The number of prescriptions for psychotropic drugs written for very young children appears to have leveled off, according to a new study. These drugs are prescribed to treat attention deficit hyperactivity disorder (ADHD), mood disorders, anxiety and other mental health conditions.

Researchers studied data from a national sample of more than 43,000 children ages 2 to 5. They found prescriptions for psychotropic drugs in these children peaked between 2002 and 2005, and leveled off from 2006 to 2009, Time.com reports.

Warnings about the potential risks of these drugs in children likely played a role in the change in medication use, the article notes. The Food and Drug Administration started adding its strictest black box warning, about potential health risks, to antidepressant medications in the mid-2000s.

Changes to guidelines about diagnosing mood and behavior disorders in children also may have played a role. “Our findings underscore the need to ensure that doctors of very young children who are diagnosing ADHD, the most common diagnosis, and prescribing stimulants, the most common kind of psychotropic medications, are using the most up-to-date and stringent diagnostic criteria and clinical practice guidelines,” the authors wrote in Pediatrics.

According to American Academy of Pediatrics guidelines, children ages 4 and 5 with ADHD should first be treated with behavioral interventions, such as group or individual parent training in behavior management techniques, before drugs are prescribed.

“Given the continued use of psychotropic medications in very young children and concerns regarding their effects on the developing brain, future studies on the long-term effects of psychotropic medication use in this age group are essential,” lead researcher Tanya Froehlich, MD, a pediatrician at Cincinnati Children’s Hospital, said in a news release.