SU108. Back to Basics of Basic Symptoms Concept: Which Phenomenon Scales Measure?

Abstract

Background: Basic symptoms (BS) have been firstly defined by Huber in 1957 as prepsychotic basic states made from “endogenous/organic, neurological/psychopathological transition symptomatology” depicting early subtle subclinical self-experienced disturbances. Recent research in clinical high-risk population have suggested that BS are a core as their phenomenological characterization enable a better prediction of transition to psychosis. Since the Bonn Scale for the Assessment of Basic Symptoms (BSABS) in 1987, new scales have been published including the Examination of Anomalous Self-Experience (EASE; 2005) and the Schizophrenia Proneness Instrument, Child and Youth version (SPI-CY; 2013) and each scale assesses heterogeneous aspects of BS. However, given the fact that each scale presents an important variability in the assessment of symptoms, it becomes difficult for clinicians and researchers to choose the appropriate scale. Consequently, a description of which phenomena are specifically highlighted by the different scales could be useful. Methods: A comparative content analysis of items from the BSABS,1 EASE,2 SPI-CY,3 Inventory of Psychotic-Like Anomalous Self-Experiences (IPASE),4 and Self-Experience Lifetime Frequency (SELF)5 scale has been conducted to identify phenomena associated with each scale. Results: Hundreds of items can be abbreviated to 22 phenomena. Analysis shows that several of BSABS items are focused on neurovegetative symptoms (25%) and sensory/perceptual distortions (28%) whereas EASE items focus mostly on self-consciousness disorders (19%), anxiety symptoms (15%), and thought disorders (13%). The SPI-CY’s main focus is adynamia dimension (19%) and sensory/perceptual distortions (31%). Finally, both IPASE and SELF scales are mainly focused on self-consciousness disorder (35% and 25%, respectively). Conclusion: Unraveling and comparing all items of the existing scales bring a better understanding of the BS concept and help derive some recommendations on their utilization. First, we found that BSABS is mostly focused on neurovegetative and perceptual symptoms and that the recent scales as EASE, IPASE, and SELF have shifted the concept of basic symptoms more toward self-consciousness disorders. Then, some scale such as the SPI-CY scale may be more useful for the prediction of conversion to psychosis as it is more focused on dimensions, which have been found to predict the onset. Finally, for their part, self-administered scales such as IPASE and SELF offer a more cost-effective assessment of BS but still need further validation, especially in clinical high-risk population.