The use of antidepressants and stimulants such as Prozac and Ritalin to treat hyperactivity, attention deficit and bipolar disorders in teenagers and young children has become a subject of sharp controversy.
Proponents say these powerful drugs, known as psychotropics, target newly identified conditions that were undertreated or misdiagnosed in the past.
Critics say the medications are being used too broadly, addressing behavioural problems that should be tackled by softer therapies.
Drawing from data on nearly 600,000 youngsters 19 years old and younger, the study is one of the first rigorous comparisons across several countries of how these medications are dispensed among the young.
In 2000, nearly seven percent of children in the US took psychotropics of some kind, while 2.9 and 2.0 percent, respectively, did so in the Netherlands and Germany, according to the study.
One in 12 of American children aged five to nine were taking these medications, four times the European levels.
Lead researcher Julie Zito, a University of Maryland pharmacologist, said psychotropic use in the United States may have increased since the data was collected.
"The US trends appear to be continuing," she told AFP in an email.
Seeking explanations for the disparity on either side of the Atlantic, the study noted that direct-to-consumer drug advertising was allowed in the United States, but banned in Europe.
Cultural differences could also play a role, they suggest.
"The increased use of medication in the US reflects the individualist and activist therapeutic mentality of US medical culture," Zito said.
There are also differences in the way behavioural disorders are defined and classified.
The diagnosis of "hyperkinetic disorder" in the European medical system, for example, is more stringent than that of the "attention deficit hyperactivity disorder" (ADHD), the equivalent syndrome in the US classification.
Another difference is who is handing out the medication: there are more psychiatrists per capita in the United States, which could influence prescription patterns, the study says.
Reimbursement policies and government regulatory constraints may also be factors.
Amphetamines and other stimulants are rarely prescribed for children in Western Europe. In France, their use was banned during the period covered by the study, 1999 and 2000.
Government health plans in Europe have also cut down on the use of expensive, patent-protected drugs, especially antipsychotics and antidepressants.
The study was published online, on Thursday, in the British-based open access journal BioMed Central.