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Minor hallucinations in isolated rapid eye movement sleep behavior disorder indicative of early phenoconversion: A

Yukiyoshi Sumi¹, Ayaka Ubara^1,2,3, Yuji Ozeki¹

¹Department of Psychiatry, Shiga University of Medical Science, Shiga, Japan.

Acta Neurologica Scandinavica

|November 24, 2021

Abstract

Objectives:

Minor hallucinations (MH) are psychotic symptoms that can occur anywhere between prodromal to early Parkinson's disease and after onset of motor problems. MH include visual illusions, presence hallucinations, and passage hallucinations. Isolated rapid eye movement sleep behavior disorder (RBD) is a harbinger of neurodegenerative diseases. We conducted a retrospective cohort study to investigate the clinical characteristics of isolated RBD with MH and the risk of phenoconversion.

Materials And Methods:

We retrospectively analyzed the data of 36 patients with isolated RBD (four females; median age, 75.0 years). We defined cases reporting at least one minor hallucination as RBD with MH. Demographic data and cognitive function were compared between patients with and without MH, and Cox proportional hazards models estimated the risk of phenoconversion.

Results:

We included 10 (27.8%) patients with MH and 26 (72.2%) without MH. Patients with MH were older, had less dopamine transporter accumulation, more severe autonomic dysfunction, more depressive symptoms, and lower verbal fluency and symbol coding test scores than patients without MH. After follow-up (median, 2.50 years), 13.9% (5/36) of all patients developed phenoconversion (Parkinson's disease, two patients; dementia with Lewy bodies, three patients). The rate of phenoconversion was significantly higher in patients with MH (40.0% vs. 3.8%, p = .005). The Cox proportional hazards model adjusted for age, sex, and disease duration revealed that MH was a significant risk factor for phenoconversion (hazard ratio, 14.72; 95% confidence interval, 1.35-160.5).

Conclusions:

Minor hallucinations may be utilized as early clinical markers for prodromal estimation of neurodegenerative diseases.

Insights

Minor hallucinations in isolated rapid eye movement sleep behavior disorder (RBD) indicate a higher risk of developing neurodegenerative diseases like Parkinson's. These hallucinations can serve as early clinical markers for disease progression.

Area of Science:

Neurology
Sleep Medicine
Psychiatry

Background:

Minor hallucinations (MH) are psychotic symptoms occurring in prodromal to early Parkinson's disease (PD) and after motor symptom onset.
Isolated rapid eye movement sleep behavior disorder (RBD) is a known harbinger of neurodegenerative diseases.
Understanding the clinical characteristics of isolated RBD with MH is crucial for early diagnosis.

Purpose of the Study:

To investigate the clinical characteristics of patients with isolated RBD and minor hallucinations (MH).
To determine the risk of phenoconversion in patients with isolated RBD and MH.
To identify MH as a potential early marker for neurodegenerative disease progression.

Main Methods:

Retrospective cohort study of 36 patients with isolated RBD.
Patients were categorized based on the presence or absence of minor hallucinations.
Demographic data, cognitive function, and phenoconversion rates were analyzed using Cox proportional hazards models.

Main Results:

Patients with MH were older, exhibited less dopamine transporter accumulation, and had more severe autonomic dysfunction and depressive symptoms.
Cognitive assessments revealed lower verbal fluency and symbol coding scores in patients with MH.
Phenoconversion occurred in 13.9% of patients; the rate was significantly higher in the MH group (40.0% vs. 3.8%, p=0.005).
MH was identified as a significant risk factor for phenoconversion (HR, 14.72).

Conclusions:

Minor hallucinations in isolated RBD patients are associated with distinct clinical characteristics.
Minor hallucinations significantly increase the risk of phenoconversion to neurodegenerative diseases.
MH may serve as valuable early clinical markers for prodromal estimation of neurodegenerative diseases.

Read full analysis

Keywords:

REM sleep behavior disorder hallucinations neurodegenerative disease retrospective study

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