Title: Loneliness Is Associated with Frailty in Community‐Dwelling Elderly Adults
Abstract: To the Editor: Loneliness is considered to be a prevalent public health problem in elderly populations.1 It refers to a subjective feeling of being alone, separated, or apart from others, causing distress to the individual as a result of lack of satisfaction from social relationships.2 Loneliness has been associated with various adverse health-related outcomes such as depression, functional decline, and mortality,1, 3 which are also associated with the syndrome of frailty. Frailty represents a vulnerability state, the social elements (e.g., individual and neighborhood socioeconomic status, educational level, employment benefits, the presence of abuse, having a partner) and outcomes of which are less understood than its biological ones.4 Thus, to the knowledge of the authors of this letter, the association between loneliness and frailty has not been reported elsewhere. The aim of the present study was to determine the association between loneliness and frailty in a population of Mexican community-dwelling elderly adults. This was a cross-sectional study of 927 community-dwelling members of the Coyoacán Cohort aged 70 and older. Loneliness was assessed using a slightly modified version of the short form of the revised University of California at Los Angeles (UCLA) loneliness scale (three-item scale, range 3–9 points, ≥6 indicating loneliness).5 Frailty was defined according to the phenotype proposed by Fried (weight loss, exhaustion, low physical activity, slowness, weakness), and subjects were categorized as frail if they fulfilled three or more criteria, prefrail if they fulfilled one or two, and nonfrail if they fulfilled none.6 Multinomial logistic regression analyses were performed to test the independent association between loneliness and frailty, adjusting for age, sex, living status, education, comorbidity (stroke, myocardial infarction, hypertension, osteoarthritis, diabetes mellitus), activities of daily living (ADLs), cognitive impairment (Mini-Mental State Examination (MMSE) score ≤ 24), and depressive symptoms (Geriatric Depression Scale (GDS) score ≥ 6). All statistical tests were performed at the .05 level of significance. The mean age of the participants was 78.2 ± 6.2; 54.9% were female. Hypertension was the most frequently reported chronic disease (55.9%). Depressive symptoms were present in 13.9% of the participants, and 29.1% of subjects had ADL disability. Frailty was found in 14.1% of participants and loneliness in 13.2%. Table 1 presents the comparative analyses of sociodemographic and health characteristics according to frailty status. As expected, frail participants were older (P < .001) and more likely to be female (P < .001) and live alone (P < .001). Likewise, frail participants reported more chronic diseases (P < .001), more depressive symptoms (P < .001), poorer cognitive performance (P < .001), and greater disability (P < .001). Prefrail (17.6%) and frail (23.1%) participants were more likely to report loneliness than nonfrail participants (6.9%) (P < .001). Unadjusted multinomial logistic regression analysis showed an association between loneliness and prefrail and frail status. After adjusting for the above-mentioned covariates, the association between loneliness and prefrailty (odds ratio (OR) = 3.7, 95% confidence interval (CI) = 1.89–7.10, P < .001) and frailty (OR = 2.7, 95% CI = 1.08–6.98, P = .03) remained unchanged. Loneliness was found to be independently associated with frailty in a group of Mexican community-dwelling elderly adults. To the knowledge of the authors, this is the first study to demonstrate an association between loneliness and frailty. A large body of literature suggests that several multisystem pathophysiological processes, including chronic inflammation and immune and endocrine dysregulation, are involved in the pathogenesis of frailty. An independent association between frailty and high serum levels of interleukin-6 (IL-6) has long been described. Moreover, other inflammatory molecules such as C-reactive protein (CRP) and tumor necrosis factor alpha (TNF-a), have also been found to be high in frail elderly adults.7 This inflammatory state may also be present in lonely individuals. Lonely healthy adults under acute stress exhibited greater synthesis of TNF-a and IL-6 than those who are not lonely.8 In addition, social environment has a significant effect on immune functioning, indexed according to Epstein-Barr virus antibodies.9 These findings might suggest that frailty and loneliness share a proinflammatory phenotype. Loneliness has also been associated with cardiovascular disease,10 which is being studied as a determining factor for the development of frailty. Previous work has also shown that elderly subjects without significant social integration have altered neuroendocrine activity,11 which also fits the current paradigm aiming to explain frailty. Therefore, further study on the association between loneliness and frailty is needed to better understand the relationship between these two entities, their determining elements, and their combined outcomes. This research was conducted as part of the Mexican Study of Nutritional and Psychosocial Markers of Frailty among Community-Dwelling Elderly. This project was funded by the National Council for Science and Technology of Mexico (SALUD-2006-C01–45075). Conflict of Interest: All authors state no financial interest, stock, or derived direct financial benefit. Author Contributions: Herrera-Badilla, Navarrete-Reyes: study concept and design, data analysis and interpretation, writing the manuscript. Amieva, Ávila-Funes: supervision. Sponsor's Role: None.