Effects of methylphenidate on the lower urinary tract in patients with attention deficit hyperactivity disorder and without voiding dysfunction.

Background: Attention deficit hyperactivity disorder (ADHD) is characterised by a range of symptoms, such as excessive mobility, difficulty in maintaining attention and inadequate impulse control. Methylphenidate (MPH) is widely prescribed as a treatment for ADHD. In the literature, studies investigating the effects of MPH on the lower urinary tract (LUT) are limited.

Objective: The aim of the study was to evaluate MPH-induced LUT symptoms (LUTSs) in patients with ADHD without a diagnosis of voiding dysfunction (VD).

Study Design: After ethical committee approval, volunteers aged 7-17 y were divided into two groups, with group 1 composed of individuals diagnosed with ADHD but not VD and group 2 (control) composed of healthy individuals. Lower urinary tract symptoms and quality of life, in addition to uroflowmetry test results and postvoiding residual volume (PVRV), were evaluated in both groups at baseline and again 4 wk later. The individuals in group 1 were treated with MPH after baseline screening. The dysfunctional voiding scoring system questionnaire was used for scoring LUTSs. Postvoiding residual volume was measured by ultrasound. Bladder capacity (BC) was calculated as the sum of voided volume (VV) and PVRV. The means of the maximum flow rate (Q max), mean flow rate (Q mean), VV, PVRV and BC were recorded.

Results: After exclusions, there were 43 participants in group 1 and 39 participants in group 2. There was no significant difference between the mean age of groups (p = 0.727). Compared with the baseline, VV and BC increased significantly in group 1 (p = 0.001 and p = 0.002, respectively) at the 4-wk follow-up. There was no significant difference in these parameters in group 2.

Discussion: This study demonstrated that VV and BC increased after MPH treatment in patients with ADHD without a diagnosis of VD. The mechanism underlying this effect is unclear, but it may be associated with dopaminergic and noradrenergic effects.

Conclusion: The findings of the present study can inform further studies on the mechanism underlying the effect of MPH on the LUT. In a future study, the authors suggest evaluating the effects of MPH in a urodynamic study in patients with ADHD diagnosed with VD.