Alzheimer’s disease usually comes first as the underlying brain change, and dementia symptoms appear as a result. Dementia is not a disease itself but a description of how the brain is not working well. Alzheimer’s is one cause that leads to dementia. The brain damage from Alzheimer’s builds up over years before symptoms show. When memory loss and confusion start affecting daily life, that is called dementia. So the disease process starts first, but the symptoms are what people notice and name as dementia.