Associations of C-reactive protein and homocysteine concentrations with the impairment of intrinsic capacity domains over a 5-year follow-up among community-dwelling older adults at risk of cognitive decline (MAPT Study).

Abstract

The World Health Organization (WHO) recently proposed an innovative model of care focusing on functional rather than disease-based perspectives, based on a construct of intrinsic capacity (IC). This study aimed to analyze if low-grade inflammation (LGI) (chronically raised C-reactive protein - CRP) and hyperhomocysteinemia (HHcy) were associated with variation in IC domains (mobility, cognition, psychological and vitality) and in a combined IC Z-score over a 5-year follow-up among non-demented, community-dwelling older adults at risk of cognitive decline. This observational study included 1516 subjects ≥70 years (64.5% female, mean age 75.4 years, SD = 4.5), volunteers from the interventional study Multidomain Alzheimer Preventive Trial (MAPT). Plasma CRP (at baseline, 6 and 12 months) and homocysteine (at baseline) concentrations were measured. LGI was defined as having ≥2 consecutively CRP readings >3 to 10 mg/L between baseline and 12 months, and HHcy was defined as homocysteine >15 μM/L. IC domains were operationalized as follows: Psychological. Depressive symptoms evaluated by the Geriatric Depression Scale (GDS); Mobility. Assessed by the Short Physical Performance Battery (SPPB); Cognitive function. Examined by a Z-score combining four tests; Vitality. Based on hand grip strength. Outcomes were combined into a composite IC Z-score. IC Z-score decreased among groups with no inflammation and LGI after 5 years, but this decrease was more pronounced among the LGI group (unadjusted mean group difference: 0.09, 95%CI: 0.01 to 0.16; p = 0.032). Participants with HHcy also presented IC Z-score decreases over time. Combined conditions provided more pronounced declines, even after adjusting for potential confounders. LGI and HHcy were both related with impairment on the combined IC levels among older adults after a 5-year follow-up. Identifying biomarkers that strongly associate with IC may help to settle strategies aiming to prevent the incidence and slow down the evolution of age-related functional decline and care dependency.