Odor perception and hedonics in chronic schizophrenia and in first episode psychosis
Received 28 October 2018
Accepted for publication 8 January 2019
Published 5 March 2019 Volume 2019:15 Pages 647—654
Checked for plagiarism Yes
Review by Single anonymous peer review
Peer reviewer comments 3
Editor who approved publication: Dr Roger Pinder
Małgorzata Urban-Kowalczyk,1 Dominik Strzelecki,1 Janusz Śmigielski,2 Magdalena Kotlicka–Antczak1
1Department of Affective and Psychotic Disorders, Medical University of Łódź, Łódź, Poland; 2State Higher Vocational School in Konin, Konin, Poland
Background and purpose: The study evaluated olfactory performance and pleasantness rating of odors in patients with first episode psychosis (FEP) and chronic schizophrenia (SCH) with regard to the severity of psychopathological symptoms and plasma β-endorphin concentration.
Patients and methods: Twenty patients with FEP, 27 with SCH and 29 healthy individuals, were recruited to the research . The University of Pennsylvania Smell Identification Test (UPSIT), subjective odor hedonic judgment and plasma levels of β-endorphin (BE) assay were performed in all participants.
Results: Individuals with SCH revealed higher BE concentration than other study groups (P=0.000). All patients identified pleasant odors poorer than controls, however, SCH made more identification errors (P=0.000) than those with FEP. Moreover, participants with FEP rated pleasant odors as more pleasant than individuals with chronic schizophrenia and healthy controls (P=0.009). Nevertheless, higher β-endorphin level was related with lower scores in pleasant odor identification (Rs=–0.452; P=0.046) and more severe psychotic symptoms in FEP sample. Chronic schizophrenia patients did not demonstrate any relationship between symptom severity, odor identification performance and β-endorphin concentration. No relationship was found between BE concentration and hedonic judgment of the presented odors among all study groups. Chronically ill subjects identified odors significantly more poorly than those with first episode psychosis. Deficits in identifying pleasant odors might not be the only potential risk factor for undergoing chronic, recurrent schizophrenia. All patients subjectively overrated pleasant odors. Those with SCH and more severe negative symptoms made significantly more identification errors.
Conclusion: The endogenous morphine system deregulation is observed in first episode psychosis as well as in chronic schizophrenia. In first episode schizophrenia higher beta-endorphin concentration is related to pleasant odor identification deficit.
Keywords: olfaction, negative symptoms, endogenous opioids, schizophrenia
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