THE REASONS: Researchers say the conclusion makes sense. Working tends to keep people physically active, socially connected and mentally challenged — all things known to help prevent mental decline.
ABOUT DEMENTIA: About 35 million people worldwide have dementia, and Alzheimer's is the most common type. In the U.S., about 5 million have Alzheimer's — 1 in 9 people aged 65 and over.
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