Category: Parkinson's Disease (Other)
Objective: To assess motor dysfunction in individuals with polysomnography (PSG)-confirmed isolated REM Sleep Behaviour Disorder (iRBD), self-reported RBD (sRBD), and sRBD with smell loss (hyposmia).
Background: The Bradykinesia Akinesia Incoordination (BRAIN) test is a validated online test used to assess motor dysfunction in Parkinson’s disease (PD)1. A previous study showed that patients with PSG-iRBD had slow and arrhythmic keyboard tapping2.
Method: This is a longitudinal study comparing BRAIN test performance in people with PSG-iRBD, sRBD (defined by answering yes to the single item RBD questionnaire3) and normal smell, sRBD with hyposmia, and healthy controls. The BRAIN test parameters, including kinesia score (KS, number of alternate taps in 30s), akinesia time (AT, mean dwell-time on each tap in ms) and incoordination score (IS, variance of travelling time between taps) were analysed over a three-year period. Baseline parameters were compared using t-tests or Wilcoxon signed-rank tests. A linear mixed effect model adjusted for age and sex was used to compare the change of BRAIN test parameters in the non-dominant hand over time.
Results: We included 11 PSG-iRBD, 149 sRBD, 41 sRBD with hyposmia and 1445 controls. At baseline, people with PSG-iRBD, sRBD and sRBD with hyposmia demonstrated significantly higher variability (IS) on the BRAIN test (p=0.12, p<0.001, p=0.003, respectively) and tapped fewer alternating keys (KS) (p=0.05, p=0.02, p<0.001) than controls. The most pronounced difference from controls was observed in the sRBD with hyposmia. Over time, there were no statistically significant changes in BRAIN test parameters in any groups compared to controls. KS showed a subtle decreasing trend of 1.74 per year in PSG-iRBD (95% CI -5.65 to 2.16, p=0.38). In contrast, KS exhibited a slight increase in the sRBD cohorts, with and without hyposmia, by 0.75 (95% CI -1.29 to 2.78, p=0.47) and 0.73 (95% CI -0.41 to 1.86, p=0.21) per year, respectively, compared to controls.
Conclusion: Similar to PSG-iRBD, individuals with sRBD performed slower than controls at baseline. The most notable difference were observed in a cohort with enriched risk (sRBD with hyposmia). However, BRAIN test performance showed no significant change over three years. The small sample size may limit subgroup differentiation, and the three time points may not be sufficient to detect changes in hand dexterity scores.
References: 1Noyce AJ, Nagy A, Acharya S, Hadavi S, Bestwick JP, Fearnley J, Lees AJ, Giovannoni G. Bradykinesia-akinesia incoordination test: validating an online keyboard test of upper limb function. PLoS One. 2014 Apr 29;9(4):e96260.
2 Simonet C, Pérez-Carbonell L, Galmés-Ordinas MA, Huxford BFR, Chohan H, Gill A, Leschziner G, Lees AJ, Schrag A, Noyce AJ. The Motor Dysfunction Seen in Isolated REM Sleep Behavior Disorder. Mov Disord. 2024 Jun;39(6):1054-1059.
3Postuma RB, Arnulf I, Hogl B, Iranzo A, Miyamoto T, Dauvilliers Y, Oertel W, Ju YE, Puligheddu M, Jennum P, Pelletier A. A single‐question screen for rapid eye movement sleep behavior disorder: a multicenter validation study. Movement Disorders. 2012 Jun;27(7):913-6.
To cite this abstract in AMA style:
H. Chohan, T. Tocino, L. Pérez-Carbonell, G. Leschziner, J. Bestwick, A. Schrag, A. Noyce, C. Simonet. Longitudinal Analysis of BRAIN test in isolated REM sleep behaviour disorder with and without hyposmia. [abstract]. Mov Disord. 2025; 40 (suppl 1). https://www.mdsabstracts.org/abstract/longitudinal-analysis-of-brain-test-in-isolated-rem-sleep-behaviour-disorder-with-and-without-hyposmia/. Accessed October 5, 2025.« Back to 2025 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/longitudinal-analysis-of-brain-test-in-isolated-rem-sleep-behaviour-disorder-with-and-without-hyposmia/