Robitaille et al., 2013. Longitudinal mediation of processing speed on age-related change in memory and fluid intelligence.

Robitaille, A., Piccinin, A. M., Muniz-Terrera, G., Hoffman, L., Johansson, B., Deeg, D. J., Aartsen, M.J., Comijs, H.C. & Hofer, S. M. (2013). Longitudinal mediation of processing speed on age-related change in memory and fluid intelligence. Psychology and aging, 28(4), 887.

Year: 
2013
Status: 
complete
Abstract: 

Age-related decline in processing speed has long been considered a key driver of cognitive aging. While the majority of empirical evidence for the processing speed hypothesis has been obtained from analyses of between-person age differences, longitudinal studies provide a direct test of within-person change. Using recent developments in longitudinal mediation analysis, we examine the speed—mediation hypothesis at both the within-and between-person levels in two longitudinal studies, Longitudinal Aging Study Amsterdam (LASA) and Origins of Variance in the Oldest-Old (OCTO-Twin). We found significant within-person indirect effects of change in age, such that increasing age was related to lower speed, which in turn relates to lower performance across repeated measures on other cognitive outcomes. Although between-person indirect effects were also significant in LASA, they were not in OCTO-Twin which is not unexpected given the age homogeneous nature of the OCTO-Twin data. A more in-depth examination through measures of effect size suggests that, for the LASA study, the within-person indirect effects were small and between-person indirect effects were consistently larger. These differing magnitudes of direct and indirect effects across levels demonstrate the importance of separating between- and within-person effects in evaluating theoretical models of age-related change. (PsycINFO Database Record (c) 2016 APA, all rights reserved)

Robitaille, 2014. Physical Activity And Cognitive Functioning in the Oldest Old

Robitaille, A., Muniz, G., Lindwall, M., Piccinin, A. M., Hoffman, L., Johansson, B., & Hofer, S. M. (2014). Physical activity and cognitive functioning in the oldest old: within-and between-person cognitive activity and psychosocial mediators. European Journal of Ageing, 11(4), 333-347.

Year: 
2012
Status: 
complete
Presentation Citations: 

Robitaille, A., Muniz, G., Lindwall, M., Piccinin, A.M., Hoffman, L., Johansson, B., & Hofer, S.M. (October, 2012). Physical activity and cognitive functioning among older adults: Within- and between-person cognitive and psychosocial mediators.  Poster session presented at the 41th Annual Scientific and Educational Meeting of the CAG, Vancouver, BC.

Abstract: 

The current study examines the role of social contact intensity, cognitive activity, and depressive symptoms as within- and between-person mediators for the relationships between physical activity and cognitive functioning. All three types of mediators were considered simultaneously using multilevel structural equations modeling with longitudinal data. The sample consisted of 470 adults ranging from 79.37 to 97.92 years of age (M = 83.4; SD = 3.2) at the first occasion. Between-person differences in cognitive activity mediated the relationship between physical activity and cognitive functioning, such that individuals who participated in more physical activities, on average, engaged in more cognitive activities and, in turn, showed better cognitive functioning. Mediation of between-person associations between physical activity and memory through social contact intensity was also significant. At the within-person level, only cognitive activity mediated the relationship between physical activity and change in cognition; however, the indirect effect was small. Depressive symptomatology was not found to significantly mediate within- or between-person effects on cognitive change. Our findings highlight the implications of physical activity participation for the prevention of cognitive decline and the importance of meditational processes at the between-person level. Physical activity can provide older adults with an avenue to make new friendships and engage in more cognitive activities which, in turn, attenuates cognitive decline.

 

Brown et al., 2012. Social Activity and Cognitive Functioning Over Time: A Coordinated Analysis of Four Longitudinal Studies

Brown, C.L., Gibbons, L.E., Kennison, R.F., Robitaille, A., Lindwall, M., Mitchell, M., Shirk, S.D., Atri, A., Cimino, C.R., Benitez, A., MacDonald, S.W.S., Zelinski, E., Willis, S.L., Schaie, K.W., Johansson, B., Dixon, R.A., Mungas, D.M., Hofer, S.M. & Piccinin, A.M.  (2012). Social activity and cognitive functioning over time: a coordinated analysis of four longitudinal studies. Journal of Aging Research, vol. 2012, Article ID 287438, 12 pages. doi:10.1155/2012/287438.

Year: 
2012
Status: 
complete
Presentation Citations: 

Brown, C.L., Piccinin, A.M.,  Gibbons, L.E., Robitaille, A., Kennison, R.F., Lindwall, M., Mitchell, M., Shirk, S.D., Atri, A., Benitez, A., MacDonald, S.W.S., Zelinski, E., Willis, S.L., Schaie, K.W., Johansson, B., Dixon, R.A., Mungas, D.M., Cimino, C.R., & Hofer, S.M. (October, 2012). Social activity and maintaining cognitive abilities in aging: Evidence from up to 21 years of longitudinal data from three nations. Poster presented at the 41th Annual Scientific and Educational Meeting of the Canadian Association on Gerontology, Vancouver, BC. 

Abstract: 

Social activity is typically viewed as part of an engaged lifestyle that may help mitigate the deleterious effects of advanced age on cognitive function. As such, social activity has been examined in relation to cognitive abilities later in life. However, longitudinal evidence for this hypothesis thus far remains inconclusive. The current study sought to clarify the relationship between social activity and cognitive function over time using a coordinated data analysis approach across four longitudinal studies. A series of multilevel growth models with social activity included as a covariate is presented. Four domains of cognitive function were assessed: reasoning, memory, fluency, and semantic knowledge. Results suggest that baseline social activity is related to some, but not all, cognitive functions. Baseline social activity levels failed to predict rate of decline in most cognitive abilities. Changes in social activity were not consistently associated with cognitive functioning. Our findings do not provide consistent evidence that changes in social activity correspond to immediate benefits in cognitive functioning, except perhaps for verbal fluency.

Comijs et al., 2009. Classification models for early identification of persons at risk for dementia, a replication study.

Year: 
2009
Status: 
complete
Presentation Citations: 

Comijs, H. Van Den Kommer, T. N., Bontempo, D. E., Hofer, S. M., Dik, M., Piccinin, A. M., Deeg, D. J., & Johansson, B. (2009, November). Classification models for early identification of persons at risk for dementia, a replication study.  In S. M. Hofer (Chair), Coordinated and pooled data analyses of longitudinal studies of aging: Aging and dementia-related change in cognition, affect, and physical functioning. Paper symposium conducted at the annual meeting of the Gerontological Society of America, Atlanta.

Abstract: 

Background: The goal of the present study is to develop a classification model for use in primary care using markers which are relatively easy to determine to aid early identification of persons at risk for dementia. 

Methods: Data were used from the Origins of Variance in the Old-Old (OCTO-Twin) study. The baseline sample included 521 non-demented subjects aged 80 and older. Relevant predictors on dementia were collected two years prior to dementia diagnosis. Dementia diagnosis was based on DSM-III-R criteria. Data were analyzed using generalized estimating equations and Cox survival analyses. 

Results: Overall, the two-year incidence of dementia was 6.9%. Reporting memory complaints was the strongest predictor of dementia. Memory complaints and a MMSE score ≤ 25 resulted in a predictive value for dementia of 28.8%. No memory complaints, drinking no alcohol and a MMSE score ≤ 24 resulted in a predictive value of 18.0%. Reporting no memory complaints, drinking alcohol, having functional limitations and a MMSE score ≤ 24 resulted in a percentage of 24.7% identified with dementia after two years of follow-up. 

Conclusions: The developed classification tree could contribute to early identification of persons at risk for dementia in primary care in a feasible and cost-effective way.

 

Denier et al., 2017. Retirement and Cognition: A Life Course View.

Denier, N., Clouston, S. A., Richards, M., & Hofer, S. M. (2017). Retirement and cognition: A life course view. Advances in life course research, 31, 11-21. DOI: 10.1016/j.alcr.2016.10.004.

Year: 
2017
Status: 
complete
Abstract: 

This study examines the relationship between retirement and cognitive aging. We build on previous research by exploring how different specifications of retirement that reflect diverse pathways out of the labor market, including reason for leaving the pre-retirement job and duration spent in retirement, impact three domains of cognitive functioning. We further assess how early-life factors, including adolescent cognition, and mid-life work experiences, condition these relationships. To do so, we draw on longitudinal data from the Wisconsin Longitudinal Study, a cohort study of Wisconsin high school graduates collected prospectively starting in 1957 until most recently in 2011 when individuals were aged 71. Results indicate that retirement, on average, is associated with improved abstract reasoning, but not with verbal memory or verbal fluency. Yet, when accounting for the reason individuals left their pre-retirement job, those who had retired for health reasons had both lower verbal memory and verbal fluency scores and those who had retired voluntarily or for family reasons had improved abstract memory scores. Together, the results suggest that retirement has an inconsistent effect on cognitive aging across cognitive domains and that the conditions surrounding the retirement decision are important to understanding cognitive functioning at older ages.

Cadar et al., 2017. An International Evaluation of Cognitive Reserve and Memory Changes in Early Old Age in 10 European Countries.

Cadar, D., Robitaille, A., Clouston, S., Hofer, S. M., Piccinin, A. M., & Muniz-Terrera, G. (2017). An international evaluation of cognitive reserve and memory changes in early old age in 10 European countries. Neuroepidemiology, 48(1-2), 9-20.

Year: 
2017
Status: 
complete
Abstract: 

Background: Cognitive reserve was postulated to explain individual differences in susceptibility to ageing, offering apparent protection to those with higher education. We investigated the association between education and change in memory in early old age. 

Methods: Immediate and delayed memory scores from over 10,000 individuals aged 65 years and older, from 10 countries of the Survey of Health, Ageing and Retirement in Europe, were modeled as a function of time in the study over an 8-year period, fitting independent latent growth models. Education was used as a marker of cognitive reserve and evaluated in association with memory performance and rate of change, while accounting for income, general health, smoking, body mass index, gender, and baseline age. 

Results: In most countries, more educated individuals performed better on both memory tests at baseline, compared to those less educated. However, education was not protective against faster decline, except for in Spain for both immediate and delayed recall (0.007 [SE = 0.003] and 0.006 [SE = 0.002]), and Switzerland for immediate recall (0.006 [SE = 0.003]). Interestingly, highly educated Italian respondents had slightly faster declines in immediate recall (-0.006 [SE = 0.003]). 

Conclusions: We found weak evidence of a protective effect of education on memory change in most European samples, although there was a positive association with memory performance at individuals' baseline assessment.

Dodge et al., 2017. Cohort effects in verbal memory function and practice effects: a population-based study.

Dodge, H. H., Zhu, J., Hughes, T. F., Snitz, B. E., Chang, C. C. H., Jacobsen, E. P., & Ganguli, M. (2017). Cohort effects in verbal memory function and practice effects: a population-based study. International psychogeriatrics, 29(1), 137-148.

Year: 
2017
Status: 
complete
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.