This review of global mental illness literature finds that the economic cost of mental illness is far greater than the direct treatment costs.  The author notes the limitations of cross-country and cross-study comparisons and urges caution in the use and interpretation of the estimates.  

Hu, T. W. (2006). Perspectives: an international review of the national cost estimates of mental illness, 1990-2003. Journal of Mental Health Policy and Economics, 9(1): 3-13. 23 Mar. 2006. http://www.icmpe.org/test1/journal/issues/v9i1/v9i1abs02.html

Author: Teh-wei Hu