Neurological conditions /

Alzheimer’s disease and dementia

Dementia is a general term for a decline in mental ability that is severe enough to affect daily life. It encompasses a set of symptoms including memory loss and difficulties with thinking, problem-solving and language. It can be caused when the brain is damaged by disease or injury. Alzheimer’s disease is the most common cause of dementia.

Who is affected?

Although dementia should not be considered an inevitable part of ageing, it primarily affects older people. It is estimated to affect one in 14 people over the age of 65 and one in six over 80.

Increases in life expectancy mean that more people have dementia than ever before. There are estimated to be more than 850,000 people living with dementia in the UK today, and 210,000 new cases diagnosed every year.

Dementia in younger people is much less common but around 42,000 people under the age of 65 years in the UK have early-onset dementia.

The impact of dementia

Dementia is cruel and unrelenting. It gradually strips people of their ability to function. There are no effective treatments to prevent, cure or slow the progression of the diseases that cause dementia.

Dementia is a leading cause of death, responsible for almost 80,000 deaths every year in the UK. This is 1 in 8 of all deaths.

And whilst the number of deaths from the other leading killers – including stroke, heart disease and cancer – have all fallen in recent years, the number of deaths from Alzheimer’s and dementia is increasing. This reflects the increasing prevalence and the lack of any effective treatments.

Types of dementia

There are a number of different types of dementia; these may present with slightly different symptoms and have different underlying causes. It is possible to have more than one type of dementia at the same time.

Alzheimer’s disease is the most common cause of dementia, responsible for almost two thirds of cases. It often develops slowly over several years and is not always obvious to begin with. Early symptoms such as mild forgetfulness can often be mistaken for normal signs of ageing.

Vascular dementia is the second most common cause of dementia. It can be caused when blood supply to the brain is interrupted or reduced. The symptoms can occur suddenly, after a brain injury such as a stroke, or they can develop over time, as a result of a progressive disease or a series of mini strokes.

Dementia with Lewy bodies involves tiny abnormal structures forming inside brain cells. These disrupt the chemistry of the brain and lead to the death of brain cells. Dementia with Lewy bodies is closely related to Parkinson’s disease and can have similar symptoms, including difficulty with movement.

Frontotemporal dementia (sometimes called Pick’s disease) is a form of dementia that mainly affects younger people, usually those between the ages of 45 and 64. It is caused by damage to cells in areas of the brain called the frontal and temporal lobes, the front and side parts of the brain.


There is no cure for dementia and no treatments have been proven to slow its progression. However, there are drugs and non-drug treatments that can reduce symptoms. Ongoing research is advancing our knowledge of the causes of Alzheimer’s disease and other dementias, and exploring the development of new drugs either to give better relief from symptoms or – if possible – to slow down or stop the underlying disease in the brain. We are currently funding an important piece of research by Professor Jonathan Schott at UCL Institute of Neurology. He and colleagues are undertaking a landmark study of a group of people born in the same week in 1946 to explore the interaction of genes and lifestyle in the development of Alzheimer’s and other brain diseases.