This chapter contains sections titled: Conceptual Issues at the Interface of Theory, Design, and Analysis, Analytic Approaches for Understanding Within‐Person Change and Variation Methodological Applications in Developmental and Aging Research, Integrative Data Analysis: Within‐Person Change in the Context of Cohort, Country, and Culture, Acknowledgments, References.

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.

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.

In this chapter we discuss a variety of issues concerning designed, measurements, and analysis of data from quasi-experimental studies with thte main aim of identifying and explaining individual differences in developmental processes.

The study of change rests on the assumption that observed differences in measurements over time reflect true change in the construct being measured. If measurement properties change over time, there is a threat to internal validity, which results in ambiguity in the conclusions about change.

Aging reflects ongoing transactions between context and person across many decades of life. Life course sociology is now central to investigations focused on the dynamic social context of aging, with its distinctive emphasis on long-term patterns in people's statuses, roles, and relationships. Recent advances in the understanding of the genome and its measurement have created new and exciting possibilities for studying the genetic basis of aging-related outcomes. The relationship between context and genetic factors may often be transactional, with influences extending reciprocally among environmental factors and genetic processes. This chapter reviews studies that suggest links between social and molecular processes extending across the phases of life. Very few empirical studies of aging draw upon both the life course and molecular genetics, but there is a rapidly growing number of studies from each perspective that suggest points of intersection. It emphasizes studies of health, broadly defined as “a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity,” because many gene–environment studies focus on indicators of physical and mental well-being. Despite the growing relevance of molecular genetics to studies of life course sociology and aging, several cautionary points are appropriate. Epigenetic mechanisms could provide insight into vulnerable windows very early in life that then have long-term implications for health and well-being. Behavioral studies of aging that are informed by molecular genetics present exciting challenges to the technical and creative skills of a new generation of scientists.

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

In A. Gross (Chair), Novel research designs and innovative methods for analysis of retest effects in cognitive aging.

Engagement in cognitively stimulating activities has been considered to maintain or strengthen cognitive skills, thereby minimizing age-related cognitive decline. While the idea that there may be a modifiable behavior that could lower risk for cognitive decline is appealing and potentially empowering for older adults, research findings have not consistently supported the beneficial effects of engaging in cognitively stimulating tasks. Using observational studies of naturalistic cognitive activities, we report a series of mixed effects models that include baseline and change in cognitive activity predicting cognitive outcomes over up to 21 years in four longitudinal studies of aging. Consistent evidence was found for cross-sectional relationships between level of cognitive activity and cognitive test performance. Baseline activity at an earlier age did not, however, predict rate of decline later in life, thus not supporting the concept that engaging in cognitive activity at an earlier point in time increases one's ability to mitigate future age-related cognitive decline. In contrast, change in activity was associated with relative change in cognitive performance. Results therefore suggest that change in cognitive activity from one's previous level has at least a transitory association with cognitive performance measured at the same point in time.