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Attention deficit hyperactivity disorder is an epidemic behavioural problem in childhood in the Western world. Typically, parents and teachers come up with the idea that children have problems to pay attention, they are agitated, and improve with methylphenidate. Although this paradigm has been in place for half a century, the first  systematic review of its benefits and harms was just recently published. The authors are a large group of Scandinavian psychiatric clinical researchers:

Storebø OJRamstad EKrogh HBNilausen TDSkoog MHolmskov MRosendal SGroth CMagnusson FLMoreira-Maia CRGillies DBuch Rasmussen KGauci DZwi MKirubakaran RForsbøl BSimonsen EGluud C. Cochrane Database Syst Rev. 2015 Nov 25; (11): CD009885. doi: 10.1002/14651858. CD009885. pub2. Methylphenidate for children and adolescents with attention deficit hyperactivity disorder.

They searched six of the main scientific publication systems (CENTRAL, Ovid MEDLINE, EMBASE, CINAHL, PsycINFO, Conference Proceedings Citations Index), as well as trials registers and looked for trials in reference lists. They asked the manufacturers of methylphenidate for further published and unpublished data. But they included only randomised controlled trials of  methylphenidate versus placebo or no intervention in children and adolescents aged 18 years and younger with a diagnosis of ADHD in which at least 75% of participants had na IQ of at least 70. This is very relevant, because in my practice I get a majority of children refered by teachers and heavily supported by parents with speech or learning disabilities who have not been submitted to appropriate neurological evaluation. Children who have obvious difficulties in the verbal domains, sometimes even in other, endocrine , motor, spastic problems, who the educational and familial systems look for na easy way out in the neurologist and the methylphenidate prescription.

Seventeen review authors extracted the data and two review authors performed all tasks with standard Cochrane procedures. They found 38 parallel-group trials (5111 participants) and 147 cross-over trials (7134 participants), boys-to-girls ratio of 5:1, ages 3 to 18 years, mean 9.7 years, most from high-income countries; average duration of treatment 75 days. Methylphenidate was compared to placebo (175 trials) or no intervention (10 trials). All 185 trials were assessed to be at high risk of bias. Methylphenidate may improve teacher-rated ADHD symptoms. There was a minimal change in the ADHD Rating Scale, considered clinically to represent the minimal relevant difference. There was no evidence that methylphenidate was associated with an increase in serious (e.g. life threatening) adverse events. Among those prescribed methylphenidate, there was a 29% increase in the overall risk of any non-serious adverse events. The most common were sleep problems and decreased appetite. Children in the methylphenidate group were at 60% greater risk for trouble sleeping/sleep problems and 266% greater risk for decreased appetite than children in the control group. Teacher-rated general behaviour seemed to improve with methylphenidate. Methylphenidate may improve parent-reported quality of life (very low-quality evidence).

They concluded methylphenidate may improve teacher-reported symptoms, behaviour, and parent-reported quality of life. But low quality evidence means and short follow-up, ass well as the high frequency of sleep problems and decreased appetite make it impossible to quantify the magnitude of the positive effect. There is no real idea about serious adverse events. “Better designed trials are needed”.

The authors are particularly worried about the ethics, because children cannot sign informed consent, and these studies cannot be appropriately blinded. “Finally, the findings highlight the urgent need for large RCTs of non-pharmacological treatments”

Dr Paulo Bittencourt

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