Many years passed before doctors discovered that persons with the disorder were not mentally slow or disabled.

许多年之后医生才发现，患此症者的智力并不低下，身体也并不残缺。

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They were believed to make people mentally slow.

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Studies have shown that staying mentally and physically active can slow or even prevent Alzheimer's-related dementia.

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Much of her recent work at Stanford University has debunked stereotypes about how older people are uniformly slow, cranky and mentally impaired.

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