DELUSION, BELIEF, AND CONVICTION: THE QUESTION OF NORMALITY FROM THE VIEWPOINT OF PSYCHOLOGY, PHYSIOLOGY, AND MOLECULAR BIOLOGY

According to the classic definition, delusion is a fixed false belief that is incompatible with reality and cannot be modified and corrected by persuasion and facts. More recently, it is often considered as a phenomenon similar to everyday belief formation, in which sensory and reasoning biases play an important role. Biased processing of social signals, unusual experiences, and search for meaning lead to beliefs via early jumping to conclusions, attributional biases, and mentalization. These processes may be modulated by social context and may turn into a self-reinforcing circle. In this paper, I present data demonstrating the normal distribution of delusion-like phenomena in the general population, similarly to their physiological and molecular markers (habituation of autonomic arousal, activation of the AKT intracellular messenger system). From a neurochemical point of view, dopamine has a positive effect ameliorating apathy and some cognitive deficits in neurological disorders, but its receptor agonists may induce psychotic-like phenomena, including overvalued ideas in patients with Parkinson’s disease. This can be explained by increased aberrant salience in simple conditioning paradigms. The most important challenge for future research is to identify the disease-predictive effect of these subclinical signs and biological markers.