Olfactory identification deficit and its relationship with hedonic traits in patients with first-episode schizophrenia and individuals with schizotypy

Objective: Olfactory identification impairments have been consistently found in schizophrenia patients. However, few previous studies have investigated this in first-episode patients. There are also inconsistent findings regarding olfactory identification ability in psychometrically-defined schizotypy individuals. In this study, we directly compared the olfactory identification ability of first-episode schizophrenia patients with schizotypy individuals. The relationship between olfactory identification impairments and hedonic traits was also examined. Methods: Thirty-five first-episode schizophrenia patients, 40 schizotypy individuals as defined by the Chapman's Anhedonia Scales and 40 demographically matched controls were recruited. The University of Pennsylvania Smell Identification Test was administered. Hedonic capacity was assessed using the Temporal Experience of Pleasure Scale (TEPS). Results: The results showed that both the schizophrenia and schizotypy groups showed poorer olfactory identification ability than controls, and the impairment was significantly correlated with reduced pleasure experiences. Conclusion: Our findings support olfactory identification impairment as a trait marker for schizophrenia.