Children who are on medications for attention deficit hyperactivity disorder tend to have lower bone density when compared to children who do not take the same medications, a new study found.

For this study, the researchers examined data on at least 5,300 children between the ages of eight and 17 that were compiled from a government survey. The team found that on average, children who took prescription stimulants and non-stimulants for ADHD, such as Ritalin, Adderall and Srattera, had lower bone density in their hip and lower back in comparison to children of similar age who were not taking ADHD medications.

Overall, about a quarter of children taking ADHD medications had lower than normal bone density, which is also known as osteopenia. Although osteopenia during childhood has not been tied to an increased risk of osteoporosis later on in life, good bone development is important during childhood and into adolescence. Osteoporosis can increase risk of brittle bones and fractures.

The researchers noted that since they found an association and not a cause-and-effect relationship, they are not recommending parents to stop their children from taking these medications.

"I'm in no way saying that kids shouldn't be on these medications," said senior researcher, Dr. Jessica Rivera, from the U.S. Army Institute of Surgical Research at Fort Sam Houston, Texas. "This is an early study and it's not something that should change practice."

The researchers did not determine how ADHD medications could potentially be affecting bone density but they reasoned that since ADHD medications can reduce appetite and be hard on the stomach, children who take them might not be eating a well-balanced and nutritious diet.

"Parents of patients taking ADHD medications should be informed of potential bone loss, especially if the findings of this study are validated in prospective studies," Rivera said.

The U.S. Centers for Disease Control and Prevention (CDC) reported in 2011 that an estimated 6.4 million children were diagnosed with ADHD with about 3.5 million of them being on some kind of medication for it.

Rivera will be presenting the findings at the American Academy of Orthopedic Surgeons meeting.