Impact of obesity in children with narcolepsy

Recommended protocols for the Multiple Sleep Latency Test and Maintenance of Wakefulness Test in children: guidance from the American Academy of Sleep Medicine

The American Academy of Sleep Medicine commissioned a task force of clinical experts in pediatric sleep medicine to review published literature on performing the Multiple Sleep Latency Test (MSLT) and Maintenance of Wakefulness Test for diagnosis and management of central disorders of hypersomnolence among children and adolescents. This paper follows a format similar to that of the paper "Recommended protocols for the Multiple Sleep Latency Test and Maintenance of Wakefulness Test in adults: guidance from the American Academy of Sleep Medicine" that was published in 2021. Since there is insufficient evidence to specify a recommended protocol for the Maintenance of Wakefulness Test in children and adolescents, this paper focuses only on the MSLT protocol. This protocol paper provides guidance to health care providers who order, sleep specialists who interpret, and technical staff who administer the MSLT to pediatric patients. Similar to the adult protocol paper, this document provides guidance based on pediatric expert consensus and evidence-based data when available. Topics include patient preparation, evaluation of medication and substance use, sleep needs before testing, scheduling considerations, optimal test conditions for youth, and documentation. Specific changes recommended for pediatric MSLT protocols include (1) provision of a minimum of 7 hours of sleep (with a minimum 8-hour recording time) on polysomnography the night before the MSLT, ideally meeting age-based needs; (2) use of clinical judgment to guide the need for sleep-disordered breathing treatments before polysomnography-MSLT testing; and (3) shared patient-health care provider decision-making regarding modifications in the protocol for children and adolescents with neurodevelopmental/neurological disorders, young age, and/or delayed sleep phase.

CITATION

Maski KP, Amos LB, Carter JC, Koch EE, Kazmi U, Rosen CL. Recommended protocols for the Multiple Sleep Latency Test and Maintenance of Wakefulness Test in children: guidance from the American Academy of Sleep Medicine. J Clin Sleep Med. 2024;20(4):631-641.

Effectiveness of an intervention program on physical activity in children with narcolepsy type 1

OBJECTIVES

Physical activity (PA) is recommended as part of the management of narcolepsy type 1 (NT1). This study aimed at 1) characterizing PA in children and adolescents treated for NT1 using objective and subjective measurements, 2) evaluating how PA is associated with NT1 symptoms and comorbidities, and 3) evaluating the effects of an Adapted Physical Activity (APA) program on PA and clinical characteristics.

PATIENTS/METHODS

Patients with NT1 from the National Reference Center of Narcolepsy (Lyon, France) were consecutively included in an APA intervention protocol. Narcolepsy symptoms and comorbidities were collected using standardized questionnaires and sustained attention was evaluated using the Bron-Lyon Attention Stability Test before and after the four-week APA intervention. PA was measured objectively using actigraphy throughout the study.

RESULTS

Twenty-seven NT1 patients were included (median age 14.7 years [8.3-18.4], cataplexy 88.9%, obesity 37.0%). At baseline, 52.4% of the patients had satisfactory PA levels according to international recommendations. Patients with leisure-time PA (LTPA) showed higher quality of life than patients without. 45% of the patients increased PA during the intervention compared to baseline. These responsive patients had more depressive feelings and tended to have lower objective PA than non-responsive patients at baseline. No significant correlation was found between PA levels before and during the intervention and other clinical data.

CONCLUSIONS

Most children with NT1 showed satisfying PA levels despite their daytime sleepiness. LTPA engagement was associated with higher quality of life. An APA intervention could be effective in children with narcolepsy, especially for those with depressive feelings.

Identification of bidirectional causal links between gut microbiota and narcolepsy type 1 using Mendelian randomization

STUDY OBJECTIVES

Narcolepsy type 1 (NT1), characterized by cataplexy and orexin deficiency, is a rare and frequently debilitating neurological disorder. It has been noted to have connections with the gut microbiota, yet the exact causal relationships remain unclear.

METHODS

We conducted a comprehensive bidirectional Mendelian randomization (MR) study to rigorously investigate the causal links between the gut microbiota and NT1, utilizing genetic datasets from the MiBioGen consortium and FinnGen consortium, respectively. The inverse-variance weighted (IVW) method was employed to obtain the primary MR estimates, supplemented by several alternative methods as well as sensitivity analyses including Cochran's Q, MR-Egger, MR pleiotropy residual sum and outlier, leave-one-out, and genetic colocalization.

RESULTS

Our findings indicated that an increased relative abundance of five genera including Blautia (p = 4.47E-5), Collinsella (p = 0.036), Gordonibacter (p = 0.047), Hungatella (p = 0.015), and Lachnospiraceae UCG010 (p = 0.027) may be associated with a decreased risk of NT1. Conversely, an increased relative abundance of class Betaproteobacteria (p = 0.032), genus Alloprevotella (p = 0.009), and genus Ruminiclostridium6 (p = 0.029) may potentially heighten the risk of NT1. The onset of NT1 may lead to a decrease in the relative abundance of genus Eubacterium eligens group (p = 0.022), while a increase in the family Family XI (p = 0.009), genus Hungatella (p = 0.005), genus Prevotella (p = 0.013), and unknown genus id.2001 (p = 0.019). These findings remained robust under all sensitivity analyses.

CONCLUSIONS

Our results offer robust evidence for the bidirectional causal links between particular gut microbial taxa and NT1, underscoring the significance of the microbiota-gut-brain axis in the pathological process of NT1.

Effect of sodium oxybate on body mass index in pediatric patients with narcolepsy

STUDY OBJECTIVES

We examined body mass index (BMI) changes associated with sodium oxybate treatment (SXB) in pediatric patients with narcolepsy with cataplexy who participated in a double-blind, placebo-controlled, randomized withdrawal study and an open-label continuation period.

METHODS

Participants were aged 7-16 years at screening. SXB-naive participants titrated to twice-nightly dosing of SXB then entered a 2-week stable-dose period; participants taking SXB at study entry entered a 3-week stable-dose period. After a 2-week randomized withdrawal period, all participants entered an open-label safety period (OLP; main study duration: ≤ 52 weeks). Participants who completed the OLP were allowed to enter the open-label continuation period (an additional 1-2 years). BMI percentile categories were defined as underweight (< 5th), normal (5th to < 85th), overweight (≥ 85th to < 95th), and obese (≥ 95th).

RESULTS

Median BMI percentile decreased from baseline to OLP week 52 in SXB-naive participants who were normal weight at baseline (decreased from 77.0 to 35.0) or overweight/obese at baseline (98.0 to 86.7). Median BMI percentile decreased to a lesser extent in participants taking twice-nightly SXB at study entry who were normal weight at baseline (54.6 to 53.0) or overweight/obese at baseline (96.5 to 88.9). Shifts in BMI category from baseline to week 52 were sometimes noted. In SXB-naive participants, 9/10 (90.0%) who were overweight became normal weight, 7/25 (28.0%) who were obese became normal weight, 3/25 (12.0%) who were obese became overweight, and 1/16 (6.3%) who was normal weight became obese. In participants taking SXB at baseline, 5/8 (62.5%) who were overweight became normal weight, 3/6 (50.0%) who were obese became overweight, 1/14 (7.1%) who was normal weight became overweight, and 2/14 (14.3%) who were normal weight became underweight. Median BMI percentiles at months 6 and 12 of the open-label continuation period were similar to those at OLP end (OLP week 52). In SXB-naive participants, the evident BMI z-score decrease over time was relative to the screening values.

CONCLUSIONS

Decreases in BMI percentile and z-score, and downward shifts in BMI category, were observed within 1 year of SXB treatment in pediatric participants with narcolepsy with cataplexy. BMI decreases plateaued after approximately 1 year.

CLINICAL TRIAL REGISTRATION

Registry: ClinicalTrials.gov; Name: A Multicenter Study of the Efficacy and Safety of Xyrem With an Open-Label Pharmacokinetic Evaluation and Safety Extension in Pediatric Subjects With Narcolepsy With Cataplexy; URL: https://clinicaltrials.gov/study/NCT02221869; Identifier: NCT02221869.

CITATION

Dauvilliers Y, Lammers GJ, Lecendreux M, et al. Effect of sodium oxybate on body mass index in pediatric patients with narcolepsy. J Clin Sleep Med. 2024;20(3):445-454.

Connecting the dots: An updated review of the role of autoimmunity in narcolepsy and emerging immunotherapeutic approaches

BACKGROUND

Narcolepsy type 1 (NT1) is a chronic disorder characterized by pathological daytime sleepiness and cataplexy due to the disappearance of orexin immunoreactive neurons in the hypothalamus. Genetic and environmental factors point towards a potential role for inflammation and autoimmunity in the pathogenesis of the disease. This study aims to comprehensively review the latest evidence on the autoinflammatory mechanisms and immunomodulatory treatments aimed at suspected autoimmune pathways in NT1.

METHODS

Recent relevant literature in the field of narcolepsy, its autoimmune hypothesis, and purposed immunomodulatory treatments were reviewed.

RESULTS

Narcolepsy is strongly linked to specific HLA alleles and T-cell receptor polymorphisms. Furthermore, animal studies and autopsies have found infiltration of T cells in the hypothalamus, supporting T cell-mediated immunity. However, the role of autoantibodies has yet to be definitively established. Increased risk of NT1 after H1N1 infection and vaccination supports the autoimmune hypothesis, and the potential role of coronavirus disease 2019 and vaccination in triggering autoimmune neurodegeneration is a recent finding. Alterations in cytokine levels, gut microbiota, and microglial activation indicate a potential role for inflammation in the disease's development. Reports of using immunotherapies in NT1 patients are limited and inconsistent. Early treatment with IVIg, corticosteroids, plasmapheresis, and monoclonal antibodies has seldomly shown some potential benefits in some studies.

CONCLUSION

The current body of literature supports that narcolepsy is an autoimmune disorder most likely caused by T-cell involvement. However, the potential for immunomodulatory treatments to reverse the autoinflammatory process remains understudied. Further clinical controlled trials may provide valuable insights into this area.

Quality of life in adolescents with narcolepsy type 1- a transversal study in a tertiary hospital

PURPOSE

- Narcolepsy type 1 (NT1) is a rare chronic sleep disorder, usually arising by adolescence that negatively impacts quality of life. It is characterized by excessive daytime sleepiness (EDS), cataplexy, hypnagogic/hypnopompic hallucinations, sleep paralysis and sleep fragmentation. The goals of this work were to characterize NT1 adolescents regarding sleep characteristics, health-related quality of life (HRQoL) and future life perspectives and later to compare this group with a control group of healthy adolescents (HA).

METHODS

- Transversal descriptive/analytical study including NT1 patients followed in a sleep center of a tertiary hospital and 23 HA. Data were collected through an online survey, fulfilled by the participants, including four sections: demographics; questionnaire evaluating sleep and EDS; questionnaire evaluating HRQoL; inquiry regarding future perspectives. An extra section for the NT1 group only, comprising questions about the characterization of narcolepsy, was included.

RESULTS

22 NT1 adolescents were included, with a median age of 15.0 years-old. Beyond EDS, all had presented cataplexy - 19 still reported it. Twenty patients took psychostimulants regularly for EDS, while 13 patients took venlafaxine or fluoxetine for cataplexy. Nineteen adolescents took regular naps and 19 maintained psychological appointments. Self-reported sleep quality was similar between groups (p = 0.112). EDS was identified in seven NT1 patients and none in the control group. HRQOL was significantly lower in NT1 patients only for the physical well-being domain (p = 0.001). Regarding future perspectives, results were similar, except for a lower probability of getting a driver's license in NT1 patients, despite no statistical significance (p = 0.104).

DISCUSSION

Daytime sleepiness is difficult to control in NT1, despite specialized treatment. HRQoL was similar between groups in all domains except for the physical well-being. Despite good adherence to pharmacological and non-pharmacological treatments (namely psychological therapy) that account for these good results, the physical well-being domain is difficult to manage.

Calcium, magnesium, potassium, and sodium oxybates oral solution for cataplexy or excessive daytime sleepiness associated with narcolepsy

INTRODUCTION

Lower-sodium oxybate (LXB) is a novel formulation that is approved by the US Food and Drug Administration (FDA) to treat cataplexy and excessive daytime sleepiness (EDS) in adult patients and children ≥ 7 years with narcolepsy. LXB contains 92 percent less sodium than sodium oxybate (SXB), which adds 550-1640 mg of sodium/day at usual doses of 3-9 grams per day. The FDA has declared LXB to be clinically superior to SXB due to greater safety by reducing the chronic sodium load. Narcolepsy patients have high comorbidities for hypertension and cardiovascular disease, conditions which can be adversely affected by high sodium intake.

AREAS COVERED

This drug review discusses narcolepsy, current and upcoming pharmacotherapy, and LXB chemistry, pharmacodynamics, pharmacokinetics, and metabolism. Published results from LXB's phase 1 studies, a phase 3 study, and 2 post-marketing studies are reviewed. Databases searched included Pubmed, Google Scholar, Lexi-Comp, Scopus, Science, and Ovid.

EXPERT OPINION

LXB is efficacious in treating daytime sleepiness and cataplexy in adults and children ≥ 7 years with narcolepsy. Using LXB instead of SXB formulations may benefit narcolepsy patients with cardiovascular comorbidities and hypertension, but long-term studies are needed to prove it.

French Sleepiness Scale for Adolescents-8 items: A discriminant and diagnostic validation

The objective of the present study was to validate the Short Version of French Sleepiness Scale for Adolescents (FSSA) with eight items (FSSA8).

METHODS

A total of 384 adolescents, aged between 12 and 18 years, completed the FSSA8. These included 269 nonclinical adolescents and 115 adolescents admitted for overnight polysomnography and Multiple Sleep Latency Test (MSLT) because of suspected hypersomnia (85 patients with narcolepsy and 30 with other sleep disorders). Item response theory (IRT) assumptions were tested and psychometric properties were analysed. Matching on sex ratio and age was conducted to estimate concurrent criterion, diagnostic validity and cut-offs.

RESULTS

IRT assumptions were validated confirming the one-dimensionality of the FSSA8. The latent continuum sleepiness for which the scale and its items are reliable encompassed most of the clinical subjects. FSSA8 is weakly correlated with MSLT. Distribution of scores for the nonclinical group and the clinical group differed significantly; the FSSA8 had very good screening validity in sleep disorders. The cut-off was seven points.

CONCLUSION

The FSSA8 appeared to be more reliable for patients than for nonclinical participants and to be a good tool for screening excessive daytime sleepiness in sleep disorders.

Possible Implications of Obesity-Primed Microglia that Could Contribute to Stroke-Associated Damage

Microglia, the resident macrophages of the central nervous system, are essential players during physiological and pathological processes. Although they participate in synaptic pruning and maintenance of neuronal circuits, microglia are mainly studied by their activity modulating inflammatory environment and adapting their phenotype and mechanisms to insults detected in the brain parenchyma. Changes in microglial phenotypes are reflected in their morphology, membrane markers, and secreted substances, stimulating neighbor glia and leading their responses to control stimuli. Understanding how microglia react in various microenvironments, such as chronic inflammation, made it possible to establish therapeutic windows and identify synergic interactions with acute damage events like stroke. Obesity is a low-grade chronic inflammatory state that gradually affects the central nervous system, promoting neuroinflammation development. Obese patients have the worst prognosis when they suffer a cerebral infarction due to basal neuroinflammation, then obesity-induced neuroinflammation could promote the priming of microglial cells and favor its neurotoxic response, potentially worsening patients' prognosis. This review discusses the main microglia findings in the obesity context during the course and resolution of cerebral infarction, involving the temporality of the phenotype changes and balance of pro- and anti-inflammatory responses, which is lost in the swollen brain of an obese subject. Obesity enhances proinflammatory responses during a stroke. Obesity-induced systemic inflammation promotes microglial M₁ polarization and priming, which enhances stroke-associated damage, increasing M₁ and decreasing M₂ responses.

Approach to a sleepy child: Diagnosis and treatment of excessive daytime sleepiness in children and adolescents

The aim of this review is to give updated information to pediatric neurologists on the correct diagnostic approach and treatment of excessive daytime sleepiness (EDS) in children and adolescents. Due to the change in the society habits, EDS is becoming an emerging problem for the health system. At the present there are few articles specifically devoted to the evaluation of EDS. EDS is often reported in several manuscripts as a side effect of other sleep disorders (obstructive sleep apnea, circadian disorders, etc.) or of the use of drugs or of the substance abuse or as a consequence of bad sleep habits and poor sleep hygiene. EDS, especially in children, may manifest with paradoxical symptoms like hyperactivity, inattention, and impulsiveness. However, common sign of EDS in children are the propensity to sleep longer than usual, the difficulty waking up in the morning, and falling asleep frequently during the day in monotonous situation. The diagnosis should include subjective (sleep diaries, questionnaires) and objective (polysomnography, multiple sleep latency test, etc.) instruments to avoid misdiagnosis. Narcolepsy is the most studied central disorder of hypersomnolence, and it is a predominantly pediatric disease with a peak age of onset in prepuberty but the diagnosis is often delayed especially in mild forms. The early and correct treatment of narcolepsy and of other form of EDS is extremely important since late and inappropriate treatments can affect the psychosocial development of the children and adolescents.

Precocious puberty in narcolepsy type 1: Orexin loss and/or neuroinflammation, which is to blame?

Narcolepsy type 1 (NT1) is a rare neurological sleep disorder triggered by postnatal loss of the orexin/hypocretin neuropeptides. Overweight/obesity and precocious puberty are highly prevalent comorbidities of NT1, with a close temporal correlation with disease onset, suggesting a common origin. However, the underlying mechanisms remain unknown and merit further investigation. The main question we address in this review is whether the occurrence of precocious puberty in NT1 is due to the lack of orexin/hypocretin or rather to a wider hypothalamic dysfunction in the context of neuroinflammation, which is likely to accompany the disease given its autoimmune origins. Our analysis suggests that the suspected generalized neuroinflammation of the hypothalamus in NT1 would tend to delay puberty rather than hastening it. In contrast, that the brutal loss of orexin/hypocretin would favor an early reactivation of gonadotropin-releasing hormone (GnRH) secretion during the prepubertal period in vulnerable children, leading to early puberty onset. Orexin/hypocretin replacement could thus be envisaged as a potential treatment for precocious puberty in NT1. Additionally, we put forward an alternative hypothesis regarding the concomitant occurrence of sleepiness, weight gain and early puberty in NT1.

Pediatric Narcolepsy—A Practical Review

Pediatric narcolepsy is a chronic sleep-wakefulness disorder. Its symptoms frequently begin in childhood. This review article examined the literature for research reporting on the effects of treatment of pediatric narcolepsy, as well as proposed etiology and diagnostic tools. Symptoms of pediatric narcolepsy include excessive sleepiness and cataplexy. In addition, rapid-eye-movement-related phenomena such as sleep paralysis, sleep terror, and hypnagogic or hypnapompic hallucinations can also occur. These symptoms impaired children’s function and negatively influenced their social interaction, studying, quality of life, and may further lead to emotional and behavioral problems. Therefore, early diagnosis and intervention are essential for children’s development. Moreover, there are differences in clinical experiences between Asian and Western population. The treatment of pediatric narcolepsy should be comprehensive. In this article, we review pediatric narcolepsy and its treatment approach: medication, behavioral modification, and education/mental support. Pharmacological treatment including some promising newly-developed medication can decrease cataplexy and daytime sleepiness in children with narcolepsy. Other forms of management such as psychosocial interventions involve close cooperation between children, school, family, medical personnel, and can further assist their adjustment.

Characterization of rapid weight gain phenotype in children with narcolepsy

Objectives

To characterize the rapid weight gain (RWG) phenotype associated with the onset of childhood narcolepsy and to determine whether it could constitute a marker of severity of the disease.

Methods

RWG was defined using the BMI z‐score slope reported to one year (>0.67 SD) from symptom onset to disease diagnosis. We compared the clinical, metabolic, and sleep characteristics between patients with or without RWG at diagnosis. Pharmacological management, anthropometric, and clinical progression were also evaluated during the follow‐up.

Results

A total of 84 de novo narcoleptic pediatric patients were included; their median age at diagnosis was 12.0 years; 59.5% boys, 90.5% cataplexy, and 98.7% HLA‐DQB1*06:02, 57% had RWG profile. RWG patients were younger at diagnosis than non‐RWG patients, despite a shorter diagnostic delay. They had a higher BMI z‐score and a higher prevalence of obesity at diagnosis, but not at symptom onset, and higher adapted Epworth Sleepiness Scale and Insomnia Severity Index scores than non‐RWG patients. No differences on nocturnal polysomnography and multiple sleep latency tests were found between groups at disease diagnosis. After a median follow‐up of 5 years, RWG patients still had a higher BMI z‐score and a higher prevalence of obesity despite benefiting from the same therapeutic management and displaying improvement in sleepiness and school difficulties.

Conclusions

Narcoleptic RWG patients were younger, sleepier, and the prevalence of obesity was higher at diagnosis despite a shorter diagnostic delay than that of non‐RWG patients. These patients had also a higher risk of developing a long‐term obesity, despite a positive progression of their narcoleptic symptoms. RGW could then represent a maker of a more severe phenotype of childhood narcolepsy, which should inspire a prompt and more offensive management to prevent obesity and its complications.

Finnish children who experienced narcolepsy after receiving the Pandemrix vaccine during the 2009-2010 H1N1 pandemic demonstrated high level of psychosocial problems

AIM

We assessed psychosocial burdens in children who developed narcolepsy after receiving the Pandemrix H1N1 vaccine during the 2009-2010 pandemic. Parental quality of life was also assessed.

METHODS

This multicentre study covered four of the five Finnish University Hospital Districts, which dealt with about 90% of the paediatric narcolepsy cases after the Pandemrix vaccination. The medical records of children diagnosed from 2010 to 2014 were reviewed. The questionnaires included the Youth Self-Report (YSR), Children's Depression Inventory (CDI), the Child Behaviour Checklist (CBCL) and questions on parental resources, stress and quality of life.

RESULTS

We obtained the medical records of 94 children who were aged 5-17 years at the time of their narcolepsy diagnosis and questionnaire data for 73 of those children. Most children had strong narcolepsy symptoms, and 25% had CDI scores that suggested depression. In addition, 41% had total CBCL problem scores above the clinically significant limit and 48% were anxious, withdrawn and had somatic complaints. Sleep latency was weakly associated with the CBCL total problem score. Half of the children needed psychiatric interventions and parental stress was common.

CONCLUSION

Depression and behavioural problems were common in children with narcolepsy after the Pandemrix vaccination and their parents frequently reported feeling stressed.

Narcolepsy treatment in Sweden: An observational study

OBJECTIVES

To describe the pharmacological treatments (2005-2017) and the healthcare utilization (1997-2016) for patients with narcolepsy in Sweden in order to create a framework for future organizational and economic analyses.

MATERIAL & METHODS

Patients of all ages with a diagnosis of narcolepsy registered in the National Patient Registry in specialist care in Sweden were included and information on treatments for narcolepsy was retrieved from The Swedish Prescribed Drug Register.

RESULTS

We collected 2508 patients with narcolepsy, 43,3% men and 56,7% women and 47,9% were prescribed modafenil, 33,8% metylphenidate and 26,2% amphetamine. In total, 3817 treatments were initiated. Patients treated with amphetamine had a higher mean age. More women than men used modafinil, methylphenidate, amphetamine and antidepressants. The narcolepsy population had more outpatient than inpatient healthcare. Patients treated with sodium oxybate had more outpatient visits than other narcolepsy patients, before and during treatment (p = .00).

CONCLUSIONS

This study gives valuable information on pharmaceutical treatments and healthcare utilization for patients with narcolepsy and can be used to estimate the healthcare cost in the future. Patients with sodium oxybate treatment had more outpatient visits than other patients before and during treatment which may be due to the need to monitor potentially severe side-effects or may indicate that patients with sodium oxybate treatment have a severe disease. The number of included patients was less than expected; however, this may depend on patients escaping our collection of data, which does not contain information from primary care.

Disrupted nighttime sleep and sleep instability in narcolepsy

STUDY OBJECTIVES

This review aimed to summarize current knowledge about disrupted nighttime sleep (DNS) and sleep instability in narcolepsy, including self-reported and objective assessments, potential causes of sleep instability, health consequences and functional burden, and management.

METHODS

One hundred two peer-reviewed publications from a PubMed search were included.

RESULTS

DNS is a key symptom of narcolepsy but has received less attention than excessive daytime sleepiness and cataplexy. There has been a lack of clarity regarding the definition of DNS, as many sleep-related symptoms and conditions disrupt sleep quality in narcolepsy (eg, hallucinations, sleep paralysis, rapid eye movement sleep behavior disorder, nightmares, restless legs syndrome/periodic leg movements, nocturnal eating, sleep apnea, depression, anxiety). In addition, the intrinsic sleep instability of narcolepsy results in frequent spontaneous wakings and sleep stage transitions, contributing to DNS. Sleep instability likely emerges in the setting of orexin insufficiency/deficiency, but its exact pathophysiology remains unknown. DNS impairs quality of life among people with narcolepsy, and more research is needed to determine its contributions to cardiovascular risk. Multimodal treatment is appropriate for DNS management, including behavioral therapies, counseling on sleep hygiene, and/or medication. There is strong evidence showing improvement in self-reported sleep quality and objective sleep stability measures with sodium oxybate, but rigorous clinical trials with other pharmacotherapies are needed. Treatment may be complicated by comorbidities, concomitant medications, and mood disorders.

CONCLUSIONS

DNS is a common symptom of narcolepsy deserving consideration in clinical care and future research.

CITATION

Maski K, Mignot E, Plazzi G, Dauvilliers Y. Disrupted nighttime sleep and sleep instability in narcolepsy. J Clin Sleep Med. 2022;18(1):289-304.

Differential characteristics of repeated polysomnography and multiple sleep latency test parameters in narcolepsy type 1 and type 2 patients: a longitudinal retrospective study

PURPOSE

Narcolepsy is a chronic disorder and its phenotype is dichotomized into narcolepsy type 1 (NT1) and narcolepsy type 2 (NT2). The clinical course and pathophysiological mechanisms of these two clinical entities and their differences are not adequately defined. This study aimed to explore the differential longitudinal patterns of polysomnography (PSG) and multiple sleep latency test (MSLT) in NT1 and NT2.

METHODS

In this retrospective study demographic characteristics, PSG, and MSLT parameters at baseline and follow-up were compared between NT1 and NT2 patients. Patients with both follow-up MSLT and PSG were selected for sub-group analysis. Baseline and follow-up MSLT and PSG parameters were compared.

RESULTS

Of 55 patients with narcolepsy, mean follow-up periods were 7.4 ± 3.5 years for NT1 and 5.5 ± 2.9 for NT2. Demographic data showed increased body mass index and prevalence of sleep paralysis in NT1. Baseline PSG characteristics between NT1 and NT2 showed decreased sleep latency (p = 0.016) and REM latency (p = 0.046) in NT1 group when compared with NT2. Nocturnal SOREMP on PSG was more prevalent in NT1 (p = 0.017), and half of NT2 patients with nocturnal SOREMP on PSG changed their diagnoses to NT1. On follow-up PSG, NT1 displayed reductions in sleep stage N2 (p = 0.006) and N3 (p = 0.048), while wake after sleep onset (WASO) (p = 0.023) and apnea-hypopnea index (AHI) (p = 0.007) were significantly increased.

CONCLUSION

Differential MSLT and PSG characteristics of NT1 and NT2 in at baseline and follow-up indicate that NT1 and NT2 are distinct disease phenotypes, and that they present with a contrasting course of disease.

Narcolepsy: the impact of aging, hypocretin deficiency, and years of formal education in olfactory function and abdominal obesity

BACKGROUND

Narcolepsy is a disease resulting from the loss of hypocretin-producing cells or other dysfunctions of the hypocretinergic system. In addition to sleep disorders, affected patients may experience increased weight gain, olfactory changes, and poorer quality of life.

METHODS

This study aimed to investigate the relationship between narcolepsy and weight gain, years of study, sleep parameters, and olfactory dysfunction in patients with narcolepsy type 1 and narcolepsy type 2. Anthropometric, olfactory, socioeducational, and excessive daytime sleepiness evaluations were performed in 77 patients.

RESULTS

Greater weight gain and abdominal obesity were observed in patients with type 1 narcolepsy. Patients with higher education level had lower scores of daytime sleepiness, higher scores on the olfactory function test, and lower rates of abdominal obesity.

DISCUSSION

Patients with narcolepsy type 1 showed an increased body weight and abdominal obesity when compared to narcolepsy type 2. The patients with a higher schooling level showed a reduction of the daytime sleepiness scores, lower rates of abdominal obesity, and better scores on the olfactory function test.

CONCLUSION

Among all the patients with narcolepsy, the data indicated that aging and hypocretin deficiency are associated with abdominal obesity, while years of study is the variable that mostly influences olfaction function.

Narcolepsy type 1 features across the life span: age impact on clinical and polysomnographic phenotype

STUDY OBJECTIVES

Narcolepsy type 1 (NT1) is a chronic neurological disorder typically arising during adolescence and young adulthood. Recent studies demonstrated that NT1 presents with age-specific features, especially in children. With this study we aimed to describe and to compare the clinical pictures of NT1 in different age groups.

METHODS

In this cross-sectional, multicenter study, 106 untreated patients with NT1 enrolled at the time of diagnosis underwent clinical evaluation, a semistructured interview (including the Epworth Sleepiness Scale), nocturnal video-polysomnography, and the Multiple Sleep Latency Test. Patients were enrolled in order to establish 5 age-balanced groups (childhood, adolescence, adulthood, middle age, and senior).

RESULTS

The Epworth Sleepiness Scale score showed a significant increase with age, while self-reported diurnal total sleep time was lower in older and young adults, with the latter also complaining of automatic behaviors in more than 90% of patients. Children reported the cataplexy attacks to be more frequent (> 1/d in 95% of patients). "Recalling an emotional event," "meeting someone unexpectedly," "stress," and "anger" were more frequently reported in adult and older adult patients as possible triggers of cataplexy. Neurophysiological data showed a higher number of sleep-onset rapid eye movement periods on the Multiple Sleep Latency Test in adolescent compared to senior patients and an age-progressive decline in sleep efficiency.

CONCLUSIONS

Daytime sleepiness, cataplexy features and triggers, and nocturnal sleep structure showed age-related difference in patients with NT1; this variability may contribute to diagnostic delay and misdiagnosis.

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.

Gut Microbiota in Patients with Type 1 Narcolepsy

PURPOSE

To explore the characteristics of gut microbiota and its relationship between clinical manifestations in patients with type 1 narcolepsy (NT1).

PATIENTS AND METHODS

Scale and polysomnography were performed in 20 NT1 patients and 16 healthy controls (HC group) to evaluate the clinical characteristics of NT1. Illumina sequencing was performed on bacterial 16S ribosomal RNA gene using V3-V4 regions to compare the fecal microbiota in all subjects. Associations between clinical characteristics and gut microbiota were analyzed using partial correlation analysis.

RESULTS

Compared with the HC group, the NT1 group had a significantly higher ESS score, longer total sleep time, increased wakefulness, decreased sleep efficiency, disturbance of sleep structure, shorter mean sleep latency, and increased sleep-onset REM periods (all P < 0.05). No differences in alpha and beta diversity were observed between the two groups. In contrast, there were significant differences at the level of class, order, family, and genus (all P < 0.05). LEfSe analysis showed that the relative abundance of Klebsiella in the NT1 group was higher than that in the HC group (P < 0.05), while the relative abundance of Blautia, Barnesiellaceae, Barnesiella, Phocea, Lactococcus, Coriobacteriia, Coriobacteriales, Ruminiclostridium_5, and Bilophila were lower (all P < 0.05). Partial correlation analysis revealed that partial differential bacteria in the NT1 group were correlated with total sleep time, sleep efficiency, stage 1 sleep, arousal index, and sleep latency (all P < 0.05).

CONCLUSION

Our data revealed differences in intestinal flora structure between NT1 patients and the normal population, thus providing a theoretical basis for future microecological therapy for narcolepsy. However, future larger sample size studies and different study designs are needed to further clarify the possible pathogenesis and potential causality of intestinal flora in NT1 patients and explore the new treatment strategies.

Gut microbiota composition is associated with narcolepsy type 1

OBJECTIVE

To test the hypothesis that narcolepsy type 1 (NT1) is related to the gut microbiota, we compared the microbiota bacterial communities of patients with NT1 and control subjects.

METHODS

Thirty-five patients with NT1 (51.43% women, mean age 38.29 ± 19.98 years) and 41 controls (57.14% women, mean age 36.14 ± 12.68 years) were included. Stool samples were collected, and the fecal microbiota bacterial communities were compared between patients and controls using the well-standardized 16S rRNA gene amplicon sequencing approach. We studied alpha and beta diversity and differential abundance analysis between patients and controls, and between subgroups of patients with NT1.

RESULTS

We found no between-group differences for alpha diversity, but we discovered in NT1 a link with NT1 disease duration. We highlighted differences in the global bacterial community structure as assessed by beta diversity metrics even after adjustments for potential confounders as body mass index (BMI), often increased in NT1. Our results revealed differential abundance of several operational taxonomic units within Bacteroidetes, Bacteroides, and Flavonifractor between patients and controls, but not after adjusting for BMI.

CONCLUSION

We provide evidence of gut microbial community structure alterations in NT1. However, further larger and longitudinal multiomics studies are required to replicate and elucidate the relationship between the gut microbiota, immunity dysregulation and NT1.

Narcolepsy in children and young people in Ireland: 2006-2017

AIM

To describe the population of young people in Ireland diagnosed with narcolepsy with regards to vaccine exposure, symptomatology, investigation results and experience of medical treatment.

METHOD

Retrospective review of medical records at the single tertiary referral centre for young people with narcolepsy in Ireland.

RESULTS

Sixty-seven patients were diagnosed with narcolepsy between July 2006 and July 2017. Sixty-one (91%) of these developed symptoms after receiving the Pandemrix vaccine. The population was largely homogeneous with low hypocretin (87.5%), HLA DQB1∗0602 positivity (95%) and unremarkable findings on MRI Brain (100%). 77.6% experienced cataplexy; we also measured high levels of obesity, school non-attendance and psychosocial complexity. Symptoms often continued despite treatment, with multiple medications prescribed in 76.1% of patients. Prescription of sodium oxybate was associated with a significant reduction in BMI standard deviation scores at 6 months, with improved IOTF obesity scores seen at 36 month follow-up.

CONCLUSIONS

This paper describes the experience of narcolepsy in children and young people in Ireland from 2006 - 2017 at the national tertiary referral centre. Narcolepsy in children and young people in Ireland carries a significant burden of illness, with impact on participation in education as well as physical and mental health. Symptoms can be refractory to medical treatment. Referral to tertiary centres for prompt treatment and multidisciplinary input is essential.

Narcolepsy with cataplexy: Does age at diagnosis change the clinical picture?

Objective

To compare symptoms and sleep characteristics in patients diagnosed with narcolepsy‐cataplexy (NC) before and after the age of 18 years.

Methods

De novo patients with NC diagnosis completed a standardized questionnaire and interview, followed by a sleep study. The clinical and sleep measures were compared between patients diagnosed before (46 children, median age: 12 year old) and after (46 adults, median age: 28.5 year old) 18 years of age.

Results

The frequency of obesity (54% vs 17%), night eating (29% vs 7%), parasomnia (89% vs 43%), sleep talking (80% vs 34%), and sleep drunkenness (69% vs 24%) were higher in children than in adults, the frequency of sleep paralysis was lower (20% vs 55%) but the frequency of cataplexy and the severity of sleepiness were not different. Children scored higher than adults at the attention‐deficit/hyperactivity disorder (ADHD) scale. Depressive feelings affected not differently children (24%) and adults (32%). However, adults had lower quality of life than children. There was no difference between groups for insomnia and fatigue scores. Quality of life was essentially impacted by depressive feelings in both children and adults. Obstructive apnea‐hypopnea index (OAHI) was lower in children with higher mean and minimal oxygen saturation than in adults. No between‐group differences were found at the multiple sleep latency test. The body mass index (z‐score) was correlated with OAHI (r = .32).

Conclusion

At time of NC diagnosis, children have more frequent obesity, night eating, parasomnia, sleep talking, drunkenness, and ADHD symptoms than adults, even if sleepiness and cataplexy do not differ. These differences should be considered to ensure a prompt diagnosis.

Role of Brown Adipose Tissue in Adiposity Associated With Narcolepsy Type 1

Narcolepsy type 1 is a neurological sleep-wake disorder caused by the destruction of orexin (hypocretin)-producing neurons. These neurons are particularly located in the lateral hypothalamus and have widespread projections throughout the brain, where they are involved, e.g., in the regulation of the sleep-wake cycle and appetite. Interestingly, a higher prevalence of obesity has been reported in patients with narcolepsy type 1 compared to healthy controls, despite a normal to decreased food intake and comparable physical activity. This suggests the involvement of tissues implicated in total energy expenditure, including skeletal muscle, liver, white adipose tissue (WAT), and brown adipose tissue (BAT). Recent evidence from pre-clinical studies with orexin knock-out mice demonstrates a crucial role for the orexin system in the functionality of brown adipose tissue (BAT), probably through multiple pathways. Since BAT is a highly metabolically active organ that combusts fatty acids and glucose toward heat, thereby contributing to energy metabolism, this raises the question of whether BAT plays a role in the development of obesity and related metabolic diseases in narcolepsy type 1. BAT is densely innervated by the sympathetic nervous system that activates BAT, for instance, following cold exposure. The sympathetic outflow toward BAT is mainly mediated by the dorsomedial, ventromedial, arcuate, and paraventricular nuclei in the hypothalamus. This review focuses on the current knowledge on the role of the orexin system in the control of energy balance, with specific focus on BAT metabolism and adiposity in both preclinical and clinical studies.

Obesity and other medical comorbidities among NT1 patients after the Norwegian H1N1 influenza epidemic and vaccination campaign

Study Objectives

Narcolepsy type 1 (NT1) may be complicated by comorbidities. We aimed to study the extent of obesity and other medical comorbidities in a Norwegian population of NT1 patients with debut of symptoms after the 2009 H1N1 influenza epidemic and vaccination campaign. We also aimed to explore factors associated with obesity.

Methods

Ninety-one patients (48 children and 43 adults) were included in this cross-sectional study, 80 of whom were H1N1-vaccinated. All participants were hospitalized and underwent sleep investigation and physical examination, and completed a semi-structured clinical interview.

Results

In children, 16 females (70%) and 10 males (40%) were classified as overweight or obese. Twenty children (42%) had a co-existing medical disorder. Medical comorbidity was significantly positively associated with BMI in children (p = .032). In adults, 19 females (58%) and 7 males (70%) were classified as overweight or obese. Twenty-six adults (61%) had a co-existing medical disorder. We found no factors significantly associated with BMI in adults. On a fatigue scale from 0 to 100, lower scores indicating more fatigue, we found a mean (SD) total fatigue score of 50 (17) in children and 39 (16) in adults.

Conclusion

In a cohort of predominantly H1N1-vaccinated NT1 patients, we found a high prevalence of overweight or obesity. Half of the cohort presented with one or more additional medical comorbidities, and patients reported a clinically relevant degree of fatigue. Our findings highlight the importance of carefully monitoring patients with NT1 with regard to the development of obesity, which is a significant risk factor for cardiovascular disorders.

Validation of Multiple Sleep Latency Test for the diagnosis of pediatric narcolepsy type 1

Objective

To validate polysomnographic markers (sleep latency and sleep-onset REM periods [SOREMPs] at the Multiple Sleep Latency Test [MSLT] and nocturnal polysomnography [PSG]) for pediatric narcolepsy type 1 (NT1) against CSF hypocretin-1 (hcrt-1) deficiency and presence of cataplexy, as no criteria are currently validated in children.

Methods

Clinical, neurophysiologic, and, when available, biological data (HLA-DQB1*06:02 positivity, CSF hcrt-1 levels) of 357 consecutive children below 18 years of age evaluated for suspected narcolepsy were collected. Best MSLT cutoffs were obtained by receiver operating characteristic (ROC) curve analysis by contrasting among patients with available CSF hcrt-1 assay (n = 228) with vs without CSF hcrt-1 deficiency, and further validated in patients without available CSF hcrt-1 against cataplexy (n = 129).

Results

Patients with CSF hcrt-1 deficiency were best recognized using a mean MSLT sleep latency ≤8.2 minutes (area under the ROC curve of 0.985), or by at least 2 SOREMPs at the MSLT (area under the ROC curve of 0.975), or the combined PSG + MSLT (area under the ROC curve of 0.977). Although specificity and sensitivity of reference MSLT sleep latency ≤8 minutes and ≥2 SOREMPs (nocturnal SOREMP included) was 100% and 94.87%, the combination of MSLT sleep latency and SOREMP counts did not improve diagnostic accuracy. Age or sex also did not significantly influence these results in our pediatric population.

Conclusions

At least 2 SOREMPs or a mean sleep latency ≤8.2 minutes at the MSLT are valid and reliable markers for pediatric NT1 diagnosis, a result contrasting with adult NT1 criteria.

Classification of evidence

This study provides Class III evidence that for children with suspected narcolepsy, polysomnographic and MSLT markers accurately identify those with narcolepsy type 1.

In-field assessment of sodium oxybate effect in pediatric type 1 narcolepsy: an actigraphic study

Study Objectives

Sodium oxybate (SXB) is a GABAergic agent widely used as off-label treatment in pediatric type 1 narcolepsy (NT1). Here, we aimed at analyzing by wrist actigraphy the sleep/wake profile of NT1 children and adolescents in drug-naïve condition and after 1 year of SXB treatment. As secondary aim, we investigated changes on sleepiness, cataplexy, and children's anthropometric profile after 1 year of SXB treatment.

Methods

Twenty-four drug-naïve NT1 children underwent 7 days of actigraphy during the school week. Information on sleepiness, narcolepsy symptoms, and anthropometric features were collected during the same week with questionnaires and semistructured clinical interview. Children started SXB treatment and underwent a second evaluation encompassing actigraphy, clinical interview, questionnaires, and anthropometric assessment after 1 year of stable treatment.

Results

Actigraphy effectively documented an improvement of nocturnal sleep quality and duration coupled with a reduction of diurnal total sleep time, nap frequency, and duration at 1 year follow-up. Reduction of sleepiness, cataplexy frequency and severity, and weight loss, mainly in obese and overweight NT1 children, were also observed at the 1 year follow-up.

Conclusions

Actigraphy objectively documented changes in nocturnal sleep quality and diurnal napping behavior after 1 year of SXB treatment, thus representing a valid approach to ecologically assess SXB treatment effect on NT1 children's sleep/wake profile. NT1 symptoms severity and children's anthropometric features also changed as expected. Actigraphy offers the possibility to longitudinally follow up children and has potential to become a key tool to tailor treatment in pediatric patients.

Impaired histaminergic neurotransmission in children with narcolepsy type 1

OBJECTIVE

Narcolepsy is a sleep disorder characterized in humans by excessive daytime sleepiness and cataplexy. Greater than fifty percent of narcoleptic patients have an onset of symptoms prior to the age of 18. Current general agreement considers the loss of hypothalamic hypocretin (orexin) neurons as the direct cause of narcolepsy notably cataplexy. To assess whether brain histamine (HA) is also involved, we quantified the cerebrospinal fluid (CSF) levels of HA and tele-methylhistamine (t-MeHA), the direct metabolite of HA between children with orexin-deficient narcolepsy type 1 (NT1) and controls.

METHODS

We included 24 children with NT1 (12.3 ± 3.6 years, 11 boys, 83% cataplexy, 100% HLA DQB1*06:02) and 21 control children (11.2 ± 4.2 years, 10 boys). CSF HA and t-MeHA were measured in all subjects using a highly sensitive liquid chromatographic-electrospray/tandem mass spectrometric assay. CSF hypocretin-1 values were determined in the narcoleptic patients.

RESULTS

Compared with the controls, NT1 children had higher CSF HA levels (771 vs 234 pmol/L, P < 0.001), lower t-MeHA levels (879 vs 1924 pmol/L, P < 0.001), and lower t-MeHA/HA ratios (1.1 vs 8.2, P < 0.001). NT1 patients had higher BMI z-scores (2.7 ± 1.6 vs 1.0 ± 2.3, P = 0.006) and were more often obese (58% vs 29%, P = 0.05) than the controls. Multivariable analyses including age, gender, and BMI z-score showed a significant decrease in CSF HA levels when the BMI z-score increased in patients (P = 0.007) but not in the controls. No association was found between CSF HA, t-MeHA, disease duration, age at disease onset, the presence of cataplexy, lumbar puncture timing, and CSF hypocretin levels.

CONCLUSIONS

Narcolepsy type 1 children had a higher CSF HA level together with a lower t-MeHA level leading to a significant decrease in the t-MeHA/HA ratios. These results suggest a decreased HA turnover and an impairment of histaminergic neurotransmission in narcoleptic children and support the use of a histaminergic therapy in the treatment against narcolepsy.

Physical Activity and Sleep/Wake Behavior, Anthropometric, and Metabolic Profile in Pediatric Narcolepsy Type 1

Objectives: Regular physical activity is routinely recommended in children and adolescents suffering from narcolepsy type 1 (NT1), but controlled studies analyzing its influence on sleep/wake behavior, metabolic, and anthropometric profile in pediatric NT1 are lacking. Methods: Fifty consecutive drug-naïve NT1 children and adolescents were assessed through actigraphic, clinical, and metabolic evaluations. Patients were compared with respect to their engagement in leisure-time physical activities (LTPA): patients engaged in LTPA (n = 30) and patients not engaged (No-LTPA, n = 20), respectively. Results: LTPA patients presented lower BMI, with different BMI categories distribution and higher HDL cholesterol, when compared with No-LTPA subjects. Increased night-sleep duration, higher sleep quality, and reduction of nap frequency were documented through actigraphy in LTPA subjects. Subjective sleepiness, as measured by ESS-CHAD, was also lower in LTPA subjects while cataplexy frequency proved similar between the two groups. Discussion: In pediatric NT1 patients, regular engagement in LTPA is associated with significant differences on sleepiness, anthropometric and metabolic profile and objectively assessed sleep/wake behavior. Engagement in LTPA is beneficial and should be strongly encouraged in pediatric NT1 patients.

Clinical Characteristics and Burden of Illness in Pediatric Patients with Narcolepsy

BACKGROUND

Narcolepsy is a chronic and lifelong neurologic disorder with onset commonly occurring in childhood or adolescence, and affecting approximately 0.025% to 0.05% of the general population. The primary symptom is excessive daytime sleepiness, which is accompanied by cataplexy in 70% of patients. Other common symptoms include sleep paralysis, hallucinations upon falling asleep or waking, and disrupted nocturnal sleep. Narcolepsy is associated with a considerable burden of illness (BOI), which has been well characterized in adults, and is exacerbated by delays in symptom recognition, diagnosis, and intervention.

METHODS

This review describes the specific characteristics and BOI of pediatric narcolepsy, using a wide range of published research data.

RESULTS

Pediatric narcolepsy presents distinct challenges in diagnosis and management. Narcolepsy symptoms often initially manifest differently in children and adolescents versus adults, which may pose diagnostic dilemmas. Children often respond to sleepiness with irritability, hyperactivity, and poor attention, which may be misinterpreted as misbehavior or neurocognitive sequelae of other conditions. Pediatric cataplexy symptoms may include subtle and unusual facial expressions or choreic-like movements, which are not observed in adults. Insufficient sleep and circadian rhythm disorders presenting with excessive daytime sleepiness are common in adolescents, potentially confounding narcolepsy diagnosis. Pediatric narcolepsy is also associated with comorbidities including rapid weight gain, precocious puberty, and attention deficit hyperactivity disorder, and increased risk for deficits in social functioning, depression, and anxiety. School performance is also typically impaired, requiring special education services.

CONCLUSIONS

Thus, the discrete BOI of pediatric narcolepsy underscores the need for prompt and accurate diagnosis, and appropriate treatment of this disorder.

Unexpected Fat Distribution in Adolescents With Narcolepsy

Narcolepsy type 1 is a chronic sleep disorder with significantly higher BMI reported in more than 50% of adolescent patients, putting them at a higher risk for metabolic syndrome in adulthood. Although well-documented, the body fat distribution and mechanisms behind weight gain in narcolepsy are still not fully understood but may be related to the loss of orexin associated with the disease. Orexin has been linked to the regulation of brown adipose tissue (BAT), a metabolically active fat involved in energy homeostasis. Previous studies have used BMI and waist circumference to characterize adipose tissue increases in narcolepsy but none have investigated its specific distribution. Here, we examine adipose tissue distribution in 19 adolescent patients with narcolepsy type 1 and compare them to 17 of their healthy peers using full body magnetic resonance imaging (MRI). In line with previous findings we saw that the narcolepsy patients had more overall fat than the healthy controls, but contrary to our expectations there were no group differences in supraclavicular BAT, suggesting that orexin may have no effect at all on BAT, at least under thermoneutral conditions. Also, in line with previous reports, we observed that patients had more total abdominal adipose tissue (TAAT), however, we found that they had a lower ratio between visceral adipose tissue (VAT) and TAAT indicating a relative increase of subcutaneous abdominal adipose tissue (ASAT). This relationship between VAT and ASAT has been associated with a lower risk for metabolic disease. We conclude that while weight gain in adolescents with narcolepsy matches that of central obesity, the lower VAT ratio may suggest a lower risk of developing metabolic disease.

A Longitudinal Follow-Up Study on Multiple Sleep Latency Test and Body Mass Index of Patients With Narcolepsy Type 1 in Korea

STUDY OBJECTIVES

Narcolepsy is a chronic disorder with numerous adverse long-term consequences including increased obesity, high mortality rates, and decreased quality of life. With emerging attention to the long-term course of the disorder and importance of accurate diagnosis, the diagnostic stability of the Multiple Sleep Latency Test (MSLT)-the mostly frequently used test to identify narcolepsy-is often challenged.

METHODS

In this study, we compared the baseline and follow-up demographic characteristics and body mass index (BMI) of patients with narcolepsy type 1. Moreover, MSLT results from repeated tests conducted on 48 patients with narcolepsy type 1 were compared, with mean follow-up of approximately 10 years.

RESULTS

BMI from the baseline to the follow-up visit was significantly increased in the participants. There were no significantly different parameter changes in MSLT results.

CONCLUSIONS

MSLT has good test-retest validity in patients with narcolepsy type 1. Close surveillance for the detection and management of obesity is warranted in clinical settings.

The Medical and Economic Burden of Narcolepsy: Implications for Managed Care

BACKGROUND

The neurologic disorder narcolepsy results from dysregulation of the sleep-wake cycle and is primarily characterized by chronic, severely excessive daytime sleepiness and cataplexy, an emotionally induced muscle weakness. The prevalence of narcolepsy is approximately 0.05%, and onset generally occurs during the first 2 decades of life. Narcolepsy is believed to be an autoimmune disorder with destruction of hypocretin-producing neurons in the lateral hypothalamus.

OBJECTIVES

To provide an enhanced understanding of narcolepsy and establish the need for early diagnosis and rapid initiation of effective treatment for patients with narcolepsy.

DISCUSSION

Narcolepsy reduces daily functioning and is associated with a substantial medical and economic burden, with many patients being on full disability. The annual direct medical costs are approximately 2-fold higher in patients with narcolepsy than in matched controls without this condition ($11,702 vs $5261, respectively; P <.0001). Further contributing to the overall burden is a lack of recognition of the signs and symptoms of narcolepsy and an absence of easily measurable biomarkers, resulting in a diagnostic delay that often exceeds 10 years and may be associated with misdiagnosis and inappropriate resource utilization. Because narcolepsy generally has an onset in childhood or in adolescence, is often misdiagnosed, has no known cure, and requires lifelong treatment, it is an important disease from a managed care perspective. Clinical features, as well as objective testing, should be used to ensure the timely diagnosis and treatment of patients with narcolepsy.

CONCLUSION

Policies for the diagnosis and treatment of narcolepsy should be based on the current treatment guidelines, but they should also encourage shared decisions between clinicians and patients to allow for individualized diagnostic and treatment choices, as suggested in best practice recommendations.

Intravenous Immunoglobulin Therapy in Pediatric Narcolepsy: A Nonrandomized, Open-Label, Controlled, Longitudinal Observational Study

STUDY OBJECTIVES

Previous case reports of intravenous immunoglobulins (IVIg) in pediatric narcolepsy have shown contradictory results.

METHODS

This was a nonrandomized, open-label, controlled, longitudinal observational study of IVIg use in pediatric narcolepsy with retrospective data collection from medical files obtained from a single pediatric national reference center for the treatment of narcolepsy in France. Of 56 consecutively referred patients with narcolepsy, 24 received IVIg (3 infusions administered at 1-mo intervals) in addition to standard care (psychostimulants and/or anticataplectic agents), and 32 continued on standard care alone (controls).

RESULTS

For two patients in each group, medical files were unavailable. Of the 22 IVIg patients, all had cerebrospinal fluid (CSF) hypocretin ≤ 110 pg/mL and were HLA-DQB1*06:02 positive. Of the 30 control patients, 29 were HLA-DQB1*06:02 positive and of those with available CSF measurements, all 12 had hypocretin ≤ 110 pg/mL. Compared with control patients, IVIg patients had shorter disease duration, shorter latency to sleep onset, and more had received H1N1 vaccination. Mean (standard deviation) follow-up length was 2.4 (1.1) y in the IVIg group and 3.9 (1.7) y in controls. In multivariate-adjusted linear mixed-effects analyses of change from baseline in Ullanlinna Narcolepsy Scale (UNS) scores, high baseline UNS, but not IVIg treatment, was associated with a reduction in narcolepsy symptoms. On time-to-event analysis, among patients with high baseline UNS scores, control patients achieved a UNS score < 14 (indicating remission) less rapidly than IVIg patients (adjusted hazard ratio 0.18; 95% confidence interval: 95% confidence interval: 0.03, 0.95; p = 0.043). Shorter or longer disease duration did not influence treatment response in any analysis.

CONCLUSIONS

Overall, narcolepsy symptoms were not significantly reduced by IVIg. However, in patients with high baseline symptoms, a subset of IVIg-treated patients achieved remission more rapidly than control patients.

COMMENTARY

A commentary on this article appears in this issue on page 363.

New developments in the management of narcolepsy

Narcolepsy is a life-long, underrecognized sleep disorder that affects 0.02%-0.18% of the US and Western European populations. Genetic predisposition is suspected because of narcolepsy's strong association with HLA DQB1*06-02, and genome-wide association studies have identified polymorphisms in T-cell receptor loci. Narcolepsy pathophysiology is linked to loss of signaling by hypocretin-producing neurons; an autoimmune etiology possibly triggered by some environmental agent may precipitate hypocretin neuronal loss. Current treatment modalities alleviate the main symptoms of excessive daytime somnolence (EDS) and cataplexy and, to a lesser extent, reduce nocturnal sleep disruption, hypnagogic hallucinations, and sleep paralysis. Sodium oxybate (SXB), a sodium salt of γ hydroxybutyric acid, is a first-line agent for cataplexy and EDS and may help sleep disruption, hypnagogic hallucinations, and sleep paralysis. Various antidepressant medications including norepinephrine serotonin reuptake inhibitors, selective serotonin reuptake inhibitors, and tricyclic antidepressants are second-line agents for treating cataplexy. In addition to SXB, modafinil and armodafinil are first-line agents to treat EDS. Second-line agents for EDS are stimulants such as methylphenidate and extended-release amphetamines. Emerging therapies include non-hypocretin-based therapy, hypocretin-based treatments, and immunotherapy to prevent hypocretin neuronal death. Non-hypocretin-based novel treatments for narcolepsy include pitolisant (BF2.649, tiprolisant); JZP-110 (ADX-N05) for EDS in adults; JZP 13-005 for children; JZP-386, a deuterated sodium oxybate oral suspension; FT 218 an extended-release formulation of SXB; and JNJ-17216498, a new formulation of modafinil. Clinical trials are investigating efficacy and safety of SXB, modafinil, and armodafinil in children. γ-amino butyric acid (GABA) modulation with GABA_A receptor agonists clarithromycin and flumazenil may help daytime somnolence. Other drugs investigated include GABA_B agonists (baclofen), melanin-concentrating hormone antagonist, and thyrotropin-releasing hormone agonists. Hypocretin-based therapies include hypocretin peptide replacement administered either through an intracerebroventricular route or intranasal route. Hypocretin neuronal transplant and transforming stem cells into hypothalamic neurons are also discussed in this article. Immunotherapy to prevent hypocretin neuronal death is reviewed.

Sleep-wake patterns, non-rapid eye movement, and rapid eye movement sleep cycles in teenage narcolepsy

BACKGROUND

To further characterize sleep disorders associated with narcolepsy, we assessed the sleep-wake patterns, rapid eye movement (REM), and non-REM (NREM) sleep cycles in Chinese teenagers with narcolepsy.

METHODS

A total of 14 Chinese type 1 narcoleptic patients (13.4 ± 2.6 years of age) and 14 healthy age- and sex-matched control subjects (13.6 ± 1.8 years of age) were recruited. Ambulatory 24-h polysomnography was recorded for two days, with test subjects adapting to the instruments on day one and the study data collection performed on day two.

RESULTS

Compared with the controls, the narcoleptic patients showed a 1.5-fold increase in total sleep time over 24 h, characterized by enhanced slow-wave sleep and REM sleep. Frequent sleep-wake transitions were identified in nocturnal sleep with all sleep stages switching to wakefulness, with more awakenings and time spent in wakefulness after sleep onset. Despite eight cases of narcolepsy with sleep onset REM periods at night, the mean duration of NREM-REM sleep cycle episode and the ratio of REM/NREM sleep between patients and controls were not significantly different.

CONCLUSION

Our study identified hypersomnia in teenage narcolepsy despite excessive daytime sleepiness. Sleep fragmentation extended to all sleep stages, indicating impaired sleep-wake cycles and instability of sleep stages. The limited effects on NREM-REM sleep cycles suggest the relative conservation of ultradian regulation of sleep.

[Narcolepsy in sleepy obese children. Two case reports]

Narcolepsy is a disabling disorder, characterized by excessive daytime sleepiness, irresistible sleep attacks, and partial or complete cataplexy. Many cases of obesity and precocious puberty have been reported in narcoleptic children, suggesting that the deficiency of hypocretin in narcolepsy could also be implicated in appetite stimulation. We report the observations of two young girls, who were referred for obesity and who developed narcolepsy accompanied by an abrupt weight gain. In both cases, specific drugs promoted wakefulness and overweight stabilization. Narcolepsy has to be suspected in sleepy obese children and not misdiagnosed as obstructive apnea. A nocturnal polysomnography with multiple sleep latency tests should be performed to confirm the diagnosis and begin specific treatment that is effective for sleep disorders and weight gain.

The role of sleep in the regulation of body weight

Sleep participates in the regulation of body weight. The amount of sleep and synchronization of the biological clock are both necessary to achieve the energy balance and the secretion of hormones that contribute to weight regulation. In this review, we first reconsider what normal physiological sleep is and what the normative values of sleep are in the general population. Second, we explain how the biological clock regulates the hormones that may be involved in weight control. Third, we provide some recent data on how sleep may be disturbed by sleep disorders or reduced by sleep debt with consequences on weight. Finally, we explore the relationships between sleep debt and obesity.