An Exaggerated Cardiovascular Response to Methylphenidate in ADHD Children with Anxiety

Abstract

The cardiovascular responses to methylphenidate (MPH) were investigated in anxious and nonanxious children with attention-deficit hyperactivity disorder (ADHD). A randomized, double-blind, placebo-controlled crossover design was used to evaluate the acute effects of three doses (0.3, 0.6, and 0.9 mg/kg) of MPH on cardiovascular function in 63 children (34 nonanxious, 29 anxious), aged 6 to 12 years, with ADHD. Resting heart rate as well as systolic and diastolic blood pressure readings were taken prior to 1 hr after, and 2 hrs after administration of medication. Results indicated that baseline cardiovascular measures were similar for the two diagnostic groups. MPH produced the expected dose-dependent and time-dependent increases in heart rate and both systolic and diastolic blood pressure in all children. However, MPH produced significantly greater increases in diastolic blood pressure in the anxious ADHD group, particularly 1 hr after its administration, than in the nonanxious ADHD children. Although these stimulant-induced changes were generally of little clinical concern, the exaggerated response of the ADHD/ANX children to MPH challenge supports the hypothesis of increased sensitivity to augmented noradrenergic function in this group. The presence of high levels of trait anxiety in some ADHD children alters the cardiovascular response to MPH, suggesting that highly anxious children with ADHD may constitute a distinct subgroup of children with ADHD. In this study, anxiety was defined by the child's self-report, so the findings attest to the importance of obtaining children's self-report of internalizing symptomatology. The presence of self-reported anxiety in ADHD children should alert clinicians to the possibility of a differential response to psychostimulants in anxious ADHD children.