What changes first? Mapping the temporal ordering of age-related functional decline across domains using 30-Year longitudinal data

Abstract

Introduction: Age-related functional decline is assumed to be a complex process in which declines in one domain may trigger decline in others. Yet research empirically identifying the temporal ordering of age-related decline across emotional, cognitive, physical, and social functioning as well as health-behavioral factors is still scarce. Methods: We analyzed up to 10 waves of the Longitudinal Aging Study Amsterdam (LASA) cohort over 30 years (n = 1,560), covering fifteen indicators of physical, cognitive, emotional and social functioning, and health-behavioral factors. We used directed dynamic time warping to quantify the temporal ordering of within-person changes in these indicators. Average temporal relationships were visualized as a network graph and by rank-ordering indicators according to their tendency to precede (high out-strength) or follow (high in-strength) changes in other indicators. Results: Participants were on average 62.3 +/- 5.50 years old at baseline, 53.8% female, with 14.8 +/- 4.74 years of follow-up. Physical and cognitive declines (e.g., physical performance and episodic memory) tended to precede decline in other domains, while changes in social functioning (e.g., social participation) tended to follow. No clear temporal ordering was found between emotional functioning (e.g., depression and anxiety) and other domains. Conclusion: The study offers insights into early detection and prevention strategies for healthy aging. Assuming that physical and cognitive domains are primarily driven by age-related biological changes, our findings support theories proposing that biological changes precede functional decline and theories emphasizing the importance of psychosocial resilience. Moreover, this study highlights the potential of adopting a complex systems approach and innovative within-person analytical methods in gerontology.As people age, they may start experiencing challenges in different areas of life, such as their memory, physical ability, emotions, social life, or health behaviors. These difficulties do not always happen at the same time, and it is unclear whether problems in one area come before others. In this study, we followed more than 1,500 adults in the Netherlands for up to 30 years as part of the Longitudinal Aging Study Amsterdam. We looked at how changes in different aspects of their daily functioning developed over time. To do this, we used a technique that allows us to compare changes within each person over time, across five different domains of functioning simultaneously, rather than looking only at group averages or having only one or two outcome domains. We found that physical and cognitive functioning - like walking speed or memory - often changed earlier in the aging process than social functioning. Changes in emotional functioning, such as feelings of depression or anxiety, did not show a clear pattern in relation to the other areas. These results suggest that physical and cognitive abilities might be early warning signs of broader changes in aging. Spotting these early shifts could help with detecting risks sooner and possibly delaying further decline. Our study also shows the value of using new types of analyses that focus on how individuals change over time using a holistic framework, helping researchers and clinicians better understand the complex nature of aging.