UCLA research shows that ADHD medications have no impact on future substance abuse, contradicting decade-old research that says stimulants have a protective effect.

Taking stimulant medication to treat attention deficit hyperactivity disorder (ADHD) doesn’t increase or decrease a child’s risk of using illicit substances later in life, according to a new study published in JAMA Psychiatry.

The findings contradict a widely cited study that claimed ADHD medications reduce a person’s risk of developing drug dependency.

Researchers from the University of California, Los Angeles, and other agencies used data from 15 longitudinal studies conducted between 1980 and 2012 involving 2,565 patients with ADHD, some of whom were treated with stimulants.

The most common and often first-line treatment for ADHD is stimulant medication, typically methylphenidate sold under the brand name Ritalin.

Researchers used the 15 previous studies to investigate lifetime substance use and abuse of alcohol, cocaine, marijuana, nicotine, and other drugs in children diagnosed with ADHD.

They found that taking stimulant medication neither increased nor decreased a child’s risk of using any of these substances. This is a significant finding because the issues associated with ADHD include novelty-seeking behaviors and trouble with impulse control.

These latest findings contradict research done 10 years ago concluding that treatment with ADHD medications is associated with a reduced risk of future substance use or abuse.

That study, which UCLA researchers called “highly influential as evidenced by its high citation rate,” incorporated data from only six studies.

“These results provide an important update and suggest that treatment of attention-deficit/hyperactivity disorder with stimulant medication neither protects nor increases the risk of later substance use disorders,” the UCLA researchers conclude.

While the UCLA research updates some information about the effects of stimulants, other recent research casts doubt on other long-held beliefs about ADHD medications.

For more than a decade, researchers believed that abnormal levels of dopamine transmitters in the brain were a biomarker for ADHD, but new research published in the journal PLOS One shows that the phenomenon may actually be caused by the medication itself.

Dopamine is an important brain chemical, especially for patients with ADHD. Low levels of dopamine in the brain have been linked to high levels of novelty-seeking behavior, such as participating in high-risk sports and abusing drugs.

Researchers from the Brookhaven National Laboratory studied 11 adults with ADHD who had never been treated with stimulants. After one year of therapy with Ritalin, researchers compared brain scans taken before the trial and found that the increase in dopamine transmitters occurred only after stimulant therapy.

It turns out that we still have a lot to learn about the ADHD brain.