What are the different types of dementia?

Dementia is the dirty word of ageing.

It haunts us all, and with good reason. Dementia Australia (DA) estimates more than 421,000 Australians live with dementia. Without a medical breakthrough, the number of people with dementia is expected to increase to more than 812,500 by 2054.

And while it’s a major health concern, we tend to hide our heads in the sand with regards to what it means. Dementia is actually not one diagnosis, but an umbrella term for several conditions. We explain what they are.

Alzheimer’s disease

Probably the best-known form of dementia, it’s also the most common. Named after Alois Alzheimer, a German psychiatrist, Alzheimer’s causes an estimated 60-80 per cent of all dementia cases.

A deep dive into Alzheimer’s will give you a lot of scientific and medical terms, but breaking it down to the basics, it’s caused by damage to the neurons that are responsible for carrying messages around your brain. A build-up of protein around the neurons eventually kills them, and as a result your brain volume and function shrinks. 

Early symptoms include problems with memory and learning, language difficulties and changed behaviour. 

While it can be categorised into early, middle and late stages, Alzheimer’s progresses at different speeds for different people.

There is no single test to diagnose Alzheimer’s, and clinicians will make a diagnosis on several markers. While the symptoms can be treated, there is no cure.

Vascular dementia

Vascular dementia is caused by impaired blood flow to your brain. It can be caused by a stroke, a series of strokes or high blood pressure, thickening of arteries and inadequate blood flow around the brain.

It can occur alongside other diagnoses, such as Alzheimer’s, and the symptoms can differ depending on which part of the brain is damaged.

It’s the second most common form of dementia and your chances of suffering from the condition increase as you get older. 

There is no single treatment for it, but much can be done to improve a sufferer’s situation including medication. Giving up the ciggies, alongside a healthy diet and exercise, should decrease the risk of further damage.

Lewy body dementias

As the name would suggest, this diagnosis covers two forms of dementia: dementia with Lewy bodies and Parkinson’s disease dementia.

These two forms of dementia are grouped because they both involve damage to the brain caused by Lewy bodies.

Lewy body dementias cause changes in your thinking, movement, behaviour and bodily functions. However, it will depend on which part of the brain is affected and the changes will often come and go. 

It is a disease associated with abnormal deposits of a protein called alpha-synuclein in the brain. 

People who have been diagnosed with Parkinson’s disease and begin to experience mental decline will likely be given a diagnosis of Parkinson’s disease dementia.

The slightly better news is that it usually has a much slower rate of progress than other forms of dementia.  

If you have a diagnosis of dementia, and then at least 12 months later you begin to experience symptoms of Parkinson’s disease, you’re likely to receive a diagnosis of dementia with Lewy bodies.

As well as the common symptoms, people with Lewy body dementia may also have problems with sight, planning, attention and even experience hallucinations.

It can be hard to diagnose in the early stages, and very little can be done once the disease advances. 

Alcohol-related brain injury

The cause of this dementia is rather obvious. You can recover some of the damage if it’s treated early, but often alcoholism has damaged the brain enough that without intervention the will and ability to stop drinking is gone. 

Men over 45 with a long history of alcohol abuse are the most likely to develop it. However, many people who have a long history of alcohol dependence will not develop the condition.

It’s unclear why some people develop the condition and some don’t, but it’s believed a lack of thiamine (vitamin B1) is involved. Thiamine is vital for brain health and alcohol makes it harder for the body to absorb it. Alcoholics also often have a poor diet, so may not be getting enough thiamine from their food. 

Younger onset dementia

This is a blanket term for any dementia that is diagnosed before the age of 65, it’s also known as early onset dementia.

It usually progresses much more slowly than other forms of dementia but can be difficult to diagnose.

Sufferers can often lead a relatively normal life in the early stages, but will need some form of support system. 

According to DA, there is no medical difference between dementia and younger onset dementia. But if you’re younger, dementia can affect your life in different ways such as having more responsibilities and being more active. 

Down syndrome and Alzheimer’s disease

Unfortunately, there is a strong link between Down syndrome and Alzheimer’s disease

Studies have shown that by the age of 40, almost all people with Down syndrome have evidence of the brain changes characteristic of Alzheimer’s disease. However, this does not mean that everyone with Down syndrome will develop symptoms of Alzheimer’s disease.

According to BetterHealth, there is a complex connection between chromosome 21 (of which people with Down syndrome have three copies instead of two) and Alzheimer’s disease, but the mechanisms that trigger the brain changes are not understood. 

Frontotemporal dementia

Frontotemporal dementia (FTD) is an umbrella term for a group of brain diseases that mainly affect the frontal and temporal lobes of the brain.

People with FTD may experience changes in their behaviour, personality, language and movement. Memory isn’t always affected, especially in the early stages. These changes get worse over time.

Most people with FTD are diagnosed in their 40s and early 60s. 

Posterior cortical atrophy

From the front to the back of the brain, posterior cortical atrophy (PCA) is a brain and nervous system syndrome that causes brain cells to die over time. 

More specifically, PCA is the gradual and progressive degeneration of the outer layer of the brain (the cortex) in the part of the brain located in the back of the head (posterior).

People often experience the first symptoms of posterior cortical atrophy in their mid-50s or early 60s. However, it can also affect older people.

It is not known whether posterior cortical atrophy is a unique disease or a possible variant form of Alzheimer’s disease.

This area of the brain processes visual information, so sufferers will have trouble with visual tasks such as reading a line of text, judging distances, distinguishing between moving objects and stationary objects, inability to perceive more than one object at a time, disorientation, and difficulty manoeuvering, identifying and using tools or common objects. 

Chronic traumatic encephalopathy

Chronic traumatic encephalopathy or CTE is gaining awareness for all the wrong reasons as sportspeople who took a lot of knocks in their careers are developing the condition. 

There’s even a current ABC series about it called Plum.

It’s caused by repeated head injuries that destroy nerve cells in the brain. It’s believed the condition is made worse by sufferers not completely recovering from an initial injury and being injured again.

Prevention is the best protection against the condition. 

Childhood dementia

Sadly, very young children and teens can suffer from dementia. There are many different genetic causes, but the outcome is the same. Sufferers rarely live past 18.

Children will be developing normally, then gradually lose their ability to talk, walk and care for themselves. They may suffer memory loss as well as seizures, and lose their hearing and sight. 

One in every 2900 babies worldwide is born with a condition that will lead to childhood dementia.

HIV-associated dementia

According to DA, HIV-associated dementia is the most severe form of HIV-associated neurocognitive disorder. It affects thinking, mood, behaviour and movement. 

Thankfully, due to worldwide research and advanced medical treatment in Australia HIV-associated dementia is rare in this country. 

Not everyone who has HIV/AIDS will develop HIV-associated dementia.

Did you know about all these types of dementias? Do you think there is enough being done about awareness? Why not share your thoughts in the comments section below?

Also read: Australians don’t know enough about dementia, and that’s a problem