Use of biomarkers in depression diagnostics

Depression is a major and costly global health burden that affects millions of people. The current diagnostic screen for depression relies on subjective structured interviews, but there is growing interest in exploring objective methods that involve depression biomarkers. In the current paper we perform a systematic review of recent articles on depression biomarkers that were published from 2012 to 2016. A screening procedure was developed and implemented to identify articles that have examined and compared biomarker levels in control (healthy) and study (diagnosed with major depressive disorder) groups. Seven biomarkers from three research articles were identified: vascular endothelial growth factor (VEGF) and Neutrophil gelatinase-associated lipocalin (NGAL) in plasma; and citrate, tyrosine, hippurate, phenylalanine, and alanine in urine. 95% confidence intervals were calculated for biomarker levels in control and study groups. Differences in measured biomarker levels between these two groups were statistically significant for all biomarkers, and trends were consistent with prior studies. We also note that the detected levels vary widely (up to several orders of magnitude) across biomarkers. For low-level biomarkers, this can present an analytical challenge in regions where the required instrument for analysis is too costly or the analytical technique is too complex to perform. For the scientific community, this presents an opportunity for pursuing analytical methods development in tandem with research on identifying suitable biomarkers for depression diagnostics.