寄生虫（弓形虫）可能引发精神分裂症

　　 英国利兹大学的Glenn A. McConkey 博士带领下进行的一项研究显示，能引起弓形虫病的寄生虫已经与精神分裂症有关，并且可能已经发现了引起精神分裂症的原因。这种原因就是，感染的生物体产生了一种酶，而这种酶能够刺激大脑中的一种化学物质――多巴胺的生成增多。
弓形虫是一种寄生虫，主要由猫科动物携带，但也可以感染其他哺乳动物。人感染弓形虫则会得弓形虫病；弓形虫病一般是种比较轻微的疾病，但如果孕妇感染可以直接传染给胎儿，引起严重后果，该寄生虫如果感染成人大脑，则会使免疫系统受损。
McConkey博士说“有好几项研究发现弓形虫病与精神分裂症有统计学关系，因此，与普通人群相比，精神分裂症患者有弓形虫病的可能性更高。另外一方面，其他证据显示多巴胺与精神分裂症也是有关的，因为治疗精神分裂症的药物氟哌啶醇的作用就是阻抑多巴胺。该研究是第一个显示寄生虫本身可能是神经递质来源的研究。”
该研究发表在《公共科学图书馆?综合》期刊中，该研究小组发现寄生虫的基因结构包含了能增加多巴胺产生的一种酶。
但如果基于McConkey 博士的研究而建议修改精神分裂症的治疗方法还为时尚早。弓形虫病的筛查有必要进行心理分析。
McConkey与他的同事现在计划探讨弓形虫在其他与多巴胺相关的神经系统疾病中可能发挥的作用，包括孤独症，帕金森氏症，和多发性抽动综合征。

Parasite may trigger schizophrenia

　　NEW YORK (Reuters Health) - The parasite that causes toxoplasmosis has been linked to schizophrenia, and biologists in the UK may have discovered why. It seems the organism produces an enzyme that increases the production of the brain chemical dopamine.
　　 Toxoplasma is a parasite, typically carried by cats but which can infect any mammal. People who catch it may develop toxoplasmosis; this is usually a minor illness, although it can be serious when it is passed on by pregnant women to their unborn baby, and it can cause problems in people with impaired immune systems when it infects the brain.
　　 "Several studies have found a statistical correlation of toxoplasmosis with schizophrenia," one of the authors of the current study, Dr. Glenn A. McConkey at the University of Leeds, explained in an e-mail to Reuters Health. "Hence, someone with schizophrenia is more likely to have toxoplasmosis than the general population."
On the other hand, other evidence suggests a link between dopamine and schizophrenia, because treatments for schizophrenia, such as haloperidol, block dopamine.
"Ours is the first study showing that the parasite itself could be the source of the neurotransmitter," commented.
The research is reported in the March issue of the open-access journal PLoS One. The team found the parasite's genetic make-up included an enzyme that aids in the production of dopamine.
"At this point the research is too premature to suggest changes in treatment" of schizophrenia, McConkey continued. Nonetheless, "Toxoplasmosis screening would be warranted in psychological analysis."
He and his colleagues now plan to explore the possible role of toxoplasma in other neurological diseases associated with dopamine, including autism, Parkinson's disease, and Tourette's syndrome.

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