, mixed, and normal children. Biol Psychiatry. 1982; 17: 675-685.
10. Callaway E, Halliday R, Naylor H. Hyperactive children’s event-related potentials fail to support underarousal and maturational-lag theories. Arch Gen Psychiatry. 1983; 40: 1243-1248.
11. Chabot RJ, Serfontein G. Quantitative electroencephalographic profiles of children with attention deficit disorder. Biol Psychiatry. 1996; 40: 951-963.
12. Lazzaro I, Gordon E, Li W, Lim CL, Plahn M, Whitmont S, et al. Simultaneous EEG and EDA measures in adolescent attention deficit hyperactivity disorder. Int J Psychophysiol. 1999; 34: 123-134.
13. Lazzaro I, Gordon E, Whitmont S, Meares R, Clarke S. The modulation of late component event related potentials by pre-stimulus EEG theta activity in ADHD. Int J Neurosci. 2001; 107: 247-264.
14. Lazzaro I, Gordon E, Whitmont S, Plahn M, Li I, Clarke S, et al. Quantitative EEG activity in adolescent attention deficit hyperactivity disorder. Clin Electroencephalogr. 1998; 29: 37-43.
15. Clarke AR, Barry RJ, McCarthy R, Selikowitz M. Children with attention-deficit/hyperactivity disorder and comorbid oppositional defiant disorder: an EEG analysis. Psychiatr Res. 2002; 111: 181-190.
16. Lubar JF. (1991). Discourse on the development of EEG diagnostics and biofeedback for attention-deficit/hyperactivity disorders. Biofeedback Self Regul. 1991; 16: 201-225.
17. Ucles P, Lorente S. Electrophysiologic measures of delayed maturation in attention-deficit hyperactivity disorder. J Child Neurol. 1996; 155-156.
18. Magee CA, Clarke AR, Barry RJ, McCarthy R, Selikowitz M. Examining the diagnostic utility of EEG power measures in children with attention deficit/hyperactivity disorder. Clin Neurophysiol. 2005; 116: 1033-1040.
19. Clarke AR, Barry RJ, McCarthy R, Selikowitz M. EEG analysis in attention-deficit/hyperactivity disorder: a comparative study of two subtypes. Psychiatr Res. 1998; 81: 19-29.
20. Clarke AR, Barry RJ, McCarthy R, Selikowitz M. EEG-defined subtypes of children with attention-deficit/hyperactivity disorder. Clin Neurophysiol. 2001; 112: 2098-2105.
21. Clarke AR, Barry RJ, McCarthy R, Selikowitz M. Electroencephalogram differences in two subtypes of attention-deficit/hyperactivity disorder. Psychophysiology. 2001; 38: 212-221.
22. Clarke AR, Barry RJ, McCarthy R, Selikowitz M. Excess beta activity in children with attention-deficit/hyperactivity disorder: an atypical electrophysiological group. Psychiatr Res. 2001; 103: 205-218.
23. Stewart GA, Steffler DJ, Lemoine DE, Leps JD. Do quantitative EEG measures differentiate hyperactivity in attention deficit/hyperactivity disorder? Child Study J. 2001; 31: 103-121.
24. Baving L, Laucht M, Schmidt MH. Atypical frontal brain activation in ADHD: preschool and elementary school boys and girls. J Am Acad Child Adolesc Psychiatry. 1999; 38: 1363-1371.
25. Snyder SM, Hall JR. A meta-analysis of quantitative EEG power associated with attention-deficit hyperactivity disorder. J Clin Neurophysiol. 2006; 23: 440-455.
26. Clarke AR, Barry RJ, McCarthy R, Selikowitz M, Johnstone SJ, Hsu CI, et al. Coherence in children with Attention-Deficit/Hyperactivity Disorder and excess beta activity in their EEG. Clin Neurophysiol. 2007; 118: 1472-1479.
27. Robeva R, Penberthy J, Loboschefski T, Cox D, Kovatchev B. Combined psychophysiological assessment of ADHD: a pilot study of Bayesian probability approach illustrated by appraisal of ADHD in female college students. Appl Psychophysiol Biofeedback. 2004; 29: 1-18.
28. Bresnahan SM, Anderson JW, Barry RJ. Age-related changes in quantitative EEG in attention-deficit/hyperactivity disorder. Biol Psychiatry. 1999; 46: 1690-1697.