The research suggests that while it is still rare to prescribe powerful psychiatric drugs to 2-year-olds, the practice is becoming more frequent.

The data, compiled from 2000 to 2007, and published in the Journal of the American Academy of Child & Adolescent Psychiatry, could inform testimony at the upcoming Boston-area murder trials of the parents of 4-year-old Rebecca Riley. The girl died of an overdose of mood-stabilizing medication in 2006.

A Boston child psychiatrist, Kayoko Kifuji, diagnosed Riley with bipolar disorder and attention deficit hyperactivity disorder when she was 30 months old, and placed her on several powerful drugs: Depakote, an antiseizure medication also used for bipolar disorder, and clonidine, a blood pressure medication.

Kifuji's testimony may be crucial to the fate of Michael and Carolyn Riley, who face first-degree murder charges. A grand jury and a review by the state's medical licensing board cleared the doctor of wrongdoing.

Prosecutors claim the Rileys deliberately overmedicated their daughter to subdue her. The couple say they were following Kifuji's instructions and their daughter died of pneumonia.

The case has shone the spotlight again on a debate within the psychiatric profession about whether bipolar disorder can be diagnosed in very young children and whether it is wise to prescribe powerful medications.

BIPOLAR TODDLERS?

Bipolar disorder, characterized by severe mood swings, was once thought to emerge only during adolescence or later. But Dr. Joseph Biederman, a child psychiatrist at Harvard University, transformed views on the subject by arguing that children could have the disorder at extremely young ages.

He is credited with spearheading a more than 40-fold increase in the number of children diagnosed with bipolar disorder over the past decade.

Biederman was accused in 2008 by Republican U.S. Senator Charles Grassley of failing to fully disclose payments by drug companies, including some that produced medication for bipolar disorder. Biederman declined to be interviewed about the latest study.

The psychiatric diagnosis of very young children is anything but an exact science, said Harry Tracy, a psychologist and publisher of NeuroInvestment, a monthly publication specializing in central nervous system disorders.

Such disparate causes as ADHD, depression, bipolar disorder, sexual abuse, and family dysfunction can produce very similar symptoms in a toddler.

The report's author, Mark Olfson, professor of clinical psychiatry at Columbia University, said about 1.5 percent of all privately insured children between the ages of 2 and 5, or one in 70 children, received some sort of psychotropic drug -- whether an antipsychotic, a mood stabilizer, a stimulant or an antidepressant -- in 2007.

If a child is diagnosed with bipolar disorder between the ages of 2 and 5, about half are prescribed an antipsychotic, such as Eli Lilly & Co's Zyprexa, AstraZeneca Plc's Seroquel, and Johnson & Johnson's Risperdal. They are prescribed to about one in 3,000 2-year-olds, according to his report.

There might be a role for these drugs but only after you've tried other interventions, with the parents, or with the parents and child together, but that is not happening when you examine the billing records, Olfson said.

(Additional reporting by Toni Clarke; Editing by Peter Cooney)

Medicine Bipolar disorder