Nutrition, inflammation, and leptin levels in aging and frailty

OBJECTIVES: To examine nutritional indices and levels of leptin and inflammatory markers across age and frailty.
DESIGN: Observational study.
SETTING: Continuing care wards and a day hospital in Cardiff, South Wales, United Kingdom.
PARTICIPANTS: Thirty dependent patients (mean age 84.9) needing continuing inpatient care, 40 patients with falls attending a day hospital (mean age 84.2), 40 independent controls (mean age 82.7), and 30 young controls (mean age 23.3).
MEASUREMENTS: Functional status, including the five frailty indicators proposed by Fried et al., anthropometry, and serum markers of nutrition and inflammation.
RESULTS: The continuing care patients were frail, all having three to five frailty indicators. Day hospital patients were of intermediate frailty (mean Fried score 2.97), and the independent group was fittest (0.83). Body mass index, triceps skinfold thickness (TSF), and mid-arm muscle area were lowest in continuing care patients. With increasing patient frailty, albumin levels fell significantly ( P <.005) and C-reactive protein (CRP) levels increased significantly ( P <.005). Continuing care patients had significantly lower leptin levels ( P <.005) and significantly higher interleukin (IL)-6 levels ( P <.005). There was a significant correlation between log transformed leptin and TSF for each patient group.
CONCLUSION: The frailest older people displayed features of cachexia. Their leptin levels were appropriately low given their low body fat, and IL-6 and CRP levels were high. The mechanism of their cachexia may therefore be similar to that proposed in heart failure and cancer: disturbed hypothalamic feedback of leptin or effects of proinflammatory cytokines.