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Dementia Life Expectancy: progression and stages after diagnosis

Dementia Life Expectancy: progression and stages after diagnosis

Life expectancy with dementia is increasing year on year as scientists and doctors find better ways to manage the disease. However, because of the nature of its progression dementia is known as a ‘life limiting’ illness.

Estimating life expectancy, although incredibly difficult, can help you to make care plans for the future.  Try not to focus too much on how much time is left and instead on how to make the most of it. 

There are some steps that should be taken regardless of life expectancy. Organising legal and financial matters such as a Power of Attorney and Advance Directive will ensure your relative’s wishes are taken into account should they no longer be able to make their own decisions. 

In this guide we will cover the average dementia life expectancy, the factors that influence this number and talk about the stages of dementia. 

What is the life expectancy for someone with dementia?

This is an incredibly difficult question to answer as there are many influencing factors, including the persons age and gender, the type of dementia and the stage of the condition at diagnosis. The average life expectancy after diagnosis for someone with Alzheimer’s, the most common form of dementia is 10 years. However, dementia progresses differently in everyone, meaning people can live anywhere from 2 years to 26 years after diagnosis. 

The main way in which health care professionals estimate dementia life expectancy is by using the Global Deterioration Scale (GDS), also called the Reisberg Scale. It shows the average time someone is expected to live depending on which stage of dementia they are at.

Stage
Expected Duration of Stage
Expected Life Expectancy (years remaining)
Stage 1: No cognitive decline
N/A
N/A
Stage 2: Very mild cognitive decline
Unknown
More than 10 years
Stage 3: Mild cognitive decline
2-7 years
10 years
Stage 4: Moderate cognitive decline
2 years
3 to 8 years
Stage 5: Moderately severe cognitive decline
1.5 years
1.5 to 6.5 years
Stage 6: Severe cognitive decline
2.5 years
4 years or less
Stage 7: Very Severe cognitive decline
1.5 to 2.5 years
2.5 years or less

What factors can influence dementia life expectancy?

There are a lot of factors that can influence expected dementia life expectancy. Below you can find a bit more information about how each factor can alter how long someone living with dementia might live.

Age

Age is one of the largest factors affecting how long someone might live after a dementia diagnosis. Someone diagnosed at a younger age will have a much longer average life expectancy than someone diagnosed later in life. The only exception to this is in young-onset dementia, where age is less of a factor on life expectancy.

Gender

Although women are more likely to be diagnosed with dementia, on average they live 20% longer than men after a dementia diagnosis

Severity at Diagnosis

How far the dementia has progressed, will affect life expectancy. See the table above for more guidance.

Type of Dementia

The type of dementia  influences not only how quickly the dementia might progress but also the expected life expectancy. Below you can find the average life expectancies for the most common types of dementia. However, please note there are other influencing factors at play such as general health, age, gender and stage of the disease at diagnosis.

 

  • Alzheimer's Dementia
    - 8 to 12 years.
  • Vascular Dementia - 4 years. Although circumstances can change dramatically as vascular dementia is often linked to strokes.
  • Lewy body Dementia - While the average was found to be between 5-7 years, the range can be between 2 and 20 years.
  • Frontotemporal Dementia (Pick's Disease) - 8 years.
  • Young Onset Dementia - Although a diagnosis at a young age should imply a longer life expectancy, with Young Onset dementia this is sadly not the case. This type of dementia seems to progress more quickly and those diagnosed tend to live on average 2 years less than other types of dementia (~8 years).

General Health, Wellbeing and Independency

General good health, with strong cardiovascular and respiratory systems is likely to increase expected life expectancy after a dementia diagnosis. Studies suggest that people who have a higher level of function and independency, on average, tend to live longer.

The later stages of dementia

It is important to remember that not everyone living with dementia will want to know what is ahead of them. However, if you’re caring for someone living with dementia, it is useful to know about the later stages of the disease so you can make decisions about future care options.

Later stages of dementia

In the later stages of dementia, symptoms such as poor memory, confusion and other forms of cognitive impairment are joined by more physical symptoms. 

Dementia is an illness of progressive cell damage. It starts in the parts of the brain that deal with memory and slowly moves to parts of the brain that control other functions. Sadly, this will eventually cause major organs to stop working. Below you can find a summary of some of the things you can expect when caring for someone in the later stages of dementia. 

Our advice page on looking after someone with dementia might also be helpful. 

Memory

The memory of someone living with dementia will get progressively worse, especially their short-term memory. They might begin to think that the are living in an earlier period of their life. This can be particularly alarming for them, as they might be confused or worried that they should be somewhere like collecting their children from school or at the office.

 

It will also be harder for them to recognise people, and they will start to get people confused. For example they might mistake a sibling for their parent or no longer recognise their own children. This is also true for themselves as they will remember being and looking a lot younger.

 

Although lots of their conscious memory will be lost, often things that used to make them feel happy and secure will continue to do so, like listening to their favourite music. 

Cognitive Ability

Alongside memory, mental (cognitive) ability will also gradually decline. It will be harder to concentrate, to plan and organise, and to complete basic tasks. It is also likely that they will be disoriented more often. However, this doesn't mean that the person living with dementia won't be able to find enjoyment from tasks and activities they used to do. For example, the tactile feel of wool and needles will still be enjoyable to someone who liked knitting. 

Mobility

As the condition progresses is it likely that the person will gradually be less able to stand and walk around unassisted. They will also be more prone to falls. Being more sedentary can lead to other pyhsical conditons such as bed sores and blood clots. Therefore, it is important to encourage someone with dementia to move around as much and as often as they can. 

Communication

The ability to understand what is being said, and to properly communicate back will decrease as the illness progresses. They might use only a few words or sounds and repeat words back to you. Alternatively, they might say a lot but very little of it will make sense. When talking to someone in the later stages of dementia - body language, eye contact and facial expressions are very important. An Admiral Nurse (specialists in dementia care), Emma Krzyz, has recommended 15 tips to help communicate with someone who has dementia.

Eating and weight loss

People living with dementia are likely to eat less and therefore lose weight quickly. This can be for a variety of reasons including difficulty chewing and swallowing. It's important to encourage them to continue to eat. Read our tips on helping someone with dementia to eat more.

Incontinence

Urinary and faecal incontinence are common among those in the later stages of dementia. However, it is also common in other elderly related illnesses and therefore important to talk to the GP to find out if there is another, treatable reason behind it. 

Behaviour

There are many behavioural changes that might be associated with dementia. These include distress, agitation, aggression, restlessness, hallucinations, sundowning, and disrupted sleep

Care in the later stages of dementia

There are medicines used in the early stages of dementia that manage some of the behavioural symptoms. In the later stages some of these medicines can do more harm than good causing severe side effects that can increase confusion and frailty. It also becomes harder to diagnose and manage some of the normal illnesses that older people get such as Urinary Tract Infections (UTIs). UTIs can exaggerate some symptoms of dementia and increase confusion – sometimes know as delirium

Pain is also something that can be present in the later stages of dementia, but can be harder to diagnose if the person isn’t able to communicate it. For all of these reasons, it’s important to stay vigilant when looking after someone with dementia, and to talk to the GP if you are worried about anything.