Humans Alone See Brains Shrink With Age, Researchers Find

It doesn't happen to chimps. [Link]

No matter where the researchers looked, they found the human brains lost significant volume over time, while the chimpanzees didn't. "We found no age-related changes in chimpanzees," said Dr. Sherwood.

Until recently, the study of brain differences between humans and other species was a scholarly pursuit with little impact outside the field of anthropology. But the rapid growth of the aging population world-wide is turning evolutionary biology into a pressing topic of public health. By 2030, about one in every five people in the U.S. will be over 65 years old, more than twice the number of elderly a decade ago, according to the U.S. Administration on Aging.

Unlike chimpanzees and other primates, elderly humans are prey to a host of neurodegenerative diseases, such as Alzheimer's disease. Researchers hope that by understanding the basic biology of the brain, they can devise ways to treat or postpone the harmful mental effects of age.