Use of prescription drugs for attention deficit hyperactivity disorder (search) is growing at a faster rate among adults than children, new research shows.

Between 2000 and 2004, use of drugs that help keep ADHD patients focused doubled among adults aged 20 to 44, but rose only 56 percent among children, according to data compiled by Medco Health Solutions, one of the country's largest prescription benefit managers.

Franklin Lakes-based Medco's study, to be released Thursday, shows use rose 113 percent among women 20 to 44 and 104 percent among women 45 to 64, both far more than among men. Meanwhile, spending on the medicines quadrupled.

Experts say reasons for the surge range from better drugs and advertising, to parents of children newly diagnosed with ADHD realizing they have the same symptoms.

"We're seeing about 1 percent of adults being treated," but four times as many are estimated to have ADHD, Dr. Robert Epstein, Medco's chief medical officer, told The Associated Press.

Nearly 1.5 million Americans 20 and older are using the drugs, Medco said.

Those figures dispel earlier beliefs that children "grow out of the disorder," said Dr. Patricia Quinn, a developmental pediatrician at the National Center for Gender Issues and ADHD, and an adviser to Children and Adults with Attention-Deficit/Hyperactivity Disorder, an advocacy group.

"We know that 50 percent of adults continue to have problems with attention that affect their functioning," and many now are staying on medication beyond adolescence, Quinn said.

Meanwhile, awareness of the disorder is growing among the public and doctors.

The makers of Adderall XR (search) and Concerta (search) have advertised their drugs in magazines geared to parents of kids with ADHD. And Eli Lilly & Co., which makes Strattera, has been running television ads aimed at adults who may not realize they have the disorder.

ADHD symptoms include impulsivity, trouble concentrating, disorganization, procrastination and hyperactivity.

The increased medication use is good because, along with behavioral therapy, it can improve adults' relationships, job performance, parenting skills, even their sex lives, said Dr. Edward Hallowell, author of a new ADHD book, "Delivered from Distraction."

"Whenever you get someone with ADHD diagnosed and treated successfully, everyone wins," said Hallowell, who heads an ADHD center in Sudbury, Mass.

Spending on ADHD medicines has shot up with the growing popularity of new, brand-name versions that last all day, limiting ups and downs of symptoms. Sales skyrocketed from $759 million in 2000 to $3.1 billion in 2004, according to IMS Health, a pharmaceutical information and consulting firm.

"The market could easily double," as more of the drug makers receive regulatory approval specifically to market ADHD drugs to adults, said Albert Rauch, pharmaceuticals analyst at A. G. Edwards & Sons.