Dementia Life Expectancy

How long someone lives with dementia varies a great deal from person to person. The type of dementia matters, but so do the person's age, their other health conditions and how far the dementia had progressed by the time it was diagnosed. The figures below are averages. Many people live longer than them, and some live much longer.

Average life expectancy by type of dementia

These are average figures for the number of years a person may live after diagnosis, as published by the Alzheimer's Society:

A few people with Alzheimer's disease live for 15 or even 20 years after diagnosis.

Life expectancy with vascular dementia is shorter mainly because people with it are more likely to die from a stroke or heart attack than from the dementia itself. In dementia with Lewy bodies, physical symptoms such as stiffness and unsteadiness raise the risk of falls and infections. When frontotemporal dementia occurs together with motor neurone disease, the condition tends to progress much more quickly. For more on FTD, see the 7 stages of frontotemporal dementia and how FTD differs from Alzheimer's.

What affects how long a person lives with dementia?

• How advanced the dementia was at diagnosis. Someone diagnosed early, when symptoms are mild, will usually live longer after diagnosis than someone diagnosed later.
• Other health conditions. Diabetes, heart problems, cancer and other serious conditions, and how long the person has had them, all affect life expectancy.
• Age when symptoms started. People over 65 are more likely to have other conditions that shorten life. Someone diagnosed in their 90s is more likely to die from other health problems before reaching the later stages of dementia than someone diagnosed in their 70s.

How dementia shortens life

Dementia gets worse over time. You can read about how it typically progresses in the 7 stages of dementia explained.

In the later stage, a person is often very frail, has a weakened immune system, spends much of the day in bed and may find it hard to swallow. Together these make other medical problems much more likely, and these are what most often lead to death. The most common are:

• Infections, especially pneumonia. Swallowing difficulties can let food or drink get into the lungs.
• Blood clots, in the brain or lungs. Reduced mobility increases the risk.

A person with dementia can also die at any stage from an unrelated illness, such as cancer or lung disease. For what to expect and how to help in the final months, see end stage dementia.

Frequently asked questions

Is dementia a terminal illness?

Dementia is a life-limiting condition. There is currently no cure, and the diseases that cause it get worse over time. But many people live for years after diagnosis, and how long varies widely.

Does early diagnosis mean a longer life?

Being diagnosed earlier makes the time after diagnosis look longer, because it starts the count sooner. It doesn't by itself slow the disease, but it gives the person time to plan, get support and access treatments that can help with symptoms. See the importance of early diagnosis.

Can you predict how long someone has left?

Not precisely. Doctors can describe what is typical for the type and stage of dementia, but individual cases vary too much for an exact estimate. Signs that someone may be in their last months include being unable to walk, eat or speak, frequent infections and increasing sleep.