Dementia - What is it?

Key points about Alzheimer's disease and other types of dementia

• Alzheimer's and other types of dementia are often difficult for doctors to diagnose in the early stages.
• Forgetfulness and confusion are usually the first symptoms.
• There's no cure for Alzheimer's and most other dementias, but there are treatments that can help with the symptoms.
• If you think someone close to you may have Alzheimer's or another type of dementia, talk to his or her doctor. Many treatments work best early on in the disease.
• If you're caring for someone with dementia, bear in mind that you will need help.

Your brain and what it does

To understand dementia and how it's treated, it helps to understand how your brain works.

Your brain controls most things that your body does. It allows you to speak, think, move your arms and legs, recognise your family and build memories. Your brain also controls things like your breathing and body temperature.

Your brain is made up of billions of brain cells that share information with each other. Different groups of brain cells have different jobs to do. For example, some groups are involved in thinking, learning, remembering and planning. Other groups of cells deal with seeing or hearing. And other cells manage the millions of jobs that keep your body working normally.

Your brain cells need to communicate with each other. Messages travel between cells in the form of electrical signals. The electrical signals move from one cell to another with the help of brain chemicals called neurotransmitters. Signals travel back and forth across the brain in a fraction of a second. Millions of signals are flashing through your brain right now.

For your brain to work properly, the cells must be healthy and in good working order. They need to keep stores of neurotransmitters. And they also need an energy supply, which comes from chemicals in your blood. Brain cells can last a lifetime, and they normally repair themselves if they get damaged.

How memory works

Our memories are stored in brain cells. One part of the brain helps us remember what we did a few minutes or a few days ago (short-term memory). Another part of the brain holds our long-term memory. Long-term memories last for months or years. Important, useful or dramatic memories get stored in your long-term memory.[1] [2]

As well as allowing us to remember what has happened to us, memory is important for everyday tasks. Almost everything we do relies on memory. Activities such as driving, or even catching a ball or turning on a tap, rely on memory. We've learned to do these things in the past, and we need our memory to do them again.

What happens in dementia?

If you have dementia, this means your brain is not working properly. Dementia causes problems with memory, thinking, behaviour and personality.

One of the first signs of dementia is difficulty remembering things that happened recently. This is called short-term memory loss. As the condition gets worse, other memory problems can appear. For example, a person may have trouble remembering the names of friends or family. Or they may forget how to do simple tasks, such as making a cup of tea.

Language can also become a problem. Someone with dementia may not be able to find the right words when talking. Or they may not understand what other people are saying. Over time, someone with dementia may lose the ability to speak altogether.

As the illness gets worse, people with dementia may not be able to look after themselves. If they are left alone, they may wander off and get lost. Or they may hurt themselves when doing everyday tasks, such as cooking a meal. In the later stages of the disease, people with dementia often need full-time care.

What causes dementia?

Lots of conditions can cause dementia. Alzheimer's disease is the most common. The second most common is dementia with Lewy bodies. A damaged blood vessel in the brain can also cause dementia. To read more, see Causes of dementia.

Who is at risk of dementia?

We don't know why some people get dementia and others don't. But we know there are things that make it more likely that some people will get it. These things are called risk factors. For example, getting older is a risk factor. And if someone in your family has Alzheimer's, you're more likely to get it than someone without any relatives who have the disease.

To learn more, see Risk factors for dementia.