Why we still don't understand the depressed brain - Not going beyond snapshots.

Although remarkable progress has been made in the search for the brain correlates of depression with neuroimaging methods, we still find a heterogeneity of results and lack of consensus. This short commentary proposes a theoretical reason for this situation linking it to the methods of conducting neuroimaging studies of depression and the ways to interpret findings. If we only take one snapshot of the "depressed brain", the brain activity is presumably the result of four interacting components: neural predispositions, depressogenic pathology, changes caused by (chronic) depression, and compensatory brain mechanisms. The four components will be discussed briefly along with arguments why confusion of them might confuse our view of the brain in depression. After a short presentation of promising new longitudinal studies, this commentary gives first hints how we could go beyond snapshots to better understand the brain in depression.