Alzheimer's Society

The term 'dementia' is used to describe the symptoms that occur when the brain is affected by specific diseases and conditions. There are over 100 different types of dementia. Some of the more common causes are outlined below.

This is the most common cause of dementia. During the course of the disease, the chemistry and structure of the brain changes, leading to the death of brain cells.

Factsheet: What is Alzheimer's disease?

If the oxygen supply to the brain fails, brain cells may die. The symptoms of vascular dementia can occur either suddenly, following a stroke, or over time, through a series of small strokes.

Factsheet: What is vascular dementia?

This form of dementia gets its name from tiny spherical structures that develop inside nerve cells. Their presence in the brain leads to the degeneration of brain tissue.

Fact sheet: What is dementia with Lewy bodies (DLB)?

In fronto-temporal dementia, damage is usually focused in the front part of the brain. Personality and behaviour are initially more affected than memory.

Factsheet: What is fronto-temporal dementia (including Pick's disease)?

Korsakoff's syndrome is a brain disorder that is usually associated with heavy drinking over a long period. Although it is not strictly speaking a dementia, people with the condition experience loss of short term memory.

Factsheet: What is Korsakoff's syndrome?

Prions are infectious agents that attack the central nervous system and then invade the brain, causing dementia. The best-known prion disease is Creutzfeldt-Jakob disease, or CJD.

Factsheet: What is Creutzfeldt-Jakob disease (CJD)?

People with Aids sometimes develop cognitive impairment, particularly in the later stages of their illness.

Factsheet: What is Aids-related cognitive impairment?

Mild cognitive impairment (MCI) is a relatively recent term, used to describe people who have some problems with their memory but do not actually have dementia.

Factsheet: Mild cognitive impairment

There are many other rarer causes of dementia, including progressive supranuclear palsy and Binswanger's disease. People with multiple sclerosis, motor neurone disease, Parkinson's disease and Huntington's disease can also be at an increased risk of developing dementia.

Factsheet: Rarer causes of dementia