The Evaluation of Olfactory Function in Patients With Schizophrenia

Abstract

The aim of this study was to compare olfactory threshold, smell identification, intensity and pleasantness ratings between patients with schizophrenia and healthy controls, and (2) to evaluate correlations between ratings of olfactory probes and illness characteristics. Thirty one patients with schizophrenia and 31 control subjects were assessed with the olfactory n-butanol threshold test, the Iran smell identification test (Ir-SIT), and the suprathreshold amyl acetate odor intensity and odor pleasantness rating test. All olfactory tasks were performed unirhinally.Patients with schizophrenia showed disrupted olfaction in all four measures. Longer duration of schizophrenia was associated with a larger impairment of olfactory threshold or microsmic range on the Ir-SIT (P = 0.04, P = 0.05, respectively). In patients with schizophrenia, female subjects’ ratings of pleasantness followed the same trend as control subjects, whereas male patients’ ratings showed an opposite trend. Patients exhibiting high positive score on the positive and negative syndrome scale (PANSS) performed better on the olfactory threshold test (r = 0.37, P = 0.04). The higher odor pleasantness ratings of patients were associated with presence of positive symptoms.The results suggest that both male and female patients with schizophrenia had difficulties on the olfactory threshold and smell identification tests, but appraisal of odor pleasantness was more disrupted in male patients.

Sex Differences in Odor Hedonic Perception: An Overview

“…By contrast, another study ( Walsh-Messinger et al, 2018 ) showed that schizophrenic men rated pleasant odors (orange, apple, mint,…) less pleasant than healthy men whereas no difference was observed between healthy and schizophrenic women. When studies related to this topic focused on gender differences in patients with schizophrenia, some of them showed that schizophrenic men rated pleasant odorants as more pleasant than schizophrenic women and healthy participants whatever the concentration level ( Moberg et al, 2003 ; Robabeh et al, 2015 ). Other studies found no gender differences in odor hedonic judgment ( Hudry et al, 2002 ; Lui et al, 2020 ).…”

Decrease of gray matter volume in treatment-refractory schizophrenia patients

“…Olfactory bulb mitral cells synapses with neuroepithelium, retrieving information throughout the olfactory tract to primary olfactory areas and other regions that play crucial roles in emotion regulation and executive planning. Olfactory functional impairment may be a biological marker of schizophrenia susceptibility [16]. Performing a meta-analysis on olfactory dysfunction in schizophrenia patients, high risk groups and first degree relatives, Moberg PJ et al revealed that both schizophrenia patients and high risk individuals had moderate degree of olfactory dysfunction and their first degree relatives had mild or moderate olfactory dysfunction [17].…”

Olfaction, among the First Senses to Develop and Decline

“…There are several aspects of olfaction that can be assessed to characterize the schizophrenia-spectrum disorders (SSD). In particular, subjects affected by this neuropsychiatric disease present alterations in performing correctly diverse olfactory tasks, such as odor sensitivity, identification and discrimination, when exposed to different odorants [60,61,[189][190][191][192]. Due to the disbalance in olfactory activity, it has been suggested to consider this deficit as a parameter to identify SSD.…”