{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:29:57Z","timestamp":1760239797089,"version":"build-2065373602"},"reference-count":58,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2020,12,22]],"date-time":"2020-12-22T00:00:00Z","timestamp":1608595200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Science Foundation Ireland (SFI)","award":["18\/FRL\/6188"],"award-info":[{"award-number":["18\/FRL\/6188"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>In this cross-sectional study, the relationship between noninvasively measured neurocardiovascular signal entropy and physical frailty was explored in a sample of community-dwelling older adults from The Irish Longitudinal Study on Ageing (TILDA). The hypothesis under investigation was that dysfunction in the neurovascular and cardiovascular systems, as quantified by short-length signal complexity during a lying-to-stand test (active stand), could provide a marker for frailty. Frailty status (i.e., \u201cnon-frail\u201d, \u201cpre-frail\u201d, and \u201cfrail\u201d) was based on Fried\u2019s criteria (i.e., exhaustion, unexplained weight loss, weakness, slowness, and low physical activity). Approximate entropy (ApEn) and sample entropy (SampEn) were calculated during resting (lying down), active standing, and recovery phases. There was continuously measured blood pressure\/heart rate data from 2645 individuals (53.0% female) and frontal lobe tissue oxygenation data from 2225 participants (52.3% female); both samples had a mean (SD) age of 64.3 (7.7) years. Results revealed statistically significant associations between neurocardiovascular signal entropy and frailty status. Entropy differences between non-frail and pre-frail\/frail were greater during resting state compared with standing and recovery phases. Compared with ApEn, SampEn seemed to have better discriminating power between non-frail and pre-frail\/frail individuals. The quantification of entropy in short length neurocardiovascular signals could provide a clinically useful marker of the multiple physiological dysregulations that underlie physical frailty.<\/jats:p>","DOI":"10.3390\/e23010004","type":"journal-article","created":{"date-parts":[[2020,12,22]],"date-time":"2020-12-22T12:42:28Z","timestamp":1608640948000},"page":"4","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":11,"title":["Associations between Neurocardiovascular Signal Entropy and Physical Frailty"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1245-4870","authenticated-orcid":false,"given":"Silvin P.","family":"Knight","sequence":"first","affiliation":[{"name":"The Irish Longitudinal Study on Ageing (TILDA), School of Medicine, Trinity College Dublin, D02 R590 Dublin, Ireland"},{"name":"Discipline of Medical Gerontology, School of Medicine, Trinity College Dublin, D02 R590 Dublin, Ireland"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8192-0447","authenticated-orcid":false,"given":"Louise","family":"Newman","sequence":"additional","affiliation":[{"name":"The Irish Longitudinal Study on Ageing (TILDA), School of Medicine, Trinity College Dublin, D02 R590 Dublin, Ireland"},{"name":"Discipline of Medical Gerontology, School of Medicine, Trinity College Dublin, D02 R590 Dublin, Ireland"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7090-9293","authenticated-orcid":false,"given":"John D.","family":"O\u2019Connor","sequence":"additional","affiliation":[{"name":"The Irish Longitudinal Study on Ageing (TILDA), School of Medicine, Trinity College Dublin, D02 R590 Dublin, Ireland"},{"name":"Discipline of Medical Gerontology, School of Medicine, Trinity College Dublin, D02 R590 Dublin, Ireland"},{"name":"School of Medicine, Dentistry and Biomedical Sciences, The Patrick G Johnston Centre for Cancer Research, Queen\u2019s University, Belfast BT9 7BL, UK"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6388-2184","authenticated-orcid":false,"given":"James","family":"Davis","sequence":"additional","affiliation":[{"name":"The Irish Longitudinal Study on Ageing (TILDA), School of Medicine, Trinity College Dublin, D02 R590 Dublin, Ireland"},{"name":"Discipline of Medical Gerontology, School of Medicine, Trinity College Dublin, D02 R590 Dublin, Ireland"}]},{"given":"Rose Anne","family":"Kenny","sequence":"additional","affiliation":[{"name":"The Irish Longitudinal Study on Ageing (TILDA), School of Medicine, Trinity College Dublin, D02 R590 Dublin, Ireland"},{"name":"Discipline of Medical Gerontology, School of Medicine, Trinity College Dublin, D02 R590 Dublin, Ireland"},{"name":"Mercer\u2019s Institute for Successful Ageing (MISA), St. James\u2019s Hospital, D08 NHY1 Dublin, Ireland"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3882-7447","authenticated-orcid":false,"given":"Roman","family":"Romero-Ortuno","sequence":"additional","affiliation":[{"name":"The Irish Longitudinal Study on Ageing (TILDA), School of Medicine, Trinity College Dublin, D02 R590 Dublin, Ireland"},{"name":"Discipline of Medical Gerontology, School of Medicine, Trinity College Dublin, D02 R590 Dublin, Ireland"},{"name":"Mercer\u2019s Institute for Successful Ageing (MISA), St. James\u2019s Hospital, D08 NHY1 Dublin, Ireland"},{"name":"Global Brain Health Institute, Trinity College Dublin, D02 DK07 Dublin, Ireland"}]}],"member":"1968","published-online":{"date-parts":[[2020,12,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"M146","DOI":"10.1093\/gerona\/56.3.M146","article-title":"Frailty in Older Adults: Evidence for a Phenotype","volume":"56","author":"Fried","year":"2001","journal-title":"J. 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