Analysis of cardiac autonomic modulation of children with attention deficit hyperactivity disorder

Figures & data

Table 1 Average values and standard deviations for age, weight, height, and body mass index in ADHD children and controls

Variables	ADHD Average (SD) (CI)	Controls Average (SD) (CI)	P
Age (years)	9.96 (1.93) (9.21–10.71)	9.85 (1.84) (9.14–10.57)	0.832
Weight (kg)	38.76 (17.83) (31.84–45.67)	35.07 (9.09) (31.55–38.60)	0.682
Height (m)	1.39 (0.13) (1.34–1.44)	1.44 (0.10) (1.40–1.48)	0.060
BMI (kg/m^2)	19.20 (4.67) (17.39–21.02)	16.52 (1.91) (15.78–17.27)	0.021*

Note:

* P<0.05.

Abbreviations: ADHD, attention deficit hyperactivity disorder; BMI, body mass index; CI, confidence interval; SD, standard deviation.

Table 2 Linear index values of heart rate variability (frequency domain) of children with ADHD and controls

Variables	ADHD Average (SD) (CI)	Controls Average (SD) (CI)	P
LF ms^2	781.00 (449.07) (606.86–955.14)	1021.4 (723.95) (740.62–1302.1)	0.305
HF ms^2	751.64 (518.60) (550.54–952.75)	799.86 (828.35) (478.63–1121.1)	0.588
LFnu	53.81 (14.15) (48.32–59.30)	59.36 (12.24) (54.61–64.11)	0.122
HFnu	46.18 (14.15) (40.69–51.67)	40.63 (12.24) (35.88–45.38)	0.122
LF/HF	1.37 (0.75) (1.08–1.66)	1.74 (1.05) (1.33–2.14)	0.187

Abbreviations: ADHD, attention deficit hyperactivity disorder; CI, confidence interval; HF, high frequency; HFnu, high frequency in normalized units; LF, low frequency; LFnu, low frequency in normalized units; ms, milliseconds; SD, standard deviation.

Table 3 Linear index values of heart rate variability (time domain) of children with ADHD and controls

Variables	ADHD Average (SD) (CI)	Controls Average (SD) (CI)	P
RRi	714.46 (84.15) (681.83–747.10)	680.86 (99.23) (642.38–719.35)	0.108
SDNN	48.56 (13.34) (43.39–53.74)	54.51 (18.60) (47.29–61.72)	0.175
RMSSD	41.82 (17.83) (34.90–48.73)	38.15 (18.35) (31.03–45.26)	0.341
NN50	199.75 (144.00) (143.91–255.59)	127.46 (102.21) (87.82–167.10)	0.035*
pNN50	23.95 (17.31) (17.24–30.67)	16.21 (13.21) (11.08–21.33)	0.065

Note:

* P<0.05.

Abbreviations: ADHD, attention deficit hyperactivity disorder; CI, confidence interval; NN50, adjacent normal-to-normal intervals that are greater than 50 ms; pNN50, percentage of differences between adjacent normal-to-normal intervals that are greater than 50 ms; ms, milliseconds; RMSSD, root mean square of successive differences; RRi, intervals between consecutive heart beats; SD, standard deviation; SDNN, standard deviation normal-to-normal intervals.

Table 4 Mean, standard deviation, and 95% confidence interval for Poincaré plot of children with ADHD and controls

Variables	ADHD Average (SD) (CI)	Controls Average (SD) (CI)	P
SD1	29.58 (12.62) (24.69–34.48)	26.98 (12.98) (21.95–32.02)	0.333
SD2	61.64 (15.68) (55.56–67.72)	71.94 (23.66) (62.76–81.12)	0.061
SD1/SD2	0.46 (0.12) (0.41–0.51)	0.36 (0.095) (0.33–0.40)	0.002*

Note:

* P<0.05.

Abbreviations: ADHD, attention deficit hyperactivity disorder; CI, confidence interval; SD, standard deviation; SD1, standard deviation of instantaneous beat-to-beat RR interval variability; SD2, standard deviation of continuous long-term RR interval variability.