{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,13]],"date-time":"2026-03-13T03:02:50Z","timestamp":1773370970736,"version":"3.50.1"},"reference-count":17,"publisher":"MDPI AG","issue":"1","license":[{"start":{"date-parts":[[2026,3,12]],"date-time":"2026-03-12T00:00:00Z","timestamp":1773273600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Reports"],"abstract":"<jats:p>Background and Clinical Significance: Withdrawal symptoms from an abrupt discontinuation or rapid dose reduction in amantadine has been documented as early as 1987. Symptoms can align with several diagnoses, including but not limited to infection, fever, worsening of Parkinson\u2019s disease, seizures, and an altered mental status. In the case described, the timely diagnosis of amantadine withdrawal was delayed due to its nonspecific presentation. Case Presentation: A man in his 60s presented with lethargy, confusion, and delayed responses. His past medical history included parkinsonism, a seizure, type 2 diabetes, and schizoaffective disorder. Outpatient medications included amantadine, benztropine, divalproex, levetiracetam, paliperidone, risperidone, and semaglutide. He was admitted for an altered mental status, and home medications were held when he became NPO. A nasogastric tube was placed, and amantadine was restarted. Following the amantadine reinitiation, the patient returned to baseline and, after ruling out other causes, was diagnosed with amantadine withdrawal. He ultimately completed a 20-day admission and was discharged to a nursing home. Conclusions: The timely diagnosis of amantadine withdrawal was delayed due to its nonspecific presentation. For patients taking amantadine, clinicians should include amantadine withdrawal in their list of differential diagnoses, and in cases of altered mentation, a careful review of the medication list is essential.<\/jats:p>","DOI":"10.3390\/reports9010085","type":"journal-article","created":{"date-parts":[[2026,3,12]],"date-time":"2026-03-12T14:46:31Z","timestamp":1773326791000},"page":"85","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Altered Mental Status Due to Amantadine Withdrawal: A Case Report"],"prefix":"10.3390","volume":"9","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-4872-7682","authenticated-orcid":false,"given":"Nicole J.","family":"Asal","sequence":"first","affiliation":[{"name":"Department of Pharmacy Practice and Clinical Research, College of Pharmacy, University of Rhode Island, Kingston, RI 02881, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Elisa","family":"Piraino","sequence":"additional","affiliation":[{"name":"Department of Pharmacy, Brown University Health, Providence, RI 02903, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Cristina","family":"Hamacher","sequence":"additional","affiliation":[{"name":"Internal Medicine Residency Program, Brown University, Providence, RI 02903, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Husam","family":"Abu Nejim","sequence":"additional","affiliation":[{"name":"Geriatrics, Department of Medicine, Loyola Medicine, Maywood, IL 60153, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,12]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1168","DOI":"10.1001\/jama.1969.03160070046011","article-title":"Amantadine in the treatment of Parkinson\u2019s disease","volume":"208","author":"Schwab","year":"1969","journal-title":"JAMA"},{"key":"ref_2","unstructured":"Vertical Pharmaceuticals (2024, July 15). 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Case Rep."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"149","DOI":"10.1097\/NRL.0000000000000330","article-title":"Parkinsonism-hyperpyrexia Syndrome After Amantadine Withdrawal: Case Report and Review of the Literature","volume":"26","author":"Imthon","year":"2021","journal-title":"Neurologist"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"1048","DOI":"10.1016\/S1474-4422(21)00249-0","article-title":"Amantadine in the treatment of Parkinson\u2019s disease and other movement disorders","volume":"20","author":"Rascol","year":"2021","journal-title":"Lancet Neurol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"57316","DOI":"10.18632\/oncotarget.17622","article-title":"An updated meta-analysis of amantadine for treating dyskinesia in Parkinson\u2019s disease","volume":"8","author":"Kong","year":"2017","journal-title":"Oncotarget"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1159\/000460814","article-title":"A Case Report of Severe Delirium after Amantadine Withdrawal","volume":"9","author":"Marxreiter","year":"2017","journal-title":"Case Rep. 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Soc."}],"container-title":["Reports"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2571-841X\/9\/1\/85\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,3,12]],"date-time":"2026-03-12T16:00:41Z","timestamp":1773331241000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2571-841X\/9\/1\/85"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,3,12]]},"references-count":17,"journal-issue":{"issue":"1","published-online":{"date-parts":[[2026,3]]}},"alternative-id":["reports9010085"],"URL":"https:\/\/doi.org\/10.3390\/reports9010085","relation":{},"ISSN":["2571-841X"],"issn-type":[{"value":"2571-841X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,3,12]]}}}