Olfactory Dysfunction in Schizophrenia and Psychotic Disorders: A Comprehensive and Updated Meta-Analysis

Olfaction plays a key role in our daily life, influencing food enjoyment, threat detection,mood and social relationships. Numerous studies have provided evidence of abnormalolfactory function in schizophrenia and other psychotic disorders. This pre-registered meta-analysis was conducted to (a) provide an updated overview on olfactory function inschizophrenia-spectrum disorders, and (b) examine the modulatory effects of demographicand clinical variables on distinct olfactory abilities. We complied with the PRISMAguidelines, searching throughout PubMed and PsycInfo, until the 12th of August 2023. Atotal of 73 publications were included, comprising data from 3282 patients and 3321 healthycontrols. Results revealed that (a) patients performed significantly worse in higher-orderolfactory tasks (identification and discrimination) compared to healthy controls, while nodifferences were observed in odor threshold sensitivity; (b) patients’ performance in odoridentification was moderated by education, as well as disease duration and negativesymptoms. Our findings support the presence of olfactory impairments in schizophrenia-spectrum disorders, leading to significantly poorer performance in both odor identificationand discrimination, but not threshold, when compared to healthy controls.