Measurement of Narcolepsy Symptoms in School-Aged Children and Adolescents: The Pediatric Narcolepsy Severity Scale.

OBJECTIVE: We validated the Narcolepsy Severity Scale (NSS) in adults with narcolepsy type 1 (NT1) to quantify the severity, frequency, and consequences of the 5 key narcolepsy symptoms over the last month, and we now developed the Pediatric NSS (NSS-P); thus, the aims of this study were to assess NSS-P psychometric properties, validity, and reliability, and to evaluate its responsiveness to treatment in a well-characterized sample of children and adolescents with NT1. METHODS: The NSS was reformulated for children, and the item about driving was removed. The total score of the 14-item NSS-P ranges from 0 to 54, and higher scores reflect more severe disease. Children and adolescents (n = 209, 6-17 years of age) with NT1 diagnosed in 2 Reference Centers for Narcolepsy in France were consecutively asked to fill in the NSS-P. The scale was fully and correctly completed by 160 (10-18 years of age, 68 untreated). Moreover, 65 participants completed it twice (33 before/during treatment, and 32 under the same treatment). The NSS-P psychometric properties, score changes before/during treatment, and convergent validity with other clinical parameters were assessed. RESULTS: The NSS-P showed adequate psychometric properties with significant item-total score correlations. Factor analysis indicated a 4-factor solution with good reliability. The NSS-P score was lower in treated than untreated patients with a mean difference of 3.71 ± 1.45, with a minimum clinically important difference between untreated and treated patients in the longitudinal sample estimated at 4 points. Four severity levels were defined (mild, moderate, severe, very severe) with between-group differences related to treatment. The NSS-P total score was associated with self-reported sleepiness, insomnia, and depressive symptoms. Its temporal stability was satisfactory. DISCUSSION: We validated a brief instrument to assess NT1 symptom frequency, severity, and consequences in ≥10-year-old children and adolescents with 4 clinically relevant severity score ranges. This scale constitutes a relevant tool to improve and provide guidance for NT1 management in pediatric populations. The ease of administration, its good psychometric properties, and its sensitivity to detect symptom changes after treatment ensure future use of the NSS-P in clinical and research settings.

Depression and suicidal thoughts in untreated and treated narcolepsy: Systematic analysis.

OBJECTIVES: To assess the frequency and determinants of depressive symptoms and suicidal thoughts in adults with narcolepsy type 1 (NT1) and controls, as well as the changes after NT1 management and the risk factors of major depressive episode (MDE) and suicide risk (SR) in NT1. METHODS: Two hundred ninety-seven patients with NT1 (age 39 ± 17 years, 172 drug-free) and 346 controls (age 38 ± 16 years) underwent a comprehensive clinical evaluation including the Beck Depression Inventory-II (BDI-II) self-questionnaire, with 1 item on suicidal thoughts. One hundred one drug-free patients with NT1 completed the BDI-II a second time during treatment. In 162 patients with NT1, the face-to-face Mini International Neuropsychiatric Interview was performed to formally diagnose current MDE and SR. RESULTS: BDI-II total scores were higher in patients with NT1 than controls and in untreated than treated patients. Patients with moderate to severe BDI-II scores (24.9%) were less educated, were more frequently obese, and had more severe narcolepsy symptoms, more autonomic dysfunctions, and poorer quality of life. Results were unchanged in models adjusted for NT1 medication intake. Suicidal thoughts were more frequent in untreated patients than controls (22.7% vs 12.4%). Patients with suicidal thoughts were more likely to be men and to have more severe narcolepsy symptoms. After narcolepsy management, BDI-II total score and suicidal thoughts decreased. MDE was diagnosed in 29 (18.1%) and SR in 27 (16.9%) patients. CONCLUSIONS: Depression, depressive symptoms, suicidal thoughts, and SR were frequent in patients with NT1, especially those without treatment, and were associated with NT1 severity. Depressive symptoms and suicidal thoughts improved after NT1 management.

Reduced brain amyloid burden in elderly patients with narcolepsy type 1.

OBJECTIVE: To determine whether brain amyloid burden in elderly patients with narcolepsy type 1 (NT1) is lower than in controls, and to assess in patients with NT1 the relationships between amyloid burden, cerebral spinal fluid (CSF) markers of Alzheimer disease (AD), CSF orexin-A, and cognitive profile. METHODS: Cognitive and 18 F-florbetapir positron emission tomography (PET) data were compared in patients with NT1 aged ≥ 65 years (n = 23) and in age- and sex-matched controls free of clinical dementia selected from the Alzheimer's Disease Neuroimaging Initiative (ADNI; n = 69) and the Multi-Domain Intervention Alzheimer's Prevention Trial (MAPT-18F AV45-PET; n = 23) cohorts. The standardized uptake values (SUVs) of the cortical retention index for 6 regions of interest were computed and averaged to create a mean SUV ratio normalized to 3 subcortical reference regions (cerebellum, pons, and a composite region). A cortical/cerebellum SUV ratio ≥ 1.17 defined positive PET amyloid. RESULTS: Lower cortical amyloid burden was observed in the NT1 than in the ADNI and MAPT-AV45 groups (mean cortical/cerebellum SUV ratios = 0.95 ± 0.15, 1.11 ± 0.18 [p < 0.0001], and 1.14 ± 0.17 [p = 0.0005], respectively). Similar results were obtained with all subcortical reference regions and for all cortical regions of interest, except cingulum. Only 1 patient with NT1 (4.4%) had positive PET amyloid compared with 27.5% in the ADNI and 30.4% in the MAPT-AV45 group. In the NT1 group, cortical or regional amyloid load was not associated with CSF orexin-A, CSF AD biomarkers, or neuropsychological profile. INTERPRETATION: Lower brain amyloid burden, assessed by 18 F-florbetapir PET, in patients with NT1 suggests delayed appearance of amyloid plaques. ANN NEUROL 2019;85:74-83.

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.

Effect of psychostimulants on blood pressure profile and endothelial function in narcolepsy.

OBJECTIVE: To assess the effect of psychostimulant treatments on the 24-hour blood pressure (BP) profile of patients with narcolepsy type 1 (NT1). METHODS: Heart rate (HR) and BP were monitored for 24 hours and morning endothelial function was evaluated in 160 consecutive patients with NT1: 68 untreated (41 male, median age 34.9 years), 54 treated (32 male, median age 40.9 years), and 38 evaluated twice (21 male, median age 32 years), before and during treatment. RESULTS: Patients treated for NT1 showed higher 24-hour, daytime, and nighttime diastolic BP and HR values compared with the untreated group. Similarly, HR as well as 24-hour and daytime systolic BP were increased during treatment in the group evaluated twice. The combination of stimulant and anticataplectic drugs showed a synergistic effect on BP, without differences among stimulant categories. Based on 24-hour BP monitoring, hypertension was diagnosed in 58% of treated patients and in 40.6% of untreated patients. After adjustments for age, sex, and body mass index, the percentage of REM sleep remained associated with 24-hour hypertension in untreated and treated patients. Endothelial function was comparable in treated and untreated patients. CONCLUSIONS: The finding that patients with NT1 treated with psychostimulants have higher diastolic BP and HR than untreated patients suggests an increased long-term risk of cardiovascular diseases that requires careful follow-up and specific management.

Measurement of narcolepsy symptoms: The Narcolepsy Severity Scale.

OBJECTIVE: To validate the Narcolepsy Severity Scale (NSS), a brief clinical instrument to evaluate the severity and consequences of symptoms in patients with narcolepsy type 1 (NT1). METHODS: A 15-item scale to assess the frequency and severity of excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, sleep paralysis, and disrupted nighttime sleep was developed and validated by sleep experts with patients' feedback. Seventy untreated and 146 treated adult patients with NT1 were evaluated and completed the NSS in a single reference sleep center. The NSS psychometric properties, score changes with treatment, and convergent validity with other clinical parameters were assessed. RESULTS: The NSS showed good psychometric properties with significant item-total score correlations. The factor analysis indicated a 3-factor solution with good reliability, expressed by satisfactory Cronbach α values. The NSS total score temporal stability was good. Significant NSS score differences were observed between untreated and treated patients (dependent sample, 41 patients before and after sleep therapy; independent sample, 29 drug-free and 105 treated patients). Scores were lower in the treated populations (10-point difference between groups), without ceiling effect. Significant correlations were found among NSS total score and daytime sleepiness (Epworth Sleepiness Scale, Mean Sleep Latency Test), depressive symptoms, and health-related quality of life. CONCLUSIONS: The NSS can be considered a reliable and valid clinical tool for the quantification of narcolepsy symptoms to monitor and optimize narcolepsy management.

Car Crashes and Central Disorders of Hypersomnolence: A French Study.

BACKGROUND: Drowsiness compromises driving ability by reducing alertness and attentiveness, and delayed reaction times. Sleep-related car crashes account for a considerable proportion of accident at the wheel. Narcolepsy type 1 (NT1), narcolepsy type 2 (NT2) and idiopathic hypersomnia (IH) are rare central disorders of hypersomnolence, the most severe causes of sleepiness thus being potential dangerous conditions for both personal and public safety with increasing scientific, social, and political attention. Our main objective was to assess the frequency of recent car crashes in a large cohort of patients affected with well-defined central disorders of hypersomnolence versus subjects from the general population. METHODS: We performed a cross-sectional study in French reference centres for rare hypersomnia diseases and included 527 patients and 781 healthy subjects. All participants included needed to have a driving license, information available on potential accident events during the last 5 years, and on potential confounders; thus analyses were performed on 282 cases (71 IH, 82 NT2, 129 NT1) and 470 healthy subjects. RESULTS: Patients reported more frequently than healthy subjects the occurrence of recent car crashes (in the previous five years), a risk that was confirmed in both treated and untreated subjects at study inclusion (Untreated, OR = 2.21 95%CI = [1.30-3.76], Treated OR = 2.04 95%CI = [1.26-3.30]), as well as in all disease categories, and was modulated by subjective sleepiness level (Epworth scale and naps). Conversely, the risk of car accidents of patients treated for at least 5 years was not different to healthy subjects (OR = 1.23 95%CI = [0.56-2.69]). Main risk factors were analogous in patients and healthy subjects. CONCLUSION: Patients affected with central disorders of hypersomnolence had increased risk of recent car crashes compared to subjects from the general population, a finding potentially reversed by long-term treatment.