- Serum folate, vitamin B12, and homocysteine in major depressive disorder, Part 2: predictors of relapse during the continuation phase of pharmacotherapy. Papakostas, G.I., Petersen, T., Mischoulon, D., Green, C.H., Nierenberg, A.A., Bottiglieri, T., Rosenbaum, J.F., Alpert, J.E., Fava, M. The Journal of clinical psychiatry. (2004)