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

（单词翻译）

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.