Social Work: Evidence-Based Practice 

"Systematic reviews of research evidence provide practitioners with reviews of nearly all of the research studies that have been conducted about a particular question such as the efficacy of an intervention (Grinnel & Unrau, p. 522, 2008)."

Grinnel, R.M., &  Unrau, Y.A. (2008) Social work research and evaluation: Foundations of evidence-based practice. New York: Oxford University Press, 2008.

PsycInfo is an excellent source for articles that deal with mental health issues and evidence-based practice. It has a limit feature that allows you to search only for systematic reviews. To find the systematic review limit option, click on the methodology feature that is highlighted below:

Medline has journal abstracts to both medical and psychiatric literature. It includes a significant number of journal articles on mental health issues.

By clicking on Edit Limits (as shown below), you will come to a screen where you can limit your search to meta-analyses.