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Does dementia shorten life expectancy?

Dementia is a broad term used to describe various symptoms of cognitive decline. The most common types of dementia are Alzheimer’s disease, vascular dementia, dementia with Lewy bodies, and frontotemporal dementia. While dementia is more common in older adults, it is not a normal part of aging. Dementia causes a decline in memory, thinking skills, and ability to perform everyday activities. With dementia, these mental abilities get progressively worse over time.

Dementia does impact life expectancy. On average, a person with dementia lives between 3 to 10 years after diagnosis. However, dementia shortens life expectancy to different degrees depending on the type of dementia and other factors.

How does dementia shorten life expectancy?

There are a few reasons why dementia leads to a shorter life expectancy:

  • Problems with memory and cognition make it difficult for a person to care for themselves properly. Dementia patients may forget to eat, take medications, or maintain proper hygiene which impacts health.
  • Dementia causes significant stress on the body and affects the immune system’s ability to fight other diseases. This makes dementia patients more susceptible to infections and other health issues.
  • Late-stage dementia affects the brain’s ability to control automatic functions like breathing, swallowing, and heartbeat. Eventually, the body “forgets” to perform these vital functions.
  • Many people with dementia are less mobile in later stages, leading to an increased risk of pneumonia, blood clots, and sepsis from bed sores.
  • Individuals with dementia are more likely to experience falls, suffer injuries, and have difficulties recovering due to poor cognition.

In essence, the progressive neurological damage caused by dementia leads to physical decline, secondary health issues, and impairments in the brain’s ability to regulate vital systems. These factors combine to result in an earlier death for many people with dementia.

Does the type of dementia affect life expectancy?

Yes, different types of dementia have varying impacts on life expectancy:

Alzheimer’s disease

Alzheimer’s disease is the most common cause of dementia, accounting for 60-80% of cases. On average, the life expectancy after an Alzheimer’s diagnosis is:

  • Age 65: 4-8 years
  • Age 70: 3-7 years
  • Age 75: 3-5 years
  • Age 80: 2-4 years
  • Age 85+: 1-3 years

However, Alzheimer’s affects people differently. Some may live up to 20 years after diagnosis while others deteriorate much faster. Factors like age of onset and severity impact an individual’s prognosis.

Vascular dementia

Vascular dementia develops when blood flow to the brain is impaired. It accounts for about 10% of dementia cases. Studies show that on average, people with vascular dementia live about 5 years after diagnosis. Maintaining cardiovascular health can help prolong life expectancy.

Lewy body dementia

This type of progressive dementia has an average life expectancy of 5 to 7 years after diagnosis. But Lewy body dementia tends to advance rapidly with a high likelihood of early mortality. It accounts for about 5% of dementia cases.

Frontotemporal dementia

Of all the common dementia types, frontotemporal dementia or FTD has the shortest life expectancy. People with FTD often live only 2 to 3 years after diagnosis. It makes up about 5% of cases and tends to affect younger people in their 50s and 60s.

How do other health conditions affect prognosis?

Dementia patients who have certain other diseases and conditions may have shorter life expectancies. Some key factors that can negatively impact prognosis include:

  • Diabetes – Having diabetes reduces life expectancy by about 1 year.
  • Stroke – Dementia patients who have a stroke are more likely to pass away sooner.
  • Heart disease – Any heart conditions like arrhythmia or heart failure worsen outlook.
  • Infections – Dementia patients are prone to infections which may lead to death.
  • Fall injuries – Falls and resulting medical complications increase mortality risk.
  • Poor nutrition – Many dementia patients suffer from malnutrition and weight loss.
  • Lung disease – Respiratory illness like COPD or pneumonia can be fatal.

The more health issues a dementia patient faces, the poorer their prognosis tends to be. Taking steps to manage comorbidities may help extend life expectancy somewhat.

Do genetics impact life expectancy with dementia?

Research suggests there may be a genetic component that influences prognosis for some types of dementia. For example:

  • Alzheimer’s patients with the APOE e4 gene variation tend to have a shorter life expectancy.
  • A genetic mutation called C9orf72 is associated with faster disease progression in frontotemporal dementia patients.

Genetic testing can help reveal if a dementia patient has these or other high-risk variants that potentially reduce life expectancy. But more research is needed on the genetic factors in dementia.

Do demographics play a role?

Demographics like age, gender, ethnicity, and education also seem to impact a dementia patient’s prognosis:

  • Age – Younger age at diagnosis (under 70) means longer survival time.
  • Gender – Women with dementia tend to live longer than men on average.
  • Race – Black and Hispanic dementia patients have a lower life expectancy compared to Whites.
  • Education – Those with higher education levels may progress more slowly.

However, study results on demographic factors in dementia have been mixed. While these characteristics may contribute, other individual health aspects likely play a bigger role.

Does dementia stage affect life expectancy?

The stage and severity of dementia influences expected survival time. Dementia progresses through mild, moderate, and severe stages:

Mild dementia – Typically lasts 2-4 years. No significant impact on life expectancy.

Moderate dementia – Lasts 2-10 years. Some decline in life expectancy begins.

Severe dementia – Lasts 1-3 years on average. Marked decline in life expectancy.

Patients with mild impairment at diagnosis will live longer, while those already at a moderate to severe stage have a poorer prognosis.

Can anything improve life expectancy in dementia?

While challenging, certain lifestyle measures may help prolong life in dementia patients:

  • Getting regular exercise and staying active can maintain physical health longer.
  • Eating a nutritious diet and preventing weight loss.
  • Taking medications as prescribed to manage other conditions.
  • Reducing the risk of infections through vaccinations like the flu shot.
  • Using assistive devices and fall precautions to prevent injury.
  • Stimulating the brain through cognitive therapies and social engagement.
  • Controlling risk factors like smoking, obesity, and excessive alcohol intake.

Research on treatments to slow dementia progression is ongoing. Emerging therapies may help prolong life in the future as well.


Dementia shortens the life expectancy of those affected. On average, people with dementia live between 3 to 10 years after diagnosis. However, there is significant variation based on the type of dementia and other individual factors. Maintaining physical health appears key to optimizing longevity.

While no cure exists, managing comorbid conditions, promoting healthy lifestyles, and emerging treatments provide some hope for extending life with dementia. Earlier diagnosis also allows patients more time to plan care and improve quality of life.