Hofer & Clouston, 2014. Commentary: On the Importance of Early Life Cognitive Abilities in Shaping Later Life Outcomes.

Hofer, S. M., & Clouston, S. (2014). On the Importance of Early-Life Cognitive Abilities in Shaping Later-Life Outcomes. Research in Human Development, 11(3), 241-246.

Year: 
2014
Status: 
complete
Abstract: 

Early-life cognitive ability is likely to be dynamically related to life course factors including educational attainment, occupational outcomes, health behaviors, activities, health, and subsequent cognitive health. Disentangling the selective and causal processes contributing to cognitive functioning across the life span is challenging and requires long-term investments in longitudinal data. The authors discuss results from several analyses using data from the Individual Development and Adaptation longitudinal research program that provide fresh insights into the relation of early-life cognition, particularly high levels of cognitive capabilities, to educational achievement, emotional adjustment, and career success. These articles and the longitudinal data provide a remarkable window into the development and impacts of cognition, and high cognitive functioning, on a variety of important life outcomes that we hope will continue to inform us about additional outcomes in middle life, transition to retirement, and cognition and health in later years and to robustly examine how the early years matter across the whole life span.

Brown et al., 2016. Cognitive activity mediates the association between social activity and cognitive performance: A longitudinal study.

Brown, C. L., Robitaille, A., Zelinski, E. M., Dixon, R. A., Hofer, S. M., & Piccinin, A. M. (2016). Cognitive activity mediates the association between social activity and cognitive performance: A longitudinal study. Psychology and aging, 31(8), 831.
Year: 
2016
Status: 
complete
Abstract: 

Social activity is one aspect of an active lifestyle and some evidence indicates it is related to preserved cognitive function in older adulthood. However, the potential mechanisms underlying this association remain unclear. We investigate 4 potential mediational pathways through which social activity may relate to cognitive performance. A multilevel structural equation modeling approach to mediation was used to investigate whether cognitive activity, physical activity, depressive symptoms, and vascular health conditions mediate the association between social activity and cognitive function in older adults. Using data from the Victoria Longitudinal Study, we tested 4 cognitive outcomes: fluency, episodic memory, reasoning, and vocabulary. Three important findings emerged. First, the association between social activity and all 4 domains of cognitive function was significantly mediated by cognitive activity at the within-person level. Second, we observed a significant indirect effect of social activity on all domains of cognitive function through cognitive activity at the between-person level. Third, we found a within-person indirect relationship of social activity with episodic memory performance through physical activity. For these older adults, engagement in social activities was related to participation in everyday cognitive activities and in turn to better cognitive performance. This pattern is consistent with the interpretation that a lifestyle of social engagement may benefit cognitive performance by providing opportunities or motivation to participate in supportive cognitively stimulating activities. 

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.

Clouston & Denier, 2017. Mental retirement and health selection: Analyses from the U.S. Health and Retirement Study

Clouston, S. A., & Denier, N. (2017). Mental retirement and health selection: Analyses from the US Health and Retirement Study. Social Science & Medicine, 178, 78-86.

Year: 
2017
Status: 
complete
Abstract: 

Background: Research has recently suggested that retirement may decrease cognitive engagement, resulting in cognitive aging. Few studies have systematically documented whether or how selectivity into retirement shapes the relationship between retirement and cognitive aging.

Methods: We draw on data from the Health and Retirement Study (1998–2012) to examine the relationship between cognition and retirement for 18,575 labor force participants. Longitudinal regression discontinuity modeling was used to examine performance and decline in episodic memory. Models differentiated three forms of selection bias: indirect and direct selection as well as reverse causation. To further interrogate the disuse hypothesis, we adjust for confounding from health and socioeconomic sources.

Results: Results revealed that individuals who retired over the course of the panel were substantially different in terms of health, wealth and cognition when compared to those who remained employed. However, accounting for observed selection biases, significant associations were found linking longer retirement with more rapid cognitive decline.

Discussion: This study examined respondents who were in the labor force at baseline and transitioned into retirement. Analyses suggested that those who retired over the course of the panel had worse overall functioning, but also experienced more rapid declines after retirement that increased the rate of aging by two-fold, resulting in yearly losses of 3.7% (95% CI = [3.5, 4.0]) of one standard deviation in functioning attributable to retirement. Results are supportive of the view that retirement is associated with more rapid cognitive aging.

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.

Hofer et al., 2005. Short and long-term cognitive change in aging individuals.

Year: 
2005
Status: 
complete
Presentation Citations: 

Hofer, S. M., Hoffman, L., Sliwinski, M. J., & Piccinin, A. M. (2005, October). Short and long-term cognitive change in aging individuals. Paper presented at the annual meeting of the Society for Multivariate Experimental Psychology, Lake Tahoe, CA.

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