Enclosed by the tough protective casing of the skull, our brains are the centre of our nervous systems. The brain monitors and regulates our actions and reactions. It constantly receives information from our senses, rapidly analysing and co-ordinating our responses to things we see, hear, touch and taste.

The brain is also our centre of learning. It forms and stores our memories. It's involved in speech, abstract thought and consciousness as well as informing our personality and emotions. An adult brain weighs about 1.5kg (3.3lb) and contains about 90 billion nerve cells. As well as nerve cells our brains have about 90 billion other cells, plus blood vessels to help supply the nutrients and oxygen it needs. During dementia, nerve cells in different areas of the brain become damaged and eventually die. A lot of research we're supporting aims to stop this damage and protect the brain from harm.

Dementia with Lewy bodies (DLB) affects the cerebrum. In DLB small, round lumps of proteins build up in the grey matter. These spheres harm nerve cells, causing the symptoms of DLB including hallucinations and fluctuations in consciousness.

This area can also be affected by vascular dementia, the second most common cause of dementia after Alzheimer's. Vascular dementia is caused by blood flow to the brain being reduced. Blood carries essential oxygen and nourishment to the brain and without it brain cells die.

Frontotemporal dementia (or FTD) affects this area of the brain.

There are different types of frontotemporal dementia. Some affect the frontal lobes early on and patients behave inappropriately and often experience personality changes. It's thought that frontotemporal dementia is caused by proteins building up in the brain, harming nerve cells.

This part of the brain is affected by posterior cortical atrophy (PCA) a rare type of Alzheimer's.

Because this part of the brain helps us see, when it becomes damaged in PCA patients experience difficulties seeing what and where things are. Like in the more common form of Alzheimer's disease, it's affected by proteins building up and damaging nerve cells.

The hippocampus is affected by Alzheimer's disease.

Two proteins, amyloid and tau, build up and damage nerve cells. This build up starts in the hippocampus before spreading to other brain areas. The damaged nerve cells in the hippocampus mean this part of the brain can’t function properly, which can lead to the early symptoms of Alzheimer’s – memory loss and disorientation. The temporal lobe is affected by frontotemporal dementia, a rare type of dementia. There are different types of frontotemporal dementia. Some affect the temporal lobes early on and those affected have problems with language, speech and factual knowledge about the world.

This area of the brain is affected by a rare form of Alzheimer's called posterior cortical atrophy (PCA).

Because this part of the brain helps us see, when it becomes damaged in PCA, people can experience difficulties seeing where and what things are. Like in the more common form of Alzheimer's disease, it's affected by proteins building up and damaging nerve cells.

Like other areas of the brain, the cerebellum is eventually affected by Alzheimer's and other dementias.

Most dementias are 'progressive', which means they get worse over time. People's symptoms get worse as nerve cells become damaged in more and more areas of the brain. The two hallmark Alzheimer's proteins build up in this area and damage nerve cells.