Complementation of pharmacogenetics with biomarkers and neuroimaging in major depression

Abstract

Unlike other disciplines of medicine, the diagnostic process in psychiatry is based solely on clinical judgment, without incorporating lab-derived objective measures on a regular basis. Even with the advent of DMS-V, no biomarkers gathered from genomics, peripheral blood, or brain imaging have been established for the diagnostic process in psychiatric disorders. However, there is accumulating evidence of evolving biomarkers to improve diagnostic processes and treatment algorithm. Here, studies on the evaluation of markers derived from imaging and peripheral blood in patients with major depression are reviewed. An altered brain network that encompasses the anterior cingulate, the prefrontal cortex, and the hippocampus has been repeatedly found in major depression. Antidepressants exert neuroprotective effects, which determine a reduction of hippocampal and prefrontal cortex shrinkage, probably through an activation of neuromodulatory factors like BDNF. Lower BDNF plasma levels are observed in depressed patients and normalize after successful treatment. Very promising findings have also been observed within inflammatory pathways and the hypothalamic-pituitary-adrenal (HPA) axis. In both systems, there is growing evidence that drugs specifically targeting these systems may be beneficial for the treatment of depression, but only in these patients, who have marked alterations detected by the respective biomarkers.