Jun 04, 2021

The 3 most common types of dementia

History of Dementia

Dementia is a condition reported in people since 1906 when it was discovered by Alois Alzheimer. Before the 20th century it was a considered a relatively rare condition, due to the fact that people rarely lived to “old age”.

In the century since then, scientists have made significant advancements in understanding how Alzheimer’s affects the brain and have learnt ways to help improve the quality of life for individuals diagnosed and their families.

Dementia Statistics – Australia

Dementia is the second leading cause of death according to the 2016 statistics of Dementia Australia. In 2021, there are an estimated 472,000 Australians living with dementia[3] Without a medical breakthrough, the number of people with dementia is expected to increase to 590,000 by 2028 and 1,076,000 by 2058[3]]

Whilst the condition is more common in older people, it affects young people also. This year, there are an estimated 28,300 people with younger onset dementia, expected to rise to 29,350 people by 2028 and 41,250 people by 2058[3]]

The incidence of dementia increases as we grow older, from the age of 65 years, 1 in 10 people are reported to be diagnosed – with a significant increase at the age of 85 years to 3 in 10 people.

Having said this, it’s important to remember that dementia is not a ‘normal’ part of ageing, and if you do have concerns about your memory or someone close to you, we suggest seeking professional advice from a General Practitioner (GP). If you are still concerned about your memory after the visit to the GP, then request a second option and ask to see a neurologist, neuro-psychologist or geriatrician just to make sure.

The 3 Most Common Types of Dementia

Before we talk through the different types of dementia, let’s first make sure you are aware of what we mean by “dementia”. Dementia is the umbrella term used to describe a collection of symptoms that are caused by the disorders impacting the brain. Rather, it does not refer to one specific disease, but instead a number of symptoms associated with a number of different neurological conditions.

People with dementia will experience changes with their thinking, ability to perform everyday tasks and behaviour. The extent to which people experience these symptoms will vary from person to person.

Understand Alzheimer’s Disease in 3 Minutes is an easy-to-understand video that describes the progression of Alzheimer’s Disease – by TenderRoseHomeCare

The 3 most common types of dementia are listed below, and we have provided an overview of the prevalence in Australia and what symptoms may be observed.

Alzheimer’s Disease

The most common form of dementia affects up to 70% of all people diagnosed. This condition may initially be observed in subtle memory lapses until it worsens over time and eventually gets in the way of the person’s everyday living.

Mild symptoms of Alzheimer’s disease include trouble remembering things and systematising thoughts. The person over time will start to find it more difficult to remember names, recent events and dialogues. Later symptoms that can often proceed for some people are: depression, apathy, social withdrawal, mood swings, irritability and aggressiveness, change in sleeping habits, wandering, loss of inhibitions, and delusion such as the belief that something is stolen.

The underlying brain changes for Alzheimer’s are characterised by loss of nerve cells in the brain. This loss results in the depletion of affected regions, including deterioration in the temporal and parietal lobe, and parts of the frontal and medial cortex. People with Alzheimer’s have a larger number of amyloid plaques and neurofibrillary tangles, especially in the temporal lobe of their brains. Consequently, these plaques and tangles impede the activity between the nerve cells that may cause the death of cells. Persons diagnosed with Alzheimer’s also experience shortage in chemical messengers that transmit signals to the brain.

Vascular Dementia

Vascular dementia is the second most common form of dementia and may account for 15-20% of people with a diagnosis. Vascular dementia is a generic term associated with problems involving thought processes caused by damage to the brain due to chronic reduced blood flow to the brain. It can often result from a stroke or a number of mini strokes. Strokes, however, do not always result in vascular dementia.

It is thought for 50% of people diagnosed with vascular dementia is a result from high blood pressure.

Symptoms of vascular dementia include confusion, disorientation, agitation, trouble in speaking or understanding speech, and vision loss. Many of these symptoms, however, are likely to occur after a major stroke and such symptoms depend on what part of the brain is affected. If the frontal lobe is affected, symptoms may manifest through behaviour and personality. If the affected part is the temporal lobe, the problem is with memory, language skills and speech.

It’s not uncommon for people to be diagnosed with mixed vascular dementia and Alzheimer’s disease.

Dementia with Lewy Body

Lewy body dementia affects approximately 10% of Australian’s diagnosed with dementia and accounts for up to 20% of dementia cases worldwide. This form of dementia has many similarities to Alzheimer’s disease, but Lewy body disease is caused by the death of nerve cells and degeneration in the brain. The name comes from the presence of abnormal spherical structures, called Lewy bodies. Brain changes noted with this type of dementia involve the clumping of protein in the brain called alpha-synuclein.

While it is beyond a cure, early diagnosis can give way to an early treatment that may boost the patient’s quality of life.

Symptoms of Lewy body dementia that can be observed are hallucinations, delusions, mood swings, depression, and insomnia. People with Lewy body dementia might notice slowed motor skills, rigid muscles and stiff limbs. Additionally, they may have trouble judging distances and directions; as a consequence, they often fall and get lost in previously familiar environments.

Other types of dementia include: Mixed Dementia, Parkinson’s Disease Dementia (PDD), Frontotemporal Dementia, Creutzfeldt-Jacob Dementia (CJD), Normal Pressure Hydrocephalus (NPH), Huntington’s Disease, Wernicke-Korsakoff Syndrome, Mild Cognitive Impairment (MCI), Alcohol Related Dementia, and Dementia resulting from head injury/trauma (with many more).

Understanding the complexities of Dementia can be quite a challenge but ACRC’s Dementia Care Help Sheet
can provide you with more information on the different types of dementia, 10 Signs of Alzheimer’s and Worried about your memory?

Did you know there are over 100 diseases that may cause dementia?

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  1. My wife was diagnosed about 6 years ago with dementia parkinson’s (as distinct from parkinson’s dementia). dementia parkinson’s now appears to be regarded as part of Lewy body disease. Where can I find out more about this disease?


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