LAUSR

Abstract Background Schizophrenia is a disabling disorder with tremendous individual burden, reduced quality of life, leading to intense costs for society. Paranoia is a central feature of schizophrenia. In particular, paranoid experience is thought to be associated with aggressive behaviour, and poor social and functional outcome. Since paranoid threat is sometimes hard to detect in the clinical interview, a simple bedside test to identify patients suffering from paranoid experience was recently proposed: the interpersonal distance test. Methods For measuring interpersonal distance in patients with schizophrenia and age-, gender- and education-matched healthy controls, we performed a stop-distance paradigm. To accomplish the paradigm, we positioned experimenter and participant at opposite ends of the room with a distance of seven meters facing each other. The stop-distance paradigm contained four different conditions; two active conditions (i.e. participant is approaching experimenter) and two passive conditions (i.e. experimenter is approaching participant) both, with and without eye contact. Participants were instructed to stop or tell the experimenter to stop at a distance, at which they would start to feel less comfortable. Moreover, we assessed paranoid threat with the Bern Psychopathology Scale. We compared the interpersonal distance between patients with current experiences of paranoid threat, schizophrenic patients without paranoia and healthy controls. Results Patients with higher ratings in paranoid experience presented with higher interpersonal distance than patients without paranoid threat and matched healthy controls. This effect was most prominent in the passive conditions. Patients without paranoia did not differ from healthy controls in the interpersonal distance test. Discussion Interpersonal distance is a reliable indicator of current paranoid threat in patients with schizophrenia. In fact, interpersonal distance is not generally altered in schizophrenia. However, paranoid threat leads to impairments in interpersonal space regulation. This is of particular relevance as interpersonal distance might be predictive of social and functional outcome and aggressive behaviour in schizophrenia.