Allyson Schrier, co-founder of Zinnia TV, talks about what happens exactly to the cognitive decline that comes with dementia and Alzheimer’s. These diseases and others like them have four things in common. They all impact two parts of the brain, causing a loss of brain tissue. They are all chronic, progressive and fatal. When they impact two parts of the brain, the skills associated with those two parts are lost. Alzheimer’s affects the left temporal lobe, where language is stored, and the hippocampus, which is responsible for memory and wayfinding. That’s why those with Alzheimer’s eventually have trouble speaking, finding their way around, and remembering.