§ Mrs Curtis-Thomas
To ask the Secretary of State for Health what the most significant known risk factor for dementia is; how many people are living with dementia in(a) the UK and (b) Sefton; and how many of those people are under the age of 65. 
§ Dr. Ladyman
There is no routine collection of information at national or local level about the number of people living with dementia. The research, quoted by the older people's national service framework in 2001, estimated that approximately 600,000 people in the United Kingdom have dementia, of whom there are about 17,000 people under the age of 65.
The most significant known risk factor for dementia is age. It is estimated that about 5 per cent. of people over 65 have dementia, rising to about 20 per cent. in the population over 80.