Heart rate variability and methylphenidate in children with ADHD.
Source Atten Defic Hyperact Disord 2012 Feb 11.
extensive number of studies support the efficacy and tolerability of stimulants
in the treatment of attention deficit/hyperactivity disorder (ADHD), in recent
years, increasing concerns have been raised about their cardiovascular safety.
We investigated whether a time domain analysis of heart rate variability (HRV)
recordings in 24-h ECG under medication with stimulants yielded new information
about therapy control in ADHD. We analysed the HRV
parameter standard deviation of all normal sinus RR intervals over 24 h
(SDNN), percentage of successive normal sinus RR
intervals > 50 ms (pNN50) and
root-mean-square of the successive normal sinus RR interval difference (rMSSD) from 23 children diagnosed by ADHD (19 boys and 4
girls), aged 10.5 ± 2.2 years, who were consecutively referred
to our outpatient clinic for paediatric cardiology.
Eleven children received medication with methylphenidate (MPH), while twelve
children were initially examined without medication. Of these, eight probands were re-examined after therapy with MPH was
established. Controls comprised 19 children (10 boys, 9 girls) from our Holter ECG data base without any cardiac or circulatory
disease. Compared to healthy controls, the ADHD children with and without MPH
treatment showed significantly higher mean heart rates (ADHD without MPH:
94.3 ± 2.2; ADHD with MPH: 90.5 ± 1.8, controls:
84.7 ± 1.8). pNN50 (ADHD without MPH: 6.5 ± 2.7; ADHD with
MPH: 14.2 ± 6.9, controls: 21.5 ± 9.0) and rMSSD (ADHD without MPH: 26.1 ± 4.1; ADHD with
MPH: 36.7 ± 8.3, controls: 44.5 ± 10.1) were lowest in ADHD
children without MPH, middle in ADHD children with MPH and highest in controls.
SDNN values were not significantly different. The hourly analysis shows highly
significant reduced pNN50 and rMSSD values in
untreated ADHD children between 5:00 pm and 6:00 am while the pattern
approaches to levels of controls during MPH treatment. Data of this pilot study
indicate a decreased vagal tone with significantly diminished HRV and higher
heart rates in unmedicated ADHD children. These
parameters of autonomic activation are ameliorated by MPH treatment. No
evidence for negative impact of MPH on HRV was detected. Further studies will
clarify a potential cardio-protective effect of MPH in ADHD.LanguageENGPub