Edgard Garrido / Reuters
An Alzheimer's researcher of the Research Center and Advanced Studies shows a piece of brain before cutting at Insituto Politecnico in Mexico City April 20, 2012.
Phillip Toledano for TIME, Prop Stylist Rae Scarton
Andrew Holbrooke / Corbis
A nurse's aide helps an Alzheimer's patient at a care facility
Philippe Huguen / AFP / Getty
An Alzheimer's patient at a hospital in France.
FRED DUFOUR / AFP / GETTY IMAGES
A music-therapy session for Alzheimer's patients is held at a geriatric hospital near Lyon, France, in February 2008
STEVE LISS FOR TIME
Ann Persinger helps her mother Vivian, who suffers from Alzheimer's
URBANO DELVALLE FOR TIME
LIFE LINKS: An 800 number brings lost Alzheimer's patients back