Many Alzheimer's disease patients also commonly develop vascular diseases and diabetes. Whether this coincidence is bad luck or due to shared disease processes is intensely debated. Research teams have investigated the role that low-density lipoprotein (LDL), the bad cholesterol that causes atherosclerosis, cardiovascular disease and stroke, may play in the development of Alzheimer's with mixed results. However, the USF group focused on the amyloid protein's potential effects on LDL metabolism. The receptor needed to detect and use LDL is among the proteins transported by the microtubules.

As previously reported by their colleagues in the MBC paper, the second USF team found that the amyloid protein inflicts damage to the microtubule network. As a consequence, the receptor needed to pull LDL circulating throughout the bloodstream into the body's cells has trouble getting to the cell surface to retrieve this bad cholesterol. This interference with LDL metabolism may allow bad cholesterol to build up in into plaques that choke off blood supply to the brain and heart in people with Alzheimer's, Dr. Potter said.

Similarly, other key proteins - including insulin receptors and receptors for brain signaling molecules -- are also likely locked inside cells when the transport system is damaged by amyloid or other factors. "The insulin receptors are needed to get blood sugar inside the cell where it can be used for energy. The nerve cell signaling receptors help promote memory and learning," Dr. Potter said. "So, if these receptors are unable to function properly, it may lead to diabetes and problems with learning and memory."

"We're beginning to understand how conditions like cardiovascular disease and diabetes may manifest some of the same underlying disease processes as Alzheimer's disease," he said, "rather than being independent diseases that just happen to develop in the same patient."

Source: University of South Florida Health