Taking medication to treat attention deficit hyperactivity disorder (ADHD) in childhood does not affect the risk of substance abuse later in life, according to a new study. Earlier research indicated children who took ADHD drugs had a reduced risk of substance abuse, The New York Times reports.

Researchers at the University of California, Los Angeles, reviewed 15 previous studies on ADHD medication use in childhood and later risk of substance abuse. They published their results in JAMA Psychiatry.

Almost one in five boys of high school age, and 11 percent of school-age children overall, have received a medical diagnosis of ADHD in the United States, according to the Centers for Disease Control and Prevention. An estimated 6.4 million children ages 4 to 17 had received an ADHD diagnosis at some point. This represents a 16 percent increase since 2007, and a 53 percent increase in the past 10 years.

Study Senior Author Steve S. Lee said his team only knew whether a child had ever taken ADHD medication, but not how old they were when they took it, which medication they took, or how long they used it. He said it is possible that some subgroups of these children might have lower or higher risk of substance abuse later in life.

“For any particular child, parents should consult with the prescribing physician about potential side effects and long-term risks,” Lee said in a news release. “Saying that all parents need not be concerned about the use of stimulant medication for their children is an overstatement; parents should have the conversation with the physician. As with other medications, there are potential side effects, and the patient should be carefully evaluated to, for example, determine the proper dosage.”