The European Narcolepsy Network (EU-NN) database

Comorbidity of obstructive sleep apnea and narcolepsy: A challenging diagnosis and complex management

Introduction

Narcolepsy and obstructive sleep apnea syndrome (OSA) are relevant causes of excessive daytime sleepiness (EDS); although different for etiopathogenesis and symptoms, differential diagnosis is sometimes difficult, and guidelines are lacking concerning their management when coexisting in a same patient.

Methods

A narrative review of the literature was realized including PubMed, Scopus and Embase, aimed to regroup studies and case reports evaluating epidemiology, clinical and instrumental features and treatment of patients presenting comorbid NT1 and OSA. Moreover, a snowball search on the pathophysiology underpinnings of the association of the two disorder was realized.

Results

For adults, the prevalence of OSA in NT1 ranged from 24.8 % to 51.4 %. No studies were found concerning the treatment of EDS in double-diagnosis patients, but only case reports; these latter and the experience on patients with either NT or OSA suggest that modafinil, methylphenidate, pitolisant and solriamfetol are effective.

Discussion

Adults with NT1 showed a higher prevalence of OSA compared to the general population, but the reach of the results reviewed here is limited by the retrospective design of most of the studies and by the inhomogeneous utilization of diagnostic criteria. The association with OSA is likely to be explained by the involvement of orexin in hypercapnic-hypoxic responses: a deficit of orexin may promote obstructive events during sleep. Open questions warrant further investigation, especially orexin's involvement in other sleep disorders associated with EDS, and the more appropriate treatment for the OSA-narcolepsy comorbidity.

'It's like tumbleweeds everywhere': An Interpretative Phenomenological Analysis of the lived experience of being diagnosed with and living with narcolepsy

There is a lack of awareness of how sleep health and sleep disorders are experienced. Previous research has found that living with narcolepsy has a debilitating impact on several areas of an individual's life alongside significant diagnostic delays. This study uses a phenomenological, qualitative methodology to explore experiences of being diagnosed with and living with narcolepsy. Six women with type 1 narcolepsy participated in semi-structured interviews. Transcripts were analysed using Interpretative Phenomenological Analysis. Capturing the whole illness experience of narcolepsy, our analysis illuminated three superordinate themes; 'minimising, dismissing and downplaying symptoms', 'navigating the winding journey to diagnosis' and 'a different way of living'. Through our analysis, we are able to demonstrate the affective impact lack of awareness of sleep and sleep disorders has; resulting in significant diagnostic delays and a lack of support post-diagnosis. Findings demonstrate a need for greater awareness and increased support.

Gender medicine and sleep disorders: from basic science to clinical research

Several pivotal differences in sleep and sleep disorders are recognized between women and men. This is not only due to changes in hormonal balance during women's reproductive life, such as in pregnancy and menopause. Women are more likely to report insomnia and non-specific symptoms of apneas, such as fatigue or mood disturbance, compared to men. Thus, it is important for clinicians and researchers to take sex and gender differences into account when addressing sleep disorders in order to acknowledge the biology unique to women. We present a narrative review that delves into the primary sleep disorders, starting from basic science, to explore the impact of gender differences on sleep and the current status of research on women's sleep health.

Making sense of narcolepsy: A qualitative exploration of how persons with narcolepsy perceive symptoms and their illness experience

INTRODUCTION

Understanding how persons with narcolepsy conceptualize symptoms, daily impact and illness experience is key to facilitating dialogue between patients and healthcare professionals. These concepts are usually explored from the perspective of healthcare professionals/researchers and rarely from the perspective of those with narcolepsy.

METHODS

127 self-reported persons with narcolepsy were recruited from an Australian patient support group. A short demographic survey was completed. All agreed to participate in a subsequent 1:1 semi-structured interview. Saturation was reached after 24 interviews (mean age = 33 years (SD 11) with 44% reporting cataplexy). A multidisciplinary team of researchers/clinicians analyzed interview transcripts using thematic analysis.

RESULTS

Participants perceived physical fatigue, sleepiness, and two separate experiences of 'falling asleep/sleep attacks' as distinct symptoms rather than a multidimensional construct (i.e. excessive daytime sleepiness). We also identified two experiences of cataplexy, one triggered by acute emotion and another by a stressor. Participants determined their narcolepsy to be 'well-managed' by the level of functional impairment rather than the frequency of any symptom. Almost all participants described experiencing anticipated stigma and internalized or 'self-' stigma, likely stemming from societal devaluation of sleep and the conflation of sleepiness with laziness.

CONCLUSION

Descriptions of common symptoms often differed between participants and the existing literature. These differences likely impact patient-physician communication, with both parties utilizing the same terminology to communicate different concepts. The characterization of stigma in narcolepsy presents opportunities for future research exploring the impact and possible development of interventions to reduce the substantial psychological comorbidity in persons with narcolepsy.

Retrospective cohort study of hypersomnias of central origin from two Australian tertiary sleep disorders services

BACKGROUND

Hypersomnias of central origin (HOCO) are diverse in origin and symptomatology and remain poorly described in an Australian population. We hypothesised that the rate of human leukocyte antigen (HLA) DQB1*0602 positivity in the Australian cohort would be comparable to international registries.

AIMS

The current study aims to evaluate epidemiological and clinical characteristics of Australian patients with HOCO, including prevalence of HLA DQB1*0602 positivity, the most specific HLA marker associated with narcolepsy.

METHODS

This is a retrospective study. Patients ≥ 16 years of age presenting with symptoms of hypersomnolence who attended one of two Australian sleep centres (New South Wales and Queensland) in the preceding 24 months and had undergone both HLA serology and multiple sleep latency tests (MSLTs) were included. Main outcome measures included demographics, HLA DQB1*0602 positivity, MSLT, and clinical parameters (presence of auxiliary narcolepsy symptoms, laboratory tests, relevant prescribed medications).

RESULTS

Eighty-eight patients were included. HLA DQB1*0602 positivity was highest in those with type 1 narcolepsy (NT1) (95.7%) and lowest in those without a classifiable disorder (9.1%). Mean sleep latency was lowest and number of sleep-onset rapid eye movement periods (SOREMPs) highest in the NT1 group. Comorbid disorders, particularly depression and overweight/obesity, were prevalent in all cohorts. Across all diagnostic groups, dexamphetamine was the most commonly prescribed agent for excessive daytime sleepiness.

CONCLUSIONS

Patients with HOCO assessed in two specialised Australian clinics demonstrate comparable clinical characteristics to other published cohorts internationally; however, available pharmacological agents in Australia do not reflect international standards of care.

Pharmacological options for narcolepsy: are they the way forward?

INTRODUCTION

Narcolepsy is an under-recognized, rare neurologic disorder of hypersomnolence that is associated with increased mortality and medical and psychiatric co-morbidities. Narcolepsy exerts a substantial economic burden on patients and society. There is currently no cure, and life-long symptomatic therapy is needed. Available drugs do not modify the disease course.

AREAS COVERED

This manuscript provides an overview of narcolepsy symptoms, diagnosis, pathophysiology, current pharmacotherapies, and emerging treatments. Gaps and unresolved issues in diagnosis and management of narcolepsy are discussed to answer whether pharmacological options are the way forward.

EXPERT OPINION

Diagnostic criteria for narcolepsy (ICSD-3) need revision and greater clarity. Improved recognition of cataplexy and other symptoms through educational outreach, new biomarkers, improved test scoring through artificial intelligence algorithms, and use of machine learning may facilitate earlier diagnosis and treatment. Pharmacological options need improved symptomatic therapy in addition to targeted therapies that address the loss of hypocretin signaling. Optimal narcolepsy care also needs a better understanding of the pathophysiology, recognition of the different phenotypes in narcolepsy, identification of at-risk individuals and early recognition of symptoms, better diagnostic tools, and a database for research and disease monitoring of treatment, side-effects, and comorbidities.

A systematic overview of rare disease patient registries: challenges in design, quality management, and maintenance

Patient registries serve to overcome the research limitations inherent in the study of rare diseases, where patient numbers are typically small. Despite the value of real-world data collected through registries, adequate design and maintenance are integral to data quality. We aimed to describe an overview of the challenges in design, quality management, and maintenance of rare disease registries.A systematic search of English articles was conducted in PubMed, Ovid Medline/Embase, and Cochrane Library. Search terms included "rare diseases, patient registries, common data elements, quality, hospital information systems, and datasets". Inclusion criteria were any manuscript type focused upon rare disease patient registries describing design, quality monitoring or maintenance. Biobanks and drug surveillances were excluded.A total of 37 articles, published between 2001 and 2021, met the inclusion criteria. Patient registries covered a wide range of disease areas and covered multiple geographical locations, with a predisposition for Europe. Most articles were methodological reports and described the design and setup of a registry. Most registries recruited clinical patients (92%) with informed consent (81%) and protected the collected data (76%). Whilst the majority (57%) collected patient-reported outcome measures, only few (38%) consulted PAGs during the registry design process. Few reports described details regarding quality management (51%) and maintenance (46%).Rare disease patient registries are valuable for research and evaluation of clinical care, and an increasing number have emerged. However, registries need to be continuously evaluated for data quality and long-term sustainability to remain relevant for future use.

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.

The evolving diagnosis and classification of CNS hypersomnolence disorders

Purpose of Review

We describe the evolution and limitations of current diagnostic criteria and classification systems of CNS hypersomnolence disorders and propose some changes.

Recent Findings

An unsupervised cluster analysis of 1100 Europeans with hypersomnolence identified the narcolepsy type 1 phenotype but not other categories listed in ICSD-3.

Summary

There are long-standing unsolved issues regarding the diagnosis and classification of central disorders of hypersomnolence. These include delineating and identifying phenotypes and unique conditions (“sui generis”), sleep deprivation’s impact on phenotypes and how to separate sleep deprivation as a trigger from other causes, as well as the association of excessive sleepiness with other disorders. We discuss these issues and present a novel, straightforward classification system with consistent terminology to get out of the impasse and do justice to people with hypersomnolence.

Anxiety and depression in patients with narcolepsy

We analysed the co-existence of psychopathology in patients with narcolepsy at our centre. We performed an observational retrospective descriptive analysis of patients with a diagnosis of narcolepsy, with and without psychopathology, who attended our sleep disorders unit from October 2012 to October 2021. A total of 51patients with narcolepsy (mean [SD] age 41.10 [14.71] years; 23 [45.1%] males and 28 [54.90%] females) were included. In all, 27 patients (52.94%) and 24 patients (47.06%) had narcolepsy with and without cataplexy, respectively. Of the total, 18 (33.33%) had a mood disorder: 18 with anxiety disorder (33.33%). Of these patients 14 (27.45%) had major depression, two (4%) had attempted suicide, one (2%) had manic outbreak, and one (2%) had substance abuse. Of the 18 patients with anxiety and depression, 10 (55.55%) and eight (44.44%) had narcolepsy with and without cataplexy, respectively. In the comparative analysis, a statistically significant relationship was found between younger age and the presence of anxiety. The prevalence of anxiety and depression in patients with narcolepsy was triple that of the general population, especially in younger patients. Psychopathology precedes the diagnosis of narcolepsy in most patients, not being reactive to diagnosis. This high prevalence suggests a possible biological relationship between both disorders, which should be assessed with larger studies.

Gender differences in narcolepsy: What are recent findings telling us?

Three papers currently published in SLEEP using two different mouse models of narcolepsy, including either Hcrt-tTa;TetO diptheria toxin-A (DTA) or Hypocretin knock-out (Hcrt-KO) mice, suggest important gender differences in narcolepsy expression. Specifically, these recent data corroborate previous findings in mice demonstrating that females show more cataplexy events and more total cataplexy expression than males. Moreover, in the neurotoxic DTA mouse model, females show earlier onset of cataplexy expression than males during active Hcrt cell loss. Finally, females show a doubling of cataplexy during estrous compared to other phases of the estrous cycle. These findings are reviewed in the broader context of prior published literature, including reported gender differences in Hcrt expression and hormonal influences on sleep and wakefulness. Although similar findings have not been reported in humans, a systematic evaluation of gender differences in human narcolepsy has yet to be performed. Taken together, these animal data suggest that more research exploring gender differences in human narcolepsy is warranted.

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.

Effects of sex and estrous cycle on sleep and cataplexy in narcoleptic mice

Narcolepsy type 1 (NT1) is a rare neurology disorder caused by the loss of orexin/hypocretin neurons. NT1 is characterized by excessive daytime sleepiness, sleep and wake fragmentation, and cataplexy. These symptoms have been equally described in both women and men, although influences of gender and hormonal cycles have been poorly studied. Unfortunately, most studies with NT1 preclinical mouse models, use only male mice to limit potential variations due to the hormonal cycle. Therefore, whether gender and/or hormonal cycles impact the expression of narcoleptic symptoms remains to be determined. To address this question, we analyzed vigilance states and cataplexy in 20 female and 17 male adult orexin knock-out narcoleptic mice, with half of the females being recorded over multiple days. Mice had access to chocolate to encourage the occurrence of cataplectic episodes. A vaginal smear was performed daily in female mice to establish the state of the estrous cycle (EC) of the previous recorded night. We found that vigilance states were more fragmented in males than females, and that females had less paradoxical sleep (p = 0.0315) but more cataplexy (p = 0.0375). Interestingly, sleep and wake features were unchanged across the female EC, but the total amount of cataplexy was doubled during estrus compared to other stages of the cycle (p = 0.001), due to a large increase in the number of cataplexy episodes (p = 0.0002). Altogether these data highlight sex differences in the expression of narcolepsy symptoms in orexin knock-out mice. Notably, cataplexy occurrence was greatly influenced by estrous cycle. Whether it is due to hormonal changes would need to be further explored.

Data-Driven Phenotyping of Central Disorders of Hypersomnolence With Unsupervised Clustering

BACKGROUND AND OBJECTIVES

Recent studies fueled doubts as to whether all currently defined central disorders of hypersomnolence are stable entities, especially narcolepsy type 2 and idiopathic hypersomnia. New reliable biomarkers are needed, and the question arises of whether current diagnostic criteria of hypersomnolence disorders should be reassessed. The main aim of this data-driven observational study was to see whether data-driven algorithms would segregate narcolepsy type 1 and identify more reliable subgrouping of individuals without cataplexy with new clinical biomarkers.

METHODS

We used agglomerative hierarchical clustering, an unsupervised machine learning algorithm, to identify distinct hypersomnolence clusters in the large-scale European Narcolepsy Network database. We included 97 variables, covering all aspects of central hypersomnolence disorders such as symptoms, demographics, objective and subjective sleep measures, and laboratory biomarkers. We specifically focused on subgrouping of patients without cataplexy. The number of clusters was chosen to be the minimal number for which patients without cataplexy were put in distinct groups.

RESULTS

We included 1,078 unmedicated adolescents and adults. Seven clusters were identified, of which 4 clusters included predominantly individuals with cataplexy. The 2 most distinct clusters consisted of 158 and 157 patients, were dominated by those without cataplexy, and among other variables, significantly differed in presence of sleep drunkenness, subjective difficulty awakening, and weekend-week sleep length difference. Patients formally diagnosed as having narcolepsy type 2 and idiopathic hypersomnia were evenly mixed in these 2 clusters.

DISCUSSION

Using a data-driven approach in the largest study on central disorders of hypersomnolence to date, our study identified distinct patient subgroups within the central disorders of hypersomnolence population. Our results contest inclusion of sleep-onset REM periods in diagnostic criteria for people without cataplexy and provide promising new variables for reliable diagnostic categories that better resemble different patient phenotypes. Cluster-guided classification will result in a more solid hypersomnolence classification system that is less vulnerable to instability of single features.

Narcolepsy: a model interaction between immune system, nervous system, and sleep-wake regulation

Narcolepsy is a rare chronic neurological disorder characterized by an irresistible excessive daytime sleepiness and cataplexy. The disease is considered to be the result of the selective disruption of neuronal cells in the lateral hypothalamus expressing the neuropeptide hypocretin, which controls the sleep-wake cycle. Diagnosis and management of narcolepsy represent still a substantial medical challenge due to the large heterogeneity in the clinical manifestation of the disease as well as to the lack of understanding of the underlying pathophysiological mechanisms. However, significant advances have been made in the last years, thus opening new perspective in the field. This review describes the current knowledge of clinical presentation and pathology of narcolepsy as well as the existing diagnostic criteria and therapeutic intervention for the disease management. Recent evidence on the potential immune-mediated mechanisms that may underpin the disease establishment and progression are also highlighted.

The development of sleep/wake disruption and cataplexy as hypocretin/orexin neurons degenerate in male vs. female Orexin/tTA; TetO-DTA Mice

Narcolepsy Type 1 (NT1), a sleep disorder with similar prevalence in both sexes, is thought to be due to loss of the hypocretin/orexin (Hcrt) neurons. Several transgenic strains have been created to model this disorder and are increasingly being used for preclinical drug development and basic science studies, yet most studies have solely used male mice. We compared the development of narcoleptic symptomatology in male vs. female orexin-tTA; TetO-DTA mice, a model in which Hcrt neuron degeneration can be initiated by removal of doxycycline (DOX) from the diet. EEG, EMG, subcutaneous temperature, gross motor activity, and video recordings were conducted for 24-h at baseline and 1, 2, 4, and 6 weeks after DOX removal. Female DTA mice exhibited cataplexy, the pathognomonic symptom of NT1, by Week 1 in the DOX(-) condition but cataplexy was not consistently present in males until Week 2. By Week 2, both sexes showed an impaired ability to sustain long wake bouts during the active period, the murine equivalent of excessive daytime sleepiness in NT1. Subcutaneous temperature appeared to be regulated at lower levels in both sexes as the Hcrt neurons degenerated. During degeneration, both sexes also exhibited the "Delta State", characterized by sudden cessation of activity, high delta activity in the EEG, maintenance of muscle tone and posture, and the absence of phasic EMG activity. Since the phenotypes of the two sexes were indistinguishable by Week 6, we conclude that both sexes can be safely combined in future studies to reduce cost and animal use.

Idling for Decades: A European Study on Risk Factors Associated with the Delay Before a Narcolepsy Diagnosis

PURPOSE

Narcolepsy type-1 (NT1) is a rare chronic neurological sleep disorder with excessive daytime sleepiness (EDS) as usual first and cataplexy as pathognomonic symptom. Shortening the NT1 diagnostic delay is the key to reduce disease burden and related low quality of life. Here we investigated the changes of diagnostic delay over the diagnostic years (1990-2018) and the factors associated with the delay in Europe.

PATIENTS AND METHODS

We analyzed 580 NT1 patients (male: 325, female: 255) from 12 European countries using the European Narcolepsy Network database. We combined machine learning and linear mixed-effect regression to identify factors associated with the delay.

RESULTS

The mean age at EDS onset and diagnosis of our patients was 20.9±11.8 (mean ± standard deviation) and 30.5±14.9 years old, respectively. Their mean and median diagnostic delay was 9.7±11.5 and 5.3 (interquartile range: 1.7-13.2 years) years, respectively. We did not find significant differences in the diagnostic delay over years in either the whole dataset or in individual countries, although the delay showed significant differences in various countries. The number of patients with short (≤2-year) and long (≥13-year) diagnostic delay equally increased over decades, suggesting that subgroups of NT1 patients with variable disease progression may co-exist. Younger age at cataplexy onset, longer interval between EDS and cataplexy onsets, lower cataplexy frequency, shorter duration of irresistible daytime sleep, lower daytime REM sleep propensity, and being female are associated with longer diagnostic delay.

CONCLUSION

Our findings contrast the results of previous studies reporting shorter delay over time which is confounded by calendar year, because they characterized the changes in diagnostic delay over the symptom onset year. Our study indicates that new strategies such as increasing media attention/awareness and developing new biomarkers are needed to better detect EDS, cataplexy, and changes of nocturnal sleep in narcolepsy, in order to shorten the diagnostic interval.

Efficacy of Pitolisant on the Treatment of Narcolepsy: A Systematic Review

Narcolepsy is characterized by excessive daytime sleepiness (EDS) and cataplexy. Histamine neurons play an important role in enhancing wakefulness. The objective of our study was to evaluate the efficacy of pitolisant, a histamine 3 (H3)-receptor antagonist/inverse agonist, in patients with a high burden of narcolepsy symptoms. We conducted an advanced PubMed search strategy with inclusion and exclusion criteria. The outcome included the Epworth Sleepiness Scale (ESS) and adverse effects frequency. Our primary outcome included the mean ESS score at the endpoint and showed that pitolisant was superior to the placebo, but not non-inferior to modafinil. Adverse effects were less common and shorter in duration in the pitolisant group compared to the modafinil-treated patients. Pitolisant was efficacious in reducing excessive daytime sleepiness and cataplexy compared with placebo, and it was well-tolerated in patients with severe narcolepsy symptoms as compared with modafinil.

New 2013 incidence peak in childhood narcolepsy: more than vaccination?

Increased incidence rates of narcolepsy type-1 (NT1) have been reported worldwide after the 2009-2010 H1N1 influenza pandemic (pH1N1). While some European countries found an association between the NT1 incidence increase and the H1N1 vaccination Pandemrix, reports from Asian countries suggested the H1N1 virus itself to be linked to the increased NT1 incidence. Using robust data-driven modeling approaches, that is, locally estimated scatterplot smoothing methods, we analyzed the number of de novo NT1 cases (n = 508) in the last two decades using the European Narcolepsy Network database. We confirmed the peak of NT1 incidence in 2010, that is, 2.54-fold (95% confidence interval [CI]: [2.11, 3.19]) increase in NT1 onset following 2009-2010 pH1N1. This peak in 2010 was found in both childhood NT1 (2.75-fold increase, 95% CI: [1.95, 4.69]) and adulthood NT1 (2.43-fold increase, 95% CI: [2.05, 2.97]). In addition, we identified a new peak in 2013 that is age-specific for children/adolescents (i.e. 2.09-fold increase, 95% CI: [1.52, 3.32]). Most of these children/adolescents were HLA DQB1*06:02 positive and showed a subacute disease onset consistent with an immune-mediated type of narcolepsy. The new 2013 incidence peak is likely not related to Pandemrix as it was not used after 2010. Our results suggest that the increased NT1 incidence after 2009-2010 pH1N1 is not unique and our study provides an opportunity to develop new hypotheses, for example, considering other (influenza) viruses or epidemiological events to further investigate the pathophysiology of immune-mediated narcolepsy.

The Impacts of Age and Sex in a Mouse Model of Childhood Narcolepsy

Narcolepsy is a sleep disorder caused by selective death of the orexin neurons that often begins in childhood. Orexin neuron loss disinhibits REM sleep during the active period and produces cataplexy, episodes of paralysis during wakefulness. Cataplexy is often worse when narcolepsy develops in children compared to adults, but the reason for this difference remains unknown. We used orexin-tTA; TetO DTA mice to model narcolepsy at different ages. When doxycycline is removed from the diet, the orexin neurons of these mice express diphtheria toxin A and die within 2-3 weeks. We removed doxycycline at 4 weeks (young-onset) or 14 weeks (adult-onset) of age in male and female mice. We implanted electroencephalography (EEG) and electromyography (EMG) electrodes for sleep recordings two weeks later and then recorded EEG/EMG/video for 24 h at 3 and 13 weeks after removal of doxycycline. Age-matched controls had access to doxycycline diet for the entire experiment. Three weeks after doxycycline removal, both young-onset and adult-onset mice developed severe cataplexy and the sleep-wake fragmentation characteristic of narcolepsy. Cataplexy and maintenance of wake were no worse in young-onset compared to adult-onset mice, but female mice had more bouts of cataplexy than males. Orexin neuron loss was similarly rapid in both young- and adult-onset mice. As age of orexin neuron loss does not impact the severity of narcolepsy symptoms in mice, the worse symptoms in children with narcolepsy may be due to more rapid orexin neuron loss than in adults.

[Narcolepsy in adults: Definition, etiology and treatment]

Narcolepsy is a hypersomnolence disorder of central origin that presents with a disturbance of the wake-sleep regulation. Lead symptoms consist of excessive daytime sleepiness and cataplexy. Nowadays, two types of narcolepsy are distinguished. Type 1 narcolepsy, formerly known as narcolepsy with cataplexy, is based on hypocretin deficiency. The cause of type 2 narcolepsy, formerly known as narcolepsy without cataplexy, remains mainly unknown. A multimodal approach is necessary for diagnosis. The mean latency between the onset of disease and diagnosis in Europe ranges 14 years. Narcolepsy has a major impact on workability and quality of life. The management of narcolepsy is usually life-long and includes non-pharmacological approaches and a symptomatic pharmacological treatment.

Evaluation of the Effectiveness of the Risk Minimization Measures of Sodium Oxybate in the European Union

BACKGROUND

Sodium oxybate (Xyrem^®), approved by the European Medicines Agency (EMA) for narcolepsy with cataplexy, is only available through risk mitigation programs due to potential adverse effects including respiratory and central nervous system depression, neuropsychiatric events, and misuse.

OBJECTIVE

We report findings from a survey evaluating effectiveness of the European Union Xyrem^® Risk Management Plan (RMP).

PATIENTS AND METHODS

A cross-sectional, online, multiple-choice survey was distributed to randomly selected healthcare professionals (HCPs) from six European countries (April 2016-May 2018). Eligibility criteria: current/potential Xyrem^® prescriber and/or sleep disorder specialist; contact information available; on the Xyrem^® RMP educational materials mailing list.

PRIMARY OUTCOME

proportion of respondents answering each question correctly (< 50% responses correct = unsatisfactory comprehension, 50% to < 70% = satisfactory, ≥ 70% = excellent), with precision assessed using 95% confidence intervals (CIs).

RESULTS

Of the 709 HCPs contacted, 601 did not agree to take part, 108 were screened with 35/108 eligible for inclusion; 31 HCPs completed the survey. Of the 31 respondents, 29 (93.5%; 95% CI 84.4-100.0) reported receiving Xyrem^® safety information, commonly from a sales representative, EMA Summary of Product Characteristics (SmPC), or educational meeting; only 9/31 (31.0%; 14.3-50.0) recalled receiving mailed educational materials. The number of HCPs answering dosing-related questions correctly ranged from 24/31 to 31/31. All Xyrem^® contraindications were correctly identified by 26/31 (83.9%; 70.0-96.7) respondents. All respondents 'always' or 'sometimes' completed SmPC recommended activities upon treatment initiation. The majority indicated signs of abuses/misuse/diversion (23/31; 74.2%; 58.6-88.0) and criminal use (23/31; 74.2%; 59.4-89.3) should be monitored at follow-up.

CONCLUSIONS

These data demonstrate the importance of providing a range of educational materials. However, the low sample size limits interpretation; increased HCP engagement would improve understanding of how best to develop educational materials.

EUROPEAN POST-AUTHORIZATION STUDY (PAS) REGISTER NUMBER

EUPAS15024.

Welfare consequences for people diagnosed with attention deficit hyperactivity disorder (ADHD): A matched nationwide study in Denmark

There is insufficient data regarding the excess direct and indirect costs associated with attention deficit hyperactivity disorder (ADHD). Using the Danish National Patient Registry (2002-2016), we identified 83,613 people of any age with a diagnosis of ADHD or who were using central-acting medication against ADHD (primarily methylphenidate, with at least two prescriptions) and matched them to 334,446 control individuals. Additionally, 18,959 partners of patients aged ≥18 years with ADHD were identified, and compared with 74,032 control partners. Direct costs were based on data from the Danish Ministry of Health. Information about the use and costs of drugs were obtained from the Danish Medicines Agency. The frequencies of visits and hospitalizations, and costs of general practice were derived from data from the National Health Security. Indirect costs were obtained from Coherent Social Statistics. The average annual health care costs for people with ADHD and their partners were, respectively, €2636 and €477 higher than those of the matched controls. A greater percentage of people with ADHD and their partners compared with respective control subjects received social services (sick pay or disability pension). Those with ADHD had a lower income from employment than did controls for equivalent periods up to five years before the first diagnosis of ADHD. The additional direct and indirect annual costs (for those aged ≥18 years) including transfers of ADHD compared with controls were €23,072 for people with ADHD and €7,997 for their partners. ADHD has substantial socioeconomic consequences for individual patients, their partners and society.

Automatic detection of microsleep episodes with feature-based machine learning

STUDY OBJECTIVES

Microsleep episodes (MSEs) are brief episodes of sleep, mostly defined to be shorter than 15 s. In the electroencephalogram (EEG), MSEs are mainly characterized by a slowing in frequency. The identification of early signs of sleepiness and sleep (e.g. MSEs) is of considerable clinical and practical relevance. Under laboratory conditions, the maintenance of wakefulness test (MWT) is often used for assessing vigilance.

METHODS

We analyzed MWT recordings of 76 patients referred to the Sleep-Wake-Epilepsy-Center. MSEs were scored by experts defined by the occurrence of theta dominance on ≥1 occipital derivation lasting 1-15 s, whereas the eyes were at least 80% closed. We calculated spectrograms using an autoregressive model of order 16 of 1 s epochs moved in 200 ms steps in order to visualize oscillatory activity and derived seven features per derivation: power in delta, theta, alpha and beta bands, ratio theta/(alpha + beta), quantified eye movements, and median frequency. Three algorithms were used for MSE classification: support vector machine (SVM), random forest (RF), and an artificial neural network (long short-term memory [LSTM] network). Data of 53 patients were used for the training of the classifiers, and 23 for testing.

RESULTS

MSEs were identified with a high performance (sensitivity, specificity, precision, accuracy, and Cohen's kappa coefficient). Training revealed that delta power and the ratio theta/(alpha + beta) were most relevant features for the RF classifier and eye movements for the LSTM network.

CONCLUSIONS

The automatic detection of MSEs was successful for our EEG-based definition of MSEs, with good performance of all algorithms applied.

Therapy for Cataplexy

Purpose of the review

Cataplexy, an involuntary loss of muscle activity triggered by strong emotions is the most impressive symptom in narcolepsy. This review gives an overview of the current understanding of cataplexy and its available treatment options.

Recent findings

With the discovery of hypocretin/orexin, the understanding of the pathophysiology of cataplexy advanced in the past decades. In the recent years, with the development of new anticataplectic agents (e.g., Pitolisant) symptomatic treatment of cataplexy has further improved. Abrupt cessation of anticataplectic medication especially antidepressants increase the risk of status cataplecticus, a virtually continuous series of long-lasting cataplectic attacks.

Summary

Cataplexies still remain an under-recognized phenomenon due to missing diagnostic measures. Treatment for cataplexy still remains symptomatic but new agents with better tolerability and usability are continuously developed. New therapeutic actions either targeting the autoimmune mechanisms underlying orexin cell death or substituting orexin action are promising treatments for the near future.

Factors influencing harmonized health data collection, sharing and linkage in Denmark and Switzerland: A systematic review

INTRODUCTION

The digitalization of medicine has led to a considerable growth of heterogeneous health datasets, which could improve healthcare research if integrated into the clinical life cycle. This process requires, amongst other things, the harmonization of these datasets, which is a prerequisite to improve their quality, re-usability and interoperability. However, there is a wide range of factors that either hinder or favor the harmonized collection, sharing and linkage of health data.

OBJECTIVE

This systematic review aims to identify barriers and facilitators to health data harmonization-including data sharing and linkage-by a comparative analysis of studies from Denmark and Switzerland.

METHODS

Publications from PubMed, Web of Science, EMBASE and CINAHL involving cross-institutional or cross-border collection, sharing or linkage of health data from Denmark or Switzerland were searched to identify the reported barriers and facilitators to data harmonization.

RESULTS

Of the 345 projects included, 240 were single-country and 105 were multinational studies. Regarding national projects, a Swiss study reported on average more barriers and facilitators than a Danish study. Barriers and facilitators of a technical nature were most frequently reported.

CONCLUSION

This systematic review gathered evidence from Denmark and Switzerland on barriers and facilitators concerning data harmonization, sharing and linkage. Barriers and facilitators were strictly interrelated with the national context where projects were carried out. Structural changes, such as legislation implemented at the national level, were mirrored in the projects. This underlines the impact of national strategies in the field of health data. Our findings also suggest that more openness and clarity in the reporting of both barriers and facilitators to data harmonization constitute a key element to promote the successful management of new projects using health data and the implementation of proper policies in this field. Our study findings are thus meaningful beyond these two countries.

Sleep-Related Disorders in Neurology and Psychiatry

BACKGROUND

Sleep-related disorders are a group of illnesses with marked effects on patients' quality of life and functional ability. Their diagnosis and treatment is a matter of common interest to multiple medical disciplines.

METHODS

This review is based on relevant publications retrieved by a selective search in PubMed (Medline) and on the guide- lines of the German Society for Sleep Medicine, the German Neurological Society, and the German Association for Psychiatry, Psychotherapy and Psychosomatics.

RESULTS

A pragmatic classification of sleep disorders by their three chief complaints-insomnia, daytime somnolence, and sleep-associated motor phenomena-enables tentative diagnoses that are often highly accurate. Some of these disorders can be treated by primary care physicians, while others call for referral to a neurologist or psychiatrist with special experience in sleep medicine. For patients suffering from insomnia as a primary sleep disorder, rather than a symptom of another disease, meta-analyses have shown the efficacy of cognitive behavioral therapy, with high average effect sizes. These patients, like those suffering from secondary sleep disorders, can also benefit from drug treatment for a limited time. Studies have shown marked improvement of sleep latency and sleep duration from short-term treatment with benzodiazepines and Z-drugs (non- benzodiazepine agonists such as zolpidem and zopiclone), but not without a risk of tolerance and dependence. For sleep disorders with the other two main manifestations, specific drug therapy has been found to be beneficial.

CONCLUSION

Sleep disorders in neurology and psychiatry are a heterogeneous group of disorders with diverse manifestations. Their proper diagnosis and treatment can help prevent secondary diseases and the worsening of concomitant conditions. Care structures for the treatment of sleep disorders should be further developed.

Welfare consequences for people diagnosed with nonepileptic seizures: A matched nationwide study in Denmark

OBJECTIVE

We aimed to evaluate the excess direct and indirect costs associated with nonepileptic seizures.

METHODS

From the Danish National Patient Registry (2011-2016), we identified 1057 people of any age with a diagnosis of psychogenic nonepileptic seizures (PNESs) and matched them with 2113 control individuals. Additionally, 239 partners of patients with PNES aged ≥18 years were identified and compared with 471 control partners. Direct costs included frequencies and costs of hospitalizations and outpatient use weighted by diagnosis-related group, and specific outpatient costs based on data from the Danish Ministry of Health. The use and costs of drugs were based on data from the Danish Medicines Agency. The frequencies of visits and hospitalizations and costs of general practice were derived from National Health Security data. Indirect costs included labor supply-based income data, and all social transfer payments were obtained from Coherent Social Statistics.

RESULTS

A higher percentage of people with PNES and their partners compared with respective control subjects received welfare benefits (sick pay, disability pension, home care). Those with PNES had a lower employment rate than did controls for equivalent periods up to three years before the diagnosis was made. The additional direct and indirect annual costs for those aged ≥18 years, including transfers to patients with PNES, compared with controls, were €33,697 for people with PNES and €15,121 for their partners.

SIGNIFICANCE

Psychogenic nonepileptic seizures have substantial socioeconomic consequences for individual patients, their partners, and society.

Exploring the clinical features of narcolepsy type 1 versus narcolepsy type 2 from European Narcolepsy Network database with machine learning

Narcolepsy is a rare life-long disease that exists in two forms, narcolepsy type-1 (NT1) or type-2 (NT2), but only NT1 is accepted as clearly defined entity. Both types of narcolepsies belong to the group of central hypersomnias (CH), a spectrum of poorly defined diseases with excessive daytime sleepiness as a core feature. Due to the considerable overlap of symptoms and the rarity of the diseases, it is difficult to identify distinct phenotypes of CH. Machine learning (ML) can help to identify phenotypes as it learns to recognize clinical features invisible for humans. Here we apply ML to data from the huge European Narcolepsy Network (EU-NN) that contains hundreds of mixed features of narcolepsy making it difficult to analyze with classical statistics. Stochastic gradient boosting, a supervised learning model with built-in feature selection, results in high performances in testing set. While cataplexy features are recognized as the most influential predictors, machine find additional features, e.g. mean rapid-eye-movement sleep latency of multiple sleep latency test contributes to classify NT1 and NT2 as confirmed by classical statistical analysis. Our results suggest ML can identify features of CH on machine scale from complex databases, thus providing 'ideas' and promising candidates for future diagnostic classifications.

Morbidity and mortality of middle-aged and elderly narcoleptics

OBJECTIVES

The objective of the study was to evaluate the morbidities and mortality in a national group of middle-aged and elderly narcolepsy patients before and after the first diagnosis of the condition.

METHODS

From the Danish National Patient Registry (NPR), 1174 patients (45.1% males) aged 20-59 years and 339 patients (44.8% males) aged 60+ who received a diagnosis of narcolepsy between 1998 and 2014 were compared, respectively, with 4716 and 1353 control citizens matched for age, gender and geography, who were randomly chosen from the Danish Civil Registration System Statistics. In the NPR, all morbidities are grouped into major WHO classes.

RESULTS

Middle-aged and elderly patients had more health contacts before and after their narcolepsy diagnosis with respect to several disease domains: infections, neoplasm, endocrine/metabolic diseases/diabetes, mental/psychiatric, neurological (including epilepsy), eye, cardiovascular (hypertension, ischemic heart disease), respiratory (upper-airway infections, sleep apnea), gastrointestinal, musculoskeletal (including discopathies) and skin diseases. Narcolepsy patients had lower reproductive rates. Furthermore, patients showed significantly more health contacts due to the evaluation and control contacts for disease and symptoms. Patients suffered from significantly more multiple diseases than did controls. The 17-year hazard ratio mortality rates were 1.35 (95% CI, 0.94-1.95, p = 0.106) among 20-59 year-olds, and 1.38 (1.12-1.69, p = 0.002) among those aged 60+ years.

CONCLUSION

There are higher rates of morbidity in several disease domains before and after a diagnosis of narcolepsy. Elderly narcolepsy patients have higher mortality rates.

Morbidity and mortality of childhood- and adolescent-onset epilepsy: A controlled national study

PURPOSE

Epilepsy is associated with significant morbidities and mortality. We aimed to evaluate the 30-year morbidities and mortality in a national group of patients after a first diagnosis of epilepsy.

METHODS

From the Danish National Patient Registry (NPR), in total, 3123 patients with epilepsy aged 0-5years and 5018 patients aged 6-20years diagnosed in 1998-2002 were identified and compared with, respectively, 6246 and 10,036 persons matched for age, gender, and place of living with randomly chosen citizens from the Danish Civil Registration System Statistics. In the NPR, all morbidities in the following 30years were grouped into major WHO disease classes.

KEY FINDINGS

Patients with epilepsy had significantly higher rates of comorbidities including almost all health-related comorbidities compared with controls. Mortality rates were elevated: the hazard ratio (5%; 95% CI) was 14.46 (11.8; 17.7, p<0.001) and 5.58 (4.9; 6.4, P<0.001) for patients aged 0-5years and 6-20years at first diagnosis of epilepsy, respectively.

SIGNIFICANCE

Epilepsy is associated with significant comorbidities and mortality including all health care domains, especially among persons who were young at the onset of epilepsy.

Treatment cost of narcolepsy with cataplexy in Central Europe

Background

Narcolepsy is a lifelong, rare neurological sleep disorder characterized by chronic, excessive attacks of daytime sleepiness. This disease is often extremely incapacitating, interfering with every aspect of life, in work and social settings.

Objective

The purpose of this study is to specify the treatment costs of patients in Central Europe (Czech Republic), while the attention is mainly paid to the drugs that were fully or partially covered by public health insurance. Furthermore, concomitant therapy is also evaluated, since it incurs a certain financial burden for patients and their family members. On the basis of the calculated costs, impact on the public budget is evaluated.

Patients and methods

This study monitors the direct costs of the drugs for 13 patients, who represent ~1.3% of the total number of diagnosed patients in the Czech Republic, and evaluates the costs associated with their treatment during the period from January 9, 2011 to April 23, 2013.

Results

Most of the treatment costs (~80%) were covered by publicly available sources. This finding is also true for the concomitant therapy of comorbidities. Additional payments for the drugs constitute about 20% of the total costs.

Morbidity of childhood onset narcolepsy: a controlled national study

Narcolepsy is associated with significant morbidities. We evaluated the morbidities and mortality in a national group of child and adolescent patients after a first diagnosis of narcolepsy.

METHODS

Identified from the Danish National Patient Registry (NPR), 243 patients (128 boys) aged 0-19 years diagnosed with narcolepsy between 1998 and 2012 with follow-up until 2014 were compared with 970 controls who were randomly chosen from the Danish Civil Registration System Statistics and matched by age, gender and geography. Comorbidities were calculated three years before and after diagnoses.

RESULTS

In addition to the more frequent health contacts due to neurological diseases, patients showed elevated odds ratios before and after diagnosis of endocrine and metabolic conditions (4.4 (95% CI, 1.9-10.4); 3.8 (1.7-8.4)), nervous disorders (16.6 (8.0-34.4); 198 (49.0-804)), psychiatric illnesses (4.5 (2.3-9.1)/5.8 (2.8-12.1)), pulmonary diseases, and other diseases (3.1 (2.0-4.9); 3.1 (2.0-4.9)). Congenital abnormalities (2.5 (1.1-5.5)), respiratory (2.9 (1.5-5-5)) and eye (5.7 (2.2-15.0)) diseases were more common before diagnosis. Injuries were also more common after diagnosis (1.5 (1.0-2.1)). Narcoleptic children presented significantly more diagnoses of multiple comorbidities than controls before and after diagnosis.

CONCLUSION

Before and after a diagnosis of narcolepsy in children, morbidity is more frequent in several domains, including metabolic, psychiatric, neurological and other diseases.