Alzheimer's disease is the most common cause of dementia. Its effects and rate of progression are different in different people. The five basic stages of most types of dementia are based on an individual's abilities in the areas of memory, communication and self-care. These stages are:

• Mild cognitive impairment. The person has some memory problems but can continue to live independently.
• Mild dementia. The person experiences impaired memory and thinking skills. He or she may no longer be able to live completely independently and requires assistance with finances, grooming and dressing, and meal planning and cooking. The individual may also become confused when in public.
• Moderate dementia. The person has severe memory impairment and difficulty in communicating. He or she can't live alone and needs help with almost every basic activity. The person can go out in public only with assistance.
• Severe dementia. The person experiences severe problems with communication, frequent incontinence and requires constant care. He or she needs hands-on assistance with dressing and eating and is too impaired to go out in public alone.
• Profound dementia. At this end stage, the person usually is bedridden.