Doctors may eventually be able to diagnose "preclinical" Alzheimer's in patients who have abnormal brain scans but who aren't yet showing behavioral symptoms of the disease. iStockphoto hide caption

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Actor and Alzheimer's advocate Seth Rogen testifies before the Senate Committee on Appropriations about the disease's damaging effects on patients and their loved ones. Mandel Ngan/AFP/Getty Images hide caption

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Vitamin E has been associated with increased risk of death in some studies, but it may also delay cognitive decline in Alzheimer's disease. iStockphoto hide caption

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Researchers have only recently been able to use brain scans to detect Alzheimer's risk factors in living people. iStockphoto hide caption

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An Indian schoolgirl dressed as Telugu Talli poses for the camera during a celebration in Hyderabad, home to a study that seems to show the onset of dementia is delayed for people who speak more than one language. Noah Seelam/AFP/Getty Images hide caption

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University of Florida researcher Jennifer Stamps administers the peanut butter sniff test to a volunteer. Jesse S. Jones/University of Florida hide caption

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Hospital intensive care units save lives, but people there often suffer from delirium. Cal EMA / Flickr hide caption

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Stressed out? Who isn't? Stress can cause physical changes in the brain that may be linked to Alzheimer's. iStockphoto.com hide caption

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Anne Jones, 62, and Robin Jones, 73, at their home in Menlo Park, Calif. He took a test that revealed proteins typical of Alzheimer's disease. Ramin Rahimian for NPR hide caption

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Depression is common among old people, affecting up to 25 percent. iStockphoto.com hide caption

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Scientists hope a new genetically modified rat will help them find Alzheimer's drugs that work on humans. Ryumin Alexander/ITAR-TASS/Landov hide caption

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Social worker Nuria Casulleres shows a portrait of Audrey Hepburn to elderly men during a memory activity at the Cuidem La Memoria elderly home in Barcelona, Spain, last August. The home specializes in Alzheimer's patients. David Ramos/Getty Images hide caption

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Scientists have found that bilingual seniors are better at skills that can fade with age than their monolingual peers. iStockphoto.com hide caption

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Brain scans using Amyvid dye to highlight beta-amyloid plaques in the brain. Clockwise from top left: a cognitively normal subject; an amyloid-positive patient with Alzheimer's disease; a patient with mild cognitive impairment who progressed to dementia during a study; and a patient with mild cognitive impairment. Slide courtesy of the journal Neurology hide caption

itoggle caption Slide courtesy of the journal Neurology