Müller et al1 provide a technically sophisticated and informative set of meta-analyses examining altered brain activity in adults with symptomatic unipolar depression. The striking overall finding of their analyses is the lack of consistent group differences across studies. The absence of replicable effects across studies remained even when they addressed a number of potentially key confounds, such as examining only patients not receiving medication, patients without comorbidities, and patients without late-life or geriatric depression. Furthermore, Müller et al1 make a number of important suggestions for conducting high-quality meta-analyses in the future that can be replicated and that can provide guidance for future research in the field. These excellent suggestions include the use of a reasonably large number of experiments with homogenous methods, avoiding region-of-interest or restricted analysis studies that may bias results, only including studies with a sufficiently stringent false-positive correction, and providing sufficient details about the methods to allow replication.
Barch DM, Pagliaccio D. Consistency, Replication, and Meta-analyses of Altered Brain Activity in Unipolar Depression. JAMA Psychiatry. Published online November 09, 2016. doi:10.1001/jamapsychiatry.2016.2844