- The main survey interview
- The CAMDEX interview
- Biological resources
- Other measures
- Proxy informant interviews
- Retrospective informant interviews
The CC75C study has collected a variety of resources – in addition to data from the series of interviews and assessments, research holdings include also biological resources.
The main survey interview
The core dataset comprises data gathered from the ten main surveys to date using the CC75C study’s structured schedule administered by trained interviewers. This has undergone slight revisions over the years, with the addition of new sections such as questions on physical activity and use of health services in Survey 3 and on recent falls in Survey 4, but maintaining continuity of core measures has remained a priority.
However, the CC75C study also holds other data resources collected at different periods in the study to examine specific topics of importance in ageing research.
The CAMDEX interview
After the baseline cognitive screening assessment, those who scored 23 or below in the Mini-Mental State Examination (MMSE), and one in three of those with MMSE scores 24 or 25, were assessed using the Cambridge Mental Disorders of the Elderly Examination (CAMDEX), a structured schedule specifically designed to detect mild dementia. After Surveys 2 and 3 all participants were invited to participate in further CAMDEX assessments. The CAMDEX includes a mental state examination, a psychiatric history, detailed cognitive testing and an interview with a proxy informant.
During Survey 4 blood tests and saliva samples were gathered for genetic studies from all participants who consented.
Magnetic resonance imaging brain scans were taken of a sub-sample following Survey 2.
It was also in Survey 2 that the brain donation programme began to identify study participants willing to donate brain tissue after their death. This programme is still running, and 230 donations have been collected so far.
In Survey 6 (Year 17) new physical measurements were recorded for the first time: in addition to the usual CC75C questionnaire, the project nurse conducted functional assessments and scanned heel bones with quantitative ultrasound as part of this survey’s focus on falls amongst over-90-year-olds.
In Survey 6 (Year 17) only, each participant was followed-up intensively for 12 months, tracking the consequences of falls in advanced old age – injuries, hospitalisation and moves into long-term care.
In Survey7 (Year 21) voice recordings were introduced to capture in their own words the perspective of very old people and their carers on important end-of-life issues, and qualitative research methods have added a further element to the wealth of quantitative data from the study.
Proxy informant interviews
All study participants were interviewed in person in Surveys 1 and 2 but interviews with proxy informants were used in subsequent surveys, if study participants could not complete interviews themselves, so as to minimise loss to follow-up that could under-represent the frailest elderly.
Retrospective informant interviews
Proxy informants are also interviewed about study participants who have died to provide information about their physical and mental health and their need for support services in the period leading up to death. These interviews concern those who became brain tissue donors when they died.