Despite warnings about possible negative side effects, doctors are prescribing Ritalin to more and more children. What's worst, they are also giving many of these same kids prescriptions to Prozac as well.

According to a new study by researchers at the University of Michigan, the 1990s saw a dramatic rise in the number of children and adolescents receiving Ritalin-type stimulant drugs and Prozac-type antidepressants. The study also documents the rise of a newer phenomenon: kids who are prescribed both kinds of drugs at the same time.

The trend toward giving two behavioral drugs to the same child raises questions, the authors said, about how physicians diagnose and treat children's mental disorders. Thirty percent of children in the study who were on the newer type of antidepressants called selective serotonin reuptake inhibitors, or SSRIs, also took stimulants.

"New drugs nearly always experience a rise in prescriptions over the first few years of their lifespan, but the consistent increase in SSRI use and in dual prescriptions is especially surprising," stated U-M pediatrician and lead author Jerry Rushton, M.D., MPH. "We need further information about whether this is due to new unrecognized mental disorders, substitution for other therapies, or overprescription."

SSRIs have only gained approval for select indications in children during the last two to three years, and little research has been done on the safety of medications in very young children and the safety of combining them with stimulants. But some physicians seem to be prescribing them nonetheless.

Rushton presented data from the study at the annual meeting of the Pediatric Academic Societies and the American Academy of Pediatrics.

Though the data are limited to a single state's Medicaid population, they provide a unique preliminary indication of how quickly stimulant and antidepressant use rose among children from 1990 to 1998, and how many children are receiving both types of medication.

The study also reveals demographic trends among those who are being given the medications. Prescription rates for the two different drugs in the studied population differed widely: 1.7% of children aged 6 to 14 received SSRIs in 1998, versus 10.7% for stimulants. The mean age of stimulant recipients is holding steady at around 9 years, while the mean age of those getting SSRIs has dropped from 15 years to around 13 years.

Three times as many boys as girls are on Ritalin and other stimulants, according to the study, while the gender gap in SSRI prescriptions that once saw twice as many girls on the drugs has closed.

Stimulants such as Ritalin and Dexedrine are most often used to treat children diagnosed with attention-deficit hyperactive disorder (ADHD). Antidepressants such as Prozac, Zoloft and Paxil are used in the treatment of serious depression, school phobias and other serious anxiety disorders, bedwetting, some bulimic-type eating disorders, and -- rarely -- for attention-deficit hyperactive disorder.

Said Dr. Rushton, "One of the biggest questions this study raises is whether the children who are prescribed both types of medication have both types of disorders, or whether their physicians are recommending these medications for other reasons."

Rushton pointed out another serious development: "The steep climb in numbers of children receiving either or both of these drugs was accompanied by an increase in the dose and duration of the stimulants and antidepressants that were prescribed."