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A study involving mice has led to a new theory about the cause of Alzheimer’s disease. Researchers compared autopsy brain tissue from mice of various ages, a human baby and an older person. They focused on an immune system protein called C1q, which builds up even in healthy brains as they age. Levels of C1q were 300 times as high in older brains as in younger ones. C1q built up mostly at synapses, the junctions between nerve cells. This possibly could get in the way of signals between cells that allow the brain to function. C1q plays a role in the brain in childhood, when some synapses are “pruned” away to allow others to develop. In the immune system, C1q clings to foreign bodies, such as bacteria, or to pieces of dying cells. This sets off a chain reaction. Other proteins build up on top of the C1q. Then other immune system cells gulp down the object.

Researchers say they have found a way to predict the risk of dementia for older adults with diabetes. The risk score was developed using information about nearly 30,000 people. All of them were age 60 or older and had type 2 diabetes. During a 10-year period, about 17% developed dementia. Researchers found that age, education level and six health problems were the strongest predictors of dementia. The problems included diabetic foot or eye disease and events of dangerously high or low blood sugar. These are all directly caused by diabetes. Most of the other conditions also are more common among diabetics. They included heart disease, depression, and stroke or related problems with circulation in the brain. Each risk factor was assigned a point total. Then researchers created a scoring system.