Narcolepsy: an interface among neurology, immunology, sleep, and genetics

Narcolepsy is a primary disorder of the central nervous system resulting from genetic, environmental, and immunological interactions defined as excessive daytime sleepiness plus cataplexy, hallucinations, sleep paralysis, and sleep fragmentation. The pathophysiology is not entirely known, but the interaction among genetic predisposition, environmental exposition, and immune component with consequent hypocretin-1 deficiency is the model to explain narcolepsy type I. The mechanism of narcolepsy type II is less understood. There is a delay of over ten years for the diagnosis of narcolepsy around the world. Patients with narcolepsy have many comorbidities with a negative impact on quality of life. The treatment of narcolepsy must contain an educational approach for the family, coworkers, and patients. Scheduled naps and sleep hygiene are essential to minimize the dose of medications. Much progress has been seen in the pharmacological treatment of narcolepsy with new stimulants, different presentations of oxybate, and recent studies with orexin agonists. Narcolepsy is a rare disease that needs to be more understood and highlighted to avoid delayed diagnosis and severe disabilities in patients.

Exploring exercise, physical wellbeing and the role of physiotherapy: perspectives from people with narcolepsy

Narcolepsy is associated with reduced quality of life and physical performance. The study aimed to explore the attitudes of people with Type 1 narcolepsy towards exercise and physical activity, their physical wellbeing, and the potential role of physiotherapy. Semi-structured interviews were conducted with 22 people with narcolepsy attending a dedicated outpatient narcolepsy clinic located in Dublin, Ireland. Transcripts were iteratively coded; a thematic analysis was undertaken, and key themes were identified. Four themes were identified: 'Barriers and Facilitators to Exercising', 'Social Concerns', 'Health Concerns' and 'Suggestions for the Role of Physiotherapy'. Future research should explore the potential role of exercise to help manage narcolepsy-related symptoms in this population.

The Influence of Sleep Disturbance on Chronic Pain

PURPOSE OF REVIEW

The purpose of this review is to present an overview of common sleep disturbance pathologies and their impact on chronic pain, while examining various factors that are implicit in the relationship between sleep disturbance and chronic pain, including neurobiochemistry, anatomy, and systemic mediators, and reviewing recent and landmark literature.

RECENT FINDINGS

Earlier literature reviews and studies have introduced the bidirectional relationship between sleep disturbance and chronic pain; that is, impaired sleep may worsen chronic pain, and chronic pain causes sleep disturbance. However, more recent reviews and studies seem to show a more associative, rather than causative relationship. There have been recent studies that attempt to determine mechanisms that link sleep disturbance and chronic pain; the results of these studies were more varied, ultimately concluding that there may be a separate, yet-to-be discovered mechanism that shows the causative relationship between sleep disturbance and pain. There are several neurotransmitters that are involved in the mediation of chronic pain and sleep disturbance as separate entities, and some studies have shown that there may be mechanisms that govern both chronic pain and sleep disturbance as a single unit. Other neuroendocrine substances also serve to mediate chronic pain and sleep disturbance. All these substances are found to be associated with various sleep disorders and are also associated with chronic pain symptoms as well. Inflammation plays a role in chronic pain and sleep disturbance, with an increase in inflammatory substances and mediators associated with an increase or worsening in chronic pain symptoms and sleep disorders. The HPA axis plays a role in chronic pain and sleep disorders, influencing pain and sleep pathways through stress response, inflammation, and maintenance of homeostasis. There are several variables that influence both chronic pain and sleep disturbance, and more research into these variables may further our understanding into the complex pathways governing the influence of sleep disturbance on pain, and ultimately to improve treatment for this issue.

Narcolepsy: Comorbidities, complexities and future directions

Patients with narcolepsy live with a lifelong sleep-wake disorder, impairing their quality of life, productivity, educational and employment outcomes. Clinicians are becoming aware that a significant aspect of the burden of this disease relates to frequent comorbid conditions, including aspects of the patient's emotional, metabolic, sleep and immune health. This review explores the literature describing the comorbidities seen in patients with narcolepsy, to enhance understanding of these often complex presentations. It hopes to encourage a multidisciplinary approach, to collaborate with patients and a broad clinical team, and to maximise clinical and quality of life outcomes, for those living with narcolepsy.

Past, present, and future of sleep medicine research in Latin America

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Sleep medicine is a relatively young field with exponential growth in development and research in the last decades. Parallel to the advances in the United States, Latin America also had its beginnings in sleep medicine housed in neuroscience laboratories. Since the very first Latin American meeting in 1985, and the first sleep society in 1993, sleep research has undergone significant development in subsequent years. From contributions in animal research that allowed understanding of the activity of the brain during sleep to the studies that improved our knowledge of sleep disorders in humans, Latin America has become a scientific hub for expansion of sleep research. In this article, we present a historical account of the development of sleep medicine in Latin America, the current state of education and the achievements in research throughout history, and the latest advances in the trending areas of sleep science and medicine. These findings were presented during World Sleep Society meeting in Vancouver in 2019 and complement the work on sleep societies and training published by Vizcarra-Escobar et al in their article "Sleep societies and sleep training programs in Latin America" (J Clin Sleep Med. 2020;16(6):983-988).

Recognizing the Symptom Spectrum of Narcolepsy to Improve Timely Diagnosis: A Narrative Review

Narcolepsy is a chronic sleep disorder with a strong negative impact on quality of life, especially when untreated. Diagnostic delay is a persistent problem, with obvious detrimental effects on patients. A diagnosis of narcolepsy may be delayed because of its broad symptom presentation which is much more encompassing than the classical "tetrad" of sleepiness, cataplexy, hallucinations, and sleep paralysis. Furthermore, symptoms can vary over time. Presentation of symptoms can also be markedly different between children and adults. Finally, common sleep-related comorbidities increase the risk of narcolepsy being masked by overlapping symptoms or treatment. In this review, we provide a detailed description of the broad and dynamic symptom spectrum of narcolepsy, with specific attention to the different manifestations in both adults and children. The overarching goal is to help not only sleep specialists, but general practitioners, pediatricians, and other caregivers with early recognition and prompt diagnosis of this severe but treatable disorder.

Activating autoantibodies against G protein-coupled receptors in narcolepsy type 1

STUDY OBJECTIVES

Narcolepsy type 1 is a rare hypersomnia of central origin, which is caused by loss of hypothalamic neurons that produce the neuropeptides hypocretin-1 and -2. Hypocretin-containing nerve terminals are found in areas known to play a central role in autonomic control and in pain signaling. Cholinergic M2 receptors are found in brain areas involved with the occurrence of hallucinations and cataplexy. In addition to classical symptoms of narcolepsy, the patients suffer frequently from autonomic dysfunction, chronic pain, and hypnagogic/hypnopompic hallucinations. We aimed to test whether narcolepsy type 1 patients have autoantibodies against autonomic β2 adrenergic receptor, M2 muscarinic receptors, or nociception receptors.

METHODS

We tested the serum of ten narcolepsy type 1 patients (five female) for activating β2 adrenergic receptor autoantibodies, M2 muscarinic receptor autoantibodies, and nociception receptor autoantibodies.

RESULTS

Ten of ten patients were positive for muscarinic M2 receptor autoantibodies (P < 0.001), 9/10 were positive for autoantibodies against nociception receptors (P < 0.001), and 5/10 were positive for β2 adrenergic receptor autoantibodies (P < 0.001).

CONCLUSIONS

Narcolepsy type 1 patients harbored activating autoantibodies against M2 muscarinic receptors, nociception receptors, and β2 adrenergic receptors. M2 receptor autoantibodies may be related to the occurrence of cataplexy and, moreover, hallucinations in narcolepsy since they are found in the same brain areas that are involved with these symptoms. The occurrence of nociception receptor autoantibodies strengthens the association between narcolepsy type 1 and pain. The connection between narcolepsy type 1, autonomic complaints, and the presumed cardiovascular morbidity might be associated with the occurrence of β2 adrenergic receptor autoantibodies. On the other hand, the presence of the autoantibodies may be secondary to the destruction of the hypocretin pathways.

Health-related quality of life in patients with narcolepsy types 1 and 2 from a Sleep Center in Brazil

INTRODUCTION

Narcolepsy patients have higher prevalence of comorbidities, such as obesity, depression, and pain. Narcolepsy symptoms and concomitant medical conditions can impact the daily activities of patients. The objective of this study is to describe the quality of life in a sample of patients with narcolepsy, and the influence of the nutritional status in health domains.

METHODS

At Unifesp, two groups of 33 patients (narcolepsy types 1 and 2 meeting 2014 criteria, concerning hypocretin-1) and 33 controls without sleepiness, matched by age and sex, filled out the SF-36.

RESULTS

Narcolepsy groups, regardless of their nutritional status, had significantly lower scores in all domains, compared to controls, mainly in Role-physical, Role-emotional, and Energy/Fatigue. Role-physical score was lower in type 1 than in type 2 and controls (37.8±1.0 vs. 50.0±1.2 vs. 85.6±1.6; p<0.0001). Obese with type 2 narcolepsy scored lower than type 1 in physical scales.

CONCLUSION

In a Sleep Center in São Paulo, Brazil, physical and mental health were impaired in narcolepsy types 1 and 2. The first report of the poor health status in Brazilians with narcolepsy type 2 suggests that obesity negatively affects physical domains.

Sleepiness comorbid to musculoskeletal pain is associated with worse quality of life and mood symptoms in a general population sample

Objectives

Musculoskeletal (MSK) pain and hypersomnolence (HPS) are very disabling conditions that may share some pathophysiological factors. This study aimed to evaluate the interaction between MSK pain and HPS and its association with mood symptoms, fatigue, quality of life, and both objective and subjective sleep quality.

Design

Cross-sectional study.

Setting

General population based sample.

Participants

510 individuals from EPISONO cohort, São Paulo (Brazil).

Measurements

All participants completed questionnaires, had clinical assessment and underwent a full-night polysomnography. HPS was defined according to Epworth Sleepiness Scale while the presence of MSK pain was defined by structured questionnaire. The sample was allocated into 4 groups: control (CTRL, n=281), HPS (n=141), MSK (n=50), and both conditions (HPS+MSK, n=38).

Results

MSK pain and HPS by themselves were associated with worse mood symptoms and quality of life. However, individuals with both associated conditions (HPS+MSK) presented higher frequencies of moderate to severe depression (44.1%) and anxiety symptoms (45.7%), as well as an additional decrease in quality of life compared to the other groups. There were no differences between HPS+MSK and MSK groups in objective sleep pattern. With regard to subjective sleep, HPS+MSK presented a higher prevalence of sleep attacks and cataplexy compared to all other groups.

Conclusions

The combination of MSK pain and HPS was associated with worse mood symptoms, quality of life and HPS-related features. This study suggests that sleepiness may be an important symptom to be investigated and treated in MSK pain-related conditions for a better quality of life.

The sensory pain of Dante's Inferno - Semantics of chronic pain in patients with narcolepsy

Objective

To examine the semantics of chronic pain in narcolepsy and to compare with the poem Inferno, from Dante Alighieri.

Methods

A cross-sectional study, in which type 1 (n=33) and type 2 (n=33) patients (hypocretin-1 quantification in cerebrospinal fluid), were studied at Departamento de Psicobiologia - Universidade Federal de São Paulo (Brazil). We assessed pain descriptors in the Present Rating Index (PRI) from McGill Pain Questionnaire.

Results

There was no significant difference in PRI between narcolepsy groups. In both groups, the most frequent words had a sensory dimension: throbbing, jumping, and tugging. Multiple correspondence analysis revealed the predominance of sensory descriptors and the deficiency of affective descriptors in these groups.

Discussion

A study that interpreted the poem Inferno, from Dante Alighieri, as McGill Pain Questionnaires descriptors suggested a contribution of the sensory dimension in pain of possibly narcolepsy patients, similar as in our results.