The Medical Research Council
Cognitive Function and Ageing Study

(MRC CFAS)

The Design of the MRC Cognitive Function and Ageing Study

The Study Population

The study has six centres across England and Wales.
 

• Cambridgeshire
• Gwynedd
• Newcastle
• Nottingham
• Oxford
• Liverpool
  
  

These centres were chosen because they represent the national variation with regards to urban-rural, socio-economic levels and in known rates of chronic disease. Furthermore, all centres had existing researchers with experience in this type of study.

Five of the centres follow an identical study design, while the centre in Liverpool, which was established earlier, has a different design.

How the population was sampled

Random samples of people in their 65th year and above were obtained from Family Health Service Authority lists from the six centres. 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 only exception to this was the centre in Liverpool which aimed to achieve a sample size of 6000.

Timetable of the main CFAS study

Studies of incidence and natural history require tests for dementia to be carried out at a minimum of two points in time, sufficiently separated for change in cognitive function to be identifiable. 

First meeting with the participants (1991/92)

• 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.
• Roughly 3 months later all the participants identified by the first interviews as possible cases of dementia had a more detailed assessment interview. In addition a sample of those participants not suspected of having dementia was also interviewed. In total 20% of the original sample had the assessment interview.

These interviews allowed CFAS to estimate the prevalence of dementia in the population.

Interviews to identify new cases of dementia (1993/94)

• After 2 years the participants who had not been identified as potential cases of dementia at the first interview were retested
• Those that were identified as possible new cases of dementia then had a more detailed assessment.

The 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 has been 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 3145 were re-interviewed.

Biological Samples

Blood or saliva samples were taken from 1733 participants having assessment interviews during 1997. Other blood samples have also been taken from smaller subgroups of participants at other times during the study and in total there are 2670 samples stored.

Participants in the study are asked if they wish to donate their brain to the study after death. The number of successful donations is now in excess of 500.

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