Attention deficit hyperactivity disorder (ADHD) is characterised by inattention, excessive activity levels and impulsive behaviours. Although it is an early developmental condition and is associated with childhood, in many instances, it is a lifelong condition. ADHD in adulthood is increasingly being recognised. Clinical guidelines and research suggest that the stimulant drug methylphenidate can reduce ADHD symptoms in adults.
However, there is also evidence showing that some adults do not tolerate methylphenidate well and experience harmful side effects. As a result, some adults withdraw from clinical trials of methylphenidate and stop taking the medication. It is unclear whether such dropout rates are higher than for adults receiving placebo. A recent systematic review and meta-analysis of existing literature investigated these issues.
It’s a common misconception that ADHD just affects children. It usually improves with age, but can continue into adulthood.
A range of electronic research databases and the Cochrane clinical trials register were searched for randomised controlled trials (RCTs) comparing use of methylphenidate to a placebo in adults with ADHD.
The primary outcome investigated was the number of patients who did not complete the study for any reason, referred to as “all-cause treatment discontinuation” in the study. The secondary outcome was the effectiveness of the drug on reducing ADHD symptoms.
Although methylphenidate does appear to be effective in alleviating ADHD symptoms in adults, its safety is not ideal. More patients receiving this drug than those receiving placebo suffered from adverse side effects which led them to discontinue the treatment and drop out of the clinical trial.
The authors of this review conclude that despite clinical guidelines suggesting using methylphenidate as a routine treatment for adult ADHD, the safety of this practice is not entirely clear.