Depression – a widespread Disease! Are Biomarkers in sight?

Around 350 million people all over the world suffer from depression, which makes it one of the most common mental disorders.

Treatments for depression usually consist of a combination of psychotherapy or counselling and drugs, which can have undesirable side effects. However, more than one-third of patients with depression do not respond properly to treatment with antidepressants, with 20 % of these failing to show any improvement at all whilts on anti-depressants (non-responders).

Research is needed, in order to answer the following questions:
Are there alternatives to the currently prescribed drugs, perhaps from the fields of natural medicine or botanical drugs, which cause fewer side effects?
Could combinations of products have better results in non-responders?
Is it possible to define different subgroups of depression and their underlying mechanisms sooner and „tailor” specific treatments to improve the symptoms more quickly?

While in the past, efficacy studies of antidepressants have been based on information obtained from questionnaires, in recent years there has been a tremendous amount of energy put into research for biomarkers for depression. Benefits for studies are still limited and it seems that THE biomarker for depression doesn’t exist. Results from preliminary studies with biomarker panels (several biomarkers that are interpreted together) seem more promising.

It is highly likely that what we generally call „depression“ today in fact comprises a number of different sub-types of depressive disturbances, each one with its own identifiable biomarkers. It would be logical to assume that different drugs would be needed to treat these different sub-types. This is exactly the goal of precision medicine: previous phenotypical diagnoses are supposed to be replaced by a new taxonomy based on endophenotypes. Endophenotypes combine specific biomarkers with clinically relevant data. One highly promising approach is neuropatternTM, a new diagnostic test that is used to differentiate endophenotypes, and suggests the appropriate treatments for individuals. Indeed, conceptual endophenotypes are used currently to differentiate and stratify between various states of exhaustion and depression syndromes.
How can we proceed further? Are biomarker panels like the panel of 9 serum biomarkers (α1-antitrypsin, apolipoprotein CIII, BDNF (brain-derived neurotrophic factor), cortisol, epidermal growth factor, myeloperoxidase, prolactin, resistin and soluble tumour necrosis factor-α receptor type II) as described by Papakostas et al. (2012) the solution? It will probably take years to state whether particular biomarkers will be useful in clinical practice and benefit a personalized treatment. Until then, it makes sense to work with conceptual endophenotypes (neuropatternTM) which facilitate the allocation of such biomarkers to causal neurobiological mechanisms and thus take a leading role in the process of further developing an adequate depression treatment.