How Dementia Kills

Medically Reviewed By William C. Lloyd III, MD, FACS
Senior woman in hospital bed

Dementia is a progressive decline in brain function. It’s often thought of as “memory loss,” but dementia affects overall brain functioning, including the brain cells that control movement and swallowing.

Alzheimer’s disease, the most common form of dementia, is the 6th leading cause of death for adults in the United States, according to the Centers for Disease Control and Prevention (CDC). For adults aged 65 years or older, it is the 5th leading cause of death.

Learning more about the final dementia stages before death will help you understand how dementia contributes as a cause of death.

Dementia Stages Before Death

At diagnosis, most people are in either the early- or mid-stage of dementia. People with early stage dementia may be a bit forgetful, but they can still function in everyday life. They live independently; many still work.

In mid-stage dementia, memory and thinking problems become more obvious. Other people notice that the affected individual is no longer operating at peak capacity. Symptoms become more pronounced as this stage progresses. Affected individuals may forget that they just ate. They may wander or get lost while walking a once-familiar route. Their sleep habits may change. It’s not uncommon for people with mid-stage dementia to sleep during the day and be up most of the night.

Eventually, dementia progresses to the point where individuals can no longer control bowel and bladder function. This loss of control is directly related to the damage occurring in the brain; the cells that normally control these functions die. And as more and more cells die, symptoms worsen. In late-stage dementia, individuals may lose the ability to walk and speak. Self-feeding becomes impossible, and as the disease progresses, many people have a hard time swallowing food or drink.

Dementia As a Cause of Death

When someone dies with dementia, death typically is the result of another underlying condition or illness, not from the dementia itself.

UTI complications

People with late-stage dementia are extremely vulnerable to infections. A person who cannot make it to the bathroom is prone to urinary tract infections (UTIs). For most younger people, UTIs aren’t particularly problematic; the infection is more uncomfortable than anything else. But it can be extremely hard to detect a UTI in an adult with dementia, particularly if that person has lost the ability to communicate. Sometimes, the infection spreads beyond the urinary system and causes a full body infection and sepsis. Sepsis can cause the organs of the body to shut down. Sepsis can be fatal.

Aspiration pneumonia

Swallowing difficulties that are common in late-stage dementia increase susceptibility to aspiration pneumonia, or pneumonia caused by the accidental inhalation of food or fluids into the lungs. Pneumonia can also progress and cause death. Most people who die from Alzheimer’s disease die because of aspiration pneumonia.

Bed sore complications

Infected bed sores can also cause death. As those with dementia lose the ability to move, they are often confined to bed or a wheelchair. Unable to move independently, they are prone to skin breakdown and pressure ulcers. If these ulcers become infected, they can cause sepsis and death.

Excellent nursing and medical care can prevent and manage many of these issues. Early diagnosis of UTIs and pneumonia can prevent sepsis. Careful feeding procedures can prevent aspiration pneumonia, and regular repositioning and skin care can prevent bed sores. However, as dementia progresses, it becomes increasingly difficult to prevent all infections and, in some cases, treating the infection is more stress on the body than simply allowing the infection to progress, while administering medication and care as needed to keep the patient comfortable.

A person with late-stage dementia who avoids infection may ultimately die of dehydration. However, it’s important to note that dehydration at this stage is not due to neglect. A loss of interest in food and water is totally normal as death approaches. The individual does not feel hungry or thirsty; the body is shutting down and they may be unresponsive. According to a 2007 study published in The International Journal of Geriatric Psychiatry, dehydration and general deterioration is the most common cause of death for dementia patients who live to the final stage.

Other Causes of Dementia Death

Many people with dementia have other coexisting medical conditions, such as diabetes, heart disease, or kidney disease. Some people will die because of one of these underlying diseases, rather than dying due to dementia’s effects on the brain.

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  8. Koopmans R, van der Sterren K, van der Steen J. The ‘natural’ endpoint of dementia: death from cachexia or dehydration following palliative care? Int J Geriatr Psychiatry. 2007;22(4): 350-355. doi: 10.1002/gps.1680. Retrieved from

Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2020 Jun 29
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