Marissa King, assistant professor of organizational behavior at the Yale School of Management, and colleagues identified large regional clusters, centered on Tennessee, where use of the drug classes was elevated. The researchers analyzed geographic differences in the use of the three classes of mental health medications, using data that covered 60 percent of U.S. prescriptions written in 2008.
It is the first study to examine local and regional patterns of use, which the authors mapped based on the ZIP codes of prescribing physicians.
"The geography of the cluster for each class of medication was different, but they overlapped each other, with Tennessee as the center point," King said in a statement.
People living within one of the clusters were 77 percent more likely to fill a stimulant prescription, 46 percent more likely to fill an antidepressant prescription and 42 percent more likely to fill an anti-psychotic prescription than residents outside of the cluster.
King and co-author Connor Essick, a graduate of the Yale School of Public Health, found use of all three classes of medications was lowest in the western part of the United States. Stimulant use, in particular, had very little use in the West, the study said.
The study is scheduled to be published in the journal Health & Place.