A new study finds that 54 percent of adults and 44 percent of children who were drug-tested by the clinical laboratory company Quest Diagnostics misused their prescription medications in 2015.

The study defined misuse as meaning patients took too much, too little or none of their medication, The Washington Post reports. The study also found evidence that 45 percent of adults were using other drugs that had not been prescribed, suggesting the potential for dangerous drug combinations in a sizeable number of patients.

Children and teens ages 17 and younger were most likely to misuse amphetamines, while adults 25 and older were most likely to misuse benzodiazepines and anti-anxiety medications.