Ethical Aspects of Prodromal Synucleinopathy Prognostic Counseling

REM sleep behaviour disorder (RBD): Personal perspectives and research priorities

The formal identification and naming of rapid eye movement (REM) sleep behaviour disorder (RBD) in 1985-1987 is described; the historical background of RBD from 1966 to 1985 is briefly discussed; and RBD milestones are presented. Current knowledge on RBD is identified with reference to recent comprehensive reviews, allowing for a focus on research priorities for RBD: factors and predictors of neurodegenerative phenoconversion from isolated RBD and patient enrolment in neuroprotective trials; isolated RBD clinical research cohorts; epidemiology of RBD; traumatic brain injury, post-traumatic stress disorder, RBD and neurodegeneration; depression, RBD and synucleinopathy; evolution of prodromal RBD to neurodegeneration; gut microbiome dysbiosis and colonic synuclein histopathology in isolated RBD; other alpha-synuclein research in isolated RBD; narcolepsy-RBD; dreams and nightmares in RBD; phasic REM sleep in isolated RBD; RBD, periodic limb movements, periodic limb movement disorder pseudo-RBD; other neurophysiology research in RBD; cardiac scintigraphy (123I-MIBG) in isolated RBD; brain magnetic resonance imaging biomarkers in isolated RBD; microRNAs as biomarkers in isolated RBD; actigraphic, other automated digital monitoring and machine learning research in RBD; prognostic counselling and ethical considerations in isolated RBD; and REM sleep basic science research. RBD research is flourishing, and is strategically situated at an ever-expanding crossroads of clinical (sleep) medicine, neurology, psychiatry and neuroscience.

Disclosing the Risk Associated with Isolated REM Behavior Disorder: The Sleep Experts' Perspective

BACKGROUND

Isolated rapid-eye-movement sleep behavior disorder (iRBD) is associated with a high risk for phenoconversion to a neurodegenerative disorder, but the optimal approach for disclosure of this risk to patients is still debated.

OBJECTIVES

The aim of this study was to explore views and experiences of iRBD experts regarding risk disclosure.

METHODS

In this qualitative study, semi-structured interviews with sleep experts caring for patients with iRBD were analyzed through a conventional content analysis approach.

RESULTS

We interviewed 22 iRBD experts (eight female, average age of 51.8 years) from 18 Italian sleep centers; 21/22 regularly disclosed the risks associated with iRBD, usually after the video-polysomnography, and 8/22 regularly mentioned phenoconversion rates. Content analysis allowed us to identify three main themes. First, sleep experts reported several points in favor of risk disclosure, especially related to the principle of beneficence, but some highlighted the need for specific learning on the topic. Second, experts favored a patient-tailored disclosure that should not upset the patient unnecessarily, since phenoconversion is uncertain. Third, risk disclosure was seen by participants as a relational task that should be carried out in person in the context of a trusting patient-physician relationship, while they had contrasting views regarding patients' previous knowledge.

CONCLUSIONS

Sleep experts generally preferred a tailored and reassuring approach to risk disclosure within a framework of relational autonomy. The results of this study indicate the need for specific education, training, and recommendations concerning risk disclosure that should also include patients' and families' preferences.

REM sleep behavior disorder: update on diagnosis and management

REM sleep behavior disorder (RBD) is characterized by a loss of atonia of skeletal muscles during REM sleep, associated with acting out behaviors during dreams. Knowledge of this pathology is important to predict neurodegenerative diseases since there is a strong association of RBD with diseases caused by the deposition of alpha-synuclein in neurons (synucleinopathies), such as Parkinson's disease (PD), multiple system atrophy (MSA), and dementia with Lewy bodies (DLB). Proper diagnosis of this condition will enable the use of future neuroprotective strategies before motor and cognitive symptoms. Diagnostic assessment should begin with a detailed clinical history with the patient and bed partner or roommate and the examination of any recorded home videos. Polysomnography (PSG) is necessary to verify the loss of sleep atonia and, when documented, the behaviors during sleep. Technical recommendations for PSG acquisition and analysis are defined in the AASM Manual for the scoring of sleep and associated events, and the PSG report should describe the percentage of REM sleep epochs that meet the criteria for RWA (REM without atonia) to better distinguish patients with and without RBD. Additionally, PSG helps rule out conditions that may mimic RBD, such as obstructive sleep apnea, non-REM sleep parasomnias, nocturnal epileptic seizures, periodic limb movements, and psychiatric disorders. Treatment of RBD involves guidance on protecting the environment and avoiding injuries to the patient and bed partner/roommate. Use of medications are also reviewed in the article. The development of neuroprotective medications will be crucial for future RBD therapy.

Awake or Sleeping? Maybe Both… A Review of Sleep-Related Dissociative States

Recent studies have begun to understand sleep not only as a whole-brain process but also as a complex local phenomenon controlled by specific neurotransmitters that act in different neural networks, which is called "local sleep". Moreover, the basic states of human consciousness-wakefulness, sleep onset (N1), light sleep (N2), deep sleep (N3), and rapid eye movement (REM) sleep-can concurrently appear, which may result in different sleep-related dissociative states. In this article, we classify these sleep-related dissociative states into physiological, pathological, and altered states of consciousness. Physiological states are daydreaming, lucid dreaming, and false awakenings. Pathological states include sleep paralysis, sleepwalking, and REM sleep behavior disorder. Altered states are hypnosis, anesthesia, and psychedelics. We review the neurophysiology and phenomenology of these sleep-related dissociative states of consciousness and update them with recent studies. We conclude that these sleep-related dissociative states have a significant basic and clinical impact since their study contributes to the understanding of consciousness and the proper treatment of neuropsychiatric diseases.

Low Specificity of Rapid Eye Movement Sleep Behavior Disorder Questionnaires: Need for Better Screening Methods

BACKGROUND

Correct diagnosis of rapid eye movement sleep behavior disorder (RBD) is critical due to its link to α-synucleinopathies and risk of injuries and requires video-polysomnography (V-PSG). Usefulness of screening questionnaires outside the context of validation studies is limited.

OBJECTIVE

The aim was to assess the performance of three validated RBD screening questionnaires compared with gold-standard V-PSG.

METHODS

In this bicentric prospective study, 400 consecutive subjects referred to a sleep center for the first time filled three RBD questionnaires (RBD Screening Questionnaire, RBD Single Question, and Innsbruck RBD Inventory) in random order before sleep experts' interview. Subjects positive for at least one questionnaire were invited to undergo V-PSG. Data from patients negative for all questionnaires undergoing V-PSG for other reasons were also evaluated. Questionnaire performances were compared to gold-standard V-PSG RBD diagnosis.

RESULTS

Three hundred ninety-nine patients (median age: 51 [interquartile range: 37-64] years, 54.9% men) participated. Two hundred thirty-eight (59.6%) were positive for at least one questionnaire, and RBD was diagnosed using V-PSG in 30 patients (7.5%). Questionnaire specificity was 48.1% to 67.4%, sensitivity 80% to 92%, accuracy 51% to 68.3%, negative predictive value 94.2% to 98%, and positive predictive value 14.1% to 20.7%, with no relevant differences in performances among the evaluated questionnaires.

CONCLUSIONS

RBD questionnaires have low specificity and low positive predictive value and should not be used as a standalone tool for the diagnosis of RBD. Further development of RBD screening methods is needed, particularly for upcoming neuroprotective trials. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.