News Bytes of the Week--On the Other Hand: The Scent of a Lemur [News]
Scientists solve mystery of patients with Alzheimer's plaques but no diseaseThe only way physicians can confirm that someone suffered from Alzheimer's disease is if an autopsy reveals a protein called amyloid beta (Aß) accumulated in a postmortem brain. But doctors occasionally find these plaques in the brains of deceased people who showed no Alzheimer's symptoms. Now Harvard Medical School researchers say they know why: Aß comes in several varieties, but apparently only one of them causes the memory-ravaging effects of Alzheimer's. The team writes in the journal Nature Medicine that they injected four varieties of the protein into the brains of rats to determine which versions cause Alzheimer's-like symptoms. Much to their surprise, only one did: a two-molecule form of the protein that is dissolvable in water. This type of Aß not only curtailed memory, but also destroyed about half of the cells in the rats' brains. By identifying the disease-causing variant of the protein, researchers can now refocus their efforts on a more specific target to fight Alzheimer's. [More]