Types of dementia

There are over 400 different types of dementia. The most common types are Alzheimer’s disease and vascular dementia. Dementia is most likely to develop in older people over 65 but can occur at a younger age. People with Down syndrome are more likely to develop dementia as they get older, particularly Alzheimer’s disease. Most dementias are progressive and a person’s function generally declines over time.

Some of the most common types of dementia are:

• Alzheimer's disease
• Vascular dementia
• Lewy Body disease
• Fronto-temporal dementia
• Early Onsetdementia

Alzheimer’s Disease

The majority of dementia cases in older people, are Alzheimer’s disease. It often develops slowly, over several years. The early stages can be the same as mild forgetfulness which can be part of normal ageing. Early signs usually include difficulty in forming new memories for recent events difficulty finding the right words figuring out problems or making decisions judging distance and finding the way to familiar places.

What’s happening in the brain?

There is a progressive build-up of abnormal clumps of protein that causes damage to the nerve cells in the brain.

Vascular Dementia

This is another common type of dementia but the name is not so well known. It can occur suddenly, for example, following a stroke affecting major blood vessels. It can also progress slowly or over time through a series of small strokes or damage to blood vessels in the brain. The signs and symptoms can sometimes be difficult to tell from Alzheimer’s and other forms of dementia.

Symptoms can include:

• memory loss,
• disorientation problems with communication and
• changes in how the person walks.

More specific symptoms differ depending on which part of the brain is affected. These may include problems with planning problems concentrating or short periods of intense confusion.

What’s happening in the brain?

When blood supply to the brain reduces because of narrowing or blockages in blood vessels, brain cells can be damaged. Vascular dementia symptoms can occur suddenly or gradually.

Lewy Body Disease

With Lewy body disease, movements may be affected so people might shuffle as they walk, and be more prone to falls. Some of the symptoms are like those who have Parkinson’s disease. People with Lewy body disease may experience periods of severe confusion. They can have hallucinations, seeing or hearing things that aren't really there. Swallowing and sleep patterns can also be affected – people can fall asleep easily during the day but have disrupted sleep at night.

What’s happening in the brain?

With ‘Lewy bodies’ there are abnormal clumps of protein that build up over time in the brain. These protein deposits disrupt nerve cell connections in the brain and cause changes in movement, thinking, behaviour and alertness.

Fronto-temporal Dementia (FTD)

This form of dementia can affect behaviour and personality and language function. Some cases of FTD are linked to motor neurone disease. With FTD the early symptoms vary, depending on which area of the brain is affected. They may include:

• changes in personality changes in eating patterns,
• lack of personal awareness (e.g. personal hygiene) or
• lack of social awareness (e.g. being tactless).
• Difficulties speaking or understanding others can be a main symptom in the early stages.

It is more common in younger people (45-65) but can also develop in older individuals.

What’s happening in the brain?

FTD affects the front section of the brain, and the temporal lobes (over the ears). If the frontal lobes are affected, the person will have increasing difficulty with motivation, planning and organising, controlling emotions and maintaining socially appropriate behaviour. If the temporal lobes are affected the person will have difficulty with speaking and/or understanding language.

Early/Younger Onset Dementia

Although most people who develop dementia are over 65, it can affect younger people too. Most people with early onset dementia are in their 40s or 50s. Doctors don’t usually suspect dementia in younger people. The process of getting a diagnosis can therefore be difficult. People who develop dementia at a younger age may have a strong family history of dementia. Genetics may have a role in the development of their condition. Early onset dementia can affect those with another health condition such as Parkinson’s disease, multiple sclerosis, Huntington’s disease, HIV or AIDS.