Individuals with Down syndrome are at significantly greater risk of developing Alzheimer’s disease as they age, often at an earlier age than their counterparts without Down syndrome. According to the National Down Syndrome Society, approximately 30 percent of people in their 50s who have Down syndrome also have Alzheimer’s; by the time they reach their 60s, the prevalence nears 50 percent. The exact reason for this comorbidity is not fully understood; however, Down syndrome is known to decrease life span and increase the risk of other diseases, such as leukemia or epilepsy. In addition, chromosome 21—of which individuals with Down syndrome have an extra copy—is responsible for the amyloid precursor protein (APP). Having an extra copy is thought to increase production of beta-amyloid, a key component of the brain plaques that are thought to be responsible for Alzheimer’s disease.