Image of a brain

Is Dementia Fatal?

This article has been medically reviewed and edited by Dr. Martin Duggan in 2021

This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified health provider with any questions you may have regarding a medical condition.

Though most people think of dementia as a specific disease, it is just a general term for a group of symptoms that tend to occur together. These symptoms include memory loss, difficulty with language, impaired problem-solving abilities, and other thinking difficulties. Many different conditions can cause dementia to develop. The answer to whether a loved one’s dementia will be fatal or not depends on the cause.

Reversible Causes of Dementia

Some cases of dementia are reversible. Reversible causes include:

  • Vitamin B12 Deficiency
  • Hypothyroidism
  • Normal Pressure Hydrocephalus
  • Infections
  • Benign Tumors

Because these conditions are fixable, newly diagnosed dementia patients will often undergo testing to see if their dementia symptoms have a treatable explanation. It is also worth mentioning that, in elderly patients, depression can take on the appearance of dementia. When this occurs, the sufferer is said to have Pseudodementia. When the depression is treated, the symptoms which create the illusion of dementia improve. You can read more about depression in the elderly here. Only after these reversible conditions are ruled out will doctors look for potentially deadly causes.

Irreversible Causes of Dementia

Unfortunately, most cases of dementia cannot be reversed because the underlying cause is not curable. Here are the most common irreversible causes of dementia listed in order of prevalence:

  • Alzheimer’s Disease
  • Vascular Dementia
  • Fronto-Temporal Dementia
  • Lewey-Body Dementia
  • Dementia associated with Parkinson’s Disease

These conditions are fatal and progressive. Doctors and scientists have yet to find a way to reverse the course of disease for these illnesses. Many of us know that someone with Alzheimer’s disease – for example – needs daily help to solve problems or remember things. But we might be surprised to learn an otherwise healthy person can die from Alzheimer’s disease. The same is true for each of the irreversible causes listed above.

According to the U.S. Center for Disease Control and Prevention, Alzheimer’s disease – the most common form of dementia – is the 5th leading cause of death in American adults who are 65 or older. Once the doctor has ruled out treatable causes and settled on one of the above diagnoses, we have to accept that our loved one is in the grip of a fatal illness. For the remainder of this article, we will use the term dementia to refer to those diseases which cause irreversible and fatal cases of dementia.

How does dementia cause death? 

Our brains are charged with several functions, much more than just remembering, understanding or thinking. The brain is responsible for overseeing our breathing, circulation, movement, and circulation. What may begin with memory and communication dysfunction can become something much more severe as time goes on.

Progressively worsening dementia slowly robs us of our ability to walk naturally. Then it robs us of our ability to stand naturally. Day by day, things that we take for granted, like “how to swallow without choking on our food,” become more and more difficult for us. As time marches on, dementia will leave us unable to sit upright, unable to eat food, unable to drink water, and then finally unable to breathe without choking.

How far along is my loved one?

Every person is unique, and each type of dementia follows a different course. Someone with vascular dementia will typically suffer from moments of rapid decline (usually after strokes or ministrokes) interspersed with moments of stability. In contrast, a person with Alzheimer’s dementia will typically suffer a more steady and consistent decline. Other causes of dementia usually have different courses entirely. Even still, not every person with Alzheimer’s dementia will decline at the same rate.

The most common type of dementia is Alzheimer’s Disease. Several tools have been designed to help caregivers plan. Most of these tools aid in planning work by grouping symptoms that typically occur together and assigning these symptoms a stage number. People exhibiting symptoms that occur early in the disease are said to be in the “early stages” of disease. People exhibiting symptoms that only happen when death is near are said to be in the “late stages” of dementia.

One of the most popular frameworks to understand how dementia progresses comes from the Alzheimer’s Association (A.A.) and is described here. The A.A. website describes three significant stages of dementia for people with Alzheimer’s Disease. These stages are not perfect, and some patients may qualify for more than one stage. The years listed are approximations only. Remember, this is just a potentially helpful resource. It can never take the place of a consultation with a doctor. Here are the stages as laid out by the A.A. website.

  • Early Stage Alzheimer’s: 1-3 years. This person may still live independently but has likely noticed difficulty finding the right word or remembering where they placed an object. Someone in the early stage might struggle with duties at work, especially planning or organization tasks.
  • Middle Stage Alzheimer’s: 2-7 years. This person almost always requires help performing daily activities. Someone in the middle stage has begun to forget events from their life. The person tends to wander and become lost. They often forget their location or the time of year. They may have difficulty controlling their bowel or bladder. Their diet may require some modification to prevent trouble with chewing or swallowing.
  • Late Stage Alzheimer’s: 6 months – 1 year. This person requires round-the-clock assistance. Someone in this stage loses their ability to walk without aid. They will often need help standing, and then eventually, they will be unable to sit upright without assistance. Their ability to speak or express themselves may decline, making it difficult for them to communicate when they have pain. As death approaches, they may frequently choke while drinking or even when trying to swallow their saliva.

With the help of a doctor, we can use these stages to interpret how far our loved one has progressed in their illness. This knowledge can help us plan for what comes next.

What is the life expectancy of someone with dementia?

When we talk about life expectancy, we have to remember that these numbers are averages. Some people will live much longer than average; others will not. The average person lives about eight years after the diagnosis of Alzheimer’s Disease. When other forms of dementia are included, the average life expectancy becomes a little more challenging to say with certainty. The Mayo Clinic gives an estimated life expectancy of somewhere between 2-11 years for irreversible dementia.


Dementia is relentless, and caring for someone with dementia is incredibly taxing. Dementia care often robs us of any sense of certainty. When we have some idea what to expect and how long we have together, we can cherish the moments together. Sometimes all we need is a little clarity on the road ahead to help us focus on what is truly important.


  1. What Is Dementia? Alzheimer’s Association,
  2. What Is Dementia? Symptoms, Types, and Diagnosis, National Institute of Aging,
  3. Stages of Dementia,

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