Methylphenidate (MPH) is the most widely prescribed therapy for attention deficit hyperactivity disorder. Animal studies have shown a potential adverse effect of MPH exposure on male fertility. We examined the impact of MPH on human male sperm parameters.
Sperm parameters of 9769 samples from patients 18 years of age or older, collected as part of the basic evaluation of couples referred to the Infertility Clinic were analyzed retrospectively. We divided the study population into three groups according to MPH purchasing information: MPH purchased ≤ 90 days prior to sperm analysis-current users (n = 83), MPH purchased > 90 days prior to sperm analysis-past users (n = 293), and MPH-naïve patients (n = 9393).
All sperm samples were analyzed by the same laboratory technician team for the following routine parameters: semen volume, sperm concentration, percentage of motile sperm, and percentage of normal morphology according to World Health Organization. The analysis of the samples was completed by evaluation of total sperm count, total sperm motility, and percentage of fast and slow motile cells. Sperm morphology was evaluated by a laboratory technician using methodological examination according to the strict Kruger-Tygerberg criteria.
Methylphenidate exposure did not affect sperm morphology but was associated with increased sperm concentration as well as increased total sperm count and total sperm motility among current and past users compared with MPH-naïve patients. In particular, progressive motility and total motile sperm count were significantly increased following MPH use. A multivariate analysis adjusting for age and current smoking was conducted, further supporting a positive correlation between current MPH use and increased values of total sperm count and total sperm motility.
Our study has several inherent weaknesses, foremost of which is its retrospective nature. Another notable weakness is that medication purchasing data may not accurately reflect MPH exposure in the study population. Patients may be purchasing MPH and not taking it as prescribed.
In the present study, we could not demonstrate a negative impact of methylphenidate treatment on sperm parameters in adults with ADHD. Hence, we may assume that methylphenidate does not negatively affect male fertility.