The lifestyle risk factors for Alzheimer's disease look a lot like those for diabetes - in other words get fat and don't exercise and your brain will suffer. Some researchers propose that Alzheimer's is a form of diabetes: "Insulin is the hormone that allows cells, including some brain cells, to take up energy in the form of glucose. Proper insulin function in the brain appears necessary to the formation and maintenance of memories. And, crucially, a lack of insulin or insulin resistance is connected both to amyloid protein regulation and to the modification of tau proteins, which can cause tangles. In other words, insulin seems to hold up a conceptual umbrella under which the amyloid and the tangle camps might finally meet. ... Type 2 diabetes is also a risk factor for Alzheimer's and cognitive decline. In 2005, researchers at Brown showed that by knocking out insulin production and causing brain insulin resistance in rats, they could create a model of Alzheimer's, complete with plaques and abnormal accumulations of tau. ... Scientists have also described links between abnormal insulin and other hallmarks of Alzheimer's, such as oxidative damage and inflammation."

Link: http://www.slate.com/id/2213755/