Intellectual engagement and cognitive ability in later life (the “use it or lose it” conjecture): longitudinal, prospective studyBMJ 2018; 363 doi: https://doi.org/10.1136/bmj.k4925 (Published 10 December 2018) Cite this as: BMJ 2018;363:k4925
- Roger T Staff, clinical scientist1,
- Michael J Hogan, senior lecturer2,
- Daniel S Williams, undergraduate3,
- L J Whalley, professor emeritus4
- 1NHS Grampian, Aberdeen, UK
- 2Department of Psychology, National University of Ireland, Galway, Ireland
- 3Department of Psychology. University of Aberdeen, UK
- 4Institute of Applied Health Sciences, University of Aberdeen, UK
- Correspondence to: R T Staff, Aberdeen Royal Infirmary, Aberdeen AB25 2ZH, UK
- Accepted 20 November 2018
Objectives To examine the association between intellectual engagement and cognitive ability in later life, and determine whether the maintenance of intellectual engagement will offset age related cognitive decline.
Design Longitudinal, prospective, observational study.
Setting Non-clinical volunteers in late middle age (all born in 1936) living independently in northeast Scotland.
Participants Sample of 498 volunteers who had taken part in the Scottish Mental Health Survey of 1947, from one birth year (1936).
Main outcome measures Cognitive ability and trajectory of cognitive decline in later life. Typical intellectual engagement was measured by a questionnaire, and repeated cognitive measurements of information processing speed and verbal memory were obtained over a 15 year period (recording more than 1200 longitudinal data points for each cognitive test).
Results Intellectual engagement was significantly associated with level of cognitive performance in later life, with each point on a 24 point scale accounting for 0.97 standardised cognitive performance (IQ-like) score, for processing speed and 0.71 points for memory (both P<0.05). Engagement in problem solving activities had the largest association with life course cognitive gains, with each point accounting for 0.43 standardised cognitive performance score, for processing speed and 0.36 points for memory (both P<0.05). However, engagement did not influence the trajectory of age related decline in cognitive performance. Engagement in intellectual stimulating activities was associated with early life ability, with correlations between engagement and childhood ability and education being 0.35 and 0.22, respectively (both P<0.01).
Conclusion These results show that self reported engagement is not associated with the trajectory of cognitive decline in late life, but is associated with the acquisition of ability during the life course. Overall, findings suggest that high performing adults engage and those that engage more being protected from relative decline.
Contributors: All authors contributed substantially to the conception and planning of the work that led to the manuscript or acquisition, analysis and interpretation of the data; contributed to the drafting and revision of the manuscript for important intellectual content, and approved the final submitted version of the manuscript; and had full access to all of the data (including statistical reports and tables) in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis. RTS is guarantor and accepts full responsibility for the work and conduct of the study and confirms that he had access to the data, and controlled the decision to publish. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.
Funding: The Aberdeen Birth Cohort Studies were initiated in 1998 by a grant from the Henry Smith Charity and later supported by the Biology and Biotechnology Science Research Council, the Medical Research Council, Wellcome Trust, Chief Scientist’s office of the Scottish Government Health Department, and Alzheimer Research UK. The study sponsor was the University of Aberdeen. The funders and sponsor played no role in the design, data collection, interpretation of the data, writing of the report, and the decision to submit the article for publication.
Competing interests: All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi_disclosure.pdf and declare: support from the University of Aberdeen for the submitted work; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.
Ethical approval: Ethics permissions were provided by the research ethics committee of University of Aberdeen and NHS Grampian. Volunteers gave written informed consent to a longitudinal observational study of brain ageing and health.
Data sharing: All data are available by application to the Aberdeen Birth Cohort steering group (https://www.abdn.ac.uk/birth-cohorts/1921/for-researchers/).
The lead author affirms that the manuscript is an honest, accurate, and transparent account of the study being reported; that no important aspects of the study have been omitted; and that any discrepancies from the study as planned (and, if relevant, registered) have been explained.
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