The impact of gender on timeliness of narcolepsy diagnosis

Ageing-related modification of sleep and breathing in orexin-knockout narcoleptic mice

Narcolepsy type-1 (NT1) is a lifelong sleep disease, characterised by impairment of the orexinergic system, with a typical onset during adolescence and young adulthood. Since the wake-sleep cycle physiologically changes with ageing, this study aims to compare sleep patterns between orexin-knockout (KO) and wild type (WT) control mice at different ages. Four groups of age-matched female KO and WT mice (16 weeks of age: 8 KO-YO and 9 WT-YO mice; 87 weeks of age: 13 KO-OLD and 12 WT-OLD mice) were implanted with electrodes for discriminating wakefulness, rapid-eye-movement sleep (REMS), and non-REMS (NREMS). Mice were recorded for 48 h in their home cages and for 7 more hours into a plethysmographic chamber to characterise their sleep-breathing pattern. Regardless of orexin deficiency, OLD mice spent less time awake and had fragmentation of this behavioural state showing more bouts of shorter length than YO mice. OLD mice also had more NREMS bouts and less frequent NREMS apneas than YO mice. Regardless of age, KO mice showed cataplexy-like episodes and shorter REMS latency than WT controls and had a faster breathing rate and an increased minute ventilation during REMS. KO mice also had more wakefulness, NREMS and REMS bouts, and a shorter mean length of wakefulness bouts than WT controls. Our experiment indicated that the lack of orexins as well as ageing importantly modulate the sleep and breathing phenotype in mice. The narcoleptic phenotype caused by orexin deficiency in female mice was substantially preserved with ageing.

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.

Long-term follow-up of symptom and quality of life changes in patients with narcolepsy during and after the COVID-19 pandemic

The COVID-19 pandemic may have a significant impact on patients with narcolepsy, yet a long-term follow-up study is currently lacking. This study aims to investigate changes in symptom severity and the quality of life of patients with narcolepsy during and after the pandemic. Patients with type 1 or type 2 narcolepsy (NT1, NT2) were retrospectively recruited and prospectively followed from 2020 to 2023. They received evaluations including the Epworth Sleepiness Scale (ESS), the visual analog scale (VAS) for hypersomnolence, the VAS for cataplexy, the Short-form 36 Health Survey questionnaire (SF-36), and a sleep diary. We compared the differences between the pre-lockdown, the lockdown, the post-lockdown, and the post-pandemic periods by repeated measures ANOVA or the Friedman test, with the Bonferroni test for post hoc analysis. A total of 100 patients completed the 4-year study (mean age, 24.06 ± 7.00 years; 55% male). We observed significant differences in the ESS (p = 0.037), total nighttime sleep (p = 0.03), total sleep time (p = 0.035), and sleep efficiency (p = 0.035) during the study period. There was also significantly worse physical role functioning in the post-pandemic period (p = 0.014). In particular, the NT1 group had significantly decreased VAS-C scores (p < 0.001) but experienced worse physical role functioning in the post-pandemic period (p = 0.009). Patients with narcolepsy continue to face challenges after the pandemic. A more flexible lifestyle with an adequate sleep time may be beneficial, and medication adherence should be emphasized.

Effects of modafinil on nocturnal sleep patterns in patients with narcolepsy: A cohort study

BACKGROUND

Patients with narcolepsy often experience disturbed nighttime sleep. Modafinil is commonly prescribed for hypersomnolence, but its impacts on nocturnal sleep remain unclear. This study uses actigraphy to examine the effect of modafinil on both hypersomnolence and nocturnal sleep patterns in patients with narcolepsy.

METHODS

Prior to treatment, 87 patients with narcolepsy wore an actigraphy for 7-14 days to assess their nighttime sleep. After evaluation, they received a daily dose of 200-400 mg of modafinil in the morning and wore an actigraphy again six months after initiating treatment. Questionnaires, including the Epworth-Sleepiness-Scale (ESS), the Visual-Analogue-for-Hypersomnolence (VAS), and the Short-Form-36-Health-Survey (SF-36), were used to evaluate hypersomnolence and quality of life both before and after treatment. Paired t-tests and independent samples t-tests were used for pre- and post-treatment comparisons and subgroup analysis. We used the Pearson's correlation test to measure the correlations between the sleep parameters of the actigraphy and data of the questionnaires.

RESULTS

Improvements in hypersomnolence were noted following modafinil treatment, and we observed no significant deterioration in nocturnal sleep parameters by the actigraphy. The total number of awakenings by actigraphy significantly decreased (p = 0.005), especially in females (p = 0.008), while sleep onset latency significantly increased in children/adolescents (p = 0.014). Correlations were found between the sleep parameters of the actigraphy and ESS, VAS, and SF-36 scores.

CONCLUSION

Modafinil treatment may not worsen nighttime sleep in patients with narcolepsy. However, it should be administered with care in children and adolescents.

Impact of Taiwan's 2021 COVID-19 lockdown on the symptom severity and quality of life of patients with narcolepsy

COVID-19 lockdowns can influence the sleep quality and daytime condition of patients with narcolepsy. Using data from our cohort study, we investigated changes in the quality of life and the symptom severity of patients with narcolepsy during Taiwan's 2021 lockdown and investigated differences by narcolepsy subtype, sex, and age. Patients with type 1 and type 2 narcolepsy (NT1 and NT2, respectively) aged 6-40 years were retrospectively recruited from our narcolepsy cohort study. These patients were regularly evaluated using the Short Form 36 Health Survey questionnaire (SF-36), the Epworth Sleepiness Scale (ESS), the visual analog scale (VAS) for hypersomnolence, the VAS for cataplexy and sleep diary. We compared the differences between the lockdown and the prelockdown periods by narcolepsy subtype, sex, and age. We used a paired t test analysis to compare differences in the SF-36, ESS, VAS scores and data of sleep diary between the prelockdown and lockdown periods (p1), and an independent t test analysis was used to compare the changes in different subgroups between the prelockdown and lockdown periods (p2). A total of 120 patients with narcolepsy were recruited (mean age 24.22 ± 6.87 years; 58% male); 80 of the patients had NT1 (mean age 25.25 ± 6.79 years; 60% male) and 40 had NT2 (mean age 22.16 ± 6.64, 53% male). During the lockdown period, the ESS score of total patients was decreased (p = 0.039) and body mass index was increased (p = 0.02). The NT1 group decreased significantly (p1 = 0.017), especially in men (p1 = 0.016) and adults (p1 = 0.04); scores for the VT domain of the SF-36 increased significantly in male and adult patients with NT2 (p1 = 0.048 and 0.012). Additionally, male patients with NT2 exhibited significantly decreased scores in the physical and emotional role functioning domains (p1 = 0.028, 0.024). The children and adolescents with NT1 had significantly decreased scores in the general health domain of the SF-36, but no significant change was noted in that of adults (p1 = 0.027, p2 = 0.012). We observed both negative and positive impacts of Taiwan's 2021 lockdown on patients with narcolepsy. A more flexible but structured daily routine with adequate sleep time should be considered for this population during lockdown and nonlockdown periods.

Characteristics and outcomes of cases with methylphenidate abuse, dependence or withdrawal: an analysis of spontaneous reports in EudraVigilance

Methylphenidate (MPH) is a central nervous stimulant, which is mainly used in attention deficit hyperactivity disorder (ADHD) and narcolepsy. In recent years, rising MPH prescription volumes have drawn attention to possible misuse. We analyzed data on suspected MPH abuse, dependence or withdrawal reported to the EudraVigilance database (1996-2019), comparing case characteristics (e.g. age, indications and outcome). In 1531 cases from 35 countries (median: 29 years, 57.6% male), 42.3% had been diagnosed with ADHD and 8.0% with narcolepsy. Narcolepsy cases were older than ADHD cases (mean age: 47 vs. 22 years), and used co-medications more frequently (79.4 vs. 47.8%). Intravenous MPH administration was most common among individuals not diagnosed with ADHD or narcolepsy. A history of abuse, dependence or withdrawal of any substance was more often documented in fatal than in nonfatal cases (49.0 vs. 22.5%), whereas differences regarding the route of administration were less pronounced. Minors, who presumably received MPH for ADHD treatment, presented less frequently with serious outcomes than older cases or those without an approved indication. Prescribers should exercise caution in adult MPH users and should make a thorough co-medication assessment. Finally, more research on substance abuse in narcolepsy patients is required, which should include comorbidities and co-medication.

Comparative Efficacy and Safety of Multiple Wake-Promoting Agents for the Treatment of Excessive Daytime Sleepiness in Narcolepsy: A Network Meta-Analysis

Purpose

Narcolepsy is a rare debilitating disorder for which multiple novel pharmacological options have been approved as treatment for the past few years. The current study systematically updates the comparative efficacy and detailed safety analysis of approved wake-promoting agents in narcolepsy.

Methods

Randomized controlled trials (RCTs) were searched for diagnosed narcolepsy with approved interventions. Efficacy outcomes included the Maintenance of Wakefulness Test (MWT), Epworth Sleepiness Scale (ESS), Clinical Global Impression of Change (CGI-C), and Patient Global Impression of Change (PGI-C). Safety outcomes including overall adverse event (AE) risk were measured. The study was registered at PROSPERO (CRD 42022334915).

Results

The final analysis included 17 RCTs with five drug treatments: modafinil/armodafinil, sodium oxybate, pitolisant, solriamfetol, and lower-sodium oxybate (LXB). For efficacy measures, interventions included in each outcome were effective compared with placebo. Furthermore, the magnitude of solriamfetol effect on MWT (9.11 minutes; 95% CI=7.05-11.16), ESS (-4.79; 95% CI=-6.56 to -3.01), and PGI-C (9.39; 95% CI= 2.37-37.19), and LXB effect on CGI-C (9.67; 95% CI=2.73-34.26) was greater than that of other treatments included in each outcome compared with placebo. For safety measures, all interventions had an acceptable safety profile with LXB having least risk for overall AEs (0.56; 95% CI=0.20-1.53), serious AEs (0.33; 95% CI=0.09-1.20), AEs leading to treatment discontinuation (0.11; 95% CI=0.01-2.04), and all-cause discontinuation (0.04; 95% CI=0.00-0.67) compared to placebo. Placebo had the lowest risk for exploratory AEs.

Conclusion

All approved interventions were effective in controlling the symptoms of narcolepsy at varying degrees with an acceptable safety profile.

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.

Central Disorders of Hypersomnolence: Association with Fatigue, Depression and Sleep Inertia Prevailing in Women

Fatigue, depression, and sleep inertia are frequently underdiagnosed manifestations in narcolepsy and idiopathic hypersomnia. Our cross-sectional study design included diagnostic interview accompanied by assessment instruments and aimed to explore how these factors influence disease severity as well as to elucidate any sex predisposition. One hundred and forty-eight subjects (female 63%) were divided into narcolepsy type 1 (NT1; n = 87, female = 61%), narcolepsy type 2 (NT2; n = 22, female = 59%), and idiopathic hypersomnia (IH; n = 39, female = 69%). All subjects completed a set of questionnaires: Epworth Sleepiness Scale (ESS), Hospital Anxiety and Depression Scales (HADS), Fatigue Severity Scale (FSS), and Sleep Inertia Questionnaire (SIQ). In narcoleptic subjects, questionnaire data were correlated with the Narcolepsy Severity Scale (NSS), and in subjects with idiopathic hypersomnia, with the Idiopathic Hypersomnia Severity Scale (IHSS). The highest correlation in narcoleptic subjects was found between NSS and ESS (r = 0.658; p < 0.0001), as well as FSS (r = 0.506; p < 0.0001), while in subjects with idiopathic hypersomnia, the most prominent positive correlations were found between IHSS and SIQ (r = 0.894; p < 0.0001), FSS (r = 0.812; p < 0.0001), HADS depression scale (r = 0.649; p = 0.0005), and HADS anxiety scale (r = 0.528; p < 0.0001). ESS showed an analogic correlation with disease severity (r = 0.606; p < 0.0001). HADS anxiety and depression scores were higher in females (p < 0.05 and p < 0.01), with similar results for FSS and SIQ scales (p < 0.05 for both), and a trend toward higher ESS values in females (p = 0.057). Our study illustrates that more attention should be focused on pathophysiological mechanisms and associations of fatigue, depression, as well as sleep inertia in these diseases; they influence the course of both illnesses, particularly in women.

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.

pitolisant, a novel histamine-3 receptor competitive antagonist, and inverse agonist, in the treatment of excessive daytime sleepiness in adult patients with narcolepsy

Narcolepsy is a debilitating sleep disorder that presents with excessive daytime sleepiness (EDS) and cataplexy, which is a sudden paralysis of muscle tone triggered by strong emotions such as laughing. It is also associated with many other disorders, including psychiatric disorders, neurologic illnesses, and medication side effects. Common causes of delayed and incorrect diagnoses of these conditions include lack of physician familiarity with narcolepsy symptoms and comorbidities which mask narcolepsy signs and symptoms. Current pharmacologic therapies include Modafinil and Armodafinil for EDS and sodium oxybate for cataplexy. This review discusses the epidemiology, pathophysiology, risk factors, presentation, treatment of narcolepsy, and the role of a novel drug, Pitolisant, in the treatment of EDS in adults with narcolepsy. Pitolisant is a histamine-3 receptor (H3R), competitive antagonist, and inverse agonist, acting through the histamine system to regulate wakefulness. It is a novel drug approved in August 2019 by the FDA, is not classified as a controlled substance, and is approved for use in Europe and the United States to treat EDS and cataplexy in narcolepsy. Recent phase II and III trials have shown that Pitolisant helps reduce the ESS score and cataplexy. In summary, based on comparative studies, recent evidence has shown that Pitolisant is non-inferior to Modafinil in the treatment of EDS but superior to Modafinil in reducing cataplexy.

Sex-related differences within sleep-wake dynamics, cataplexy, and EEG fast-delta power in a narcolepsy mouse model

Narcolepsy type 1 (NT1) is a sleep-wake disorder caused by selective loss of hypocretin (HCRT, also called orexin) neurons. Although the prevalence of NT1 is equal in men and women, sex differences in NT1 symptomatology have been reported in humans and other species. Yet, most preclinical studies fail to include females, resulting in gender bias within translational drug development. We used hcrt-tTA;TetO DTA mice (NT1 mice) that lose their HCRT neurons upon dietary doxycycline removal to examine in detail the effect of sex on NT1 symptoms and sleep-wake characteristics. We recorded 24-h electroencephalography (EEG), electromyography (EMG), and video in adult male and female NT1 mice for behavioural state quantification. While conducting this study, we recognized another type of behavioural arrest different from cataplexy: shorter lasting and with high δ power. We termed these delta attacks and propose a set of criteria for quantifying these in future research. Our findings show that both sexes exhibit high behavioural state instability, which was markedly higher in females with more behavioural arrests interrupting the wake episodes. Females exhibited increased wake at the expense of sleep during the dark phase, and decreased rapid-eye-movement (REM) sleep during the 24-h day. During the dark phase, fast-δ (2.5-4 Hz) in non-rapid-eye-movement (NREM) sleep and θ (6-10 Hz) EEG spectral power in REM sleep were lower in females compared to males. We demonstrate that biologically driven sex-related differences exist in the symptomatology of NT1 mice which calls for including both sexes in future research.

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.

Validation of the Epworth sleepiness scale for children and adolescents (ESS-CHAD) questionnaire in pediatric patients with narcolepsy with cataplexy aged 7-16 years

OBJECTIVE/BACKGROUND

The Epworth Sleepiness Scale for Children and Adolescents (ESS-CHAD) measures daytime sleepiness, but had not previously been validated in children <12 years.

PATIENTS/METHODS

Data from a sodium oxybate (SXB) study in pediatric participants with narcolepsy with cataplexy (ClinicalTrials.gov, NCT02221869) were used in this validation study. SXB-naive participants completed an open-label titration period prior to entering a 2-week stable-dose period; participants taking SXB at study entry entered a 3-week stable-dose period.

RESULTS

The analysis population (N = 100) had a mean (SD) age of 11.9 (2.39) years. Internal consistency as assessed by Cronbach's alpha was 0.750 (95% CI, 0.681-0.819). The intraclass correlation coefficient for the test-retest reliability assessment (n = 64 with stable or no stimulant use at study entry) was 0.755 (95% CI, 0.626-0.844). Responsiveness to change, measured as the mean within-person change in 1-week ESS-CHAD score over time in SXB-naive participants (n = 59) from baseline (before taking SXB) to end of the stable-dose period (taking the titrated amount of SXB), was -6.31 (95% CI: -7.61, -5.00; nominal P < 0.0001). For convergent construct validity, the mean (SD) scores for female (n = 40) and male (n = 60) participants were 13.98 (4.440) and 14.65 (4.050), respectively (nominal P = 0.4430). For divergent construct validity, the mean (SD) scores were 16.31 (2.978) in the group who were taking neither SXB nor stimulants at study entry (n = 32) and 13.47 (4.400) in the group taking SXB with or without stimulants at study entry (n = 68; nominal P = 0.0003).

CONCLUSIONS

This evidence supports the validity of the 1-week ESS-CHAD in a pediatric population with narcolepsy.

Sleep Measurements in Women

Sleep in women and men have been studied in several studies with higher prevalence of sleep complaints in women compared with men. Several factors can affect sleep and could be argued to contribute to sex and gender differences in general sleep. There are no differences in guidelines when measuring sleep in women but several sleep assessment tools have been validated or compared between sexes. Because there is still a lack of knowledge on sleep measurements in women, the present review aimed to produce an overview of the current knowledge of objective and subjective sleep measurements in women.

Polysomnographic nighttime features of narcolepsy: A systematic review and meta-analysis

Polysomnographic studies have been conducted to explore nighttime sleep features in narcolepsy, but their relationship to narcolepsy is still imperfectly understood. We conducted a systematic review of the literature exploring polysomnographic differences between narcolepsy patients and healthy controls (HCs) in EMBASE, MEDLINE, All EBM databases, CINAHL, and PsycINFO. 108 studies were identified for this review, 105 of which were used for meta-analysis. Meta-analyses revealed significant reductions in sleep latency, sleep efficiency, slow wave sleep percentage, rapid eye movement sleep (REM) latency, cyclic alternating pattern rate, and increases in total sleep time, wake time after sleep onset (WASO), awakening numbers (AWN) per hour, stage shift (SS) per hour, N1 percentage, apnea hypopnea index, and periodic limb movement index in narcolepsy patients compared with HCs. Furthermore, narcolepsy type 1 patients showed more disturbed nighttime sleep compared with narcolepsy type 2 patients. Children and adolescent narcolepsy patients show increased WASO, AWN, and SS compared with adult patients. Macro- and micro-structurally, our study suggests that narcolepsy patients have poor nighttime sleep. Sex, age, body mass index, disease duration, disease type, medication status, and adaptation night are demographic, clinical and methodological factors that contribute to heterogeneity between studies.

Narcolepsy Presentation in Diverse Populations: an Update

Purpose of Review

We performed a literature search to generate incidence and prevalence rates of narcolepsy in diverse populations based on current available data.

Recent Findings

With an onset in childhood, narcolepsy often has a delayed diagnosis due to symptoms of excessive daytime sleepiness not being recognized or being misdiagnosed. Clinical, electrophysiological, and biological tests are needed in order to diagnose narcolepsy. At the same time, the discovery of the link with the immunoregulatory human leukocyte antigen complex and the adverse events in relation to the H1N1 pandemic vaccines have shuffled the epidemiological numbers.

Summary

In this meta-review, we pooled incidence rates and prevalence rates reported in 30 countries or from 209 sets of data. Findings are reported per age, continent, and proxy race/ethnicity as well as period (i.e., before/after the pandemic). This meta-review showed that narcolepsy occurs in 0.87–1.21 of the world population, with specifically NT1 being investigated. Its pooled incidence rate in vaccinated samples is 1.58. There is furthermore an underreporting of narcolepsy in ethnic/race and gender minorities, of childhood narcolepsy type 2 and potential comorbid conditions masking the clinical complaints and hence timely diagnosis.

Living with Narcolepsy: Current Management Strategies, Future Prospects, and Overlooked Real-Life Concerns

Narcolepsy is a neurological disorder of the sleep-wake cycle characterized by excessive daytime sleepiness (EDS), cataplexy, nighttime sleep disturbances, and REM-sleep-related phenomena (sleep paralysis, hallucinations) that intrude into wakefulness. Dysfunction of the hypocretin/orexin system has been implicated as the underlying cause of narcolepsy with cataplexy. In most people with narcolepsy, symptom onset occurs between the ages of 10 and 35 years, but because the disorder is underrecognized and testing is complex, delays in diagnosis and treatment are common. Narcolepsy is treated with a combination of lifestyle modifications and medications that promote wakefulness and suppress cataplexy. Treatments are often effective in improving daytime functioning for individuals with narcolepsy, but side effects and/or lack of efficacy can result in suboptimal management of symptoms and, in many cases, significant residual impairment. Additionally, the psychosocial ramifications of narcolepsy are often neglected. Recently two new pharmacologic treatment options, solriamfetol and pitolisant, have been approved for adults, and the indication for sodium oxybate in narcolepsy has been expanded to include children. In recent years, there has been an uptick in patient-centered research, and promising new diagnostic and therapeutic options are in development. This paper summarizes current and prospective pharmacological therapies for treating both EDS and cataplexy, discusses concerns specific to children and reproductive-age women with narcolepsy, and reviews the negative impact of health-related stigma and efforts to address narcolepsy stigma.

Three Decades of Progress in Sleep Disorders and Sleep Health for Women

Over the past 3 decades, significant strides have been made in the field of sleep medicine for women. The impact of sex and gender on sleep health and sleep disorders received little attention in the early 1990s, but driven by policies ensuring inclusion of women in medical research, more recent studies have identified sex differences in sleep and investigated gender differences in sleep disorders. Nevertheless, disparities remain: diagnosis of sleep disorders, such as obstructive sleep apnea, narcolepsy, and rapid eye movement (REM) sleep behavior disorder are often delayed and underdiagnosed in women. Future research should continue to examine how biological sex and identity across the gender spectrum influence sleep health and sleep disorders, allowing for more personalized health care for all patients.

Sex and age differences in the association between anxiety disorders and narcolepsy: A nationwide population-based case control study

BACKGROUND

To examine the association between narcolepsy and anxiety disorders.

METHODS

This population-based, retrospective case-control study analyzed Taiwan's National Health Insurance Research Database between 2000 and 2013. We included narcoleptic patients aged at least 12 years, diagnosed according to the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) code 347. The cases and the propensity score-matched controls were selected in a 1:4 ratio. Each subject with anxiety disorders (ICD-9-CM code 300) was required to visit the outpatient clinic at least three times within a year. Multivariate logistic regression and interaction analyses were used to calculate the association between anxiety disorders and narcolepsy.

RESULTS

This study enrolled 478 and 1912 subjects with and without narcolepsy, respectively. After adjusting for covariates, patients with anxiety disorders had an approximately 2.7 odds ratio of developing narcolepsy when compared to the control subjects (adjusted odds ratio [aOR)] = 2.7; 95% confidence interval [CI] = 1.699-4.344). Interaction analysis and subgroup analysis showed a higher incidence of previously diagnosed anxiety disorders in narcoleptic patients aged 12 to 17 years and female patients (aOR = 25.9; 95% CI = 15.194-42.896; aOR = 3.6; 95% CI = 1.818-7.062, respectively).

LIMITATIONS

The narcolepsy and anxiety disorders were not distinguished by validated structural diagnostic instruments.

CONCLUSIONS

The results of this study revealed higher comorbidity rates of anxiety disorders in narcoleptic patients. The incidence of previously diagnosed anxiety disorders was higher in narcoleptic patients aged 12 to 17 years and female patients.

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.

Lisdexamfetamine to improve excessive daytime sleepiness and weight management in narcolepsy: a case series

Objective:

To report the successful use of lisdexamfetamine in the management of narcolepsy.

Methods:

Five narcoleptic patients received lisdexamfetamine, at different dosages and for different periods, for management of excessive daytime sleepiness and weight control.

Results:

All patients experienced improvement of excessive daytime sleepiness and lost weight without side effects.

Conclusion:

Lisdexamfetamine appears promising for the treatment of two of the most common symptoms of narcolepsy: excessive daytime sleepiness and weight gain.

Demographic and nap-related variance of the MSLT: results from 2,498 suspected hypersomnia patients: Clinical MSLT variance

OBJECTIVE

The purpose of this study was to enhance our understanding of clinical trends in sleep and rapid eye movement (REM) propensity on the multiple sleep latency test (MSLT). Demographic variables of interest included early childhood/advanced age, gender, race, and REM-suppressant use.

METHODS

Nocturnal sleep studies and 5-nap MSLTs were retrieved from a large repository of deidentified studies from various US sleep clinics between 2007 and 2015. Studies were signal processed, human-edited, and underwent rigorous quality assurance for inclusion.

RESULTS

The final sample consisted of N = 2498 MSLTs (24.2% Black; 34.2% Men; Age 4-89). In adults (age ≥ 21), sleep propensity modestly decreased across nap (90% at nap 1 to 80% at nap 5; p < 0.001). Children ≤12 years were least likely to fall asleep on any nap (∼55% at nap 5). REM propensity troughed at nap 4 (13%) and varied with age. Advanced age (≥60 years; OR: 0.28, p < 0.001), REM-suppressant use (OR:0.52, p < 0.001), and female sex (men OR: 1.48, p = 0.012) was associated with a decreased proportion of ≥2 REMs in adjusted logistic models. Children often demonstrated only 1 REM and generally had long sleep latencies, yielding a low proportion of MSLTs consistent with narcolepsy (11.0% vs. 19.2% and 16.8% in those between 13-20 and 21-59, respectively; p = 0.003).

CONCLUSIONS

MSLT outcomes vary greatly across age, gender, and use of psychotropic medication. Demographic variance should be considered when interpreting MSLT results. Robust age effect question the appropriateness of the MSLT as currently designed and implemented for children and older adults.

Comorbidities in a community sample of narcolepsy

STUDY OBJECTIVE

To assess comorbidities in a community-based cohort of narcolepsy.

METHODS

A 2000-2014 community-based narcolepsy cohort was identified in Olmsted County, Minnesota. Records were reviewed by a certified sleep specialist for accuracy of diagnosis, and comorbidities were extracted and analyzed. Comorbidities in narcolepsy subjects, both at diagnosis and upon follow-up, were compared with those in unaffected and age- and sex-matched cohort using conditional logistic regression.

RESULTS

At diagnosis, there was increased association of narcolepsy with anxiety (OR 4.56, 95% CI 1.99-10.44), thyroid disease (3.07, 1.19-7.90), hypertension (2.69, 1.22-5.93), and hyperlipidemia (2.49, 1.05-5.92). At the end of the prolonged observation period of 9.9 years (SD 7.27 years), there was increased association of narcolepsy with peripheral neuropathy (11.21, 1.16-108.11), non-migrainous headache (6.00, 1.73-20.83), glucose intolerance (2.39, 1.05-5.45), and automobile-related trauma (2.43, 1.08-5.45). Persistently increased both at diagnosis and after a prolonged observation period were associations of narcolepsy with obstructive sleep apnea (OSA) (69.25, 9.26-517.99 decreasing to 13.55, 5.08-36.14), chronic low back pain (5.46, 2.46-12.11 to 2.58, 1.39-4.77), depression (4.88, 2.45-9.73 to 3.79, 2.12-6.79), psychiatric disorders in general (4.73, 2.49-9.01 to 3.40, 1.94-5.98), endocrinopathies (4.15, 1.81-9.56 to 2.45, 1.33-4.49), and obesity (2.27, 1.13-4.56 to 2.07, 1.15-3.7).

CONCLUSIONS

In this community-based study of narcolepsy comorbidities, both at diagnosis and after prolonged follow-up, persistent comorbidities were revealed, including OSA, chronic low back pain, psychiatric disorders in general, endocrinopathies, and obesity. The comprehensive management of narcolepsy requires monitoring for and managing these important associated health conditions.

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.

Managing Sleep Disorders during Pregnancy

Sleep disturbances and disorders are common during pregnancy, and they can be risk factors for a number of serious pregnancy-related sleep disorders. These include postpartum depression, pregnancy-induced hypertension, gestational diabetes, and intrauterine growth retardation. In addition, certain chronic sleep disorders, such as narcolepsy, are quite challenging to manage in the context of pregnancy and during lactation, particularly with medications that can be teratogenic. This review discusses 4 common sleep disorders and their impacts on pregnancy, and suggests ways to deal with these disorders that improves maternal and fetal outcomes safely. The review discusses diagnosis and treatment of obstructive sleep apnea, restless legs syndrome, insomnia, and narcolepsy in pregnancy.

Frequencies and Associations of Narcolepsy-Related Symptoms: A Cross-Sectional Study

OBJECTIVES

Narcolepsy is a disabling disease with a delayed diagnosis. At least 3 years before the disorder identification, several comorbidities can be observed in patients with narcolepsy. The early recognition of narcolepsy symptoms may improve long-term prognosis of the patients. Thus, we aimed to investigate the prevalence of the symptoms associated with narcolepsy and its social and psychological association in a sample of Sao Paulo city inhabitants.

METHODS

We performed a cross-sectional evaluation with 1,008 individuals from the Sao Paulo Epidemiologic Sleep Study (EPISONO). Excessive daytime sleepiness (EDS) was assessed by the Epworth Sleepiness Scale. Volunteers were also asked about the occurrence of cataplectic-like, hypnagogic or hypnopompic hallucinations, and sleep paralysis symptoms. The participants underwent a full-night polysomnography and completed questionnaires about psychological, demographic, and quality of life parameters.

RESULTS

We observed a prevalence of 39.2% of EDS, 15.0% of cataplectic-like symptom, 9.2% of hypnagogic or hypnopompic hallucinations, and 14.9% of sleep paralysis in Sao Paulo city inhabitants. A frequency of 6.9% was observed when EDS and cataplectic-like symptoms were grouped. The other associations were EDS + hallucinations (4.7%) and EDS + sleep paralysis (7.5%). Symptomatic participants were predominantly women and younger compared with patients without any narcolepsy symptom (n = 451). Narcolepsy symptomatology was also associated with a poor quality of life and symptoms of depression, anxiety, and fatigue.

CONCLUSIONS

Narcolepsy-related symptoms are associated with poor quality of life and worse psychological parameters.

Pharmacological treatment of sleep disorders and its relationship with neuroplasticity

Sleep and wakefulness are regulated by complex brain circuits located in the brain stem, thalamus, subthalamus, hypothalamus, basal forebrain, and cerebral cortex. Wakefulness and NREM and REM sleep are modulated by the interactions between neurotransmitters that promote arousal and neurotransmitters that promote sleep. Various lines of evidence suggest that sleep disorders may negatively affect neuronal plasticity and cognitive function. Pharmacological treatments may alleviate these effects but may also have adverse side effects by themselves. This chapter discusses the relationship between sleep disorders, pharmacological treatments, and brain plasticity, including the treatment of insomnia, hypersomnias such as narcolepsy, restless legs syndrome (RLS), obstructive sleep apnea (OSA), and parasomnias.

Polysomnographic and actigraphic characteristics of patients with H1N1-vaccine-related and sporadic narcolepsy

OBJECTIVE

After the pandemic H1N1 influenza ASO3-adjuvanted vaccine, Pandemrix©, was used in late 2009 and early 2010, the incidence of narcolepsy increased in many European countries. This incidence mainly increased in children and adolescents and, to a lesser degree, in adults.

PATIENTS/METHODS

125 unmedicated patients, aged 4 to 61 years, were included in this case-series study. Of these, 69 were diagnosed to have an H1N1-vaccine-related narcolepsy and 57 had sporadic narcolepsy. Most of these patients had: an actigraphy recording of 1-2 weeks, polysomnography, a Multiple Sleep Latency Test (MSLT), and cerebrospinal fluid hypocretin-1 concentration analysis.

RESULTS

Patients with H1N1-vaccine-related narcolepsy had shorter diagnostic delays, lower periodic leg movement index during sleep, earlier sleep-wake rhythm, and were younger in age at diagnosis, compared with sporadic cases. They also had shorter sleep latency and more sleep onset REM periods in MSLT, but these results were strongly age-dependent. Actigraphy showed quantitatively less sleep and more sleep fragmentation than polysomnography.

CONCLUSION

Regarding polysomnographic and actigraphic characteristics, there were no dramatic deviations between H1N1-vaccine-related and sporadic narcolepsy. Circadian rhythms indicated some interesting new findings with respect to the H1N1-vaccine-related disease. An actigraphy recording of 1-2 weeks is useful when studying the nocturnal aspects of narcolepsy and sleep-wake rhythms of narcoleptic patients.