PTGS2 and Alzheimer disease: Additionally, a number of studies have found increased COX-2 immunoreactivity in the brains of Alzheimer's disease (AD) patients, and that this increased COX-2 immunoreactivity is related to the number of amyloid plaques in the brain (Hoozemans et al., 2008, Kadoyama et al., 2002, Hwang et al., 2002).