Dementia is an umbrella term describing the loss of various cognitive functions, such as memory, thinking, and reasoning. Alzheimer’s disease is the most common cause of dementia and can last more than 10 years, including the final stages.

The life expectancy for someone with dementia depends on the person’s age and the type of dementia, and some people with the condition can live up to 20 years. Dementia occurs in stages, with the later stages lasting for around 1–2 years.

This article examines the three stages of dementia and the life expectancy of someone who has it.

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Dementia is a group of related conditions presenting as a decline in cognitive function. It involves various symptoms, such as gradual memory loss, changes in thinking, behavior, language, and issues with planning and reasoning.

There is no cure for dementia; a person will have dementia from the time of diagnosis to the end of their life. Depending on the type and stage of dementia, life expectancy may vary.

Causes and types of dementia include:

The life expectancy figures below are averages, and some people with dementia may live longer.

Type of dementiaLife expectancy
Alzheimer’s diseaseAround 8–10 years, depending on the age of diagnosis
Vascular dementiaAround 5 years, with an increase in the risk of stroke or heart attack
Lewy body dementiaAround 6 years, with an increase in the risk of falls and infections
Frontotemporal dementiaAround 6-8 years

Although dementia is a life-limiting condition, a person can still live a fulfilling life.

Learn more about the differences between dementia and Alzheimer’s here.

Life expectancy with dementia varies greatly between people. Factors that may influence life expectancy, or how long dementia lasts, include:

Learn more about the symptoms of dementia in older adults here.

According to the National Institute on Aging (NIA), dementia ranges in severity. Initially, it may mildly affect a person’s daily functioning, progressing to the most severe stage in which a person may be wholly dependent on others.

The World Health Organization (WHO) categorizes dementia into three stages: early, middle, and late. The stages are also known as mild, moderate, and severe and may overlap. Dementia progresses differently in each person; some may progress through each stage quickly after diagnosis, and others may keep their independence for years.

The early stage of dementia may last about 2 years. Symptoms of early stage dementia may include:

  • memory loss, such as forgetting certain events or where items are
  • difficulty in planning, for example, making complex decisions about finances
  • difficulty finding the right words to use in conversations
  • poor orientation, such as getting lost in familiar places
  • perception issues, such as judging a distance accurately
  • changes in mood, such as experiencing depression, anxiety, or irritability

Learn about some early signs of dementia here.

On average, the middle stage of dementia lasts around 2–4 years. It is usually the longest stage.

Symptoms of middle stage dementia include:

  • needing help with certain activities, such as washing and dressing
  • needing a caregiver to help with certain activities
  • difficulty recognizing loved ones
  • difficulty remembering information
  • issues with following what others are saying in conversations
  • increasing orientation difficulties, such as getting up and dressed in the middle of the night
  • increasing belief in things that may not be true
  • experiencing paranoia, such as distrusting loved ones
  • having hallucinations
  • changes in behavior, such as shouting, agitation, disturbed sleep patterns, and repetitive behavior
  • difficulty in performing everyday functions, such as using the toilet
  • experiencing mobility issues

A common symptom of middle stage dementia is sundowner’s syndrome, when the person becomes agitated and distressed toward the later afternoon or end of the day.

Learn more about behavioral disturbances in dementia here.

People with late stage dementia may require extra or full-time support from caregivers. Depending on certain factors, such as the person’s age and health, the final stage can last around 1–2 years.

Symptoms can include:

  • memory issues, also known as time-shifting, in which a person may think they are at an earlier period of their life
  • inability to recognize loved ones or themselves
  • issues with language, such as understanding fewer words
  • delusions and hallucinations
  • changes in mood, such as an increase in depression and apathy
  • increase in aggression due to feeling afraid, threatened, and often confused
  • difficulty walking and needing more time sitting down or in bed
  • difficulty swallowing and needing significant help with eating
  • incontinence issues, such as losing control of their bowels
  • weight loss
  • increased risk of falling over

Learn more about dementia and how it progresses here.

Many conditions linked to dementia can lower life expectancy. These may include:

Dementia weakens the immune response, and often those with dementia have difficulties swallowing. This means they are more likely to experience other medical issues, such as:

  • blood clots to the brain
  • blood clots in the lungs
  • infections such as pneumonia

Learn more about the types and causes of dementia here.

Treatment for dementia

There is no cure for dementia, but there are options for relieving symptoms. This may include:

  • taking certain medications, such as Galantamine, rivastigmine, and donepezil, which increase communication between nerve cells
  • keeping the person safe and comfortable with intensive support
  • maintaining a routine to avoid confusion, including regular exercise, sleep, and a nutritious diet

Learn more about medications for dementia here.

Dementia can be a difficult time for family members and friends. The U.S Department of Health and Human Services recommends various tips and suggestions to those caring for loved ones with dementia.

  • Aim to maintain a regular routine with the person who has dementia. This can include bathing, eating, and dressing at the same time each day.
  • Plan and encourage the person to do activities they enjoy, such as dancing or another exercise.
  • Help the person maintain their independence and feel in control of their daily activities by using to-do lists, notebooks, and calendars to organize events and appointments.
  • Allow the person to feel as in charge as possible when doing activities with them.
  • Aim to be consistent and familiar at all times, such as when doing activities.
  • Avoid clothing with buttons, belts, and shoelaces; opt for zips and elastic waistbands instead.
  • Respect their personal space and allow them as much control over their life as possible.
  • Surround them with familiar objects and photographs that make them feel secure.
  • Listen to concerns and frustrations without questioning or dismissing them.
  • Safety-proof their living area by removing rugs they may trip over or putting away chemicals they may mistake for something else.

Learn more about caring for someone with Alzheimer’s disease here.

End-of-life care, also known as palliative care, aims to help the person with dementia feel as comfortable as possible during the later stages of the disease. It may last a few days or several years.

Managing end-of-life care for a person with dementia may include the following:

  • ensuring they have the correct medications that can help reduce symptoms
  • encouraging regular visits from loved ones to help with comforting activities, such as listening to music, or using sensory connections, such as hearing and touch
  • providing emotional or spiritual support or comfort
  • getting more help from experienced carers
  • looking at other options, such as end-of-life care at home or in a hospital or hospice

Learn more about end-of-life planning here.

Dementia can affect a person’s daily life by interfering with their ability to think, remember, and reason.

Alzheimer’s disease, the most common cause of dementia, can last many years.

Lifestyle strategies and medications can help the person with dementia, family members, and other caregivers to manage the symptoms as they develop at each stage.

Learn more about dementia in our dedicated hub here.