Is the seventh Alzheimer's disease stage the deadliest?

Stage seven of Alzheimer's disease is the last and deadliest stage of the disease, according to HelpGuide. In this stage, the patient suffers from severe dementia and cannot take care of himself.

Some medical professionals say this stage of the disease lasts from one to 2.5 years, while others claim it can last from a few weeks to a few years, depending on the care the patient receives, explains HelpGuide and the Alzheimer's Association. Death results because the functions of the brain that make life possible are destroyed, says HelpGuide. The patient becomes bedridden and is more susceptible to life-threatening diseases such as pneumonia and other dangerous infections.