By examining Veterans Health Administration records from 1997 and 2004 this article assess the effects of outpatient mental health service provider trends on per capita costs.  Though the authors found that greater numbers of mental health treatment visits occurred with non-psychiatrists this trend was not associated with lower per capita costs. 

Greenberg, G. A., Rosenheck, R. A. (2006). Trends in the professional mix and cost of outpatient mental health care. Journal of Mental Health Policy and Economics, 9(3): 133-6. http://www.icmpe.org/test1/journal/issues/v9i3/v9i3abs03.html

Authors: Greg A. Greenberg, Robert A. Rosenheck