Strategies to identify biomarkers for depression

Abstract

Usually, disease biomarkersare directly linked to the biological processes that are involved in the causation and progress of the condition. However, in the case of depression and other psychiatric disorders, the mechanisms responsible for the disease are often poorly understood. Factors that contribute to the difficulty of finding biomarkers for psychiatric diseases include the heterogeneity of each psychiatric disease, the complexity of diagnosis, and the difficult accessibility to biological samples of affected tissues. Here, we present possible approaches for the identification of depression biomarkers. The first, a knowledge-based approach, makes use of our current understanding of the underlying disease mechanisms. As an example, the stress response cascade provides a source for numerous candidate biomarkers. Second, reverse-engineering the biological effects and signaling mechanisms of known antidepressants is another promising way to obtain useful biomarkers. Third, biomarkers could be identified by means of unbiased research. The different omics technologies have recently yielded promising results in comparing biological parameters of depressive patients vs. control subjects. However, many of these studies only show an increased mean value for a candidate biomarker in depressive patients, while correlative and longitudinal studies are rare. The validity of these approaches remains to be confirmed by further studies in clinical and epidemiological settings using larger numbers of samples. © Springer Science + Business Media, LLC 2008.