As many as 5-7% of elementary school children are diagnosed with attention Deficit Hyperactivity Disorder (ADHD), a behavioral disorder that causes problems with inattentiveness, over-activity, or a combination of these traits. Now, researchers have found that long-term ADHD drug use appears to have no long-term effects on the brain.

The animal study, conducted by researchers at Wake Forest Baptist Medical Center, is published online in the journal Neuropsychopharmacology.

The majority of children with ADHD are treated with psychostimulant drugs. Although the drugs are known to be effective, little is known about their the long-term effects.

Linda Porrino, Ph.D., professor and chair of the Department of Physiology and Pharmacology, along with fellow professor Michael A. Nader, Ph.D., both of Wake Forest Baptist, and colleagues conducted an animal study in order to determine the long-term effects of these drugs.

Porrino explained:

“We know that the drugs used to treat ADHD are very effective, but there have always been concerns about the long-lasting effects of these drugs. We didn’t know whether taking these drugs over a long period could harm brain development in some way or possibly lead to abuse of drugs later in adolescence.”

The team studied 16 non-human primates, whose ages were equivalent to 6- to 10-year-old humans. 8 animals were treated with a therapeutic-level dose of an extended-release form of Ritalin, or methylphenidate (MPH), for over a year, which is equivalent to about four years in children, while 8 animals (the control group) did not receive any drug treatment.

The researchers took images of the animals brains before and after the study in order to measure brain chemistry and structure. In addition, the team looked at developmental milestones in order to address concerns that ADHD drugs negatively impact physical growth.

After the treatment and imagine studies were completed, the researchers allowed the animals to self administer cocaine over several months.

The researchers examined how susceptible the animals were to the drug, how quickly they took the drug, and how much of the drugs they took, in order to provide an index of vulnerability to substance abuse in adolescence.

The researchers found that animals who received treatment were no more vulnerable to later drug use than the control animals.

Porrino, explained:

“After one year of drug therapy, we found no long-lasting effects on the neurochemistry of the brain, no changes in the structure of the developing brain. There was also no increase in the susceptibility for drug abuse later in adolescence. We were very careful to give the drugs in the same doses that would be given to children. That’s one of the great advantages of our study is that it’s directly translatable to children.

Our study showed that long-term therapeutic use of drugs to treat ADHD does not cause long-term negative effects on the developing brain, and importantly, it doesn’t put children at risk for substance abuse later in adolescence. One of the exciting things about this research is that a ‘sister’ study was conducted simultaneously at Johns Hopkins with slightly older aged animals and different drugs and their findings were similar. We feel very confident of the results because we have replicated each other’s studies within the same time frame and gotten similar results. We think that’s pretty powerful and reassuring.”

Written by Grace Rattue