CHICAGO (AP) -- Calls to poison control centers about teens abusing attention-deficit drugs soared 76 percent over eight years, sobering evidence about the dangerous consequences of prescription misuse, a study shows.

The calls were from worried parents, emergency room doctors and others seeking advice on how to deal with the problem, which can be deadly. Four deaths were among cases evaluated in the study.

Kids taking ADHD drugs to get high or increase alertness may not realize that misuse of the drugs can cause serious, sometimes life-threatening symptoms, including agitation, rapid heartbeat, extremely high blood pressure.

"They say, 'It's FDA approved, how dangerous could it be?'" said Steve Pasierb, head of The Partnership for a Drug-Free America, based in New York.

In the study, researchers from Cincinnati Children's Hospital Medical Center evaluated 1998-2005 data from the American Association of Poison Control Centers. During that time, nationwide calls related to teen abuse of ADHD drugs, specifically stimulants, increased from 330 to 581 yearly, and there were four deaths. Overall, 42 percent of teens involved had moderate to severe side-effects and most ended up getting emergency-room treatment.

The true number of teen abusers who have bad side effects is likely much higher, because many cases don't result in calls to poison control centers, said study author Dr. Randall Bond, medical director of the hospital's Drug and Poison Information Center.

The surge, from 1998 to 2005, outpaced calls for teen substance abuse generally. It also paralleled an 86 percent rise in ADHD medicine prescriptions for kids aged 10 to 19, from about 4 million to nearly 8 million during that time.

"It's more bad news on an entrenched problem," Pasierb said. His nonprofit group was not involved in the study. Its own research suggests that about 19 percent of teens have abused prescription drugs including medicine for attention deficit hyperactivity disorder.

Government-sponsored surveys suggest that teen abuse of stimulants including ADHD drugs has declined in recent years.

The new study was for release Monday in the August edition of Pediatrics.

Mark Stein, a psychiatry professor and ADHD expert at University of Illinois at Chicago, said abuse typically involves crushing and snorting the pills, which speeds up the effects and can produce a buzz or sense of euphoria -- along with dangerous side effects.

Kids who develop serious side effects should be taken to the emergency room, where sedatives can be used to treat the problem, Stein said.

The study lacks information on whether abusers were teens with ADHD, but anecdotal evidence suggests many are not.

Stein said the study should not deter use of ADHD drugs in teens who really need them, particularly since there's evidence that kids with ADHD who don't get medication are at risk for abusing illicit drugs.

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