What is dementia?

Background

• Dementia is a term used to describe a general decline in all areas of mental ability.
• Symptoms include deterioration in mental processes including memory and language.
• In the UK, dementia affects around 800,000 people.
• About 60-80 per cent of dementia cases are the result of Alzheimer’s disease.

Alzheimer’s disease

• Causes 60-80 per cent of dementia cases
• Alzheimer’s causes tangles to form in the brain made from a protein called tau.
• These tangles kill the nerve cells in the brain causing it to shrink.
• This results initially in difficulties with day-to-day memory, problem solving and making decisions but can eventually lead to severe disorientation and confusion.

Vascular dementia

• About 10 per cent of people with dementia have vascular dementia.
• This is due to reduced blood flow to the brain because of blockages in the arteries leading up to the brain.
• These blockages are usually a result of atherosclerosis, where blood vessels become clogged with fatty deposits, such as cholesterol.

Lewy body dementia

• About 10 per cent of people with dementia have Lewy body dementia.
• Lewy bodies are tiny spherical deposits of protein that form in the nerve cells of the brain.
• It is not known exactly how these deposits form
• The presence of Lewy bodies is linked to low levels of chemical messengers, such as dopamine, and a loss of communication between nerve cells.

Reversible dementia

• Only about 10 per cent of dementia cases are treatable or potentially reversible.
• In these cases the dementia is often caused by short-term illnesses such as vitamin B12 deficiency, a brain tumour, syphilis infection or alcohol dependence.

Pre-senile vs senile dementia

• Traditionally, dementia was divided into ‘presenile’ or ‘senile’.
• Presenile dementia has an onset before 65 years of age.
• Senile dementia has an onset after 65 years of age.
• This separation has helped in the search for genetic causes of early-onset Alzheimer’s.
• An early diagnosis can help people with dementia get the right support, maintain their general wellbeing and help their close family and friends to prepare for the future.