Current Understanding of Narcolepsy 1 and its Comorbidities: What Clinicians Need to Know

Oveporexton, an Oral Orexin Receptor 2-Selective Agonist, in Narcolepsy Type 1

BACKGROUND

Narcolepsy type 1 is a disorder of hypersomnolence caused by a loss of orexin neurons, which results in low orexin levels in the brain.

METHODS

In this phase 2, randomized, placebo-controlled trial, participants with narcolepsy type 1 received once- or twice-daily oveporexton (TAK-861), an oral orexin receptor 2-selective agonist, or placebo. The primary end point was the mean change from baseline to week 8 in average sleep latency (the time it takes to fall asleep) on the Maintenance of Wakefulness Test (MWT) (range, 0 to 40 minutes; normal, ≥20). Secondary end points included the change from baseline to week 8 in the Epworth Sleepiness Scale (ESS) total score (range, 0 to 24; normal, ≤10), the weekly cataplexy rate at week 8, and the occurrence of adverse events.

RESULTS

A total of 90 participants received oveporexton (0.5 mg twice daily, 23 participants; 2 mg twice daily, 21 participants; 2 mg followed by 5 mg daily, 23 participants; and 7 mg once daily, 23 participants), and 22 received placebo. The mean changes from baseline to week 8 in average sleep latency on the MWT were 12.5, 23.5, 25.4, 15.0, and -1.2 minutes, respectively (adjusted P≤0.001 for all comparisons vs. placebo). The mean changes in the ESS total score at week 8 were -8.9, -13.8, -12.8, -11.3, and -2.5, respectively (adjusted P≤0.004 for all comparisons vs. placebo). The weekly incidence of cataplexy at week 8 was 4.24, 3.14, 2.48, 5.89, and 8.76, respectively (adjusted P<0.05 for 2 mg twice daily and 2 mg followed by 5 mg daily vs. placebo). The most common adverse events associated with oveporexton were insomnia (in 48% of the participants; most cases resolved within 1 week), urinary urgency (in 33%), and urinary frequency (in 32%), without any hepatotoxic effects.

CONCLUSIONS

In this phase 2 trial involving participants with narcolepsy type 1, oveporexton significantly improved measures of wakefulness, sleepiness, and cataplexy over a period of 8 weeks. (Funded by Takeda Development Center Americas; TAK-861-2001 ClinicalTrials.gov number, NCT05687903.).

Sodium Oxybate: Practical Considerations and Patient Perspectives

Narcolepsy is a rare, chronic sleep disorder with significant impacts on the quality of life of people affected by the disorder. People with narcolepsy (PWN) are a diverse patient population with evolving symptoms, comorbidities, and perspectives. As PWN have varying needs, clinicians should consider a more personalized approach to therapy, including active participation of PWN in their care and shared decision-making between patient and clinician to achieve optimal outcomes. In this review, we discuss the various characteristics and challenges of PWN, present illustrative clinical case scenarios of PWN, provide clinicians with a proposed framework to best address therapy for PWN, and demystify concerns with sodium oxybate.

Increased neutrophil-to-lymphocyte ratio as a possible marker to detect neuroinflammation in patients with narcolepsy type 1

STUDY OBJECTIVES

Narcolepsy type 1 (NT1) is an autoimmune disease caused by the selective immune attack against orexin-producing neurons. However, the pathophysiology of narcolepsy type 2 (NT2) and idiopathic hypersomnia (IH) remains controversial. The neutrophil-to-lymphocyte ratio (NLR) is an easily calculated parameter from the white blood cell count, which has already been extensively used as an inflammatory marker in immunological disorders. In this study, we examined the white blood cell count of patients with NT1, NT2, and IH compared to healthy controls (HC) and evaluated the NLR to test the possibility of identifying an easy biofluid marker for detecting inflammation and distinguishing patients from HC.

METHODS

White blood cell count and NLR were compared between 28 patients with NT1, 17 with NT2, 11 with IH, and 21 sex/age-matched HC. These parameters were correlated with cerebrospinal fluid levels of orexin-A, the cerebrospinal fluid/serum albumin ratio (as a marker of blood-brain barrier integrity), and polysomnographic parameters.

RESULTS

Patients with NT1 (NLR 2.01 ± 0.44) showed significantly higher NLR than those with NT2 (NLR 1.59 ± 0.53) or IH (NLR 1.48 ± 0.37) and HC (NLR 1.48 ± 0.43). Correlation analysis did not document significant associations between NLR and the other biological markers in each group of patients. The receiver operating characteristic curve analysis detected an optimal cutoff value to discriminate patients with NT1 from those with NT2, IH, and HC for values of NLR ≥ 1.60, 1.62, and 1.59, respectively.

CONCLUSIONS

Patients with NT1 showed a higher NLR than those with NT2, IH, and HC, possibly reflecting lymphocyte migration within the central nervous system, supporting the hypothesis of a neuroinflammatory attack of lymphocytes against orexin-producing neurons. Considering its sensitivity, this easily obtainable biofluid marker could help to screen patients with NT1.

CITATION

Conti M, Cirillo F, Maio S, et al. Increased neutrophil-to-lymphocyte ratio as a possible marker to detect neuroinflammation in patients with narcolepsy type 1. J Clin Sleep Med. 2025;21(1):101-107.

Connecting clinicians and patients: The language of narcolepsy

Narcolepsy is a rare lifelong sleep disorder characterized by excessive daytime sleepiness with variable expression of cataplexy, sleep paralysis, sleep-related hallucinations and disrupted nocturnal sleep. Affected individuals also experience additional impairing symptoms, including (but not limited to) difficulties with attention, memory and concentration, brain fog, mood instability and fatigue, with a substantial impact on everyday life. Diagnostic delays of up to 10 years are common, primarily due to the substantial heterogeneity in clinical presentation of narcolepsy symptoms and presence of significant comorbidities. The disconnect in language used by clinicians and patients could be a factor contributing to diagnostic delays, but it has not been much studied. We followed a two-part approach to investigate the impact of this possible mismatch in language use. Firstly, a comprehensive literature search was conducted to identify publications reporting discrepancies in language relating to narcolepsy symptoms used by clinicians and patients. As a gap in the literature was anticipated, we supplemented the search results with practical strategies based on our clinical experience to facilitate dialog between clinicians and people living with narcolepsy, as well as proposing future research ideas. The findings of the narrative review, complemented by expert clinical opinion, are intended to help clinicians recognize narcolepsy symptoms and to refer patients with suspected narcolepsy, when appropriate. Although it is unknown to what extent a disconnect in language may contribute to diagnostic delays, we hope that better recognition of the varied clinical presentations of narcolepsy will lead to timelier diagnosis and help improve patient outcomes.

Psychiatric comorbidity in Danish patients with narcolepsy type 1, narcolepsy type 2, and idiopathic hypersomnia: a case-control study

Study Objectives

To examine the difference in psychiatric comorbidity of Danish patients with Narcolepsy type 1 (NT1), Narcolepsy type 2 (NT2), and idiopathic hypersomnia (IH).

Methods

Polysomnography (PSG), Multiple Sleep Latency Test (MSLT), and lumbar puncture were performed on 505 patients referred to a sleep clinic for diagnostic evaluation of hypersomnia. Diagnosis, clinical characteristics, electrophysiologic data, and cerebrospinal fluid hypocretin-1 (Csf-Hcrt-1) results were retrieved. Subsequently, the patients were identified in the Danish national health registers to collect information on psychiatric diagnoses and psychotropic medication use 10 years before the sleep disorder diagnosis. The prevalence of psychiatric comorbidities per hypersomnia group was compared to a 1:4 general population control group matched on age, gender, and educational level.

Results

A diagnosis of NT2 and IH was significantly associated with total psychiatric comorbidity compared to the matched controls but not NT1 (NT1: OR = 1.5; NT2: OR = 6.1; IH: OR = 5.2). NT1 was not significantly associated with any psychiatric disorder. NT2 was significantly associated with schizophrenia spectrum disorders (OR = 8.5), mood disorders (OR = 6.7), neurotic disorders (OR = 3.8), personality disorders (OR = 3.1), and behavioral and emotional disorders (OR = 4.3). IH was significantly associated with schizophrenia spectrum disorders (OR = 3.3), mood disorders (OR = 5.9), neurotic disorders (OR = 3.0), and behavioral and emotional disorders (OR = 4.0).

Conclusions

NT2 and IH had a close relationship to psychiatric disorders before diagnosis of their sleep disorder, while NT1 did not. This supports previous studies finding higher rates of psychiatric illness in patients with hypersomnia; however, it highlights the similarity between NT2 and IH. We believe this link to psychiatric disorders could play a role in the pathophysiology. Future studies evaluating the relation between hypersomnias of central origin and psychiatric diseases should include hypersomnia subclassifications to further the understanding of the differences in these disorders.

Burden of narcolepsy in Japan: A health claims database study evaluating direct medical costs and comorbidities

OBJECTIVE

This study aimed to determine the burden of narcolepsy in terms of direct medical costs and comorbidities and compare it with the respective burden of schizophrenia, epilepsy, and ulcerative colitis as controls.

METHODS

Patients diagnosed with narcolepsy (at least once based on the International Statistical Classification of Diseases and Related Health Problems, 10th Revision, code G47.4) between April 2017 and March 2022 were identified on the health insurance claims database compiled by JMDC Inc. Patients with schizophrenia (F20), epilepsy (G40), and ulcerative colitis (K51) were matched as controls. Direct medical costs (including inpatient, outpatient, and medication costs) and comorbidities were analyzed.

RESULTS

We identified 4,594 patients with narcolepsy (≥18 years), 18,376 with schizophrenia, 18,376 with epilepsy, and 4,594 with ulcerative colitis. The total annual direct medical cost per person with narcolepsy was 349,188 JPY. The cost for narcolepsy was less than that for schizophrenia, epilepsy, and ulcerative colitis. Several comorbidities, such as sleep apnea, attention deficit hyperactivity disorder (ADHD), and obesity were more prevalent in the narcolepsy group.

CONCLUSIONS

The total direct cost for narcolepsy was approximately three times higher than the national medical expense for people aged 15-44 years (122,000 JPY in 2020), but lower than the total cost for all control diseases. The patients with narcolepsy were also likely to have comorbidities that affected their burden. These findings can contribute to future discussions on medical expense assistance programs for patients with narcolepsy.

Exploring the Literature on Narcolepsy: Insights into the Sleep Disorder That Strikes during the Day

Narcolepsy is a chronic sleep disorder that disrupts the regulation of a person's sleep-wake cycle, leading to significant challenges in daily functioning. It is characterized by excessive daytime sleepiness, sudden muscle weakness (cataplexy), sleep paralysis, and vivid hypnagogic hallucinations. A literature search was conducted in different databases to identify relevant studies on various aspects of narcolepsy. The main search terms included "narcolepsy", "excessive daytime sleepiness", "cataplexy", and related terms. The search was limited to studies published until May 2023. This literature review aims to provide an overview of narcolepsy, encompassing its causes, diagnosis, treatment options, impact on individuals' lives, prevalence, and recommendations for future research. The review reveals several important findings regarding narcolepsy: 1. the classification of narcolepsy-type 1 narcolepsy, previously known as narcolepsy with cataplexy, and type 2 narcolepsy, also referred to as narcolepsy without cataplexy; 2. the genetic component of narcolepsy and the complex nature of the disorder, which is characterized by excessive daytime sleepiness, disrupted sleep patterns, and potential impacts on daily life activities and social functioning; and 3. the important implications for clinical practice in the management of narcolepsy. Healthcare professionals should be aware of the different types of narcolepsies and their associated symptoms, as this can aid in accurate diagnosis and treatment planning. The review underscores the need for a multidisciplinary approach to narcolepsy management, involving specialists in sleep medicine, neurology, psychiatry, and psychology. Clinicians should consider the impact of narcolepsy on a person's daily life, including their ability to work, study, and participate in social activities, and provide appropriate support and interventions. There are several gaps in knowledge regarding narcolepsy. Future research should focus on further elucidating the genetic causes and epigenetic mechanisms of narcolepsy and exploring potential biomarkers for early detection and diagnosis. Long-term studies assessing the effectiveness of different treatment approaches, including pharmacological interventions and behavioral therapies, are needed. Additionally, there is a need for research on strategies to improve the overall well-being and quality of life of individuals living with narcolepsy, including the development of tailored support programs and interventions.

Understanding Sleep Regulation in Normal and Pathological Conditions, and Why It Matters

Sleep occupies a peculiar place in our lives and in science, being both eminently familiar and profoundly enigmatic. Historically, philosophers, scientists and artists questioned the meaning and purpose of sleep. If Shakespeare's verses from MacBeth depicting "Sleep that soothes away all our worries" and "relieves the weary laborer and heals hurt minds" perfectly epitomize the alleviating benefits of sleep, it is only during the last two decades that the growing understanding of the sophisticated sleep regulatory mechanisms allows us to glimpse putative biological functions of sleep. Sleep control brings into play various brain-wide processes occurring at the molecular, cellular, circuit, and system levels, some of them overlapping with a number of disease-signaling pathways. Pathogenic processes, including mood disorders (e.g., major depression) and neurodegenerative illnesses such Huntington's or Alzheimer's diseases, can therefore affect sleep-modulating networks which disrupt the sleep-wake architecture, whereas sleep disturbances may also trigger various brain disorders. In this review, we describe the mechanisms underlying sleep regulation and the main hypotheses drawn about its functions. Comprehending sleep physiological orchestration and functions could ultimately help deliver better treatments for people living with neurodegenerative diseases.