A comprehensive systematic review updated in 2022 reveals that methylphenidate, a common medication prescribed for children and adolescents with attention deficit hyperactivity disorder (ADHD), may improve ADHD symptoms and general behaviour. However, the certainty of the evidence for all outcomes remains very low due to the high risk of bias in the included trials, underreporting of relevant outcome data, and significant statistical variation between trial results. The findings were published in the Cochrane Database of Systematic Reviews.
ADHD is one of the most commonly diagnosed and treated childhood psychiatric disorders, characterized by difficulty paying attention, hyperactivity, and impulsivity. It affects children’s academic performance and social interactions, often resulting in more disciplinary issues than their peers. Methylphenidate, a psychostimulant medication, is frequently prescribed to help children and adolescents with ADHD by increasing activity in parts of the brain responsible for concentration.
The updated review included 212 trials with 16,302 participants aged 18 years and younger, most of which compared methylphenidate with a placebo. The studies covered a wide range of treatment durations, from one day to 425 days, with an average of around one month. Most of the studies took place in the United States, and 41% were funded or partly funded by the pharmaceutical industry.
According to the analysis, methylphenidate may improve teacher-rated ADHD symptoms and general behaviour but may not affect the quality of life. The medication may also cause non-serious adverse events like sleep problems and decreased appetite, but the risk of serious adverse events appears to be low. However, data on adverse events were only available from 43 of the 212 included trials and only 93 of the trials reported on specific and overall non-serious adverse events. This limitation makes it difficult to rule out the possibility that non-serious harms may be more prevalent than reported in the review.
One of the main challenges in studying methylphenidate is the potential for unblinding due to easily recognized adverse effects. This issue could be addressed by using an active placebo that mimics the adverse effects of methylphenidate, thus preventing unblinding and improving the quality of future randomized trials.
Given the uncertainty of the evidence, clinicians should consider using methylphenidate for short periods, carefully monitoring benefits and harms. If no clear improvement in symptoms is observed or harmful effects appear, the use of the medication should be ceased. Clinicians must also be cautious when relying on anecdotal evidence and case reports, as these can lead to inaccurate perceptions of treatment benefits and harms.
Future studies should focus on reporting adverse effects and assessing the long-term effects of the drug, as most of the included studies were short-term. Moreover, investigating subgroups of ADHD patients who may benefit most or least from methylphenidate is essential. By analyzing individual participant data, researchers could explore predictors and modifiers such as age, comorbidity, and ADHD subtypes.
The updated systematic review suggests that methylphenidate may provide some benefits for children and adolescents with ADHD, but the low certainty of evidence and potential adverse effects warrant further research. Long-term studies with a focus on reporting adverse effects and identifying patient subgroups that would benefit the most from the medication are necessary to provide more reliable evidence for clinicians and families.