Capacidade intrinseca e incapacidade funcional em idosos: influências das diferenças de gênero, biomarcadores e fatores socioeconômicos

Abstract

INTRODUCTION: Gender differences in Intrinsic Capacity (IC) and functional disability processes are not yet fully understood, which hinders the development of effective interventions for healthy aging. The literature suggests that biological, socioeconomic, and health factors influence IC; however, how these factors interact and differently affect men and women remains unclear. Furthermore, the relationship between inflammatory and neurodegenerative biomarkers and IC over time has not been extensively explored, limiting the identification of early markers of functional decline. The impact of socioeconomic status on functional disability, particularly regarding participation frequency in daily activities and perceived limitations, also requires further investigation, especially in multicultural contexts. OBJECTIVES: This thesis comprises three papers. #Paper 01 aimed to estimate IC levels in a community-dwelling older population and identify the factors associated with IC decline in both genders. #Paper 02 examined whether cross-sectional and longitudinal associations between blood biomarkers related to inflammation and neurodegeneration and IC differ by sex. Lastly, #Paper 03 aimed to determine whether the associations between socioeconomic status and late-life disability vary by gender in a multicultural sample. METHODS: The #Paper 01 and #Paper 03 used cross-sectional data from the third wave of the International Mobility and Aging Study (IMIAS), collected in 2016. Specifically, the #Paper 01 analyzed data from 1,484 older adults. Based on a reflexive methodology, four functions were selected from the IMIAS database to assess the domains of IC: i. Locomotion (Short Physical Performance Battery), ii. Cognition (Leganes Cognitive Test), iii. Vitality (Handgrip Strength), and iv. Psychological Well-being (Center for Epidemiologic Studies Depression). A composite IC score was calculated (ranging from 0 to 100; the higher, the better). Socioeconomic and healthrelated factors included: age, marital status (single, married, divorced/widowed), educational level (lowest, middle, and highest), income sufficiency (not/not very well, suitably, very well), occupation (manual and non-manual), number of chronic diseases (≤ 1, 2 – 3, and ≥ 4), body mass index (underweight/normal weight, overweight, obesity), and history of falls in the last year (yes and no). Multiple linear regression analyses were used to investigate factors associated with reduced IC in both genders. #Paper 03 assessed late-life disability in 1,362 older adults using the disability component (frequency and limitation) of the Late-Life Function Disability Instrument (LLFDI). Socioeconomic status was self-reported through the variables: i. educational level (less than secondary, secondary, post-secondary), ii. income sufficiency (not/not very well, suitably, very well), and iii. occupation (manual and non-manual). Multiple linear regression models were used to examine gender-specific associations between late-life disability (frequency and limitation subscales) and SES. Finally, #Paper 02 used longitudinal data from 1,117 older adults from the Multidomain Alzheimer Preventive Trial (MAPT). The domains of IC were operationalized using the following functions: i. Cognition (Mini-Mental State Examination), ii. Locomotion (Short Physical Performance Battery), iii. Vitality (Handgrip Strength), and iv. Psychological Well-being (Geriatric Depression Scale), each scaled from 0 (worst possible IC) to 100 (best possible IC). Biomarkers related to inflammation and neurodegeneration included: i. Interleukin 6 (IL-6, pg/mL), ii. Growth Differentiation Factor 15 (GDF15, pg/mL), iii. Tumor Necrosis Factor Receptor 1 (TNFR1, pg/mL), iv. Neurofilament Light Chain (NfL, pg/mL), v. Progranulin (PGRN, ng/mL), and vi. Beta-Amyloid protein (Aβ42/40). Mixed linear models were performed to examine whether sex modified the cross-sectional and longitudinal association between biomarkers and IC. RESULTS: Findings indicated that women had significantly lower IC scores than men (M = 77.43; SD = 9.06 vs. M = 72.26; SD = 9.31; p < 0.001). Age, study site, marital status, multiple chronic conditions, and history of falls were negatively associated with IC scores in both genders. Additionally, insufficient income (B = -2.130; p = 0.043) and obesity (B = -1.645; p = 0.039) were negatively associated with IC scores in women, whereas low educational level (B = -2.124; p = 0.012) was a significant predictor for men. Longitudinal analyses revealed a significant interaction between sex and IL-6 (p = 0.005), where higher IL-6 levels were associated with a faster IC decline in men (B = -0.385; p = 0.055) but not in women (B = 0.287; p = 0.041). Regarding functional disability, low educational level (B = −3.11; p < 0.001) and manual occupations (B = −1.79; p < 0.05) were associated with reduced participation frequency in men, while insufficient income (B = −3.55; p < 0.01) and manual occupations (B = −2.25; p < 0.01) played a negative role in women's participation. In both men (B = −2.39; p < 0.05) and women (B = −3.39; p < 0.01), insufficient income was the only factor linked to greater perceived limitations in daily tasks. CONCLUSION: Women showed lower IC scores compared to men. Age, study locations, multiple chronic conditions, and history of falls were factors associated with reduced IC in both genders. Educational level appears to particularly influence IC in men, while income insufficiency and obesity are more significant factors for women. These findings highlight the need for genderspecific strategies to address the distinct determinants of IC, aiming to promote healthier aging. Among all biomarkers, only IL-6 showed sex-dependent associations, being linked to a rapid decline in IC in men but not in women. Men and women experienced different patterns of disability in old age. For men, previous occupational status and educational level were associated with a decrease in frequency of participation, whereas for women, this reduction was associated with perceived income and previous occupational status.