Understanding dementia and its various forms

Dementia develops differently in each person it touches and has a myriad of symptoms, often making it a complex condition to understand.  But by learning more about it, you’ll be better placed to recognise the most suitable services or support to offer someone with the condition.



As a broad term, dementia describes a group of symptoms occurring simultaneously and causing progressive damage to the brain.  In Australia, 1 in 10 people over the age of 65 have a dementia diagnosis.

With a gradual onset, the condition affect’s a person’s ability to think, remember and function in everyday activities.  Changes to their personality, mood and difficulty using or understanding language may also occur.

The most common forms of dementia are outlined below:


Although the terms of ‘dementia’ and ‘Alzheimer’s disease’ are often used interchangeably, they’re actually quite different.

Dementia refers to a group of cognitive symptoms such as memory loss and confusion, whereas Alzheimer’s refers to a specific type of irreversible dementia.  There are over 70 disease and conditions which cause irreversible dementia but Alzheimer’s is the most common, accounting for 50% – 70% of all dementia cases.  If you’d like to know more about it, including risk factors, symptoms and disease progression, take a look through our factsheets.

Vascular dementia

The second most prevalent kind is vascular dementia – the most common form of which is called multi-infarct dementia (MID).  It’s usually caused by strokes and heart disease.  In these cases, there’s a problem with the circulation of blood to the brain, with the resulting lack of oxygen causing changes or damage to brain tissue.

Dementia with Lewy Bodies (DLB)

Accounting for 10-25% of dementia cases, this is the third most common form of the disease.  DLB is a progressive type of dementia, whereby brain cells are damaged over time, leading to a decline in thinking, reasoning and independent function.



If a person has more than one type of dementia, this is known as mixed dementia.  Often this presents as a combination of  Alzheimer's disease and vascular dementia.  In fact, about 15- 20% of dementia cases are where Alzheimer’s and MID occur together.

Other mixed dementia cases involve Alzheimer's disease coupled with DLB – and sometimes a person with dementia has an unfortunate combination of all three of the most common forms of the disease. 

Mixed dementia can also refer to Alzheimer's with any other type of dementia or condition that can lead to a strain of dementia. Examples of both include:

  • Down syndrome
  • Huntington’s disease
  • AIDS
  • Creutzfeltd-Jakob disease
  • Pick’s disease
  • Parkinson’s disease
  • Wernicke-Korsakoff syndrome

With symptoms similar to Alzheimer’s disease, mixed dementia is often difficult to diagnose.  In fact, its diagnosis doesn’t usually come until after a brain autopsy.

However, researchers feel it deserves a lot more attention because the combination of two or more types of dementia impacts the brain far more than one type on its own.  This means that in mixed dementia cases, a person’s function and capability declines far more rapidly than if they only had one type of dementia to contend with.


Although medication that specifically treats mixed dementia isn’t available, those who’ve been diagnosed have responded well to some Alzheimer’s treatments.

People with a combination of Alzheimer's and vascular dementia usually have a treatment plan that incorporates blood pressure and cholesterol management.  This is to help reduce the chance of another stroke and the progression of vascular dementia.



Alzheimer’s Queensland runs informative sessions for carers and organises bespoke education for service providers.  To find out more or if you’d like support or further information about dementia, call our 24-hour Advice Line on 1800 639 331.


You can also learn more about dementia through the comprehensive factsheets on our website - and if you’re a health professional, visit Dementia Training Study Centres, which offer eLearning programs about the condition. 


Words: Ash Anand