Q: What are the risk factors that cause some people to get CAA?

A: To a considerable extent, this remains a mystery.

No food or environmental exposure has been shown to cause CAA; neither have various other conditions that affect blood vessels such as high blood pressure or diabetes. The only definite risks for CAA are advancing age (it's occasionally diagnosed in people in their 50's or 60's but is much more common in people in their 70's and 80's), the accompanying presence of AD, and some types of genes. In particular, a gene called apolipoprotein E appears to be a risk factor for CAA, but is not useful for predicting who will or won't get the disease. Most people with this gene do not develop CAA and many with the disease do not have the risky gene.