Different types of dementia

There are many different types of dementia. These are some of the main types.

Alzheimer’s disease is caused by chemical changes in the brain.

It involves the breakdown of acetylcholine which helps transmit messages between neurons or brain cells.

When this occurs, the neurons die and that part of the brain no longer works.

In Alzheimer’s this usually begins in the temporal lobe and initially affects memory and communication.

Frontotemporal dementia (FTD) also affects the transmission of messages between neurons.

There are two main types of frontotemporal dementia. The behavioural variant and the language variant.

The behavioural variant begins in the brain’s frontal lobe and initially affects behaviour. The language variant initially begins in the temporal and frontal lobes. The language variant initially affects communication and understanding of concepts.

The language variant is known as primary progressive aphasia (PPA) has three sub types called

• Semantic Dementia (SD)
• Progressive Non Fluent Aphasia (PNFA)
• Logopenic Aphasia (LPA)

Frontotemporal dementia does not typically affect memory in the early stages.

Lewy body dementia (LBD) or Dementia with Lewy bodies (DLB) involves a different protein which also affects transmission of messages between neurons.

It tends to start further back in the brain. It tends to affect the cognitive processes which are associated with vision and movement.

Lewy body dementia is diagnosed if symptoms of dementia appear first, or at the same time as, motor symptoms. In some cases, no motor symptoms may develop at all.

Parkinson’s disease dementia also affects the transmission of messages between neurons. Unlike Dementia with Lewy bodies, it starts with difficulties with movement rather than cognition.

A person will be given a diagnosis of Parkinson’s disease dementia if motor symptoms occur first and the onset of dementia occurs a year or more after the motor symptoms.

Vascular dementia is caused by blockages or bleeds in the arteries and smaller blood vessels, which leads to a disruption of the oxygenated blood flow to the brain. When neurons are deprived of oxygen, they die, causing that part of the brain to cease functioning.

These blockages can occur anywhere in the brain and the course of the disease can be unpredictable.

Posterior cortical atrophy is a rare dementia which is thought to be a variant of Alzheimer’s disease. It affects the transmission of messages between neurons in the occipital lobes and initially affects vision.

It is possible to have more than one type of dementia happening at the same time. If this is the case, then someone may be diagnosed with mixed dementia.

The most common type of mixed dementia is Alzheimer’s disease and vascular dementia. 

There are no fixed set of symptoms for mixed dementia, it will depend on the combination of the types of dementia diagnosed.

It will be helpful to understand the symptoms associated with each type diagnosed and how the person you are caring for may be affected by each type.