Predicting the clinical outcome of stimulant medication in pediatric attention-deficit/hyperactivity disorder: data from quantitative electroencephalography, event-related potentials, and a go/no-go test

Figures & data

Table 1 Demographics of the ADHD sample by sex

	Male (N=66)	Female (N=32)	Difference
Age, years (SD)	11.5 (2.4)	12.8 (3.0)	P=0.04
ADHD-C (combined subtype)	43 (65%)	15 (47%)	NS
ADHD-I (inattentive subtype)	23 (35%)	17 (53%)	NS
Total IQ	93 (15)	90 (13)	NS
Behavior problems (ODD-CD)	23 (35%)	11 (34%)	NS
Emotional problems	26 (26%)	13 (41%)	NS
Learning disordersa	36 (55%)	16 (50%)	NS
Autism spectrum disorders	9 (14%)	3 (9%)	NS
Other disordersb	7 (11%)	4 (13%)	NS

Notes:

a General learner disorder (IQ <80, special education in several school subjects) and specific learning disorder (IQ >80, dyslexia, dyscalculia);

b Tourette’s syndrome, reactive attachment disorder.

Abbreviations: ADHD, attention-deficit/hyperactivity disorder; IQ, intelligence quotient; NS, not significant; ODD-CD, oppositional defiant disorder–conduct disorder; SD, standard deviation.

Table 2 Demographics in responder (RE) and nonresponder (non-RE) groups

	REs (N=74)	Non-REs (N=24)	Difference
Age, years (SD)	11.6 (2.7)	12.7 (2.7)	NS
Sex (male: N=66, female: N=32)	Male: 47 (71%) Female: 26 (81%)	Male: 19 (29%) Female: 6 (19%)	NS
Total IQ	94 (14)	87 (15)	NS
ADHD subtype (ADHD-C: N=58, ADHD-I: N=40)	ADHD-C: 43 (74%) ADHD-I: 30 (75%)	ADHD-C: 15 (26%) ADHD-I: 10 (25%)	NS
Behavior problems (ODD-CD) (ODD-CD: N=34)	ODD: 26 (77%) No ODD: 47 (73%)	ODD: 8 (23%) No ODD: 17 (27%)	NS
Emotional problems (Em: N=30)	Em: 23 (77%) No Em: 50 (74%)	Em: 7 (23%) No Em: 18 (26%)	NS
Learning disorders (LDs: N=53)a	LD: 38 (71%) No LD: 35 (78%)	LD: 15 (29%) No LD: 10 (22%)	NS
Autism spectrum disorders (ASD: N=12)	ASD: 7 (58%) No ASD: 66 (77%)	ASD: 5 (42%) No ASD: 20 (23%)	NS
Other disorders (TS, RAD, etc: N=11)	“Other:” 5 (45%) No “other:” 68 (78%)	“Other:” 6 (55%) No “other:” 19 (22%)	P=0.05

Note:

a General LD (IQ <80, special education in several school subjects) and specific LD (IQ >80, dyslexia, dyscalculia).

Abbreviations: ADHD, attention-deficit/hyperactivity disorder; ADHD-C, combined subtype; ADHD-I, inattentive subtype; IQ, intelligence quotient; NS, not significant; ODD-CD, oppositional defiant disorder–conduct disorder; SD, standard deviation; TS, Tourette’s syndrome; RAD, reactive attachment disorder.

Table 3 Positive effects of medication reported for respondersa

Category	Number of positive reports
Emotion	26 (33%)
Increased emotional stability, reduced irritability, better mood
Social function	16 (22%)
Improved social interaction, reduced peer conflicts
Attention	59 (80%)
Improved attention and vigilance, better academic function, better at homework, more focused
Executive function	21 (28%)
Increased initiative, less dependent on others, better routines, better at completing tasks
Impulsivity	11 (15%)
Reduction of impulsive acts
Hyperactivity	26 (35%)
Reduced overactivity and restlessness
Alert	6 (8%)
More awake, engaged, increased effort
Other	10 (14%)
Reduced fatigue, fewer tics

Note:

a The number and percentage of positive patient reports in each category are shown.

Table 4 Independent samples t-tests showing continuous variables with significant differences between the responder (RE) group and the nonresponder (non-RE) groupa

Variable	Mean (SD) RE group	Mean (SD) non-RE group	P-value	t	df	Effect size Cohen’s d
Theta sum 7 sites (μV^2)	69 (45)	48 (28)	0.034	−2.15	96	0.49
Omission errors	18.4 (15)	11.4 (10)	0.013	−2.56	61.5	0.49
Reaction time (ms)	420 (77)	381 (70)	0.028	−2.23	96	0.52
Reaction time variability	16.3 (4.8)	12.8 (3.9)	0.002	−3.23	96	0.75
IC ERP CNV late amplitude	−0.936 μV (1.4)	−0.715 μV (1.1)	0.010	−2.61	96	0.58
IC ERP cue P3 amplitude	5.62 μV (2.9)	3.56 μV (1.9)	<0.001	−4.05	61.3	0.76
IC ERP P3 no-go early amplitude	6.82 μV (4.5)	10.26 μV (5.5)	0.002	3.13	94	−0.72
Performance IQ	96 (17)	87 (17)	0.031	−2.17	96	0.53

Notes:

a IC CNV late, mean power at site Cz in time interval 900–1,100 ms after stimulus 1 when this stimulus was a target. IC ERP cue P3, peak amplitude at site Pz after stimulus 1 in time interval 220–400 ms when this stimulus was a target. IC ERP P3 no-go early, peak amplitude at site Cz after stimulus 2 in time interval 250–470 ms when this stimulus was not a target.

Abbreviations: CNV, contingent negative variation; df, degrees of freedom; ERP, event-related potential; IC, independent component; IQ, intelligence quotient; SD, standard deviation; RE, responder; non-RE, non-responder.

Figure 1 The independent component cue P3 is decreased in non-responders (non-REs).

Notes: Left the independent component for the group of REs (green) and non-REs (red) in comparison with the group of healthy controls (grey). X-axis – time after the onset of the first stimulus in ms. Y-axis – amplitude of the component back-projected and measured at site Pz. Right: the standardized low-resolution brain electromagnetic tomography (sLORETA) image of the cortical generators of the component. The scale is shown below. Bottom: the map of the difference; REs minus non-REs. The scale is shown on the right.
Abbreviation: t, time.

Figure 2 The independent component no-go early is decreased in the responder (RE) group. Left: the independent component for the group of REs (green) and non-REs (red) in comparison with the group of healthy controls (grey). X-axis – time after the onset of the second stimulus in ms. Y-axis – amplitude of the component back-projected and measured at Cz. Right: the standardized low-resolution brain electromagnetic tomography (sLORETA) image of the cortical generators of the component. The scale is shown below. Bottom: the map of the difference REs minus non-REs. The scale is shown on the right.

Figure 3 Based on scores combining the three significant variables, patients were placed in four (quartile [Q]) groups. Only 36% in the first group were responders. In quartile groups 2, 3, and 4, 83%, 86%, and 89% were responders.