Zahodne et al., 2011. Education Does Not Slow Cognitive Decline with Aging: 12-Year Evidence from the Victoria Longitudinal Study

Zahodne, L.B., Glymour, M.M., Sparks, C., Bontempo, D., Dixon, R.A., MacDonald, S.W.S., & Manly, J.J. (2011). Education does not slow cognitive decline with aging: 12-year evidence from the Victoria Longitudinal Study. Journal of the International Neuropsychological Society, 17(6), 1039-1046

Year: 
2011
Status: 
complete
Abstract: 

Although the relationship between education and cognitive status is well-known, evidence regarding whether education moderates the trajectory of cognitive change in late life is conflicting. Early studies suggested that higher levels of education attenuate cognitive decline. More recent studies using improved longitudinal methods have not found that education moderates decline. Fewer studies have explored whether education exerts different effects on longitudinal changes within different cognitive domains. In the present study, we analyzed data from 1014 participants in the Victoria Longitudinal Study to examine the effects of education on composite scores reflecting verbal processing speed, working memory, verbal fluency, and verbal episodic memory. Using linear growth models adjusted for age at enrollment (range, 54–95 years) and gender, we found that years of education (range, 6–20 years) was strongly related to cognitive level in all domains, particularly verbal fluency. However, education was not related to rates of change over time for any cognitive domain. Results were similar in individuals older or younger than 70 at baseline, and when education was dichotomized to reflect high or low attainment. In this large longitudinal cohort, education was related to cognitive performance but unrelated to cognitive decline, supporting the hypothesis of passive cognitive reserve with aging. (JINS, 2011, 17, 1039–1046)

Clouston et al., 2012. Benefits of educational attainment on adult fluid cognition

Clouston, S., Kuh, D., Herd, P., Elliott, J., & Richards, M., & Hofer, S. M. (2012). Benefits of educational attainment on adult fluid cognition: International evidence from three birth cohorts. International Journal of Epidemiology, 41,1729-1736. PMID: 23108707.

Year: 
2012
Status: 
complete
Presentation Citations: 

Clouston, S., Kuh, D., Richards, M., & Hofer, S.M. (August, 2012). The implications of educational benefits and propensity for educational attainment in health research. Paper presented at the 2012 Annual Meeting of the American Sociological Association, Denver.

Clouston, S., Richards, M., Kuh, D., & Hofer, S.M. (November, 2011). Selection and causation: The Educational benefit to cognition in later life. In S. M. Hofer & D. Kuh (Chairs), The life course determinants of physical, cognitive, and emotional functioning. Symposium conducted at the 64th Annual Scientific Meeting of the Gerontological Society of America, Boston, MA.

Hofer, S. M., & Clouston, S. (2011, October). Educational benefits in adult cognition: International evidence from three birth cohort studies. Paper presented at the annual meeting of the Society of Multivariate Experimental Psychology, Norman, OK.

Clouston, S., Kuh, D., Richards, M., Deary, I. J., Cooper, R., Hardy, R., & Hofer, S. M. (August, 2011). Inequalities in life course cognition: Class reproduction, cognitive selection, and educational advantage in HALCyon cohorts. Paper presented at the 2011 Annual Meeting of the American Sociological Association, Las Vegas.

Abstract: 

Background: Educational attainment is highly correlated with social inequalities in adult cognitive health; however, the nature of this correlation is in dispute. Recently, researchers have argued that educational inequalities are an artefact of selection by individual differences in prior cognitive ability, which both drives educational attainment and tracks across the rest of the life course. Although few would deny that educational attainment is at least partly determined by prior cognitive ability, a complementary, yet controversial, view is that education has a direct causal and lasting benefit on cognitive development.

Methods: We use observational data from three birth cohorts, with cognition measured in adolescence and adulthood. Ordinary least squares regression was used to model the relationship between adolescent cognition and adult fluid cognition and to test the sensitivity of our analyses to sample selection, projection and backdoor biases using propensity score matching.

Results: We find that having a university education is correlated with higher fluid cognition in adulthood, after adjustment for adolescent cognition. We do not find that adolescent cognition, gender or parental social class consistently modify this effect; however, women benefited more in the 1946 sample from Great Britain.

Conclusions: In all three birth cohorts, substantial educational benefit remained after adjustment for adolescent cognition and parental social class, offsetting an effect equivalent of 0.5 to 1.5 standard deviations lower adolescent cognition. We also find that the likelihood of earning a university degree depends in part on adolescent cognition, gender and parental social class. We conclude that inequalities in adult cognition derive in part from educational experiences after adolescence.

Griffith et al., 2013. Harmonization of Cognitive Measures in Individual Participant Data and Aggregate Data Meta-Analysis

Griffith, L., van den Heuvel, E., Fortier, I., Hofer, S. M., Raina, P., Sohe,l N., Payette, H., Wolfson, C., & Belleville, S. (2013). Harmonization of Cognitive Measures in Individual Participant Data and Aggregate Data Meta-Analysis. Methods Research Report. (Prepared by the McMaster University Evidence-based Practice Center under Contract No. 290-2007-10060-I.) AHRQ Publication No.13-EHC040-EF. Rockville, MD: Agency for Healthcare Research and Quality. 

Year: 
2013
Status: 
complete
Abstract: 

Objectives: The aim of this study was to identify approaches to statistical harmonization which could be used in the context of summary data and/or individual participant data meta-analysis of cognitive measures and to apply and evaluate these different approaches to cognitive measures from three studies.

Data Sources: MEDLINE®, Embase, Web of Science and MathSciNet with a supplemental search using the Google search engine. The references of relevant articles were also checked and a search for more recent articles that cited the articles already identified as being of interest was undertaken.

Review methods: A two-pronged approach was taken for this environmental scan. First, a search of studies that quantitatively combined data on cognition was conducted. The second component was to identify general literature on statistical methods for data harmonization. Standard environmental scan methods were used to conduct these reviews. The search results were rapidly screened to identify articles of relevance to this review. The references of relevant articles were checked and a search for more recent articles that cited the articles already identified as being of interest was undertaken.

Results: Three general classes of statistical harmonization models were identified: (1) standardization methods (e.g., simple linear-, Z-transformations, T-scores, and C-scores); (2) latent variable models; and (3) multiple imputationmodels. Cross-sectional data from three studies including 9,269 participants were included in the applied analyses to examine the relationship between physical activity and cognition. A harmonization process was undertaken to determine the combinability of data across studies. The latent variable analysis underscored the difficulty harmonizing these cognition data. In general consistency was found among the statistical harmonization methods; however, there was some evidence that heterogeneity can be masked when specific standardization methods were used.

Conclusions: This study provides empirical evidence to inform methods of combining complex constructs using aggregate data (AD) or individual participant data meta-analysis. The results underscore that very careful consideration of inferential equivalence needs to be undertaken prior to combining cognition data across studies. Of the three methods of statistical harmonization for cognition data, T-score standardization is the least desirable compared with the centered score method or latent variable methods. Finally, assessment of the assumptions underlying statistical harmonization is not possible without some individual-level data which are required to assess the potential for bias in combining complex outcomes using AD meta-analysis.

Lindwall et al., 2012. Dynamic Associations of Change in Physical Activity and Change in Cognitive Function: Coordinated Analyses of Four Longitudinal Studies

Lindwall, M., Cimino, C. R., Gibbons, L. E., Mitchell, M., Benitez, A., Brown, C. L., Kennison, R. F., Shirk, S. D., Atri, A., Robitaille, A., MacDonald, S. W. S., Zelinski, E., Willis, S. L., Schaie, K. W., Johansson, B., Praetorius, M., Dixon, R. A., Mungas, D. M., Hofer, S. M. & Piccinin, A. M. (2012). Dynamic associations of change in physical activity and change in cognitive function: Coordinated analyses of four longitudinal studies. Journal of Aging Research, Article ID 493598, 12 pages, DOI:10.1155/2012/493598.

Year: 
2012
Status: 
complete
Presentation Citations: 

Piccinin, A.M.,  Kennison, R.F., Lindwall, M., Mitchell, M., Cimino, C.R., Benitez, A., Brown, C.L., Gibbons, L.E., MacDonald, S.W.S., Robitaille, A., Shirk, S.D., Atri, A., Zelinski, E., Willis, S.L., Schaie, K.W., Johansson, B., Dixon, R.A., Mungas, D.M., & Hofer, S.M. (October, 2012). Coordinated analysis of cross-sectional and longitudinal associations between physical and cognitive activity and cognition. Paper presented at the 41th Annual Scientific and Educational Meeting of the Canadian Association on Gerontology, Vancouver, BC.

Abstract: 

The present study used a coordinated analyses approach to examine the association of physical activity and cognitive change in four longitudinal studies. A series of multilevel growth models with physical activity included both as a fixed (between-person) and time-varying (within-person) predictor of four domains of cognitive function (reasoning, memory, fluency, and semantic knowledge) was used. Baseline physical activity predicted fluency, reasoning and memory in two studies. However, there was a consistent pattern of positive relationships between time-specific changes in physical activity and time-specific changes in cognition, controlling for expected linear trajectories over time, across all four studies. This pattern was most evident for the domains of reasoning and fluency.

Piccinin et al., 2011. An evaluation of analytical approaches for understanding change in cognition in the context of aging and health

Piccinin, A.M., Muniz, G., Sparks, C., & Bontempo, D.E. (2011). An evaluation of analytical approaches for understanding change in cognition in the context of aging and health.  Journal of Gerontology: Psychological Sciences, 66 (S1), i36-i49.

Year: 
2011
Status: 
complete
Abstract: 

Objectives. In this article, we discuss the importance of studying the relationship between health and cognitive function, and some of the methods with which this relationship has been studied.

Methods. We consider the challenges involved, in particular operationalization of the health construct and causal inference in the context of observational data. We contrast the approaches taken, and review the questions addressed: whether health and cognition are associated, whether changes in health are associated with changes in cognition, and the degree of interdependency among their respective trajectories.

Results. A variety of approaches for understanding the association between cognition and health in aging individuals have been used. Much of the literature on cognitive change and health has relied on methods that are based at least in part on the reorganization of between-person differences (e.g., cross-lag analysis) rather than relying more fully on analysis of within-person change and joint analysis of individual differences in within-person change in cognition and health.

Discussion. We make the case for focusing on the interdependency between within-person changes in health and cognition and suggest methods that would support this.

Robitaille et al., 2012. Multivariate longitudinal modeling of cognitive aging: Examining associations among change and variation in processing speed and visuospatial ability.

Robitaille, A., Muniz-Terrera, G., Piccinin, A. M., Johansson, B., & Hofer, S. M. (2012). Multivariate longitudinal modeling of cognitive aging: Examining associations among change and variation in processing speed and visuospatial ability. GeroPsych: The Journal of Gerontopsychology and Geriatric Psychiatry, 25, 15-25.

Year: 
2012
Status: 
complete
Presentation Citations: 

Robitaille, A., Piccinin, A.M., Muniz, G., Hoffman, L., Johansson, B., Deeg, D.J., Aartsen, M.J., Comijs, H.C., & Hofer, S.M., (November, 2013). Longitudinal mediation of processing speed on age-related change in memory and fluid intelligence. Poster presented at the 66th Annual Scientific Meeting of the Gerontological Society of America, New Orleans, LA.

Robitaille, A., Muniz, G., Piccinin, A.M., Hofer, S.M. (2011, October). Multivariate longitudinal modeling of cognitive change: Relationship between processing speed and other cognitive outcomes. 40th Annual Scientific and Educational Meeting of the CAG & 4th Pan American Congress of the IAGG, Ottawa, ON.

Robitaille, A., Muniz, G., Piccinin, A.M., Hofer, S.M. (November, 2011). Does Processing Speed Account for Aging-related Change in other Cognitive Functions? In A.M. Piccinin & G. Muniz (Chairs), Advances in Understanding Cognitive Aging: Longitudinal Research on Change, Variation, and Plasticity. Symposium conducted at the 64th Annual Scientific Meeting of the Gerontological Society of America, Boston, MA

Robitaille, A., Muniz, G., Piccinin, A.M., Johansson, B.,&  Hofer, S.M. (February, 2012). Multivariate longitudinal modeling of cognitive change: Relationship between processing speed and visuospatial ability. Poster session submitted to the 2012 SRCD Themed Meeting: Developmental Methodology. Tampa, Florida

Abstract: 

We illustrate the use of the parallel latent growth curve model using data from OCTO-Twin. We found a significant intercept-intercept and slope-slope association between processing speed and visuospatial ability. Within-person correlations among the occasion-specific residuals were significant, suggesting that the occasion-specific fluctuations around individual’s trajectories, after controlling for intraindividual change, are related between both outcomes. Random and fixed effects for visuospatial ability are reduced when we include structural parameters (directional growth curve model) providing information about changes in visuospatial abilities after controlling for processing speed. We recommend this model to researchers interested in the analysis of multivariate longitudinal change, as it permits decomposition and directly interpretable estimates of association among initial levels, rates of change, and occasion-specific variation.

Thorvaldsson et al., 2012. Nonlinear blood pressure effects on cognition in old age: Separating between-person and within-person associations

Thorvaldsson, V., Skoog, I., Hofer, S. M., Börjesson-Hanson, A., Östling, S., Sacuiu, S., & Johansson, B. (2012). Non-linear blood pressure effects on cognition in old age: Separating between-person and within-person associations. Psychology & Aging, 27, 375-383.

Year: 
2012
Status: 
complete
Abstract: 

Midlife hypertension is associated with increased risk of cognitive impairment in later life. The association between blood pressure (BP) in older ages and cognition is less clear. In this study we provide estimates of between-person and within-person associations of BP and cognition in a population-based sample (N = 382) followed from age 70 across 12 occasions over 30 years. Between-person associations refer to how individual differences in BP relates to individual differences in cognition. Within-person associations refer to how individual and time specific changes in BP relate to variation in cognition. Hierarchical linear models were fitted to data from three cognitive measurements (verbal ability, spatial ability, and perceptual speed) while accounting for demographic and health-related covariates. We found consistent nonlinear between-person associations between diastolic BP (DBP) and cognition, such that both low (<75 mmHg) and high (>95 mmHg) pressure were associated with poorer cognition. Within-person decreases in systolic BP (SBP) and DBP were associated with decreases in perceptual speed. Notably, between-person and within-person estimates did not reveal similar associations, suggesting the need to separate the two effects in the analysis of associations between BP and cognition in old age.

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.

Clouston et al., 2014. The Dynamic Relationship Between Physical Function and Cognition in Longitudinal Aging Cohorts

Clouston, S., Brewster, P., Kuh, D., Richards, M., Cooper, R., Hardy, R., Rubin, M., & Hofer, S. M. (2013). The dynamic relationship between physical function and cognition in longitudinal aging cohorts: A systematic review. Epidemiologic Reviews. Published online 2013 January 24.  doi: 10.1093/epirev/mxs004.

Year: 
2013
Status: 
complete
Abstract: 

On average, older people remember less and walk more slowly than do younger persons. Some researchers argue that this is due in part to a common biologic process underlying age-related declines in both physical and cognitive functioning. Only recently have longitudinal data become available for analyzing this claim. We conducted a systematic review of English-language research published between 2000 and 2011 to evaluate the relations between rates of change in physical and cognitive functioning in older cohorts. Physical functioning was assessed using objective measures: walking speed, grip strength, chair rise time, flamingo stand time, and summary measures of physical functioning. Cognition was measured using mental state examinations, fluid cognition, and diagnosis of impairment. Results depended on measurement type: Change in grip strength was more strongly correlated with mental state, while change in walking speed was more strongly correlated with change in fluid cognition. Examining physical and cognitive functioning can help clinicians and researchers to better identify individuals and groups that are aging differently and at different rates. In future research, investigators should consider the importance of identifying different patterns and rates of decline, examine relations between more diverse types of measures, and analyze the order in which age-related declines occur.

Muniz-Terrera et al., 2013. Overview of change point models in cognitive ageing research.

Year: 
2013
Status: 
complete
Presentation Citations: 

Muniz-Terrera, G., Piccinin, A.M., & Hofer, S.M. (November, 2013). Overview of change point models in cognitive ageing research. In G. Muniz (Chair), Change-point models in cognitive aging: Overview, applications, limitations and future directions. Paper symposium presented at the 66th annual scientific meeting of the Gerontological Society of America, New Orleans, LA.

Abstract: 

Paper symposium chaired by G. Muniz-Terrera. Change-point models in cognitive aging: Overview, applications, limitations and future directions. Participants: Muniz-Terrera, Hofer, Piccinin, Rast

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