Big Think | What Is Alzheimer's Disease?

Left, a healthy brain; right, a brain with advanced Alzheimer's Disease

Beta amyloid protein

Alzheimer’s disease is an incurable—and ultimately deadly form of dementia that causes loss of memory and other cognitive abilities. A degenerative disorder, the disease unravels the fundamental functions of the brain over time, taking with it many components of personality and identity. An estimated 5.3 million people in the U.S. currently have Alzheimer's, and each year the disease ranks as the nation's sixth or seventh leading cause of death. In 2007 alone, over 74,000 Americans died from Alzheimer's.

While much remains unknown about the disease, advances in research over the past decade have shed new light on its mechanisms, and on how dementia affects the aging brain. In Big Think's "Breakthroughs: Alzheimer's Disease" panel, Dr. Samuel Gandy, associate director of the Mount Sinai Alzheimer's Disease Research Center, said that the disease is first a biochemical pathology—a deficit among brain transmitters between nerve cells—but that there also does seem to be a correlation with beta amyloid proteins that can function normally among neurons for over 50 years, then "clump and accumulate and build up and kill cells of the brain."

"Synaptic function is the key to everything," responded Dr. Ottavio Arancio, a professor at the Taub Institute for Research in Alzheimer's Disease and the Aging Brain at Columbia University. Dementia and Alzheimer's disease, he says, weaken synapses among the brain’s 100 billion nerve cells and 100 trillion neural points connection points. This weakening, he says, "is the key to understand the mystery of this disease."

More at BigThink