Untreated short-term course of major depression: a meta-analysis of outcomes from studies using wait-list control groups

Authors: Posternak, M.A., Miller, I.
A meta-analysis "In the short-term, depressive symptomatology can be expected to decrease by about 10–15% on average without treatment. As many as 20% of subjects who participate in a short-term antidepressant trial may experience a spontaneous remission."