When combined with results of other neurological tests, and in the context of a thorough medical history, atrophy of the brain (shown here in an MRI scan) sometimes indicates Alzheimer's. Simon Fraser/Science Source hide caption

itoggle caption Simon Fraser/Science Source

Laury Sacks and her husband, Eric. The actress and writer developed frontotemporal dementia in her late 40s and died in 2008 at age 52. Courtesy of Eric Sacks hide caption

itoggle caption Courtesy of Eric Sacks

Greg and Mary Catherine O'Brien with their kids, at daughter Colleen's marriage to Matt Everett last August. Greg has early-onset Alzheimer's. From left, Brendan O'Brien, Greg O'Brien, Colleen O'Brien, Matt Everett, Mary Catherine O'Brien, and Conor O'Brien. Courtesy of Greg O'Brien hide caption

itoggle caption Courtesy of Greg O'Brien

Caregivers who are trained in responding to anxiety or aggression in people with dementia can effectively reduce those symptoms, studies find. iStockphoto hide caption

itoggle caption iStockphoto

About 1 in 3 patients with dementia who live in nursing homes are being sedated with antipsychotic drugs, the GAO says. Outside nursing homes, about 1 in 7 dementia patients are getting the risky drugs. Wladimir Bulgar/iStockphoto hide caption

itoggle caption Wladimir Bulgar/iStockphoto

Greg O'Brien gathers his thoughts before a run in 2013. "Running is essential," he says. Michael Strong/Living With Alzheimers hide caption

itoggle caption Michael Strong/Living With Alzheimers
Maria Fabrizio for NPR

Greg O'Brien (left), with Colleen, Mary Catherine, Conor, and Brendan O'Brien, has been grappling with Alzheimer's disease for the last five years. Courtesy Greg O'Brien hide caption

itoggle caption Courtesy Greg O'Brien

When he was 59 years old, Greg O'Brien was diagnosed with early-onset Alzheimer's disease. Five years later, he is speaking publicly about his experience, even as his symptoms worsen. Courtesy of Greg O'Brien hide caption

itoggle caption Courtesy of Greg O'Brien

Leaks in a barrier between blood vessels and brain cells could contribute to the development of Alzheimer's. VEM/Science Source hide caption

itoggle caption VEM/Science Source

Marian Grunwald (from left), Earl Elfstrom and Verna Matheson bounced a balloon back and forth with nursing assistant Rick Pavlisich on Dec. 13, 2013, at an Ecumen nursing home in Chisago City, Minn. Glen Stubbe/Star Tribune, Minneapolis St. Paul hide caption

itoggle caption Glen Stubbe/Star Tribune, Minneapolis St. Paul

Antipsychotic drugs aren't necessary in the vast majority of dementia cases, gerontologists say. The pills can be stupefying and greatly raise the risk of falls — and hip fracture. iStockphoto hide caption

itoggle caption iStockphoto

A tangle of protein (green) in this scanning electron micrograph of a brain cell of an Alzheimer's patient lies within the cytoplasm (blue) of the cell. The tangle consists of clumps of a toxic form of tau. Thomas J. Deerinck/Corbis hide caption

itoggle caption Thomas J. Deerinck/Corbis

Loretta Jackson gently stretches the hands of her sister, Shirlene English, to aid physical rehabilitation after Shirlene's brain aneurysm and stroke. Andrew Nixon/Capital Public Radio hide caption

itoggle caption Andrew Nixon/Capital Public Radio

Rick and Marianne wash dishes together. She no longer remembers that he is her husband. Andrew Nixon/Capital Public Radio hide caption

itoggle caption Andrew Nixon/Capital Public Radio