Developing and validating intrinsic capacity scores in early adulthood and midlife: 15-year follow-up from the Northern Finland Birth Cohort 1966
File(s)
Published version (pre-proof)
Author(s)
Hillari, Leah
Hosang, Georgina M
Nedelec, Rozenn
Lewin, Alex
Järvelin, Marjo-Riitta
Type
Journal Article
Abstract
Background
Intrinsic capacity (IC) – the aggregate of physical and mental capacities - has been studied in older adults, but research on its profile and prognostic value earlier in adulthood is scarce. Existing IC measurement approaches also lack theoretical alignment, psychometric evaluation, and validation. We therefore developed and validated IC scores in adulthood using a theory-aligned formative-reflective approach.
Methods
IC was assessed at ages 31 and 46 in 8756 participants from the Northern Finland Birth Cohort 1966 using 33 variables across psychological, cognitive-sensory, locomotor, and vitality domains. Domain scores were derived using unidimensional confirmatory factor analysis and aggregated to composite scores. Construct validity of scores was examined through stability, change and known-groups gradients. Predictive validity was tested using covariate-adjusted logistic regression models of associations between 31-year IC and incident mental disorder, cardiovascular disease, type 2 diabetes, functional limitations, and low well-being at age 46.
Results
Domain models demonstrated acceptable fit and reliability. Mean composite IC was moderate-to-high at age 31 (67 on a 0–100 scale) but declined significantly by age 46 (61), with the steepest reductions in locomotor capacity. Lower composite IC was observed in groups with socioeconomic disadvantage, unhealthy behaviours, and health conditions. Higher 31-year composite IC predicted lower odds of all outcomes at age 46 (odds ratios per 10-point increase: 0.69–0.82, all p < 0.001).
Conclusions
Composite IC declined from early adulthood to midlife, and predicted key physical, mental, and functional outcomes. Formative-reflective approaches and earlier IC assessment may strengthen prevention-oriented healthy ageing strategies.
Intrinsic capacity (IC) – the aggregate of physical and mental capacities - has been studied in older adults, but research on its profile and prognostic value earlier in adulthood is scarce. Existing IC measurement approaches also lack theoretical alignment, psychometric evaluation, and validation. We therefore developed and validated IC scores in adulthood using a theory-aligned formative-reflective approach.
Methods
IC was assessed at ages 31 and 46 in 8756 participants from the Northern Finland Birth Cohort 1966 using 33 variables across psychological, cognitive-sensory, locomotor, and vitality domains. Domain scores were derived using unidimensional confirmatory factor analysis and aggregated to composite scores. Construct validity of scores was examined through stability, change and known-groups gradients. Predictive validity was tested using covariate-adjusted logistic regression models of associations between 31-year IC and incident mental disorder, cardiovascular disease, type 2 diabetes, functional limitations, and low well-being at age 46.
Results
Domain models demonstrated acceptable fit and reliability. Mean composite IC was moderate-to-high at age 31 (67 on a 0–100 scale) but declined significantly by age 46 (61), with the steepest reductions in locomotor capacity. Lower composite IC was observed in groups with socioeconomic disadvantage, unhealthy behaviours, and health conditions. Higher 31-year composite IC predicted lower odds of all outcomes at age 46 (odds ratios per 10-point increase: 0.69–0.82, all p < 0.001).
Conclusions
Composite IC declined from early adulthood to midlife, and predicted key physical, mental, and functional outcomes. Formative-reflective approaches and earlier IC assessment may strengthen prevention-oriented healthy ageing strategies.
Date Issued
2026-09-25
Date Acceptance
2026-09-23
Citation
Experimental Gerontology, 2026
ISSN
0531-5565
Publisher
Elsevier
Journal / Book Title
Experimental Gerontology
Copyright Statement
© 2026 Published by Elsevier Inc. This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (https://creativecommons.org/licenses/by-nc-nd/4.0/).
Identifier
10.1016/j.exger.2026.113340
Publication Status
Published online
Article Number
113340
Date Publish Online
2026-09-25