Giving amphetamines to adults with attention deficit hyperactivity disorder (ADHD) can help them control their symptoms, but the side effects mean that some people do not manage to take them for very long, according to research published in a new Cochrane Systematic Review.

Although ADHD is a childhood onset disorder, half of people with it find that the symptoms of hyperactivity, mood instability, irritability, difficulties in maintaining attention, lack of organization, and impulsive behaviors persist into adulthood. “We wanted to see whether amphetamines could reverse the underlying neurological problems that feature in ADHD, and so improve ADHD symptoms,” Xavier Castells, MD, who led a team of five researchers in Spain, said in a press release.

After searching through medical literature, the researchers identified seven studies that had enrolled a total of 1,091 participants in clinical trials. The three amphetamine based medicines they considered (dextroamphetamine, lisdexamphetamine and mixed amphetamine salts [MAS]) all reduced ADHD symptoms, although there was no evidence that higher doses worked better than lower ones. The researchers did not find any difference in effectiveness between formulations that release the amphetamines rapidly, and those that have a sustained-release.

While there was evidence that people taking amphetamines drop out of treatment due to adverse events slightly more than those on placebo controls, the researchers were quick to point out that only 9% of people taking amphetamines withdrew from treatment. Looking at the different formulations of amphetamines, those on MAS had lower drop-out rates than those on other versions of the drug. Furthermore, most studies had a duration of between two and seven weeks, therefore precluding the possibility of drawing conclusions regarding amphetamine’s efficacy and safety in the long-term.

In many clinical trials, doctors randomly allocate some patients to “treatment group” and give them the active medication, while others are placed in a “control group” and receive a placebo. This experimental system only works, though, if the patients have no idea which group they are in.

“One of the problems with trying to make sense of this research is that you cannot do a properly controlled study because the amphetamines have such a distinct set of effects. Patients instantly know whether they are on the treatment or the placebo, so you have to be more cautious about the way you interpret the data,” Castells said.

Source

Short-Term Use of Amphetamines Can Improve ADHD Symptoms in Adults [Cochrane Systematic Reviews]