{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T03:47:30Z","timestamp":1760240850873,"version":"build-2065373602"},"reference-count":25,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2019,9,29]],"date-time":"2019-09-29T00:00:00Z","timestamp":1569715200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>We aimed to explore the online signature modality for characterizing early-stage Alzheimer\u2019s disease (AD). A few studies have explored this modality, whereas many on online handwriting have been published. We focused on the analysis of raw temporal functions acquired by the digitizer on signatures produced during a simulated check-filling task. Sample entropy was exploited to measure the information content in raw time sequences. We show that signatures of early-stage AD patients have lower information content than those of healthy persons, especially in the time sequences of pen pressure and pen altitude angle with respect to the tablet. The combination of entropy values on two signatures for each person was classified with two linear classifiers often used in the literature: support vector machine and linear discriminant analysis. The improvements in sensitivity and specificity were significant with respect to the a priori group probabilities in our population of AD patients and healthy subjects. We show that altitude angle, when combined with pen pressure, conveys crucial information on the wrist-hand-finger system during signature production for pathology detection.<\/jats:p>","DOI":"10.3390\/e21100956","type":"journal-article","created":{"date-parts":[[2019,9,30]],"date-time":"2019-09-30T05:58:33Z","timestamp":1569823113000},"page":"956","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":9,"title":["Online Signature Analysis for Characterizing Early Stage Alzheimer\u2019s Disease: A Feasibility Study"],"prefix":"10.3390","volume":"21","author":[{"given":"Zelong","family":"Wang","sequence":"first","affiliation":[{"name":"Electronics and Physics Department, Telecom SudParis, Institut Polytechnique de Paris, 9 rue Charles Fourier, 91011 Evry, France"}]},{"given":"Majd","family":"Abazid","sequence":"additional","affiliation":[{"name":"Electronics and Physics Department, Telecom SudParis, Institut Polytechnique de Paris, 9 rue Charles Fourier, 91011 Evry, France"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5048-9313","authenticated-orcid":false,"given":"Nesma","family":"Houmani","sequence":"additional","affiliation":[{"name":"Electronics and Physics Department, Telecom SudParis, Institut Polytechnique de Paris, 9 rue Charles Fourier, 91011 Evry, France"},{"name":"SAMOVAR, Telecom SudParis, CNRS, Institut Polytechnique de Paris, 9 rue Charles Fourier, 91011 Evry, France"}]},{"given":"Sonia","family":"Garcia-Salicetti","sequence":"additional","affiliation":[{"name":"Electronics and Physics Department, Telecom SudParis, Institut Polytechnique de Paris, 9 rue Charles Fourier, 91011 Evry, France"},{"name":"SAMOVAR, Telecom SudParis, CNRS, Institut Polytechnique de Paris, 9 rue Charles Fourier, 91011 Evry, France"}]},{"given":"Anne-Sophie","family":"Rigaud","sequence":"additional","affiliation":[{"name":"AP-HP, Groupe Hospitalier Cochin Paris Centre, H\u00f4pital Broca, P\u00f4le G\u00e9rontologie, 75013 Paris, France"},{"name":"L\u2019unit\u00e9 de Recherche Universitaire EA 4468, Universit\u00e9 Paris Descartes, 75006 Paris, France"}]}],"member":"1968","published-online":{"date-parts":[[2019,9,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Caligiuri, M.P., and Linton, A.M. 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