Vol 6 n° 1 - Predictors of Response to Treatment in Neuropsychiatry
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ear Colleagues, Treatment has always been the ultimate goal of psychiatry. However, truly effective treatments have been scarce for most of psychiatry’s history. It is only in the last 50 years that drugs acting on the central nervous system and capable of influencing behavior have been discovered, and often by serendipity. The discovery that chemical compounds could influence the brain led to research into the mechanisms of action of these drugs, and more generally to progress in neuroscience. Thus, indirectly, drug discovery strongly contributed to our current knowledge of the brain’s biology. To a large extent, research has elucidated the mechanisms of action of drugs, and we know today— more or less—why treatment works. However, it is also worth asking ourselves why treatment does not work in some cases. Understanding the mechanisms of nonresponse is extremely instructive. However, this question is complex because of the many factors influencing treatment response. Sources of variation between patients include diagnostic criteria, biological parameters, the heterogeneity of individual responses to dynamic tests or  therapeutic  models,  nutritional  or  metabolic  disturbances,  pharmacogenetic  polymorphism,  and environmental factors, to name but a few. Current diagnostic classifications do not identify homogeneous groups of patients, who respond in a predictable way to a given drug.This calls into question the usefulness of these classifications in drug studies. It has been suggested that the diagnosis of a disorder is not sufficient for such research.Treatment response or nonresponse should be correlated with additional parameters: underlying personality;  quantification  of  symptoms;  neuropsychological  tests;  laboratory  findings  derived  from neuroendocrinology or pharmacogenetics; brain imaging, either purely functional (electroencephalography [EEG], quantitative EEG, sleep recordings, or magneto-EEG) or structural and functional (magnetic resonance imaging, single-photon emission computed tomography, or positron emission tomography); and the response to certain models. Patients, disorders, and ad hoc treatments should be characterized under relatively standardized conditions to ensure a better evaluation of the correlates of nonresponse. Understanding the determinants of nonresponse and poor response is important in order to predict the prognosis and course of a disorder, as well as to evaluate the social cost of a disease.The current questions raised by various national health authorities concerning the social and economic aspects of diseases, in particular mental disorders, cannot be answered without knowing the reasons for nonresponse or poor response to treatment. All this explains why this difficult question of nonresponse to treatment is one of the concerns of the members of the Editorial Board of Dialogues in Clinical Neuroscience. We have therefore contributed to a special issue of the journal on this problem, to express our point of view and debate a question of current importance. Your sincerely, Jean-Paul Macher, MD Marc-Antoine Crocq, MD E d i t o r i a l D 1