What is dementia?

Dementia is the decline of mental ability, affecting memory, thinking, problem solving, concentration and perception; it also affects behaviour, for example inducing repetitive behaviour. Eventually dementia erodes the personality, which is perhaps the most distressing aspect of it.

Only five people in 100 over the age of 65 have dementia of any type. Of those who are over 80, only 20 per cent have dementia.

Dementia can be the result of brain injury, pressure on the brain from a brain tumour for example, and prolonged alcohol abuse. The commonest forms, however, are Alzheimer's disease, which accounts for 60 per cent of dementias, vascular dementia and dementia with Lewy bodies which has a close relationship with Parkinson's disease.