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)

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.