Neural, Genetic, and Peripheral Correlates of SSRI Pharmaco-Response

The aim of this pharmaco-MRI study is to investigate neural correlates of variable antidepressant treatment response driven by genetic variation in multiple genes involved in depression. Thirty Major Depressive Disorder (MDD) patients with a concurrent major depressive episode will undergo three MRI scanning sessions at baseline, 4 hours and 8 weeks after escitalopram treatment initiation. During each MRI session, one structural and 3 fMRI scans each engaging different brain circuitries will be performed. All subjects will undergo extensive behavioral assessment and will be genotyped. Furthermore, potential peripheral markers such lymphocyte mRNA or pharmacological parameters on platelets or lymphocytes will be assessed. The investigators expect that genetic variants which have been associated with variable response to SSRIs in previous Imaging Genetics studies are modulating neural targets of drug response. Moreover, peripheral markers are expected to correlate with these brain region measurements. Imaging measures have been suggested to be superior for drug response assessment as compared to psychometric scales, which hardly correlate with biological parameters. Since imaging techniques are too expensive and sophisticated for a broad clinical use, this study will provide pilot data on peripheral biomarkers of neural activation being related to drug response. Furthermore, this study will demonstrate whether and how genotypes impact on the dynamics of neural drug response in vivo.