Cardiovascular effects of methylphenidate, risperidone, and their combination in children and adolescents with attention-deficit/hyperactivity disorder: a prospective 3-month observational study

Background We aimed to evaluate changes in hemodynamic parameters and electrocardiographic (ECG) indices related to ventricular arrhythmia risk after three months of treatment with methylphenidate (MPH), risperidone (RIS), or their combination in children and adolescents with ADHD. Methods A total of 150 children and adolescents with DSM-5-diagnosed ADHD were prospectively enrolled at Qods Hospital. Participants received methylphenidate ( n = 50), risperidone ( n = 50), or combination therapy ( n = 50). Cardiovascular outcomes were assessed using age- and weight-adjusted two-way repeated-measures ANCOVA to evaluate changes over time and differences among treatment groups. Results Significant group × time interactions were observed for systolic blood pressure, diastolic blood pressure, heart rate, and QTc interval after adjustment for baseline age and weight. After three months, systolic and diastolic blood pressure increased in the methylphenidate and combination therapy groups, while heart rate showed an overall increase, with the greatest rise observed in the methylphenidate group. QTc interval increased over time across all treatment groups, with the largest prolongation observed in the combination therapy group (377.9 ± 25.4 to 424.5 ± 24.9 ms). However, mean QTc values remained below commonly accepted thresholds for clinically significant QT prolongation, and no significant longitudinal changes were observed in QRS duration or PR intervals. Conclusion Treatment with methylphenidate, risperidone, and combination therapy was associated with modest changes in heart rate, blood pressure, and QTc interval over three months. These findings highlight the importance of baseline and follow-up cardiovascular monitoring in children and adolescents receiving ADHD medications.