ADHD medication may stop by 6 p.m.

CLEVELAND, Nov. 12 (UPI) -- More than half of U.S. parents surveyed say drugs stop working before 6 p.m. for their children under 12 with attention-deficit hyperactivity disorder.

Lead study author Dr. Robert Findling, of Case Western Reserve University, in Cleveland, says that in the absence of treatment, children with this neurobiological disorder show impaired academic and social functioning.

"This may be important because ADHD doesn't only impact a child's school performance but can also impact interactions with friends, coaches and other family members," Findling said in a statement.

The survey of parents of children with ADHD ages 6 to 12 was conducted via Internet interviews. All of the children took their medication once daily in the morning. Of the 219 children taking ADHD stimulant medications, 70 percent of the parents said that their child's medication lasted 11 hours or less.

The survey findings, funded by bio-pharmaceutical company Shire plc, were presented at the Children and Adults with Attention-Deficit Hyperactivity Disorder annual conference in Crystal City, Va.