The leading cause of death among people with Alzheimer’s disease is pneumonia. One of the ways dementia disorders affect the body is that they destroy the ability to swallow safely. Food and liquids can slip down the windpipe rather than the esophagus. When that happens, an infection can develop in the lungs, leading to aspiration pneumonia.

Another study that examined autopsy reports of people with dementia found the main causes of death were pneumonia, cardiovascular diseases, pulmonary embolism, cachexia, and dehydration. Other factors that impact the death rate in Alzheimer's disease include advanced age, increased falls, and delirium.