Increase in bipolar disorder diagnosis in young children?

http://news.yahoo.com/s/nm/20100115/hl_nm/us_usa_child_trial_research

From the article:

"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."