The Relationship Between Antipsychotic Treatment and Plasma β-Endorphin Concentration in Patients with Schizophrenia
Received 1 November 2020
Accepted for publication 12 January 2021
Published 16 February 2021 Volume 2021:17 Pages 503—512
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 Magdalena Kotlicka-Antczak,1 Dominik Strzelecki,1 Ewa Rudecka,2 Janusz Śmigielski3
1Department of Affective and Psychotic Disorders, Medical University of Lodz, Lodz, Poland; 2Faculty of Human Nutrition and Consumer Sciences, Warsaw University of Life Sciences SGGW, Warsaw, Poland; 3State High Vocational School in Konin, Konin, Poland
Correspondence: Małgorzata Urban-Kowalczyk
Department of Affective and Psychotic Disorders, Medical University of Lodz, Czechosłowacka 8/10, 92-216, Lodz, Poland
Tel +48 42 675 73 71
Fax +48 42 675 74 03
Objective: Some studies indicate the presence of elevated opioid levels in cases of schizophrenia and their relationship with negative symptoms. The pathogenesis of schizophrenia may be associated with an imbalance in the modulatory effect of opioids on the dopaminergic system. The aim of the study was to identify the association between β-endorphin (BE) concentration and the outcome of short-term schizophrenia treatment.
Methods: We examined 49 patients hospitalized due to exacerbation of schizophrenia symptoms and 47 controls without schizophrenia. The severity of psychopathological symptoms was evaluated using Positive and Negative Syndrome Scale (PANSS) at the onset of hospitalization, and after four, six and ten weeks of treatment. Patients were classified into negative (NEG) and mixed (M) psychopathological subtypes according to the PANSS composite index. &Bgr;-endorphin (BE) plasma concentrations were assessed in all participants; in patients on inclusion to the study and after six weeks of treatment.
Results: The patients with schizophrenia demonstrated higher BE levels than controls. During six-week antipsychotic treatment, BE concentration significantly increased in both NEG (p=0.000) and M (p=0.007), and positive symptoms were effectively reduced. In the NEG group, the prevalence of negative symptoms decreased only transiently and returned to approximately baseline values after 10 weeks (p=0.268). In the M patients, the prevalence of negative symptoms increased gradually (p=0.001), with more severe positive and, notably, negative symptoms correlating with higher BE2 concentrations at the 10-week assessment (R= 0.47, p= 0.0135 vs R= 0.74, p=0.0000). In both NEG and M, a greater rise in BE2 level correlated with a lower composite index during treatment.
Conclusion: Patients with schizophrenia demonstrate higher BE levels compared to controls. These changes in BE concentration during antipsychotic treatment could reflect the interaction between dopaminergic transmission and endogenous opioids. A rise in BE level following effective antipsychotic therapy could be a potential predictor of persisting negative symptoms.
Keywords: negative symptoms, endogenous opioids, schizophrenia, psychosis
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