CHICAGO (AP) - One of the first studies of a so-called ``smart drug'' for Down syndrome suggests it does not boost children's intellectual ability, despite testimonials on television and the Internet.

In fact, the drug, called piracetam, had side effects such as aggression, irritability and poor sleep in some of the youngsters.

``We did not identify even a single case that would suggest the possibility that piracetam therapy generally improved cognition,'' researchers said in the study, which appears in April's Archives of Pediatrics & Adolescent Medicine.

The study of 18 children ages 6 through 12 found no significant difference in mental function between those who took the drug and those who were given placebo pills.

Each child received four months of piracetam and four months of placebos.

Though parents of 11 children thought they seemed brighter or more focused on piracetam, intelligence tests showed no improvement compared with the placebo. The behavioral side effects in seven children suggested the drug has a stimulant effect, the researchers said.

Dr. Nancy Lobaugh of the University of Toronto, who led the study, said some parents might mistake that effect - like being ``wired'' on coffee - with improved mental function.

Her study follows numerous TV reports and Internet testimonials touting the benefits of piracetam for children with Down syndrome, a chromosomal abnormality that is a common cause of mental retardation.

While the severity of Down syndrome varies, such children can learn and progress as they mature. Critics of piracetam say some parents are mistakenly crediting the drug for normal developmental changes.

The study ``should temper our enthusiasm for piracetam markedly,'' said Dr. Chris Feudtner of the University of Washington's Child Health Institute. In an accompanying editorial, Feudtner said the results illustrate the difficulty of ``sorting good ideas from bad ones'' in the Internet age.

Piracetam (pronounced pur-AHS-uh-tam) is in a class of drugs called nootropics that are purported to improve cognitive function. The drug is made by several overseas companies and has been used, mostly abroad, for conditions such as stroke, Alzheimer's disease and dyslexia. It has been available by prescription in some countries and is sold by mail-order and over the Internet.

The National Down Syndrome Society and National Down Syndrome Congress do not recommend piracetam, given the lack of research on its effects.

Suzan Leake, associate director of medical affairs for UCB Pharma, a Belgian maker of piracetam, said the company hopes to begin U.S. studies this year on piracetam's use in treating a muscle disorder called myoclonus. Leake declined to say whether the company believes piracetam can help children with Down syndrome.

Copyright 2001 The Associated Press. All rights reserved.