Objective: To assess whether body vs brain-first PD phenotypes differ in their autonomic, motor and non-motor burden in their early stages.

Background: A growing body of literature supports the notion that PwP with premotor RBD display a higher autonomic burden (1,2), supporting the use of a “body-first  versus brain-first” model of the disease.

Method: Adult PwP with <24 months duration of motor symptoms were offered to participate if they met no exclusion criteria: prior diagnosis of polyneuropathy, history of alcohol abuse or diabetes mellitus, prior administration of intravenous chemotherapy, prior diagnosis of OSA and onset of RBD concomitant or after motor onset.

Patients were classified as body-first if they had pre-existent dream enactment consistent with RBD, after evaluation by a sleep specialist. Otherwise, they were listed as brain-first.

All PwP underwent clinical, autonomic and electrophysiological examination measuring: MDS-UPDRS, SCOPA-AUT, NMSS, nerve conduction studies, small fibre studies (cutaneous sympathetic response and cutaneous silent period), Ewing test and electrochemical conductance in all four limbs using Sudoscan (3).

Statistical analyses were carried out using Jamovi v2.6.45 (4).

The study was approved by our institution’s research committee. Permission to use scales was granted by MDS.

Results: 38 patients (7F) were included. Median duration disease was 7 months (IQR 7.47, range 3-24) at the time of the evaluation. 12 patients (31.6%) were classified as body-first group.  Baseline characteristics were not dissimilar between groups. Global median Hoehn&Yahr stage was 2 (IQR 1) with no significant differences detected between groups.

After controlling for false discovery rate, we found a significant difference in the SCOPA-AUT score (17.9 vs 10.3; mean difference 7.6 points; confidence interval for the mean difference ranging from −12.83 to −2.45; p=0.005) but not for the any other variables tested.

There were no between group differences when “any alteration” in ECC and presence of polyneuropathy).

Conclusion: Our findings align with previous findings supporting a higher autonomic burden in PwP with premotor RBD. Nevertheless, we found no relevant differences in objective autonomic and small fibre testing early in the disease.

Major limitations include the small size of the sample and the lack of PSG-confirmed RBD in all subjects.

References: 1) Borghammer P, Van Den Berge N. Brain-First versus Gut-First Parkinson’s Disease: A Hypothesis. J Parkinsons Dis. 2019;9(s2):S281-S295. doi: 10.3233/JPD-191721. PMID: 31498132; PMCID: PMC6839496.
2) Al-Qassabi A, Pelletier A, Fereshtehnejad SM, Postuma RB. Autonomic Sweat Responses in REM Sleep Behavior Disorder and Parkinsonism. J Parkinsons Dis. 2018;8(3):463-468. doi: 10.3233/JPD-181357. PMID: 30040743.
3) Casellini C.M., Parson H.K., Richardson M.S., Nevoret M.L., Vinik A.I. Sudoscan, a noninvasive tool for detecting diabetic small fiber neuropathy and autonomic dysfunction. Diabetes Technol. Ther. 2013;15:948–953. doi: 10.1089/dia.2013.0129.
4) The jamovi project (2025). jamovi (Version 2.6) [Computer Software]. Retrieved from https://www.jamovi.org

« Back to 2026 International Congress

MDS Abstracts - https://www.mdsabstracts.org/abstract/testing-the-body-vs-brain-first-hypothesis-in-early-pd-a-cross-sectional-study/