People who have even a mild case of Covid-19 may have accelerated aging of the brain and other changes to it, according to a new study.

一项新的研究表明，即使是患上新冠肺炎轻症，人们的大脑也会加速老化并且还会发生其他改变。

The study, published Monday in the journal Nature, is believed to be the largest of its kind. It found that the brains of those who had Covid-19 had a greater loss of gray matter and abnormalities in the brain tissue compared with those who didn't have Covid-19. Many of those changes were in the area of the brain related to the sense of smell.

于周一发表在期刊《自然》上的这篇调查据称是规模最大的一项研究。该项研究发现，与没有患新冠肺炎的人相比，得过新冠肺炎的人的大脑灰质流失更多，脑结构也会有异常。许多这些变化出现在与嗅觉相关的脑部区域。

"We were quite surprised to see clear differences in the brain even with mild infection," lead author Gwenaëlle Douaud, an associate professor of neurosciences at the University of Oxford, told CNN in an email.

首席作者、牛津大学神经学助教Gwenaëlle Douaud在邮件中表示：“即使是新冠肺炎轻症，患者的大脑还是有非常明显的差异，这让我们非常意外。”

Douaud and her colleagues evaluated brain imaging from 401 people who had Covid-19 between March 2020 and April 2021, both before infection and an average of 4½ months after infection. They compared the results with brain imaging of 384 uninfected people similar in age, socioeconomics and risk factors such as blood pressure and obesity. Of the 401 infected people, 15 had been hospitalized.

Douaud和她的同事在2020年3月和2021年4月之间评估了401位新冠肺炎患者在感染新冠肺炎之前和感染新冠肺炎平均4.5个月后的大脑图像。他们将上述患者的大脑图像与384位未感染新冠肺炎的人进行对比，这384位未感染新冠肺炎的人在年龄以及诸如血压和肥胖等社会经济学和风险因素方面与上述的401位新冠肺炎患者类似。在401位感染新冠肺炎的人群中，15位曾住院治疗。

The 785 participants were between the ages of 51 and 81 and were all part of the UK Biobank, an ongoing government health database of 500,000 people begun in 2012.

这785位患者的年龄在51岁到81岁之间并且都属于英国生物样本库（UK Biobank）-一个始于2012年并且还在持续更新的政府健康数据库（含50万人的数据）。

Douaud explained that it is normal for people to lose 0.2% to 0.3% of gray matter every year in the memory-related areas of the brain as they age, but in the study evaluation, people who had been infected with the coronavirus lost an additional 0.2% to 2% of tissue compared with those who hadn't been infected.

Douaud解释说，随着人们的年龄增加，大脑中的灰质每年减少0.2%-0.3%是正常的。但在研究评估中，曾经得过新冠肺炎的人与没有得过新冠肺炎的人相比，大脑组织还会额外减少0.2%到2%。

In addition to imaging, the participants were tested for their executive and cognitive function using the Trail Making Test, a tool used to help detect cognitive impairments associated with dementia and test a person's brain processing speed and function. The researchers found that those who had the greatest brain tissue loss also performed the worst on this exam.

除了大脑图像之外，参加者还会接受连线测试（Trail Making Test）以检测其执行和认知功能。连线测试是一个检测工具，其可以帮助检测与痴呆有关的认知受损并测试一个人的大脑处理速度和功能。研究人员发现，大脑组织损失最多的人在测试中的表现也是最差的。

Although the areas of the brain most affected appear to be related to the olfactory system, Douaud said it wasn't clear why that was the case.

尽管受影响最大的大脑区域似乎与嗅觉系统有关，但是Douaud表示，目前两者之间产生关联的原因还尚不明确。

"Since the abnormal changes we see in the infected participants' brains might be partly related to their loss of smell, it is possible that recovering it might lead to these brain abnormalities becoming less marked over time. Similarly, it is likely that the harmful effects of the virus (whether direct, or indirect via inflammatory or immune reactions) decrease over time after infection. The best way to find out would be to scan these participants again in one or two years' time," she said.

她表示：“由于我们观察到感染过新冠肺炎的参与者其大脑的异常变化可能与丧失嗅觉存在部分关联，那么恢复嗅觉可能会使大脑的异常变化随着时间推移变得不那么明显。同样，病毒的危害（不管是直接的，还是通过炎症或免疫发生产生的间接危害）可能会在感染后随着时间的推移而减少。找到这一答案的最佳方式可能是等1或2年再次对上述参与者的脑部进行扫描。”

Douaud added that the researchers anticipate reimaging and testing the participants in one or two years.

Douaud补充表示，研究者们期望等1到2年后再次对参与者进行扫描并检测。

And while the study finds some association between infection and brain function, it's still not clear why. Previous studies have shown people with significant and repeated loss of smell also have an associated loss of gray matter. However, this study did not evaluate whether people actually had a loss of smell.

尽管研究发现感染和脑部功能之间存在某些关联，但是产生关联的原因目前还尚不明确。此前的研究表明，出现明显的嗅觉丧失和反复丧失嗅觉的人的大脑灰质也会有所减少。但是，该研究并未评估人们是否确实会丧失嗅觉。

The authors cautioned that the findings were only of a moment in time but noted that they "raise the possibility that longer-term consequences of SARS-CoV-2 infection might in time contribute to Alzheimer's disease or other forms of dementia."

作者提醒表示，研究结果仅仅是暂时的，但是也强调表示，“研究结果意味着从长远来看，感染SARS-CoV-2可能会导致阿兹海默症或其他类型的痴呆的可能性增加。”

The findings were noticeable, but they weren't enough to cause alarm, said Dr. Richard Isaacson, a neurologist and director of the Florida Atlantic University Center for Brain Health. Isaacson was not involved in the study.

研究的结果十分令人关注，但是还不足以引起恐慌，Richard Isaacson，佛罗里达大西洋大学脑部健康中心的神经学家和主任表示。Isaacson并未参与该项研究。

Isaacson said the findings were noticeable for clinicians, but he added that the overall impact on individuals was difficult to determine and could be small. "It's really hard to know the long-term clinical impact and quality of life impact in a situation like this," he said.

Isaacson表示，研究结果值得临床医师关注。但他补充表示，新冠肺炎对个体的总体影响很难测定而且可能是非常微小。“在类似的情况下，我们很难真正了解其长期的临床影响以及对生活质量的影响”，他表示。

"The brain may be affected by other mechanisms such as immune, inflammatory, vascular or psychological/behavioral change but not direct infection," said Dr. Alan Carson, a professor of neuropsychiatry at the Center for Clinical Brain Sciences at the University of Edinburgh, who was not involved in the study.

爱丁堡大学临床大脑科学中心神经精神病学教授Alan Carson表示：“大脑可能会受到其他机制的影响，比如免疫、炎症、血管或心理/行为的变化，而非直接的感染。”Alan本人并未参与该项研究。

"What this study almost certainly shows is the impact, in terms of neural changes," he said. "But I don't think it helps us understand the mechanisms underpinning cognitive change after Covid infection."

他表示：“这项研究几乎明确地表明了新冠肺炎在神经变化方面的影响。但是在我看来，这项研究并没有帮助我们了解到感染新冠肺炎后导致认知发生变化的机制。”

来源：美国电视新闻网

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