VOA标准英语2012--Silent Strokes Tied to Memory Loss Among Older Adults

Silent Strokes Tied to Memory Loss Among Older Adults

The results of a stroke are painfully evident as this patient struggles to get out of a wheelchair and walk again.
Sudden numbness¹, physical weakness, difficulty speaking and comprehending and loss of balance are all common symptoms.
Stroke patients lucky enough to get to an emergency room in time often get the right treatment, and with physical therapy, manage to recover some of the motor skills they once had.
But scientists have found that a silent stroke, with no obvious symptoms, is often not diagnosed or treated as quickly. The patient continues daily routines, unaware² that something has happened inside the brain. The damage is detected only when the patient undergoes a special MRI imaging procedure.
In this scan of a patient who has had two strokes, the arrows point to dark holes filled with fluid. Neuropsychologist Adam Brickman at the Columbia University School of Medicine, says these dark spots were once healthy cells killed by blood clots³ traveling to the brain.
The hippocampus - the red block in another section of the brain - controls memory, and may also be affected⁴ by a stroke.
“When we see memory changes in aging, we usually attribute those changes to some sort of functional⁵ change or structural⁶ change in the hippocampus. What we found was that in silent strokes, the presence of strokes in the brain was also related to memory functioning,” Brickman said.
Brickman and his colleagues studied a group of more than 650 men and women 65 years and older with no previous signs of dementia or severe memory loss. They underwent MRI brain scans, as well as tests to measure their ability to absorb information. Previous studies had found that changes in the size of the hippocampus and strokes were related to cognitive⁷ functioning, but Brickman says this research confirms a strong link between silent strokes and a decline in memory.
"What our study shows is that they're both independently related to memory functioning, and that's a new observation," Brickman explained.
The MRI scans identified silent strokes in one fourth of the participants who also did not do as well on memory tests. The researchers hope to follow the group in coming year, watching for signs of Alzheimer’s Disease, the most serious form of dementia.

1 numbness   

n.无感觉，麻木，惊呆

参考例句：

• She was fighting off the numbness of frostbite. 她在竭力摆脱冻僵的感觉。 来自《简明英汉词典》
• Sometimes they stay dead, causing' only numbness. 有时，它们没有任何反应，只会造成麻木。 来自时文部分

2 unaware   

a.不知道的，未意识到的

参考例句：

• They were unaware that war was near. 他们不知道战争即将爆发。
• I was unaware of the man's presence. 我没有察觉到那人在场。

3 clots   

n.凝块( clot的名词复数 )；血块；蠢人；傻瓜v.凝固( clot的第三人称单数 )

参考例句：

• When you cut yourself, blood clots and forms a scab. 你割破了，血会凝固、结痂。 来自《简明英汉词典》
• Milk clots when it turns sour. 奶变酸就凝块。 来自《现代英汉综合大词典》

4 affected   

adj.不自然的，假装的

参考例句：

• She showed an affected interest in our subject.她假装对我们的课题感到兴趣。
• His manners are affected.他的态度不自然。

5 functional   

adj.为实用而设计的，具备功能的，起作用的

参考例句：

• The telephone was out of order,but is functional now.电话刚才坏了，但现在可以用了。
• The furniture is not fancy,just functional.这些家具不是摆着好看的，只是为了实用。

6 structural   

adj.构造的，组织的，建筑（用）的

参考例句：

• The storm caused no structural damage.风暴没有造成建筑结构方面的破坏。
• The North American continent is made up of three great structural entities.北美大陆是由三个构造单元组成的。

7 cognitive   

adj.认知的，认识的，有感知的

参考例句：

• As children grow older,their cognitive processes become sharper.孩子们越长越大，他们的认知过程变得更为敏锐。
• The cognitive psychologist is like the tinker who wants to know how a clock works.认知心理学者倒很像一个需要通晓钟表如何运转的钟表修理匠。