Intrinsic Capacity Predictors of Dementia and Mortality in the Sydney Memory and Ageing Study

Intrinsic Capacity (IC) is a developing concept focussed on promoting healthy ageing by maintaining functional abilities. It has been proposed as a better predictor of outcomes like dementia and mortality, compared to traditional frailty measures that focus on deficits. This study aims to replicate the five-factor structure of IC among older adults in Australia and to evaluate its effectiveness in predicting long-term health outcomes, in comparison with existing frailty measures.

IC scores were computed for 400 older adults aged 70 to 90 participating in the Sydney Memory and Ageing Study (MAS). Structural equation modelling, including second-order confirmatory analysis, was used to compute the five IC domains. Cox proportional hazard models were used to compare the predictive value of the second-order IC factor with the Frailty Phenotype and Frailty Index for dementia over 10 years and mortality over 12 years.

Factor loadings for the IC structure yielded five subgroups (cognitive function, psychological health, locomotive ability, sensory function, vital function) with one global factor. The structure had good fit (SRMR = 0.054, GFI = 0.966). IC was associated with lower hazard (risk) of dementia (HR = 0.567, p < 0.001) over 10-year and lower hazard of mortality (HR = 0.649, p < 0.001) over 12-year, controlling for age, sex, and education. Finally, IC explained additional variance beyond the Frailty Phenotype when predicting both incident dementia and mortality risk. Compared with the Frailty Index, IC contributed additional variance for dementia risk but not for mortality.

Evaluation of a person's IC at baseline explains additional variance compared to traditional frailty measures when predicting the risk of future negative health outcomes such as dementia incidence and mortality.