Several models have been developed that describe the progressive worsening of symptoms and the loss of function of Alzheimer's disease. One of the most commonly used is the Global Deterioration Scale (GDS) developed by B Reisberg and colleagues. It is used to answer some of the most frequently asked questions from caregivers and patients with Alzheimer's disease; " How long have we got?" and "What stage of the disease is he/she in?".

The GDS gives, in seven stages, a guide to understanding abilities and changes that will occur to a person with Alzheimer's disease. I thought it would be helpful to give you some brief information about those stages. It can help you understand what it is like to experience Alzheimer's disease, what activities they are capable of and how much help they may need.

Stage 1

This is defined as a normal adult with no decline in function or memory.

Stage 2

This is described as very mild decline. Memory difficulties are of a normal older adult, a feature of natural aging, rather than a disease process. Memory lapses, is a good way to describe things such as forgetting people's names and where they have put objects.

Stage 3 Alzheimer's Disease

Is mild decline, also described as early Alzheimer's disease.

Signs may include:

Getting lost traveling to an unfamiliar location

Work colleagues begin to notice low performance because of organizational and planning problems.

People close to the affected person notice name and word-finding deficits. They are unable to remember the name of a recently introduced person, their  ability to recall information from a book becomes difficult.

They may misplace or lose a valuable object.

Concentration may begin to become affected.

Stage 4 Alzheimer's Disease

This is described as mild Alzheimer's disease with moderate cognitive decline (e.g. problems with thinking, memory, planning, problem solving). There are clear signs of Alzheimer's disease in a clinical interview.

People at stage 4 begin to require assistance in complicated tasks such as planning or handling finances. Remembering the time sequence and events of their lives becomes difficult. They forget recent history and have trouble concentrating. They may be subdued and anxious especially in challenging situations.

Stage 5 Alzheimer's Disease

Stage five is described as moderate, mid-stage Alzheimer's disease. At this stage people will begin to require some help with activities of daily living. There is some disorientation in time and they may be confused about where they are. At interview they may be unable to recall important information about themselves, their family and others.

Stage 6 Alzheimer's Disease

This is described as moderately severe or mid stage Alzheimer's disease.

Memory problems worsen and people at this stage of the disease start to forget significant amounts of information about themselves, their surroundings. They can wander and may become lost.