which only £4.3 billion is spent on health care [1]. Consid- ering also that a third of people in the UK born in 2015 will develop dementia in their lifetime [2] and the lack of an effective treatment for dementia [3], focusing on preven- tion of dementia certainly deserves to be high in health pol- icy agenda [4]. Decision-makers urgently need evidence about the cost-effectiveness of the potential prevention strategies [3].