Alzheimer 's disease is a disease with a long and progressive course, leading inevitably to total disability, both mental and physical. It can be divided into three stages - mild, moderate and profound - but the most commonly used is the one introduced by Reisberg, which divides the disease into seven individual stages. Knowing these is useful not only for clinicians, but also for carers of people with Alzheimer's disease, to enable them to better understand their client and allow them to plan individual actions as the disease progresses.