Olfactory Functioning in First-Episode Psychosis

Abstract

Background: Though olfactory deficits are well-documented in schizophrenia, fewer studies have examined olfactory performance profiles across the psychosis spectrum. The current study examined odor identification, discrimination, and detection threshold performance in first-episode psychosis (FEP) patients diagnosed with schizophrenia, schizoaffective disorder, bipolar disorder with psychotic features, major depression with psychotic features, and other psychotic conditions.

Method: FEP patients (n = 97) and healthy adults (n = 98) completed birhinal assessments of odor identification, discrimination, and detection threshold sensitivity for lyral and citralva. Participants also completed measures of anticipatory pleasure, anhedonia, and empathy. Differences in olfactory performances were assessed between FEP patients and controls and within FEP subgroups. Sex-stratified post hoc analyses were employed for a complete analysis of sex differences. Relationships between self-report measures and olfactory scores were also examined.

Results: Individuals with psychosis had poorer scores across all olfactory measures when compared to the control group. Within the psychosis cohort, patients with schizophrenia-associated psychosis had poorer odor identification, discrimination, and citralva detection threshold scores relative to controls. In schizophrenia patients, greater olfactory disturbance was associated with increased negative symptomatology, greater self-reported anhedonia, and lower self-reported anticipatory pleasure. Patients with mood-associated psychosis performed comparable to controls though men and women in this cohort showed differential olfactory profiles.

Conclusions: These findings indicate that olfactory deficits extend beyond measures of odor identification in FEP with greater deficits observed in schizophrenia-related subgroups of psychosis. Studies examining whether greater olfactory dysfunction confers greater risk for developing schizophrenia relative to other forms of psychosis are warranted.

Fig. 1.

Olfactory task performance (±SE) in first-episode psychosis (FEP) patients with schizophrenia-associated psychosis (SAP) and mood-associated psychosis (MAP) relative to healthy comparison (HC) subjects. Note: Individuals in the SAP group performed significantly worse across both tasks compared to the control group (P < .001) whereas the MAP group did not differ significantly from controls.

Fig. 2.

Odor threshold detection sensitivity (±SE) to lyral and citralva in first-episode psychosis (FEP) patients with schizophrenia-associated psychosis (SAP) and mood-associated psychosis (MAP) relative to healthy comparison (HC) subjects. Note: The SAP subgroup had poorer odor detection thresholds for citralva (P = .01) but not lyral compared to the control group. The MAP group did not differ significantly from controls. Y-axis values closer to −4.00 indicate poorer odor detection threshold sensitivity.