The five stages of dementia caused by Alzheimer's disease vary in length, depending on the individual, according to Mayo Clinic. Dementia is a general medical term that describes symptoms that impair a person's social, intellectual and daily functioning. Alzheimer’s disease is a progressive brain disorder that causes dementia. Most people live eight to 10 years after diagnosis.
The five stages of Alzheimer's are preclinical, mild cognitive impairment, mild dementia, moderate dementia and severe dementia, states Mayo Clinic. People in the preclinical stage of the disease do not exhibit any symptoms, but imaging technology can detect amyloid beta deposits on the brain. People with mild cognitive impairment have a few memory lapses but not enough to interfere with daily functioning. Doctors most frequently diagnose people with Alzheimer's when they reach the mild dementia stage because they have significant problems with memory that others notice. They may need help with daily care when they reach the moderate dementia stage.
People lose physical ability and cognition in the severe stage of Alzheimer's disease, according to the Alzheimer's Association. They may lose the ability to communicate with words or express their level of pain. These patients require full time care and eventually lose the ability to swallow. They become vulnerable to infections, especially pneumonia.