Changes in dementia prevalence: Implications for public health

Abstract

The Medical Research Council (MRC) cognitive functioning and ageing study (CFAS) I study collected epidemiologically representative data between 1989 and 1994 in people aged 65 and over in England and Wales; it estimated dementia prevalence to be 8.3% in this age group, standardised to the 2011 population. CFAS II replicated the survey in Cambridgeshire, Newcastle and Nottingham in 2008-11 and found a dementia prevalence of 6.5%, a statistically significant relative decrease of 21% over 20 years. CFAS I had an 80% response rate, with a 56% response rate in CFAS II: sensitivity analyses showed that assuming non-responders were 50% more likely to have dementia increased estimated prevalence in CFAS II to 7.7% and if they were twice as likely to have dementia, prevalence would have been 8.5%. A total of 5% of people aged 65 and over lived in care homes in CFAS I of whom 56% had dementia, but by CFAS II only 3% of the sample were care home residents, though dementia prevalence among these had increased to 79%: the net effect was that by CFAS II a higher proportion of people with dementia resided in their own homes. Newcastle's estimated standardised dementia prevalence of 7.2% was higher than that of Nottingham (6.0%) and Cambridgeshire (6.1%). © 2014 Royal College of Physicians of Edinburgh.