Seasonality of Methylphenidate Administration among Children in Israel.

Background: Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder characterized by inattention, impulsivity and hyperactivity. Recently, increases in ADHD prevalence and methylphenidate use have been reported. There is evidence that children and adolescents use ADHD medication only during the school year.
Objectives: To investigate trends in methylphenidate dispensing over a period of 3 years (2010-2012) at the monthly level and to investigate whether there is any monthly variation, especially during the summer season.
Methods: The database of Clalit Health Services (the largest of the four health funds in Israel) was used to identify (i) patients aged 6-17 years with a diagnosis of ADHD, and (ii) methylpenidate dispensation during the period 2010-2012.
Results: Among children aged 6-17 years diagnosed with ADHD, 43% were treated with methylphenidate. For the period 2010 to 2012 there was an annual drop in methylphenidate dispensing, beginning in June and continuing through the 2 months of summer vacation, with a 2.5-fold reduction from July as compared to May. This decline was consistently followed by a rise in medications dispensed starting August. A similar small drop was observed during the Passover school vacation. The summer drop decreased over the years.
Conclusions: Our findings showed a decrease in the number of methylphenidate prescriptions dispensed during the summer months and Passover as compared to the rest of the year. However, this phenomenon appears to be decreasing. Given that ADHD is a chronic disease state that can effectively be managed with pharmacotherapy, discontinuation of treatment may be harmful for patients and should be considered only on a patient-by-patient basis.