Stages of dementia and prognosis

It is often helpful to categorise dementia into stages of severity to help doctors formulate a treatment plan, and for the person and their family to consider options for care. Dementia is often divided into early, middle and late stages, but medical professionals use a more detailed seven-stage scale, based on a person’s symptoms and assessment of cognitive decline.

Not all of these signs are always present, since dementia can be caused by many underlying conditions, but they represent the typical progression, particularly of the most common form of dementia, Alzheimer’s disease.

7 stages of dementia

1. Appears normal

Normal, no obvious signs, although brain changes may be occurring

2. Very mild

No noticeable symptoms different to normal ageing. Brain imaging may reveal plaques or degeneration.

3. Mild

Mild cognitive deficits – increased forgetfulness or disorientation, difficulty finding words. Loved ones begin to notice decline.

4. Moderate

Memory of recent events affected; difficulty with complex tasks and managing personal affairs; may be in denial or withdrawn from family. Decline is obvious to a doctor. Family and friends notice symptoms.

5. Moderately severe

Major memory lapses, including significant life events; needs help with daily activities such as dressing or preparing meals; can no longer
manage personal affairs. 

6. Severe

Can no longer care for self; starts to forget names of family members; difficulty finishing tasks; speech affected; incontinence, depression, agitation, delusions may be evident.

7. Very severe

Full time care is needed; loss of speech; requires assistance with all daily activities, including eating, bathing, toileting; may lose the ability to walk.


Prognosis of dementia

How does the disease progress and how does it become fatal?

Because dementia is caused by many different underlying conditions, progression will vary. A person’s age, physical health and cognitive reserve – how resilient someone is to brain changes – will also affect how fast the disease progresses. 

The average time from the appearance of obvious symptoms until death is about 8-10 years for Alzheimer’s disease; 4-8 years for Lewy-body and frontotemporal dementias; and 5 years for vascular dementia. 

People may live 20 years or more with dementia, depending on its cause and the age, health and genetics of the person diagnosed. Dementia reduces life expectancy and is not often listed as the direct cause of death. Death is typically caused by complications related to the loss of brain function – infections such as pneumonia (accounting for two-thirds of cases), malnutrition, dehydration or falls.