Alzheimer's disease is usually of a comparatively gradual onset although it can seem that it happens quickly. By that I mean that changes in someone's memory and personality are often attributed to something else or overlooked until it becomes very obvious someone is suffering from Alzheimer's. Symptoms can seem like depression, the menopause, the result of psychological or family trauma.
Here are two links to information you may find helpful
Symptoms of Alzheimer's Disease
Ten Warning Signs of Alzheimer's Disease
No it does not. I know for I have it.