A new study finds Ritalin can successfully treat attention deficit hyperactivity disorder (ADHD) in people with substance dependence. People with both conditions often do not respond well to ADHD medication, according to MedicalXpress.

The study by Swedish researchers finds ADHD treatment in people with substance dependence works well if Ritalin is administered in higher doses. The drug, methylphenidate, is also sold under several other brand names, including Concerta.

ADHD is much more common in people with substance dependence issues than in the population at large, the article notes. It is possible that standard doses of methylphenidate are not effective in people with both ADHD and long-standing substance dependence because they have developed a tolerance to the drugs, the researchers said.

In the study, researchers studied the effect of the medication on 54 prison inmates who had ADHD and dependence on amphetamines. One group of prisoners was given a placebo, while the other group was given up to double the dose of methylphenidate used in previous studies. The study lasted for 24 weeks. Prisoners given the drug had fewer relapses into drug use, fewer symptoms of ADHD, and adhered to their treatment regimen for longer, compared with prisoners given a placebo.

“We’ve shown for the first time that ADHD in these patients is treatable,” lead author Dr Maija Konstenius of the Karolinska Institute said in a news release. “Moreover, the treatment led to fewer relapses to drug use, which is a very significant finding since a return to crime is often linked to drug abuse in this group.”

The findings are published in the journal Addiction.