What is dementia?

The word dementia describes a set of symptoms that may include memory loss and difficulties with thinking, problem-solving or language. These changes are often small to start with, but for someone with dementia they have become severe enough to affect daily life. A person with dementia may also experience changes in their mood or behaviour.

Dementia is caused when the brain is damaged by diseases, such as Alzheimer's disease or a series of strokes. Alzheimer's disease is the most common cause of dementia but not all dementia is due to Alzheimer's. The specific symptoms that someone with dementia experiences will depend on the parts of the brain that are damaged and the disease that is causing the dementia.

Symptoms

Each person is unique and will experience dementia in their own way. The different types of dementia tend to affect people differently, especially in the early stages. How others respond to the person, and how supportive or enabling the person's surroundings are, also greatly affect how well someone can live with dementia.

A person with dementia will have cognitive symptoms (problems with thinking or memory). They will often have problems with some of the following:

• day-to-day memory - difficulty recalling events that happened recently

• concentrating, planning or organising - difficulties making decisions, solving problems or carrying out a sequence of tasks (eg cooking a meal)

• language - difficulties following a conversation or finding the right word for something

• visuospatial skills - problems judging distances (eg on stairs) and seeing objects in three dimensions

• orientation - losing track of the day or date, or becoming confused about where they are.

• Alzheimer's disease - This is the most common cause of dementia. Brain cells are surrounded by an abnormal protein and their internal structure is also damaged. In time, chemical connections between brain cells are lost and some cells die. Problems with day-to-day memory are often noticed first, but other symptoms may include difficulties with: finding the right words, solving problems, making decisions, or perceiving things in three dimensions.

• Vascular dementia - If the oxygen supply to the brain is reduced because of narrowing or blockage of blood vessels, some brain cells become damaged or die. This causes vascular dementia. The symptoms can occur either suddenly following one large stroke, or over time through a series of small strokes or damage to small blood vessels deep in the brain. The symptoms of vascular dementia vary and may overlap with those of Alzheimer's disease. Many people have difficulties with problem-solving or planning, thinking quickly and concentrating. They may also have short periods when they get very confused.

• Mixed dementia - This is when someone has more than one type of dementia, and a mixture of symptoms. It is common for someone to have Alzheimer's disease and vascular dementia together.

• Dementia with Lewy bodies - This type of dementia involves tiny abnormal structures (Lewy bodies) developing inside brain cells. They disrupt the brain's chemistry and lead to the death of brain cells. Early symptoms can include fluctuating alertness, difficulties with judging distances and hallucinations. Day-to-day memory is usually affected less than in early Alzheimer's disease. Dementia with Lewy bodies is closely related to Parkinson's disease and often has some of the same symptoms, including difficulty with movement.

• Frontotemporal dementia (including Pick's disease) - In frontotemporal dementia, the front and side parts of the brain are damaged over time when clumps of abnormal proteins form inside nerve cells, causing them to die. At first, changes in personality and behaviour may be the most obvious signs. Depending on where the damage is, the person may have difficulties with fluent speech or may forget the meaning of words or objects.
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As well as these cognitive symptoms, a person with dementia will often have changes in their mood. For example, they may become frustrated or irritable, withdrawn, anxious, easily upset or unusually sad.

With some types of dementia, the person may see things that are not really there (visual hallucinations) or believe things that are not true (delusions).

Dementia is progressive, which means the symptoms gradually get worse over time. How quickly dementia progresses varies greatly from person to person.

As dementia progresses, the person may develop behaviours that seem unusual or out of character. These behaviours may include repetitive questioning, pacing, restlessness or agitation. They can be distressing or challenging for the person and their carer.

A person with dementia, especially in the later stages, may have physical symptoms such as muscle weakness or weight loss. Changes in sleep pattern and appetite are also common.

What causes dementia?

There are many diseases that result in dementia. The most common types of dementia are outlined below:

The symptoms of these types of dementia are often different in the early stages but become more similar in the later stages. This is because more of the brain becomes affected as the different diseases progress.

In the later stages of dementia, the person will need more and more support to carry out everyday tasks. However, many people with dementia maintain their independence and live well for years after their diagnosis. Information, advice and support are available for the person and their carer to help them live well with dementia.

SOURCE: Alzheimers Society