Associations between olfactory identification and (social) cognitive functioning: A cross-sectional study in schizophrenia patients and healthy controls

Schizophrenia patients have difficulties identifying odors, possibly a marker of cognitive and social impairment. This study investigated olfactory identification (OI) differences between patients and controls, related to cognitive and social functioning in childhood and adolescence, to present state cognition and to present state social cognition. 132 schizophrenia patients and 128 healthy controls were assessed on OI performance with the Sniffin' Sticks task. Multiple regression analyses were conducted investigating OI in association with cognitive and social functioning measures in childhood/adolescence and in association with IQ, memory, processing speed, attention, executive functioning, face recognition, emotion recognition and theory of mind. Patients had reduced OI performance compared to controls. Also, patients scored worse on childhood/adolescence cognitive and social functioning, on present state cognitive functioning and present state social cognition compared to controls. OI in patients and controls was significantly related to cognitive and social functioning in childhood/adolescence, to present state cognition and to present state social cognition, with worse functioning being associated with worse OI. In this study, findings of worse OI in patients relative to controls were replicated. We also showed associations between OI and cognitive and social functioning which are not specific to schizophrenia.