How biomarkers will change psychiatry. Part II: Biomarker selection and potential inflammatory markers of depression

The Effect of Omega-3 Fatty Acids on Thromboxane, Brain-Derived Neurotrophic Factor, Homocysteine, and Vitamin D in Depressive Children and Adolescents: Randomized Controlled Trial

In the DEPOXIN project, we have found that a high ratio of omega-6/omega-3 fatty acids (FA) is associated with worsening of depressive symptoms in children and adolescents with depressive disorder (DD) and that the 12-week omega-3 FA supplementation modulates DD symptoms. Here we present our results of the secondary outcomes: the levels of thromboxane (TXB), brain-derived neurotrophic factor (BDNF), homocysteine (HCy) and vitamin D. Fifty-eight patients were randomized into two arms. One group received a fish oil emulsion enriched with omega-3 FA, and the other received a sunflower oil emulsion containing omega-6 FA, for 12 weeks. Depressive symptoms were evaluated, using the Child's Depressive Inventory (CDI). The patients with DD had elevated TXB levels and decreased vitamin D levels, as compared to healthy controls. Both CDI and omega-6/omega-3 ratio correlated positively with TXB and negatively with BDNF at baseline. Compared to the omega-6 FA group, the supplementation with omega-3 FA for 12 weeks significantly reduced plasma TXB (p = 0.024) and increased BDNF (p = 0.011) levels. No changes in HCy and vitamin D were observed. Our results demonstrate the possible role of TXB and BDNF in the pathophysiology of DD and the benefits of omega-3 FA supplementation. The study was registered with the ISRCTN registry (ISRCTN81655012).

hsa_circRNA_103636: potential novel diagnostic and therapeutic biomarker in Major depressive disorder

Aim: This study aimed to determine whether circular RNA (circRNA) molecules in peripheral blood mononuclear cells (PBMCs) could be used as novel non-invasive biomarkers for major depressive disorder (MDD). Materials & methods: Differentially expressed circRNAs were screened using an Arraystar Human CircRNA Array (which includes 13,617 human circRNAs) and qRT-PCR. Thirty MDD patients were randomly selected to retest the circRNA levels after 4-week and 8-week antidepressant regimens. Results: Four differentially expressed circRNAs were identified between MDD patients and controls, and only down-regulated hsa_circRNA_103636 was significantly altered after the 8-week treatment in MDD patients. Conclusion: These results suggest that altered expression of hsa_circRNA_103636 in PBMCs is a potential novel biomarker for the diagnosis and treatment of MDD.

Risk assessment and predicting outcomes in patients with depressive symptoms: a review of potential role of peripheral blood based biomarkers

Depression is one of the major global health challenges and a leading contributor of health related disability and costs. Depression is a heterogeneous disorder and current methods for assessing its severity in clinical practice rely on symptom count, however this approach is unreliable and inconsistent. The clinical evaluation of depressive symptoms is particularly challenging in primary care, where the majority of patients with depression are managed, due to the presence of co-morbidities. Current methods for risk assessment of depression do not accurately predict treatment response or clinical outcomes. Several biological pathways have been implicated in the pathophysiology of depression; however, accurate and predictive biomarkers remain elusive. We conducted a systematic review of the published evidence supporting the use of peripheral biomarkers to predict outcomes in depression, using Medline and Embase. Peripheral biomarkers in depression were found to be statistically significant predictors of mental health outcomes such as treatment response, poor outcome and symptom remission; and physical health outcomes such as increased incidence of cardiovascular events and deaths, and all-cause mortality. However, the available evidence has multiple methodological limitations which must be overcome to make any real clinical progress. Despite extensive research on the relationship of depression with peripheral biomarkers, its translational application in practice remains uncertain. In future, peripheral biomarkers identified with novel techniques and combining multiple biomarkers may have a potential role in depression risk assessment but further research is needed in this area.

Behavioral studies on anxiety and depression in a drug discovery environment: keys to a successful future

The review describes a personal journey through 25 years of animal research with a focus on the contribution of rodent models for anxiety and depression to the development of new medicines in a drug discovery environment. Several classic acute models for mood disorders are briefly described as well as chronic stress and disease-induction models. The paper highlights a variety of factors that influence the quality and consistency of behavioral data in a laboratory setting. The importance of meta-analysis techniques for study validation (tolerance interval) and assay sensitivity (Monte Carlo modeling) are demonstrated by examples that use historic data. It is essential for successful discovery of new potential drugs to maintain a high level of control in animal research and to bridge knowledge across in silico modeling, and in vitro and in vivo assays. Today, drug discovery is a highly dynamic environment in search of new types of treatments and new animal models which should be guided by enhanced two-way translation between bench and bed. Although productivity has been disappointing in the search of new and better medicines in psychiatry over the past decades, there has been and will always be an important role for in vivo models in-between preclinical discovery and clinical development. The right balance between good science and proper judgment versus a decent level of innovation, assay development and two-way translation will open the doors to a very bright future.

Inflammation: a mechanism of depression?

In recent decades, major depression has become more prevalent and research has shown that immune activation and cytokine production may be involved. This review is mainly focused on the contribution of inflammation to depression. We first briefly introduce the inflammatory biomarkers of depression, then discuss the sources of cytokines in the brain, and finally describe the neuroimmunological mechanisms underlying the association between inflammation and depression.