Biomarkers in Child Mental Health: a bio-psycho-social perspective is needed.

Abstract

© 2015 Rothenberger et al. This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons. org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Rethinking the past There is still an increasing interest in biomarkers in (child) psychiatry although some disappointment took place within the last decades for those who expected simplistic solutions. For example, the Dexamethasone Suppression Test (DST) showed initial promise to diagnose endogeneous depression, drug response and clinical relapse, but finally it was of limited clinical value and abandoned [1]. The same holds true for former expectations to find a certain gene for a certain mental health disorder and treat it by genetic therapy. Fortunately, neurobiological research in psychiatry has overcome such simplistic models. Meanwhile our scientific knowledge has increased tremendously and we discuss the highly complex pathophysiological background of mental disorders on a broad empirical basis. Hence, to find biomarkers of clinical utility we should rethink our approach. Not only a fresh and critical look at the biological underpinnings of mental disorders is recommended, but also one should take into account aspects of their interaction with environment and translation into patient care. There are many papers just comparing people with typical development with a group of psychiatric patients to report an association between one parameter or several single biological parameters (e.g. genes, brain oscillations, cortisol, oxytocin, BDNF, event-related potentials, fMRI regions) and the disorder. They frequently conclude that the investigated parameter “may be a promising biomarker” [2, 3, 4]. This approach is more or less on the wrong track, if no further steps for testing the validity of the biomarkers are undertaken, as is rarely the case. Especially, things become more challenging when developmental aspects have to be added in studies with minors. In order to understand why earlier research paved such a simplistic way one should go back to the point where and how the idea of biomarkers in psychiatry was promoted. Since decades psychiatrists are trying to elucidate the biological underpinnings and neuroscientific dynamics of mental disorders in children (e.g. [5, 6]). This approach is still valid and should be followed further in parallel to the research on the objectives related to biomarkers. With the advent of new technologies like brain mapping, neuroimaging, genetics, epigenetics, proteomics, neurotransmitters, metabolic assessment, neuropsychology, brain-computer-interface, many researchers and clinicians expressed the hope to advance the field by developing a biologically guided psychiatric classification, diagnostic system and treatment recommendation [1, 7]. In other words, a paradigm shift in psychiatry with a promise of rescuing the validity of symptom based psychiatric diagnosis through its link to the pathophysiology of mental disorders. However, so far, the limited robust facts did not allow for implementing such an approach into DSM-V. Moreover, Peterson [8] stated that the NIMH promoted Research Domain Criteria (RDoC), i.e. a mechanistically and neurobiologically oriented new approach to psychiatric nosology, is still “premature, ... theoretically problematic and its measures psychometrically untested”. Thus “it seems unlikely that a single RDoC domain validly represents a single link in the causal pathway from genes to behavior.” Hence, it can hardly be expected that related biomarkers will be clinically more relevant than those related to DSM-V categories and the intrinsic dimensions.