Objective: This study aimed to assess the severity of neuropsychiatric symptoms in individuals with idiopathic/isolated rapid eye movement (REM) sleep behavior disorder (iRBD) according to their cognitive status.
Background: iRBD is a parasomnia characterized by abnormal motor activity during REM sleep. It is also recognized as a prodromal stage of alpha-synucleinopathies, including Parkinson’s disease and dementia with Lewy bodies (DLB)1. Mild cognitive impairment (MCI) affects approximately 30% of iRBD patients1, and neuropsychiatric symptoms – such as depression, anxiety, apathy, and hallucinations – are present in about 25% of iRBD patients2. However, the relationship between cognitive status and neuropsychiatric symptoms in iRBD remains poorly understood.
Method: We recruited 179 polysomnography-confirmed iRBD patients free of dementia, including 67 (37%) with MCI, as well as 99 age-, gender-, and education-matched controls. MCI was diagnosed based on neuropsychological assessment2. Questionnaires measuring symptoms of depression (BDI-II), anxiety (BAI-II), hallucinations (UPDRS-I), and apathy (UPDRS-I) were completed. Group comparisons were conducted using ANOVA and chi-square tests. Pearson or Spearman correlations were performed to examine the association between cognitive performance and neuropsychiatric symptoms.
Results: Hallucinations were more frequent in patients with MCI compared to patients without MCI and controls (22% vs. 9% vs. 0%; p < 0.05). Symptoms of depression, anxiety, and apathy were more severe in both iRBD groups compared to controls (p < 0.05). Moreover, hallucinations were associated with poorer performance on tests assessing visuospatial abilities (p = 0.009).
Conclusion: These findings highlight hallucinations as a distinguishing neuropsychiatric feature in iRBD patients with MCI. This subgroup may be at increased risk of developing DLB, a neurodegenerative disorder associated with hallucinations3. Longitudinal studies are needed to further elucidate the progression of neuropsychiatric symptoms in relation to cognitive decline and the onset of neurodegenerative diseases in iRBD.
References: [1] Gagnon JF et al. (2009) Annals of Neurology. [2] Postuma RB et al. (2019) Brain. [3] McKeith IK et al. (2017) Neurology.
To cite this abstract in AMA style:
M. Trepanier Maurais, C. Zigrand, R. B. Postuma, J. Montplaisir, I. Rouleau, J. Gagnon. Hallucinations as a Distinguishing Neuropsychiatric Feature in Idiopathic Rapid Eye Movement Sleep Behavior Disorder Patients [abstract]. Mov Disord. 2025; 40 (suppl 1). https://www.mdsabstracts.org/abstract/hallucinations-as-a-distinguishing-neuropsychiatric-feature-in-idiopathic-rapid-eye-movement-sleep-behavior-disorder-patients/. Accessed November 20, 2025.« Back to 2025 International Congress
MDS Abstracts - https://www.mdsabstracts.org/abstract/hallucinations-as-a-distinguishing-neuropsychiatric-feature-in-idiopathic-rapid-eye-movement-sleep-behavior-disorder-patients/