{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T01:37:31Z","timestamp":1760060251190,"version":"build-2065373602"},"reference-count":70,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2025,8,20]],"date-time":"2025-08-20T00:00:00Z","timestamp":1755648000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Institute on Aging (NIA)","award":["R01AG070088","AG027771","NS060722","NIH M01RR10732","C06RR016499"],"award-info":[{"award-number":["R01AG070088","AG027771","NS060722","NIH M01RR10732","C06RR016499"]}]},{"name":"National Institute of Neurological Disorders and Stroke (NINDS)","award":["R01AG070088","AG027771","NS060722","NIH M01RR10732","C06RR016499"],"award-info":[{"award-number":["R01AG070088","AG027771","NS060722","NIH M01RR10732","C06RR016499"]}]},{"name":"Penn State Hershey General Clinical Research Center","award":["R01AG070088","AG027771","NS060722","NIH M01RR10732","C06RR016499"],"award-info":[{"award-number":["R01AG070088","AG027771","NS060722","NIH M01RR10732","C06RR016499"]}]},{"name":"GCRC Construction Grants","award":["R01AG070088","AG027771","NS060722","NIH M01RR10732","C06RR016499"],"award-info":[{"award-number":["R01AG070088","AG027771","NS060722","NIH M01RR10732","C06RR016499"]}]},{"name":"Leader Family Foundation","award":["R01AG070088","AG027771","NS060722","NIH M01RR10732","C06RR016499"],"award-info":[{"award-number":["R01AG070088","AG027771","NS060722","NIH M01RR10732","C06RR016499"]}]},{"name":"Pennsylvania Department of Health using Tobacco CURE Funds","award":["R01AG070088","AG027771","NS060722","NIH M01RR10732","C06RR016499"],"award-info":[{"award-number":["R01AG070088","AG027771","NS060722","NIH M01RR10732","C06RR016499"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Life"],"abstract":"<jats:p>Olfactory impairment was assessed in akinetic-rigid (PDAR) and tremor-predominant (PDT) subtypes of Parkinson\u2019s disease (PD), classified based on motor symptoms. Seventeen PDAR, fifteen PDT, and twenty-four cognitively normal (CN) participants completed the University of Pennsylvania Smell Identification Test (UPSIT). Groups were well-matched for age and demographic variables, with cognitive performance statistically controlled. Resting-state fMRI (rs-fMRI) and seed-based functional connectivity (FC) analyses were conducted to characterize olfactory network (ON) connectivity across groups. UPSIT scores were significantly lower in PDAR compared to PDT. Consistently, ON FC values were reduced in PDAR relative to both PDT and CN. FC of the primary olfactory cortex (POC) significantly differed between CN and the PD subtypes. Furthermore, connectivity in the orbitofrontal cortex and insula showed significant differences between PDAR and PDT, as well as between PDAR and CN. Notably, ON FC between the left hippocampus and the posterior cingulate cortex (PCC) also differed significantly between PDAR and PDT. These findings reveal distinct ON FC patterns across PDAR and PDT subtypes. Variations in UPSIT scores suggest that motor symptom subtype is associated with olfactory performance. Moreover, ON connectivity closely paralleled the UPSIT scores, reinforcing a neural basis for olfactory deficits in PD. Given the accelerated motor and cognitive decline often observed in the PDAR, these results support the potential of olfactory impairment as a clinical marker for disease severity.<\/jats:p>","DOI":"10.3390\/life15081324","type":"journal-article","created":{"date-parts":[[2025,8,20]],"date-time":"2025-08-20T13:18:14Z","timestamp":1755695894000},"page":"1324","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Olfactory Network Functional Connectivity as a Marker for Parkinson\u2019s Disease Severity"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0009-0004-3684-0906","authenticated-orcid":false,"given":"Senal","family":"Peiris","sequence":"first","affiliation":[{"name":"Department of Radiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Anupa","family":"Ekanayake","sequence":"additional","affiliation":[{"name":"Department of Radiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jiaming","family":"Lu","sequence":"additional","affiliation":[{"name":"Department of Radiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA"},{"name":"Medical School of Nanjing University, Nanjing University, Nanjing 210993, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Rommy","family":"Elyan","sequence":"additional","affiliation":[{"name":"Department of Radiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Katie","family":"Geesey","sequence":"additional","affiliation":[{"name":"Department of Radiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ross","family":"Cottrill","sequence":"additional","affiliation":[{"name":"Department of Radiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6032-7801","authenticated-orcid":false,"given":"Paul","family":"Eslinger","sequence":"additional","affiliation":[{"name":"Department of Radiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA"},{"name":"Department of Neurology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xuemei","family":"Huang","sequence":"additional","affiliation":[{"name":"Department of Neurology, School of Medicine, The University of Virginia, Charlottesville, VA 22903, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Prasanna","family":"Karunanayaka","sequence":"additional","affiliation":[{"name":"Department of Radiology, The Pennsylvania State University College of Medicine, Hershey, PA 17033, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2025,8,20]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"190","DOI":"10.1038\/nrneurol.2013.47","article-title":"New Guidelines for Diagnosis of Parkinson Disease","volume":"9","author":"Tolosa","year":"2013","journal-title":"Nat. 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