More than one in eight U.S. adults (12.6 percent) used benzodiazepines in the past year, up from previous reports. Misuse of the prescription drugs accounted for more than 17 percent of overall use, according to a study published online today in Psychiatric Services in Advance. The researchers defined misuse as any way a doctor did not direct, including using the drug without a prescription or more often or longer than prescribed. Misuse was highest among young adults 18 to 25 (5.6 percent) and was as common as prescribed use.