A team of researchers in the U.K. led by 2010 NARSAD Young Investigator Grantee Eleanor J. Dommett, Ph.D., of the Open University, used animal models to study how effective atomoxetine (ATX) is in improving symptoms of attention-deficit hyperactivity disorder (ADHD). ATX has been used to treat ADHD in adults for over a decade, and in 2008 became the first medication also to be approved for use in children and adolescents (marketed as Strattera®).

ATX has been found to be effective in people who don’t respond to the most commonly prescribed treatments, amphetamine and methylphenidate. Unlike those medications, ATX is not a stimulant, and thus has been thought to be a safer alternative, especially for young patients.

ATX is thought to work by raising levels of a neurotransmitter in the brain called noradrenalin. But as Dr. Dommett and colleagues noted in a paper published this past April in Behavioural Brain Research, at slightly higher than normal doses, ATX also impacts the dopamine neurotransmitter system. This is potentially critical, since dopamine is central in brain mechanisms giving rise to feelings of reward—and can be linked to drug addiction. Dr. Dommett’s team carefully scrutinized ATX’s impact in the most commonly used animal model of ADHD in order to further assess whether it poses an addiction risk and found no such risk.

At the same time, however, the researchers found that ATX was not effective in reducing some of the key symptoms of ADHD, particularly locomotor hyperactivity. While this may be due to the animal model the team used, it does add to evidence that this medication may not be as effective at low doses as previously believed. The research did support the previous claims of superior safety of ATX versus stimulants, but more research will be required to determine its efficacy in alleviating the core symptoms of ADHD.
 
Read the abstract of this research paper.