ABSTRACT
Analyses incorporating large independent population-based samples and identical measures are needed to investigate recent trends in cognitive function. Nationally representative independent cohorts of community living individuals in England aged 65 years or older from the MRC Cognitive Function and Ageing Study in 1991 (n = 9458) and the English Longitudinal Study of Ageing in 2002 (n = 5196) were compared. East Cambridgeshire participants aged 65–69 years in 1991 (n = 680) were also compared to an independent cohort examined in 1996 (n = 600). Semantic verbal fluency, as measured by the animal naming neuropsychological test, increased by 1.1 extra words a minute in England between 1991 and 2002 (95% CI 0.9, 1.3). A similar increase was also observed in East Cambridgeshire. Levels of semantic verbal fluency appear to have increased in the older English population, which may help to buffer the aging population from future increases in dementia.
We thank Carol Brayne, MD, University of Cambridge, for discussion on methodology and comments on the manuscript, and Fiona McDougall, MPhil, University of Cambridge, and Tony Johnson, PhD, MRC Biostatistics Unit, for comments on the manuscript. None of those acknowledged received compensation for their contributions. Dr David J. Llewellyn is funded by the University of Michigan. Dr Matthews is funded by the MRC. ELSA has been supported by grants from the NIA and several British government departments (2RO1AG7644-01A1, 2RO1AG017644). CFAS has been funded by UK Government Department of Health and is currently funded by the MRC (G8712116, G9626116, G9901400). The East Cambridgeshire study was supported by NHS Eastern Region Research and Development funding. The funders played no role in the preparation or submission of this manuscript.