ReviewThe anorexia of ageing: Physiopathology, prevalence, associated comorbidity and mortality. A systematic review☆
Introduction
The changes in the regulation of appetite and the lack of hunger frequently observed in association with ageing have been described as anorexia of ageing (AA) [1].
The main factors associated with the onset of AA can be split into three main groups: (1) physiological; (2) psychological and social; and (3) medical. Among the physiological factors, we may list those related to the process of ageing itself, including: (a) loss of acuity in taste, smell and sight; (b) changes in the secretion and peripheral action of the hormones that regulate the wish to eat, hunger and satiation; (c) changes in gastrointestinal motility; (d) changes to the central control of ingestion; and (e) chronic low-grade inflammation [2], [3]. Poverty, isolation and changes to a person's environment are the main psychological and social causes. The third group comprises medical causes, among which we can list certain pathologies and drugs [4].
Fig. 1 is a simplified and schematic representation of the appetite regulation system.
The importance of knowledge and, especially, diagnosis of AA is related to the fact that it represents a major cause of loss of weight and malnutrition, as well as of sarcopenia and fragility [5], [6].
The main aim of this review is to describe and summarize the physiopathological factors at the root of AA. Secondary aims are to assess the prevalence of AA, to report on associated comorbidities and mortality rates, and to assess possible treatments for AA.
Section snippets
Methods
We performed this review in accordance with the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-analyses) guidelines [7], [8]. The protocol of the present review was registered with PROSPERO, which is an international database of prospectively registered systematic reviews in health and social care. PROSPERO is funded by the UK National Institute for Health Research. See http://www.crd.york.ac.uk/PROSPERO/display_record.asp?ID=CRD42012002893.
Study characteristics and quality assessment
We included 27 studies, with a total population of 6208 patients. Fig. 2 presents a flow chart showing the paper selection process.
None of the protocols of the studies included in this revision was registered in any international registers.
We considered 11 studies to be good, 12 fair and 4 wanting. The main area which caused papers to be evaluated as ‘wanting’ was their statistical analysis, whether because an incorrect test was chosen or because the test that would best represent the data was
Discussion
There is much diversity in the results of studies on the hormones that regulate appetite. This confirms the complexity of the peripheral and central regulation of appetite. Nonetheless, research must continue along these lines, with particular attention to anorexic elderly people.
One of the most interesting aspects for geriatricians is the high comorbidity observed in elderly people and how it influences their clinical state and, more especially, their functional state. Despite the fact that
Conclusions
Almost all the included studies assessed the secretion of peripheral hormones related to appetite control in healthy elderly people and compared this with secretion in younger people. Future studies should assess the differences between elderly people with and without anorexia, to give a better understanding of the physiopathological mechanism at the root of appetite loss.
Environmental factors (such as isolation), sensory alterations, poor oral hygiene and polypharmacy are potential targets for
Provenance and peer review
Commissioned, externally peer reviewed.
Contributors
Dr. Vincenzo Malafarina conceived the idea of the review, performed the bibliographic search and wrote the manuscript. Dr. Francisco Úriz-Otano, Dra Lucía Gil-Guerrero and Raquel Iniesta helped interpreting the data and making comments on the final version of the manuscript.
Competing interest
The authors declare no conflict of interest.
Funding
The authors have not received any financial support.
Acknowledgments
We would like to greet the Foundation San Juan de Dios library people (Esplugues de Llobregat, Barcelona), especially Alicia Martín and Sílvia Semaan Llurba, for their help in the bibliographic searching.
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This review was registered at www.crd.york.ac.uk/prospero/prospero.asp (PROSPERO), as CRD42012002893.