Investigating three ways of measuring the intrinsic capacity domain of vitality: nutritional status, handgrip strength and ageing biomarkers

The development of intrinsic capacity measures for longitudinal research: The Longitudinal Aging Study Amsterdam

BACKGROUND

The World Health Organization has introduced the construct of intrinsic capacity (IC) as an important component of healthy ageing and overall well-being in older adults The present study aimed to develop domain-specific and composite IC scores and to validate these scores by examining their longitudinal relation with functioning.

METHODS

We used prospective data on participants aged 57 to over 90 years, with a 10-year follow-up, from the Longitudinal Aging Study Amsterdam, an ongoing cohort study of older Dutch men and women Using a formative, stepwise approach, we identified indicators across the different domains of IC, i.e. vitality, sensory, cognition, psychology, and locomotion, using a combination of unidimensional factor analyses and Partial Least Squares Structural Equation Modelling (PLS-SEM). Next, domain-specific and composite IC scores were generated, and the construct validity (score across age groups) and criterion validity (relationship with change in functional limitations) were assessed.

RESULTS

The multiple unidimensional factor analyses and PLS-SEM identified a total of 18 indicators, covering the five domains of IC. The mean composite IC score was 70.9 (SD = 0.9) in men and 69.7 (0.8) in women. The domain-specific and composite IC scores all showed good construct validity, with known-group validation results indicating age-related declines. A higher composite IC score was associated with less functional limitations over time (B = 0.20, 95%CI [0.19, 0.22]).

CONCLUSION

The developed domain-specific IC scores and the composite IC score effectively discriminated age-related declines in IC. Additionally, the composite IC score was longitudinally associated with functional limitations. By creating this comprehensive and reliable tool for tracking IC, we aim to provide valuable insights into the dynamics of ageing and support more effective strategies for promoting health and well-being throughout later life. These scores establish a foundation for future research to track longitudinal changes across various IC domains and relate these changes to key age-related outcomes.

Association Between Intrinsic Capacity and Hospital Admission Among Older Adults in the Emergency Department

This prospective cohort study assessed the impact of intrinsic capacity on hospital admissions among older adults after an Emergency Department (ED) visit. Assessing 1132 patients according to WHO's Integrated Care for Older People guidelines between March 1 and August 30, 2022, we found that 784 (69.26%) were admitted. The admission group demonstrated significantly lower intrinsic capacity scores (mean ± SD, 2.92 ± 1.29) compared to the discharge group (3.44 ± 1.23; p < .001). Multivariable logistic regression showed that higher intrinsic capacity scores were associated with lower odds of admission (adjusted odds ratio [aOR] = 0.81; 95% CI: 0.71-0.92; p < .001). Notably, patients with malnutrition had significantly higher odds of admission (OR = 3.12; 95% CI: 2.16-4.50; p < .001). These findings underscore the importance of integrating the intrinsic capacity assessment with traditional clinical indicators in the emergency care of older adults.

Handgrip strength: A simple and effective tool to recognize decreased intrinsic capacity in Chinese older adults

OBJECTIVES

Intrinsic capacity impairment results in poor outcomes among older adults. Here we tested handgrip strength as a screening tool for IC impairment in community-dwelling older adults in Xinjiang, China. We assessed the diagnostic accuracy and established optimal cut-off points for handgrip strength in the detection of intrinsic capacity impairment.

METHODS

In total, 1072 participants were included using a multilevel random sampling method. Intrinsic capacity was constructed according to the definition of the Integrated Care for Older People screening tool proposed by the WHO.

RESULTS

Altogether, 73.4 % (787/1072) participants had intrinsic capacity impairment. The prevalence of intrinsic capacity impairment for hearing, vision, mobility, cognition, psychological, and vitality domains was 8.6 %, 4.8 %, 39.6 %, 47.3 %, 12.0 %, and 18.8 %, respectively. The adjusted odds ratios [95 % confidence interval) for handgrip strength was 0.935 [0.914-0.956]. The area under the curve of the receiver operating characteristic curve for handgrip strength of older men, and handgrip strength of older women with intrinsic capacity impairment were 0.7278, and 0.7534, respectively. The handgrip strength cut-off points were 28.47 kg (60-69 years), 25.76 kg (70-79 years), and 24.45 kg (≥80 years) for men, and 20.75 kg (60-69 years), 19.90 kg (70-79 years), and 16.17 kg (≥80 years) for women.

CONCLUSIONS

Handgrip strength can be used as a convenient tool for evaluating intrinsic capacity. Weak handgrip strength and low education level were associated with intrinsic capacity impairment in community-dwelling older adults in Xinjiang. Using the cut-off points of handgrip strength for different age groups and genders, older adults with impaired intrinsic capacity can be identified, which may reduce the occurrence of adverse outcomes.

The impact of malnutrition on cognition in older adults: A systematic review

BACKGROUND

There is a lack of evidence to support the hypothesis that malnutrition may promote cognitive decline. This study aimed to explore the available literature on this topic.

METHODS

A systematic review was undertaken of studies investigating the effect of nutritional status on cognitive function in adults of any age, using Medline, Embase, PsycINFO and Global Health via OvidSP from earliest available dates to January 2024. Studies were excluded if they were conducted in animal or paediatric populations, or if they did not include measurements of baseline nutritional status or follow-up assessment of cognitive function. Selected studies were assessed for quality, and data extracted. A meta-analysis was not conducted due to the heterogeneity of the data.

RESULTS

A total of nine studies (three randomised and six observational) was retrieved, including total 8697 subjects who were all in older age groups. Study quality was generally poor. Seven of the nine studies supported the hypothesis that baseline nutritional status is predictive of change in cognitive function at later assessment, but all studies failed to control for significant confounders and six of the nine had large amounts of missing data at follow-up, so that it remains unclear whether nutrition is independently associated with later cognitive function.

CONCLUSION

Malnutrition may be associated with subsequent development of cognitive dysfunction in older adults. Higher quality studies in a wider range of age groups are needed to investigate whether nutritional status has an independent impact on cognitive function, and whether this is related to specific nutrient deficiencies.

Using cardiorespiratory fitness to operationalize vitality: a path analysis on the hierarchical structure of intrinsic capacity

BACKGROUND

There is a lack of consensus about the operationalization of vitality, which is one of the intrinsic capacity (IC) domains. In particular, no study has investigated whether cardiorespiratory fitness (CRF) can be considered a vitality indicator.

OBJECTIVE

To examine whether vitality is the upstream domain of IC, and establish the validity of CRF as a vitality indicator, using maximal oxygen consumption (VO2 max) as a representative.

METHODS

561 older adults from a longitudinal cohort study were included. Variables under consideration were VO2 max, other IC domains, instrumental activities of daily living (IADL), and handgrip strength, which was considered an already validated indicator of vitality. Using handgrip strength as the reference point, path analyses were performed to examine whether VO2 max followed a similar hierarchical structure in predicting change in IADL difficulty through other IC domains.

RESULTS

The mean age of the participants was 75.5 years. The path model in which vitality was measured by VO2 max demonstrated adequate fit, which was similar to the model in which vitality was measured by handgrip strength. Regarding the path coefficients, the model using VO2 max demonstrated significant total and indirect effects. Notably, the indirect effect was due to the locomotor domain (standardized coefficient = -0.148, p < .001), but not the cognitive or psychological domain.

CONCLUSION

Vitality is the upstream domain of IC. VO2 max can be considered an indicator to operationalize the vitality concept.

Dietary patterns and intrinsic capacity in older adults: a 6-year prospective cohort study

OBJECTIVES

Only a few studies have investigated dietary patterns and intrinsic capacity (IC). This study examined the prospective associations between dietary patterns, IC, and IC sub-domains over 6 years in community-dwelling Korean older adults.

DESIGN

A prospective cohort study.

SETTING AND PARTICIPANTS

Data were obtained from participants aged 70-84 years in the Korean Frailty and Aging Cohort Study (2016-2022). The study population included 665 enrollees at baseline who completed IC and dietary data.

METHODS

Dietary data were obtained from baseline surveys of the nutritional sub-cohort using two nonconsecutive 24-hour dietary recalls, and dietary patterns were derived using cluster analysis. IC was constructed by measuring cognitive, locomotor, vitality, sensory, and psychological domains. A generalized estimating equation was used to analyze the longitudinal associations between dietary patterns, IC, and IC sub-domain scores.

RESULTS

In total, 665 enrollees were included in the analysis. After adjusting for confounders, in older men, the dietary pattern of cluster 1 (variety of healthy foods and alcohols) compared to that of cluster 2 (rice and kimchi) was positively associated with changes in the IC score (ß = 0.41, 95% confidence interval [CI] = 0.04-0.78). In older women, the dietary pattern of cluster 1 (variety of healthy foods) was positively associated with changes in the IC score (ß = 0.30, 95% CI = 0.02-0.58), IC score group (ß = 0.11, 95% CI = 0.02-0.20), and psychological domain (ß = 0.25, 95% CI = 0.11-0.38) compared to that of cluster 3 (rice, vegetables, and kimchi).

CONCLUSIONS

Dietary patterns (variety of healthy foods) were positively associated with changes in IC scores and their sub-domains in older adults.

Phytonutrients in the promotion of healthspan: a new perspective

Considering a growing, aging population, the need for interventions to improve the healthspan in aging are tantamount. Diet and nutrition are important determinants of the aging trajectory. Plant-based diets that provide bioactive phytonutrients may contribute to offsetting hallmarks of aging and reducing the risk of chronic disease. Researchers now advocate moving toward a positive model of aging which focuses on the preservation of functional abilities, rather than an emphasis on the absence of disease. This narrative review discusses the modulatory effect of nutrition on aging, with an emphasis on promising phytonutrients, and their potential to influence cellular, organ and functional parameters in aging. The literature is discussed against the backdrop of a recent conceptual framework which describes vitality, intrinsic capacity and expressed capacities in aging. This aims to better elucidate the role of phytonutrients on vitality and intrinsic capacity in aging adults. Such a review contributes to this new scientific perspective-namely-how nutrition might help to preserve functional abilities in aging, rather than purely offsetting the risk of chronic disease.

Digging into the intrinsic capacity concept: Can it be applied to Alzheimer's disease?

Historically, aging research has largely centered on disease pathology rather than promoting healthy aging. The World Health Organization's (WHO) policy framework (2015-2030) underscores the significance of fostering the contributions of older individuals to their families, communities, and economies. The WHO has introduced the concept of intrinsic capacity (IC) as a key metric for healthy aging, encompassing five primary domains: locomotion, vitality, sensory, cognitive, and psychological. Past AD research, constrained by methodological limitations, has focused on single outcome measures, sidelining the complexity of the disease. Our current scientific milieu, however, is primed to adopt the IC concept. This is due to three critical considerations: (I) the decline in IC is linked to neurocognitive disorders, including AD, (II) cognition, a key component of IC, is deeply affected in AD, and (III) the cognitive decline associated with AD involves multiple factors and pathophysiological pathways. Our study explores the application of the IC concept to AD patients, offering a comprehensive model that could revolutionize the disease's diagnosis and prognosis. There is a dearth of information on the biological characteristics of IC, which are a result of complex interactions within biological systems. Employing a systems biology approach, integrating omics technologies, could aid in unraveling these interactions and understanding IC from a holistic viewpoint. This comprehensive analysis of IC could be leveraged in clinical settings, equipping healthcare providers to assess AD patients' health status more effectively and devise personalized therapeutic interventions in accordance with the precision medicine paradigm. We aimed to determine whether the IC concept could be extended from older individuals to patients with AD, thereby presenting a model that could significantly enhance the diagnosis and prognosis of this disease.