This document discusses epidemiology and risk factors for aging and dementia in individuals with Down syndrome. It notes that those with Down syndrome experience accelerated aging processes and highlights factors associated with this, such as shorter telomere length and earlier menopause. It also discusses how having an extra copy of chromosome 21, and therefore an extra copy of the APP gene, increases risk of Alzheimer's disease in Down syndrome due to overproduction of amyloid beta. The cumulative incidence of dementia in Down syndrome is shown to be highly age-dependent, with risk increasing substantially after age 50. Certain genetic and medical factors can further influence this risk.