Dementia affects people differently

There are different types of dementia. Each one is characterised by different patterns of symptoms, although every person with the same type of dementia won’t necessarily exhibit the same set of symptoms, especially early on. Just as our personalities can be incredibly diverse, the way dementia may affect personality and behaviour can be very different between individuals.

For example, a person with Alzheimer’s disease will have two main brain regions affected: the hippocampus and the entorhinal cortex. The entorhinal cortex is a specialised part of the brain that works together with the hippocampus to form long-term memories. Together, they take the input from all our senses to help orientate us in space and time, and also help us form declarative memories – things like facts and memories of events.

The changes in the brain of a person with another type of dementia, known as Lewy body dementia, are less established. But they include damage to a slightly different part of the hippocampus, and a loss of neurons that produce the neurotransmitters dopamine and acetylcholine. These neurons are important for various aspects of movement, visual perception, and cognition. Because of this, people with Lewy body dementia might experience hallucinations and difficulties with movement.

A person with frontotemporal dementia will experience degeneration that affects the frontal and temporal lobes of the brain, though the exact location can vary between people.

Eventually, the disease will spread to other parts of the brain. For example, the neurons in the part of the brain involved in recognising faces (called the fusiform gyrus) may degenerate, resulting in the inability to recognise people. This can happen even when a person with dementia still remembers who you are. For this reason it can be helpful to reintroduce yourself when you talk to a person with dementia.