Alzheimer's disease has four stages: preclinical, early (sometimes known as mild), middle (moderate), and late (commonly known as severe) (severe). People with Alzheimer's disease appear to be symptom-free during the preclinical period, although harmful changes in the brain are occurring. The indicators listed above may be displayed by someone who is in the early stages of Alzheimer's disease.

Memory loss and confusion worsen as Alzheimer's disease develops to the middle stage, and people may have difficulty recognizing relatives and friends. People with Alzheimer's disease lose their ability to communicate as the condition progresses. They may sleep more than usual, lose weight, and have difficulty swallowing. They will eventually require total care.