One portion of the Alzheimer's research field is focused on immune therapies - training the immune system to attack and break down amyloid beta plagues characteristic of Alzheimer's disease. It is important to note that the buildup of signs of Alzheimer's, such as amyloid beta, occurs in most people to a lesser degree, whether or not they go on to develop the condition, and that the level of this sort of damage is associated with level of mental decline with aging. Here researchers show that this may all have something to do with how effective the immune system is in clearing out unwanted junk from the brain: "Recent work in mice suggested that the immune system is involved in removing beta-amyloid, the main Alzheimer's-causing substance in the brain. Researchers have now shown for the first time that this may apply in humans. [Researchers] screened the expression levels of thousands of genes in blood samples from nearly 700 people. The telltale marker of immune system activity against beta-amyloid, a gene called CCR2, emerged as the top marker associated with memory in people. The team used a common clinical measure called the Mini Mental State Examination to measure memory and other cognitive functions. The previous work in mice showed that augmenting the CCR2-activated part of the immune system in the blood stream resulted in improved memory and functioning in mice susceptible to Alzheimer's disease. ... This is a very exciting result. It may be that CCR2-associated immunity could be strengthened in humans to slow Alzheimer's disease, but much more work will be needed to ensure that this approach is safe and effective."