This study will investigate genetic changes to a type of immune cell known as T cells. T cells regulate our immune system’s memory. Here, we will study how changes to T cells’ genetic structure might influence Alzheimer’s disease by promoting brain inflammation. We will study T cells from the blood and the brain’s cerebrospinal fluid to better understand their genetic differences using an approach known as epigenetics. Epigenetic changes are important to understand because they influence the types of genes our cells produce, and are thought to be influenced by environmental factors.