Study Design

Below you will find information on the study design of MRC CFAS, to find more about what the study is about please visit the MRC CFAS homepage; a full study background can be found here: Study-Background.

MRC CFAS has six centres across England and Wales: Cambridgeshire, Gwynedd, Newcastle, Nottingham, Oxford and Liverpool. Five of the centres started in the 1991 follow an identical study design, while the centre in Liverpool, which was established earlier in 1989, has a different design. Random samples of people in their 65th year and above were obtained from Family Health Service Authority lists from each centre. The sample was stratified by age group (65-74 years and 75 years and over) and equal numbers were randomly selected from each age group to produce an overall sample size of approximately 2500 people in each of the areas. The exceptions to this was the Liverpool centre which aimed to achieve a sample size of 6000.

Study Design

 

The first interviews established level of cognitive performance and baseline risk factors on all individuals. The interviews were designed to be fully sensitive to dementia. All of the participants identified by the first interview as possible cases of dementia had a more detailed assessment interview. In addition a sample of those participants not suspected of having dementia were also interviewed. In total 20% of the original sample had the assessment interview.

These initial interviews allowed CFAS to estimate the prevalence of dementia in the population. After two years the participants who has not been identified as potential cases of dementia at the first interview were reassessed, those identified as possible new cases of dementia then had a more detailed assessment. This number of new cases identified allowed CFAS to estimate the incidence of dementia in the population.

Follow-up of Participants

Throughout the study a subgroup of the participants were seen every year and further interviews of other selected participants took place in 1997, 1999 and 2001.

In 2002/3 all survivors in the Cambridgeshire, Gwynedd, Newcastle, Nottingham and Oxford centres were approached by the study and 3,145 were re-interviewed.

After this stage only individuals expressing an intention of donating brain tissue have been followed up at two year intervals.