Dementia Information What is dementia? Dementia is a set of symptoms relating to a loss of cognitive ability, including memory loss and issues with thinking, problem solving and language. Alzheimer's disease is the most common cause of dementia, accounting for about 62% of cases. Over 850,000 people live with dementia in the UK and this is predicted to rise to over 2 million by 2051 as the population is ageing. Dementia is a global issue. The total number of people with dementia worldwide is estimated at 47.5 million in 2015. This number will increase to an estimated 75.6 million by 2030, and 135.5 million by 2050. It is estimated that there is a new case of dementia somewhere in the world every 4 seconds. Dementia affects 1 in 14 people over the age of 65 and 1 in 6 over the age of 80, but it should not be thought of as a normal part of ageing. Younger people can be affected, although this is much less common – only 1 in 688 people under 65 have dementia. It is estimated only 1 in 4 people with Alzheimer’s disease have been diagnosed. Funds for Alzheimer's research in the NHS and Universities are inadequate, receiving a fraction of what is spent per patient on cancer research. Dementia costs the UK £26.3 billion a year. The global cost of Alzheimer’s and dementia is estimated to be over £390 billion, which is equivalent to 1% of the entire world’s gross domestic product.