DataSheet_1_Toxoplasma gondii infection in people with schizophrenia is related to higher hair glucocorticoid levels.pdf

IntroductionToxoplasma gondii (TG) is a common protozoan parasite infecting approximately one third of the human population. Animal studies have shown that this parasite can manipulate its host behavior. Based on this, human studies have assessed if TG can be involved in mental health disorders associated with important behavioral modifications such as schizophrenia. However, results have been discrepant. Given that TG has a strong impact on fear and risk-taking processes in animal studies and that fear and risk-taking behaviors are associated with the human stress response, we tested whether glucocorticoid biomarkers (salivary and hair) differ in people with schizophrenia and controls as a function of TG status.
MethodsWe measured TG antibodies in blood samples, as well as salivary and hair glucocorticoid levels in 226 people with schizophrenia (19.9% women, mean age = 39 years old) and 129 healthy individuals (controls) (45.7% women, mean age = 41 years old).
ResultsThe results showed that people with schizophrenia infected with TG presented significantly higher hair glucocorticoid concentrations than non-infected people with schizophrenia. This effect was not found in control participants. No effect was observed for salivary glucocorticoid levels. Additionally, there were no associations between TG infection and positive psychotic symptoms nor impulsivity.
DiscussionThese results show that people with schizophrenia present high levels of hair glucocorticoid levels only when they are infected with TG. Further studies performed in populations suffering from other mental health disorders are needed to determine if this effect is specific to schizophrenia, or whether it is generalized across mental health disorders.

引言：刚地弓形虫（Toxoplasma gondii, TG）是一种常见的原生动物寄生虫，全球约三分之一的人口受到其感染。动物实验研究表明，该寄生虫可调控宿主行为。基于此，学界已开展人体研究，探讨刚地弓形虫是否与精神分裂症等伴随显著行为改变的精神健康障碍相关，但相关研究结果始终存在分歧。鉴于动物实验证实刚地弓形虫对恐惧与冒险行为过程具有显著影响，而此类行为又与人类应激反应密切相关，本研究旨在检验精神分裂症患者与健康对照人群的糖皮质激素生物标志物水平是否因刚地弓形虫感染状态而异。
方法：本研究共纳入226名精神分裂症患者（女性占比19.9%，平均年龄39岁）与129名健康对照个体（女性占比45.7%，平均年龄41岁），通过血液样本检测刚地弓形虫抗体，并同步测定受试者的唾液与毛发糖皮质激素水平。
结果：研究结果显示，感染刚地弓形虫的精神分裂症患者，其毛发糖皮质激素浓度显著高于未感染该寄生虫的精神分裂症患者；而在健康对照人群中未观察到该效应。唾液糖皮质激素水平未发现显著关联。此外，刚地弓形虫感染与精神病性阳性症状、冲动性行为均无显著相关性。
讨论：本研究结果表明，仅当感染刚地弓形虫时，精神分裂症患者才会出现毛发糖皮质激素水平升高的情况。未来需在其他精神障碍人群中开展进一步研究，以明确该效应是否仅特异性存在于精神分裂症，还是可泛见于各类精神健康障碍。