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<?covid-19-tdm?>
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<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">Front. Psychiatry</journal-id>
<journal-title>Frontiers in Psychiatry</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Psychiatry</abbrev-journal-title>
<issn pub-type="epub">1664-0640</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.3389/fpsyt.2021.657316</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Psychiatry</subject>
<subj-group>
<subject>Opinion</subject>
</subj-group>
</subj-group>
</article-categories>
<title-group>
<article-title>Ursodeoxycholic Acid in Patients With Treatment-Resistant Schizophrenia Suffering From Coronavirus Disease 2019: A Hypothesis Letter</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author" corresp="yes">
<name><surname>Khosravi</surname> <given-names>Mohsen</given-names></name>
<xref ref-type="corresp" rid="c001"><sup>&#x0002A;</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/1183102/overview"/>
</contrib>
</contrib-group>
<aff><institution>Department of Psychiatry and Clinical Psychology, Zahedan University of Medical Sciences</institution>, <addr-line>Zahedan</addr-line>, <country>Iran</country></aff>
<author-notes>
<fn fn-type="edited-by"><p>Edited by: Stefania Schiavone, University of Foggia, Italy</p></fn>
<fn fn-type="edited-by"><p>Reviewed by: Angelo De Giorgi, Azienda Sanitaria Locale della Provincia di Foggia, Italy; Attilio Negri, Azienda Socio Sanitaria Territoriale di Mantova, Italy</p></fn>
<corresp id="c001">&#x0002A;Correspondence: Mohsen Khosravi <email>dr_khosravi2016&#x00040;yahoo.com</email>; <ext-link ext-link-type="uri" xlink:href="http://orcid.org/0000-0003-2970-6309">orcid.org/0000-0003-2970-6309</ext-link></corresp>
<fn fn-type="other" id="fn001"><p>This article was submitted to Molecular Psychiatry, a section of the journal Frontiers in Psychiatry</p></fn></author-notes>
<pub-date pub-type="epub">
<day>14</day>
<month>04</month>
<year>2021</year>
</pub-date>
<pub-date pub-type="collection">
<year>2021</year>
</pub-date>
<volume>12</volume>
<elocation-id>657316</elocation-id>
<history>
<date date-type="received">
<day>28</day>
<month>01</month>
<year>2021</year>
</date>
<date date-type="accepted">
<day>01</day>
<month>03</month>
<year>2021</year>
</date>
</history>
<permissions>
<copyright-statement>Copyright &#x000A9; 2021 Khosravi.</copyright-statement>
<copyright-year>2021</copyright-year>
<copyright-holder>Khosravi</copyright-holder>
<license xlink:href="http://creativecommons.org/licenses/by/4.0/"><p>This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.</p></license></permissions>
<kwd-group>
<kwd>coronavirus disease 2019</kwd>
<kwd>patient</kwd>
<kwd>schizophrenia</kwd>
<kwd>treatment</kwd>
<kwd>ursodeoxycholic acid</kwd>
</kwd-group>
<counts>
<fig-count count="0"/>
<table-count count="0"/>
<equation-count count="0"/>
<ref-count count="21"/>
<page-count count="2"/>
<word-count count="1551"/>
</counts>
</article-meta>
</front>
<body>
<p>Schizophrenia is a disabling condition with three main domains of positive, negative, and cognitive symptoms, which involves about 0.3&#x02013;0.7% of the general population (<xref ref-type="bibr" rid="B1">1</xref>). Treatment-resistant schizophrenia (TRS) is a significant challenge in one-third of patients with schizophrenia, placing a heavy burden on families, society, and health-care professionals (<xref ref-type="bibr" rid="B2">2</xref>). Moreover, if these patients are infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), medical treatment and psychosocial support systems will experience an increasing burden of treatment (<xref ref-type="bibr" rid="B3">3</xref>). Recent studies have shown that patients with schizophrenia may be vulnerable to SARS-CoV-2 infection for various reasons, including (i) poor insight and lack of decision-making capacity and effective coping skills, which lead to violation of the protective measures for inhibiting infection (e.g., physical distancing, using facial masks, and washing hands); (ii) high prevalence of comorbid metabolic disorders (more than 70%) such as hypertension, diabetes type II, coronary heart disease, and chronic pulmonary disease; (iii) high prevalence of smoking (50&#x02013;90%); and (iv) homelessness or institutionalization (<xref ref-type="bibr" rid="B4">4</xref>). Although clozapine possesses more clinical superiorities than other antipsychotic medications in cases of TRS, its use during the viral pandemic is especially challenging due to the overlap between clozapine-induced side effects and the coronavirus disease 2019 (COVID-19) symptoms and sequelae, as well as practical difficulties in regular laboratory monitoring (<xref ref-type="bibr" rid="B5">5</xref>, <xref ref-type="bibr" rid="B6">6</xref>). Accordingly, in the context of the COVID-19 crisis, new and effective therapeutic strategies need to be developed to treat and rescue these patients. Based on the current evidence, ursodeoxycholic acid (UDCA) seems to be an effective strategy in decreasing inflammation and avoiding cell death for patients with TRS infected with SARS-CoV-2. UDCA (C<sub>24</sub>H<sub>40</sub>O<sub>4</sub>) is a less toxic epimer of chenodeoxycholic acid in humans, which includes 1&#x02013;5% of total bile acid components (<xref ref-type="bibr" rid="B7">7</xref>). Recent studies have revealed that UDCA and its main conjugate (i.e., glycoursodeoxycholic acid), as cholesterol-derived bile acids, can have neuroprotective and homeostatic properties due to their capacity to inhibit glutamate release (<xref ref-type="bibr" rid="B8">8</xref>, <xref ref-type="bibr" rid="B9">9</xref>). Although the mechanism of the UDCA effect has not been wholly specified yet, a recent case report (<xref ref-type="bibr" rid="B10">10</xref>) showed that this medication could be an effective therapeutic strategy for patients with TRS. Based on the glutamate hypothesis of schizophrenia models, some of the probable therapeutic mechanisms would include (i) a decrease in the tone of glutaminergic projection neurons and, in turn, understimulation of inhibitory GABA interneurons in the ventral tegmental area, leading to the activation of mesocortical dopamine pathway, an increase of adequate dopamine release in the prefrontal cortex, and reduction of negative and cognitive symptoms of schizophrenia (<xref ref-type="bibr" rid="B11">11</xref>); and (ii) a decrease in firing of cortical glutaminergic projection neurons that causes an improvement in positive symptoms of schizophrenia through dopamine mesolimbic pathway hypoactivation (<xref ref-type="bibr" rid="B11">11</xref>, <xref ref-type="bibr" rid="B12">12</xref>). Moreover, recent studies demonstrated the beneficial action of UDCA in respiratory diseases as an antioxidant, anti-inflammatory, immunomodulatory, and anti-apoptotic agents (<xref ref-type="bibr" rid="B13">13</xref>, <xref ref-type="bibr" rid="B14">14</xref>). Some of these beneficial effects are as follows: (i) airway remodeling through the efficient modulation of Th-2-derived cytokines and inhibition of apoptosis of airway epithelial cells (<xref ref-type="bibr" rid="B15">15</xref>) and (ii) provoking alveolar fluid clearance in lipopolysaccharide-induced pulmonary edema via ALX/cAMP/PI3K pathway, which results in the improvement of acute respiratory distress syndrome (<xref ref-type="bibr" rid="B16">16</xref>). In this regard, Abdulrab et al. (<xref ref-type="bibr" rid="B17">17</xref>) and Subramanian et al. (<xref ref-type="bibr" rid="B18">18</xref>) have assumed that UDCA may have promising therapeutic effects on COVID-19-induced pneumonia and related lung edema. Bile acid derivatives have also proved to be effective in preventing virus entry by reducing the adhesion of SARS-CoV-2 spike&#x00027;s protein receptor binding domain to its angiotensin-converting enzyme 2 consensus <italic>in vitro</italic> (<xref ref-type="bibr" rid="B19">19</xref>). In addition, Yadav et al. (<xref ref-type="bibr" rid="B20">20</xref>) suggested that chenodeoxycholate and ursodeoxycholate can be potential candidates to hinder the survival of SARS-CoV-2 via disrupting the structure of envelope protein of SARS-CoV-2 and facilitating the entry of solvents/polar inhibitors into the viral cell. Interestingly, Rigamonti et al. (<xref ref-type="bibr" rid="B21">21</xref>) recently found quite low rates of symptomatic SARS-CoV-2 infection in patients with biliary cholangitis treated with UDCA. In total, these findings may highlight the emergence of novel therapeutic strategies against COVID-19 among patients with TRS. However, further studies are needed, particularly regarding efficacy and tolerability of UDCA in this group of patients.</p>
<sec id="s1">
<title>Author Contributions</title>
<p>MKH conceptualized the opinion and wrote the manuscript. The author also approved the final version of the submitted manuscript.</p>
</sec>
<sec sec-type="COI-statement" id="conf1">
<title>Conflict of Interest</title>
<p>The author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.</p>
</sec>
</body>
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