What are the symptoms?

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

Dementia isn’t a natural part of ageing. It occurs when the brain is affected by a disease.

There are many known causes of dementia – probably more than 100. The most common types are Alzheimer’s disease and vascular. Some people have a combination of these, known as mixed dementia.

  • It is predicted there will be around 850,000 people in the UK with the disease in 2018.
  • The chance of developing  the disease increases significantly with age. One in 14 people over 65 years of age, and one in six people over 80, have it. It is more common among women than men.
  • More than 40,000 younger people (under the age of 65) in the UK have the disease. This is called early-onset or young-onset dementia.
  • Dementia is an umbrella term. It describes the symptoms that occur when the brain is affected by certain diseases or conditions. There are many different types, although some are far more common than others. They are often named according to the condition that has caused the disease. Some of the more common types are outlined below.

Alzheimer’s disease

  • This is the most common cause. 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?

Vascular dementia

  • 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?

Dementia with Lewy bodies

  • This form of the disease gets its name from tiny spherical structures that develop inside nerve cells. Their presence in the brain leads to the degeneration of brain tissue.
  • Factsheet: What is dementia with Lewy bodies (DLB)?

Fronto-temporal dementia


Rarer causes of dementia

  • There are many other rarer causes, 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 the disease.
  • Factsheet: Rarer causes of dementia


Creutzfeldt-Jakob disease

  • 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: Rarer causes of dementia


Korsakoff’s syndrome

  • 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 type of the disease, people with the condition experience loss of short term memory.
  • Factsheet: What is Korsakoff’s syndrome?


HIV-related cognitive impairment


Mild 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  the disease.
  • Factsheet: Mild cognitive impairment

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