Mapping differences in memory and thinking abilities in people with and without dementia
Research project: Evidence synthesis of trajectories of cognitive change due to chronological age, death and preclinical dementia.
Lead Investigator: Dr Graciela Muniz-Terrera
Institution: University of Cambridge
Grant type: Research Fellowship
Duration: 3 years
Start date: September 2012
End date: December 2015
What was the project, and what did the researchers do?
This project looked at the role of education in how cognitive abilities - the ability to process, retain and use information - change with very early stage dementia compared to normal ageing.
Some studies have shown that people who have spent longer in education had a slower decline in their cognitive abilities, while other studies showed no difference in the rate of decline. As these studies all used slightly different techniques for measurements, it is hard to draw a conclusion. The aim of this study was therefore to compare and combine results from many studies already carried out but using different measures. By using a coordinated analytical approach, the intention was to be able to interpret the overall results.
The scientists used the same analytical model with data from 12 different studies. In this way they looked at the role of education in how cognitive abilities change over time.
What were the key results and how will this benefit people with dementia?
The main finding was that most studies show that while level of education is associated with level of cognitive performance, it is not associated with the rate of decline. Thus, better educated individuals performed better than less educated people, but they lost their cognitive abilities at the same rate.
The work also highlighted general issues about the culture of science and publication that are important in dementia research. It showed the need for open data (the primary data being available for others to analyse), and problems of publication bias (where journals prefer to accept and publish positive rather than negative results) as well as a lack of replication (where studies are not repeated, because funding and publication of such studies is more difficult). This information can be used to lobby funders and publishers to make research more accessible.
Studies such as this, which compare the many different studies that come out, give extra value in that they make other research carried out much more useful, ensuring that the overall impact of all the research put together is greater.
What happened next? Future work and additional grants
While this work showed that data could be combined, there were still many problems with the way that research such as this is conducted. Dr Muniz-Terrera is working on an initiative that aims to make analysis across different data sets more effective.
How were people told about the results? Conferences and publications
Cadar D et al. "Education, occupational status and cognitive decline in preclinical dementia: Evidence from the OCTO-Twin longitudinal study", GeroPsych The Journal of Gerontopsychology and Geriatric Psychiatry, Sept 2015
Cadar D et al. "The role of cognitive reserve on terminal decline: A cross cohort analysis from two European studies: OCTO-Twin, Sweden and Newcastle 85+, UK", International Journal of Geriatric Psychiatry, 2015, 10.1002/gps.4366, 1099-1166
Clouston SAP et al. "Educational Inequalities in Health Behaviours at Midlife: Is There a Role for Early-Life Cognition?" Journal of Health and Social Behavior, 56 (3), 323-340. Doi: 10.1177/0022146515594188 (2015)
Six abstracts were also published.
This work was presented at 26 conference presentations
The study's findings were covered by major newspapers, including the Daily Mail.