[Psychobiological background and clinical aspects of the placebo effect in psychiatry].

The placebo-effect is present in almost every field of medicine, however, in the assessment of the effect of psychotropic drugs it is a major problem. The rise of the placebo-effect in clinical trials is observed during the last decades, in spite of all efforts to introduce new methods in clinical trials to overcome this problem and the number of studies aiming to unveil the mechanisms that lie in the background that this phenomenon have risen. A considerable amount of data has accumulated regarding the psychobiological background of placeboeffect, however, the details of underlying mechanisms are still not clear. Furthermore, the lack of objective tools for the assessment of the phenotypic changes during the treatment of psychiatric disorders makes it even more difficult to differentiate the symptom intensity changes related to drug response from the placebo effect. The consequences of this scarcity of information concerning the background of placebo-effect may hinder the development of new compounds, having enormous medical, scientific and economical disadvantages. In this review we summarise the psychobiological mechanisms in the background of placebo effect and its impact on clinical trials.