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What is dementia?

The word ‘dementia’ describes a group of symptoms that

includes memory loss, difficulties with thinking, problem-solving

or language, and often changes in mood, perception

or behaviour. These changes are usually small to start with,

but for someone with dementia, they become bad enough

to affect daily life.

Dementia is not a natural part of ageing. It is caused when a

disease damages nerve cells in the brain. Nerve cells carry

messages between different parts of the brain, and to other

parts of the body. As more nerve cells are damaged, the brain

becomes less able to work properly.

Dementia can be caused by many different diseases. These

diseases affect the brain in different ways, resulting in different

types of dementia. The most common type is Alzheimer’s

disease. The next most common is vascular dementia.

A person’s symptoms depend on the disease that is causing

the dementia and which parts of their brain are affected.



Each person experiences dementia in their own way. Different

types of dementia affect people differently, especially in the

early stages.

However, there are some common

symptoms of dementia.

These include:

Memory loss – for example, problems recalling things that

happened recently.

Difficulty concentrating, planning or organising – for

example, struggling to make decisions, solve problems or

follow a series of steps (such as cooking a meal).

Problems with language and communication – for

example, difficulties following a conversation or finding the

right word for something.

Misunderstanding what is being seen – for example,

problems judging distances (such as on stairs) or perceiving

the edges of objects, or misinterpreting patterns or reflections.

Being confused about time or place – for example, losing

track of the time or date, or becoming confused about where

they are.

Mood changes or difficulty controlling emotions –

for example, becoming unusually anxious, irritable, sad

or frightened, losing interest in things, or experiencing

personality changes.

With some types of dementia, the person may have difficulty

knowing what is real and what isn’t. They may see or hear

things that are not really there (hallucinations) or strongly

believe things that are not true (delusions).

Progression and the later

stages of dementia

Dementia is progressive, which means symptoms may be

relatively mild at first, but they get worse over time.

How quickly this happens varies from person

to person and is normally very difficult to predict.

As dementia progresses, the person may start to behave in ways that seem unusual or out of character.

This might include asking the same question over and over, pacing around, or becoming 

restless or agitated. This can be distressing or challenging for the

person and those close to them.


It also becomes harder for a person to eat, drink and stay active

as dementia progresses. This may lead to muscle weakness and

weight loss, which can make a person more frail.

Many people also have other health conditions that become

more difficult to manage because of their dementia. This means

these conditions get worse quicker.

Changes in sleep patterns are also very common in the later

stages. The person may sleep more and more during the day

and have problems going to sleep at night.

What is dementia - Alzheimers Society (3)

What is dementia - Alzheimers Society (3)

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