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New study confirms double the risk of dementia after mouth herpes simplex virus
People who have had the herpes virus at some point in their lives are twice as likely to develop dementia compared to those who have never been infected. A new study from Uppsala University confirms previous research on whether herpes can be a possible risk factor for dementia.
The researchers studied 1,000 70-year-olds from Uppsala over a period of 15 years. The study, now published in the Journal of Alzheimer's Disease, found that people who had been infected with the herpes simplex virus at some point in their lives were twice as likely to develop dementia, compared to those who had never been infected.
The herpes simplex virus is very common and up to 80% of Swedish adults may be infected. The infection is lifelong, but the symptoms can come and go over different periods of life. Many people never get any symptoms linked to their infection.
"What's special about this particular study is that the participants are roughly the same age, which makes the results even more reliable since age differences, which are otherwise linked to the development of dementia, cannot confuse the results," explains Erika Vestin, a medical student at Uppsala University.
Worldwide, 55 million people are affected by dementia. Advanced age and carrying the apolipoprotein ε4 risk gene are already known risk factors. Research has previously been conducted to investigate whether the herpes simplex virus could also be a possible risk factor for dementia, something now confirmed in this study.
"It is exciting that the results confirm previous studies. More and more evidence is emerging from studies that—like our findings—point to the herpes simplex virus as a risk factor for dementia," continues Vestin.
Important conclusions from the study include the need to further investigate whether already known drugs against the herpes simplex virus can reduce the risk of dementia and the possibility of developing new vaccines.
"The results may drive dementia research further towards treating the illness at an early stage using common anti-herpes virus drugs, or preventing the disease before it occurs," adds Vestin.
注释：
herpes: n
表示" 疱疹"，如：Vesicles of herpes simplex occur around the lips. 唇部可发生单纯疱疹。
simplex: adj
表示"单工的"，means "having only one part or element"，如：herpes simplex 单纯疱疹
apolipoprotein: n
表示"载脂蛋白"，如：As a result , a codon usage clock was reported in apolipoprotein A-I. 结果显示:载脂蛋白分子演化中存在着同义密码子使用的分子进化钟。
中文简要说明：
目前无药可救的失智症，全球患者大约5500万人，这是全球各国公卫难题，掌握罹病风险、如何防治是重中之重。瑞典学界最近研究显示，上了年纪之后失智的风险比较高。曾感染唇疱疹病毒（Herpes Simplex Virus，HSV）的人，老后出现各种形式痴呆症状的风险，是未曾罹患唇疱疹者的2倍。
综合医学新闻网站Medical Xpress、英国《每日邮报》报导，瑞典乌普萨拉大学（Uppsala University）团队近日在《阿兹海默症期刊》（Journal of Alzheimer's Disease）发表最新的长期研究成果指出，人类一旦感染唇疱疹病毒，病毒片段（fragment）会一直留在体内，有证据显示，这些病毒片段会往脑部移动，引发乙型类淀粉蛋白斑块（amyloid beta plaque）与tau蛋白形成，两者都是阿兹海默症的标记。
研究团队在2001年2005年观察总共1002名70岁的瑞典人，进行为期15年的追踪研究。除了收集参与者的血液样本以检测是否感染HSV，研究人员也透过参与者的就医记录收集与失智诊断、认知障碍迹象的信息，由乌普萨拉大学医院记忆诊疗中心审查并找出确诊或可能罹患失智症的人。
结果显示，71人（7%）罹患失智症，36人（4%）罹患阿兹海默症。患有失智症与阿兹海默症的参与者之中，约89%带有HSV，没有出现认知障碍症状的参与者82%带有此病毒。研究人员加以统计分析确认，带有HSV会导致罹患失智症风险增加1倍。
HSV很常见，高达8成瑞典成年人可能都曾感染，美国估计50%至80%成年人曾感染HSV，感染病毒之后，人生不同时期可能会出现病征。病毒平时潜伏体内，在免疫系统低下、暴露在烈日或寒风、感冒或罹患其他疾病、承受压力的情况之下，都可能导致唇疱疹出现。不过，许多人从未出现任何症状。
研究人员指出，先前曾有研究想查明HSV是否可能是失智症的危险因子之一，如今乌普萨拉大学这项研究证实了这一点。这项研究特别之处在于，参与者年龄大致上年龄相同，令研究结果更加可靠，因为年龄差异与失智症病程发展有关，这项研究的结果不会因为年龄差异而产生混淆。未来需要进一步研究已知的抗HSV药物可否降低失智症风险、是否有可能开发新疫苗。
阿兹海默症（Alzheimer's disease） 是众多失智症之中最常见的一种，全美患者约600万人；第二常见的则是路易斯体路易氏体失智症（Diffuse Lewy body dementia，DLBD），全美患者约100万人。
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