As Ailment Hits More Adults, It Gets Drug Firms' Attention; New Market Emerges; Attention disorder, no longer linked only with kids, is on the increase.(HEALTH & MEDICINE)

Byline: AMY REEVES

In the last 10 years, there hasn't been a childhood-disease phenomenon quite like hyperactivity.

Since 1991, annual prescriptions in the U.S. for treating the ailment -- technically known as attention-deficit hyperactivity disorder, or ADHD -- have shot up 500% to 11 million.

Even as the makers of those drugs cash in, they're setting their sights on the next market: adults.

Some studies indicate that two-thirds of children suffering from ADHD don't grow out of it. The National Institute of Mental Health reckoned there were 8.2 million adults with ADHD in 1999. Yet only 360,000 received treatment.

The reason for the lack of treatment is obvious: Until this year, no ADHD drug was officially approved for use in adults. The Food and Drug Administration requires separate approval processes for different age groups.

So prescriptions to adults have largely been off-label, meaning doctors prescribe it outside the FDA's guidelines.