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Cohort effects in verbal memory function and practice effects: a population-based study

  • Hiroko H Dodge (a1) (a2), Jian Zhu (a3), Tiffany F. Hughes (a4), Beth E. Snitz (a5), Chung-Chou H. Chang (a6) (a7), Erin P. Jacobsen (a8) and Mary Ganguli (a5) (a8) (a9)...
Abstract
Background:

In many developed countries, cognitive functioning (as measured by neuropsychological tests) appears to be improving over time in the population at large, in parallel with the declining age-specific incidence of dementia. Here, we investigated cohort effects in the age-associated trajectories of verbal memory function in older adults. We sought to determine whether they varied by decade of birth and, if so, whether the change would be explained by increasing educational attainment.

Methods:

Pooling data from two prospective US population-based studies between 1987 and 2015, we identified four birth cohorts born 1902–1911, 1912–1921, 1922–1931, and 1932–1943. Among these cohorts, we compared age-associated trajectories both of performance and of practice effects on immediate and delayed recall of a 10-item Word List. We used mixed effects models, first including birth cohorts and cohort X age interaction terms, and then controlling for education and education X age interaction.

Results:

We observed significant cohort effects in performance (baseline and age-associated trajectories) in both immediate recall and delayed recall, with function improving between the earliest- and latest-born cohorts. For both tests, we also observed cohort effects on practice effects with the highest levels in the latest-born cohorts. Including education in the models did not attenuate these effects.

Conclusions:

In this longitudinal population study, across four decade-long birth cohorts, there were significant improvements in test performance and practice effects in verbal memory tests, not explained by education. Whether this reflects declining disease incidence or other secular trends awaits further investigation.

Copyright
Corresponding author
Correspondence should be addressed to: Dr. Mary Ganguli, WPIC, 3811 O'Hara Street, Pittsburgh, PA 15213. Email gangulim@upmc.edu.
References
Hide All
Albano, A. (2013). Equate: Statistical methods for test score equating. R package Version 1.2-0. Available at: http://CRAN.R-project.org/package=equate.
Becker, J. T., Boller, F., Saxton, J. and McGonigle-Gibson, K. L. (1987). Normal rates of forgetting of verbal and non-verbal material in Alzheimer's disease. Cortex, 23, 5972.
Bordone, V., Scherbov, S. and Steiber, N. (2015). Smarter every day: the deceleration of population ageing in terms of cognition. Intelligence, 52, 9096.
Centers for Disease Control and Prevention. (2016). Trends in Current Cigarette Smoking Among High School Students and Adults, United States, 1965-2014. National Health Interview Survey, 1965-2014. Available at: http://www.cdc.gov/tobacco/data_statistics/tables/trends/cig_smoking/index.htm; last accessed 2016.
Christensen, K. et al. (2013). Physical and cognitive functioning of people older than 90 years: a comparison of two Danish cohorts born 10 years apart. Lancet, 382, 1507–13.
Dodge, H. H., Wang, C. N., Chang, C. C. and Ganguli, M. (2011). Terminal decline and practice effects in older adults without dementia: the MoVIES project. Neurology, 77, 722–30.
Dodge, H. H., Zhu, J., Lee, C. W., Chang, C. C. and Ganguli, M. (2014). Cohort effects in age-associated cognitive trajectories. Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 69, 687–94.
Efron, B. (1979). Bootstrap methods: another look at the jackknife. Annals of Statistics, 7, 126.
Flegal, K. M., Carroll, M. D., Kit, B. K. and Ogden, C. L. (2012). Prevalence of obesity and trends in the distribution of body mass index among US adults, 1999-2010. JAMA, 307, 491–7.
Flynn, J. R. (1987). Massive IQ gains in 14 nations - what Iq tests really measure. Psychological Bulletin, 101, 171191.
Freedman, V. A., Aykan, H. and Martin, L. G. (2002). Another look at aggregate changes in severe cognitive impairment: further investigation into the cumulative effects of three survey design issues. The Journals of Gerontology Series B: Psychological Sciences and Social Sciences, 57, S126–31.
Fuld, P. A. (1981). Fuld Object-Memory Evaluation. Woodale, IL: Stoelting Co.
Ganguli, M., Dodge, H. H., Chen, P., Belle, S. and DeKosky, S. T. (2000). Ten-year incidence of dementia in a rural elderly US community population: the MoVIES Project. Neurology, 54, 1109–16.
Ganguli, M., Snitz, B. E., Lee, C. W., Vanderbilt, J., Saxton, J. A. and Chang, C. C. (2010). Age and education effects and norms on a cognitive test battery from a population-based cohort: the monongahela-youghiogheny healthy aging team. Aging and Mental Health, 14, 100–7.
Gregg, E. W. et al. (2014). Changes in diabetes-related complications in the United States, 1990-2010. New England Journal of Medicine, 370, 1514–23.
Gross, A. L. et al. (2015). Predictors of retest effects in a longitudinal study of cognitive aging in a diverse community-based sample. Journal of the International Neuropsychological Society, 21, 506–18.
Koton, S. et al. (2014). Stroke incidence and mortality trends in US communities, 1987 to 2011. JAMA, 312, 259–68.
Laird, N. M. (1988). Missing data in longitudinal studies. Statistics in Medicine, 7, 305–15.
Langa, K. M. et al. (2008). Trends in the prevalence and mortality of cognitive impairment in the United States: is there evidence of a compression of cognitive morbidity?. Alzheimer's & Dementia, 4, 134–44.
Little, R. J. A. (1995). Modeling the drop-out mechanism in repeated-measures studies. Journal of the American Statistical Association, 90, 1112–21
Livingston, S. A. (2004). Equating Test Scores (without IRT). Princeton, NJ: ETS.
Llewellyn, D. J. and Matthews, F. E. (2009). Increasing levels of semantic verbal fluency in elderly English adults. Neuropsychology, Development, and Cognition. Section B, Aging, Neuropsychology and Cognition, 16, 433–45.
Matthews, F. E. et al. (2013). A two-decade comparison of prevalence of dementia in individuals aged 65 years and older from three geographical areas of England: results of the cognitive function and ageing study I and II. Lancet, 382, 1405–12.
Monsell, S. E. et al. (2016). Results from the NACC uniform data set neuropsychological battery crosswalk study. Alzheimer Disease and Associated Disorders, 30, 134–39.
Morris, J. C. et al. (1989). The Consortium to Establish a Registry for Alzheimer's Disease (CERAD). Part I. Clinical and neuropsychological assessment of Alzheimer's disease. Neurology, 39, 1159–65.
O'Brien, E., Wu, K. B. and Baer, D. (2010). Older Americans in Poverty: A Snapshot. Washington, DC: AARP Public Policy Institute.
Osone, A., Arai, R., Hakamada, R. and Shimoda, K. (2016). Cognitive and brain reserve in conversion and reversion in patients with mild cognitive impairment over 12 months of follow-up. Journal of Clinical and Experimental Neuropsychology Epublished ahead of print. doi: 10.1080/13803395.2016.1191620.
Qiu, C., von Strauss, E., Backman, L., Winblad, B. and Fratiglioni, L. (2013). Twenty-year changes in dementia occurrence suggest decreasing incidence in central Stockholm, Sweden. Neurology, 80, 1888–94.
Sacuiu, S. et al. (2010). Secular changes in cognitive predictors of dementia and mortality in 70-year-olds. Neurology, 75, 779–85.
Satizabal, C. L., Beiser, A. S., Chouraki, V., Chene, G., Dufouil, C. and Seshadri, S. (2016). Incidence of dementia over three decades in the Framingham heart study. New England Journal of Medicine, 374, 523–32.
Schrijvers, E. M., Verhaaren, B. F., Koudstaal, P. J., Hofman, A., Ikram, M. A. and Breteler, M. M. (2012). Is dementia incidence declining?: Trends in dementia incidence since 1990 in the Rotterdam study. Neurology, 78, 1456–63.
Stern, Y. (2002). What is cognitive reserve? Theory and research applications of the reserve concept. Journal of the International Neuropsychological Association, 8, 448460.
Wechsler, D. (1987). Wechsler Memory Scale Revised. San Antonio, TX: The Psychological Corporation.
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International Psychogeriatrics
  • ISSN: 1041-6102
  • EISSN: 1741-203X
  • URL: /core/journals/international-psychogeriatrics
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