{"doi":"10.1101/2021.10.26.21265550","title":"White matter microstructure in Parkinson’s disease with and without elevated REM sleep muscle tone","abstract":"Abstract People with Parkinson’s disease who have elevated muscle activity during rapid eye movement sleep (REM sleep without atonia) typically have worse motor and cognitive impairment compared to those with normal muscle atonia during REM sleep. This study used tract-based spatial statistics to compare diffusion MRI measures of fractional anisotropy, radial, mean and axial diffusivity (measures of axonal microstructure based on the directionality of water diffusion) in white matter tracts between people with Parkinson’s disease with and without REM sleep without atonia and controls and their relationship to measures of motor and cognitive function. Thirty-eight individuals with mild-to-moderate Parkinson’s disease and twenty-one matched control subjects underwent ultra-high-field MRI (7Tesla), quantitative motor assessments of gait and bradykinesia, and neuropsychological testing. The Parkinson’s disease cohort was separated post-hoc into those with and without elevated chin or leg muscle activity during REM sleep based on polysomnography findings. Fractional anisotropy was significantly higher, and diffusivity significantly lower, in regions of the corpus callosum, projection, and association white matter pathways in the Parkinson’s group with normal REM sleep muscle tone compared to controls, and in a subset of pathways relative to the Parkinson’s disease group with REM sleep without atonia. The Parkinson’s disease group with elevated REM sleep muscle tone showed significant impairments in gait and upper arm speed compared to controls and significantly worse scores in specific cognitive domains (executive function, visuospatial memory) compared to the Parkinson’s disease group with normal REM sleep muscle tone. Regression analyses showed that gait speed and step length in the Parkinson’s disease cohort were predicted by measures of fractional anisotropy of the anterior corona radiata, whereas elbow flexion velocity was predicted by fractional anisotropy of the superior corona radiata. Visuospatial memory task performance was predicted by the radial diffusivity of the posterior corona radiata. These findings show that people with mild-to-moderate severity of Parkinson’s disease who have normal muscle tone during REM sleep demonstrate compensatory-like adaptations in axonal microstructure that are associated with preserved motor and cognitive function, but these adaptations are reduced or absent in those with increased REM sleep motor tone.","journal":"medRxiv","year":2021,"id":227303,"datarank":0.0,"base_score":0.0,"endowment":0.0,"self_citation_contribution":0.0,"citation_network_contribution":0.0,"self_endowment_contribution":0.0,"citer_contribution":0.0,"corpus_percentile":null,"corpus_rank":null,"citation_count":0,"citer_count":0,"citers_with_citation_signal":0,"citers_with_endowment":0,"datacite_reuse_total":0,"is_dataset":false,"is_dataset_confidence":0.9574,"is_data_producer":false,"deposit_databanks":null,"is_oa":true,"file_count":0,"downloads":0,"has_version_chain":false,"published_date":"2021-01-01","fair_score":null,"fair_percentile":null,"algorithm_id":"datarank_citation_only_1hop_v6","ranking_scope":"data_only","authors":[{"id":256595,"name":"Pramod Kumar Pisharady","orcid":"0000-0002-0756-1199","position":1,"is_corresponding":false},{"id":451804,"name":"Sommer L. Amundsen Huffmaster","orcid":"0000-0001-8079-328X","position":2,"is_corresponding":false},{"id":497038,"name":"Maria E. Linn‐Evans","orcid":"0000-0002-8535-2894","position":3,"is_corresponding":false},{"id":490230,"name":"Michael J. Howell","orcid":"0000-0001-7535-0724","position":4,"is_corresponding":false},{"id":426993,"name":"Jae Woo Chung","orcid":"0000-0002-9107-9038","position":5,"is_corresponding":false},{"id":392541,"name":"Matthew N. Petrucci","orcid":"0000-0003-3353-2532","position":6,"is_corresponding":false},{"id":284800,"name":"Aleksandar Videnović","orcid":"0000-0002-9237-1516","position":7,"is_corresponding":false},{"id":831645,"name":"Erin Holker","orcid":null,"position":8,"is_corresponding":false},{"id":831194,"name":"Joshua De Kam","orcid":"0009-0008-1060-180X","position":9,"is_corresponding":false},{"id":337782,"name":"Paul Tuite","orcid":"0000-0003-1413-7924","position":10,"is_corresponding":false},{"id":256596,"name":"Christophe Lenglet","orcid":"0000-0003-4646-3185","position":11,"is_corresponding":false},{"id":320268,"name":"Noam Harel","orcid":"0000-0002-6034-3801","position":12,"is_corresponding":false},{"id":375737,"name":"Colum D. MacKinnon","orcid":"0000-0002-2722-7868","position":13,"is_corresponding":false},{"id":392540,"name":"Rémi Patriat","orcid":"0000-0003-2928-3772","position":0,"is_corresponding":true}],"reference_count":80,"raw_metadata":null,"created_at":"2026-07-18T23:54:42.179886Z","pmid":null,"pmcid":null,"fwci":null,"citation_percentile":null,"influential_citations":0,"oa_status":null,"license":null,"views":0,"total_file_size_bytes":0,"version_count":0,"fair_f":null,"fair_a":null,"fair_i":null,"fair_r":null,"fair_zscore":null,"fair_rationale":null,"fair_model":null,"fair_agent_version":null,"fair_fulltext_source":null,"fair_has_llm":null,"fair_computed_at":null,"clinical_trials":[],"software_tools":[],"db_accessions":[],"linked_datasets":[],"topics":[]}