Olfactory performance segregates effects of anhedonia and anxiety on social function in patients with schizophrenia

Background: Social dysfunction is common among individuals with schizophrenia. While often attributed to anhedonia, social dysfunction could also result from unrecognized anxiety. We examined the contributions of anhedonia and anxiety to social function using olfactory function to examine whether the domains had separate underpinnings. Methods: We assessed anhedonia, anxiety and social function as well as olfactory function in well-characterized patients with schizophrenia or schizoaffective disorder and healthy controls. Results: We included 56 patients and 37 controls in our study. Patients exhibited significantly higher levels of anhedonia and anxiety than controls, and the domains were highly correlated in patients. The combination of anhedonia and anxiety more strongly predicted social dysfunction than either measure alone. Smell identification was differentially related to the symptoms, with better performance predicting less anhedonia but more social fear in male patients. Limitations: The use of self-report measures precludes differentiation between recollected or recounted experience. Aside from smell identification and odour threshold, additional measures of olfaction may be considered for future studies. Conclusion: Anhedonia and anxiety were strongly correlated and both negatively impacted social function. The olfactory biomarker results support the conclusion that these domains are separate. Social function in patients with schizophrenia may improve with interventions for anxiety, even in the presence of marked negative symptoms.