Gert Jan Lammers

A mutation in a case of early onset narcolepsy and a generalized absence of hypocretin peptides in human narcoleptic brains

We explored the role of hypocretins in human narcolepsy through histopathology of six narcolepsy brains and mutation screening of Hcrt, Hcrtr1 and Hcrtr2 in 74 patients of various human leukocyte antigen and family history status. One Hcrt mutation, impairing peptide trafficking and processing, was found in a single case with early onset narcolepsy. In situ hybridization of the perifornical area and peptide radioimmunoassays indicated global loss of hypocretins, without gliosis or signs of inflammation in all human cases examined. Although hypocretin loci do not contribute significantly to genetic predisposition, most cases of human narcolepsy are associated with a deficient hypocretin system.

EFNS guidelines on management of narcolepsy.

Management of narcolepsy with or without cataplexy relies on several classes of drugs, namely stimulants for excessive daytime sleepiness and irresistible episodes of sleep, antidepressants for cataplexy and hypnosedative drugs for disturbed nocturnal sleep. In addition, behavioral measures can be of notable value. Guidelines on the management of narcolepsy have already been published. However contemporary guidelines are necessary given the growing use of modafinil to treat excessive daytime sleepiness in Europe within the last 5–10 years, and the decreasing need for amphetamines and amphetamine‐like stimulants; the extensive use of new antidepressants in the treatment of cataplexy, apart from consistent randomized placebo‐controlled clinical trials; and the present re‐emergence of gamma‐hydroxybutyrate under the name sodium oxybate, as a treatment of all major symptoms of narcolepsy. A task force composed of the leading specialists of narcolepsy in Europe has been appointed. This task force conducted an extensive review of pharmacological and behavioral trials available in the literature. All trials were analyzed according to their class evidence. Recommendations concerning the treatment of each single symptom of narcolepsy as well as general recommendations were made. Modafinil is the first‐line pharmacological treatment of excessive daytime sleepiness and irresistible episodes of sleep in association with behavioral measures. However, based on several large randomized controlled trials showing the activity of sodium oxybate, not only on cataplexy but also on excessive daytime sleepiness and irresistible episodes of sleep, there is a growing practice in the USA to use it for the later indications. Given the availability of modafinil and methylphenidate, and the forseen registration of sodium oxybate for narcolepsy (including excessive daytime sleepiness, cataplexy, disturbed nocturnal sleep) in Europe, the place of other compounds will become fairly limited. Since its recent registration cataplexy sodium oxybate has now become the first‐line treatment of cataplexy. Second‐line treatments are antidepressants, either tricyclics or newer antidepressants, the later being increasingly used these past years despite few or no randomized placebo‐controlled clinical trials. As for disturbed nocturnal sleep the best option is still hypnotics until sodium oxybate is registered for narcolepsy. The treatments used for narcolepsy, either pharmacological or behavioral, are diverse. However the quality of the published clinical evidences supporting them varies widely and studies comparing the efficacy of different substances are lacking. Several treatments are used on an empirical basis, specially antidepressants for cataplexy, due to the fact that these medications are already used widely in depressed patients, leaving little motivation from the manufacturers to investigate efficacy in relatively rare indications. Others, in particular the more recently developed substances, such as modafinil or sodium oxybate, are evaluated in large randomized placebo‐controlled trials. Our objective was to reinforce the use of those drugs evaluated in randomized placebo‐controlled trials and to reach a consensus, as much as possible, on the use of other available medications.

The incidence of narcolepsy in Europe: Before, during, and after the influenza A(H1N1)pdm09 pandemic and vaccination campaigns

BACKGROUND In August 2010 reports of a possible association between exposure to AS03 adjuvanted pandemic A(H1N1)pdm09 vaccine and occurrence of narcolepsy in children and adolescents emerged in Sweden and Finland. In response to this signal, the background rates of narcolepsy in Europe were assessed to rapidly provide information for signal verification. METHODS We used a dynamic retrospective cohort study to assess the narcolepsy diagnosis rates during the period 2000-2010 using large linked automated health care databases in six countries: Denmark, Finland, Italy, the Netherlands, Sweden and the United Kingdom. RESULTS Overall, 2608 narcolepsy cases were identified in almost 280 million person years (PY) of follow up. The pooled incidence rate was 0.93 (95% CI: 0. 90-0.97) per 100,000 PY. There were peaks between 15 and 30 year of age (women>men) and around 60 years of age. In the age group 5-19 years olds rates were increased after the start of pandemic vaccination compared to the period before the start of campaigns, with rate ratios (RR) of 1.9 (95% CI: 1.1-3.1) in Denmark, 6.4 (95% CI: 4.2-9.7) in Finland and 7.5 (95% CI: 5.2-10.7) in Sweden. Cases verification in the Netherlands had a significant effect on the pattern of incidence over time. CONCLUSIONS The results of this incidence study provided useful information for signal verification on a population level. The safety signal of increased narcolepsy diagnoses following the start of the pandemic vaccination campaign as observed in Sweden and Finland could be observed with this approach. An increase in narcolepsy diagnoses was not observed in other countries, where vaccination coverage was low in the affected age group, or did not follow influenza A(H1N1)pdm09 vaccination. Patient level analyses in these countries are being conducted to verify the signal in more detail.

Transesophageal Echocardiography Is Superior to Transthoracic Echocardiography in Management of Patients of Any Age With Transient Ischemic Attack or Stroke

Background and Purpose— The merits of transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) in the management of transient ischemic attack (TIA) and stroke patients remains matter of debate. Methods— Two hundred and thirty-one consecutive patients with a recent TIA or stroke for which no definite cause and indication for anticoagulation was assessed after standardized work-up underwent TTE and TEE. Echocardiographic findings were categorized into minor and major risk factors. Results— A potential cardiac source of embolism was detected in 55% (127/ 231) of the patients by echocardiography, in 39% (90/231) only identified on TEE. Major risk factors, with an absolute indication for oral anticoagulation, were detected in 20% (46/231) of the patients, in 16% (38/231) of all patients identified on TEE only. A thrombus in the left atrial appendage was the most common major risk factor (38 patients, 16%). The presence of major risk factors was independent of age (&khgr;2=1.48; P=0.224). The difference in proportions of cardiac sources detected in favor of TEE was highly significant in both patients ≤45 years of age (10/39, P=0.002) and in those >45 years of age (80/192; P<0.004). Conclusions— TEE proved superior to TTE for identification of a cardiac embolic source in patients with TIA or stroke without pre-existent indication or contraindication for anticoagulation. In patients with normal TTE, a cardiac source of embolism was detected by TEE in ≈40% of patients, independent of age. More than 1 of 8 patients of any age with normal TTE revealed a major cardiac risk factor on TEE, in whom anticoagulation is warranted.

Pitolisant versus placebo or modafinil in patients with narcolepsy: A double-blind, randomised trial

BACKGROUND Narcolepsy is characterised by excessive daytime sleepiness (EDS) and cataplexy. Histamine neurons are crucial to maintain wakefulness. We assessed the safety and efficacy of pitolisant (previously called BF2.649), a selective histamine H3 receptor inverse agonist that activates these neurons, in patients with narcolepsy. METHODS For this double-blind, randomised, parallel-group controlled trial, we recruited patients with narcolepsy from 32 sleep disorder centres in five European countries. Patients were eligible if they were aged 18 years or older, had not taken psychostimulants for at least 14 days, and had EDS (defined as an Epworth Sleepiness Scale [ESS] score of at least 14). Using a computer-generated randomisation sequence, we randomly allocated patients to receive pitolisant, modafinil, or placebo (1:1:1). Treatment lasted 8 weeks: 3 weeks of flexible dosing according to investigators judgment (10 mg, 20 mg, or 40 mg a day of pitolisant; 100 mg, 200 mg or 400 mg a day of modafinil) followed by 5 weeks of stable dosing. Patients took four tablets a day in a double-dummy design to ensure masking. For the primary analysis, assessed in the intention-to-treat population, we assessed the superiority of pitolisant versus placebo, and the non-inferiority of pitolisant versus modafinil. This trial is registered with ClinicalTrials.gov, number NCT01067222. FINDINGS Between May 26, 2009, and June 30, 2010, we screened 110 patients, 95 of whom were eligible and randomly assigned to treatment: 30 to placebo, 32 to pitolisant, and 33 to modafinil. Over the 8-week treatment period, mean ESS score reductions were -3·4 (SD 4·2) in the placebo group, -5·8 (6·2) in the pitolisant group, and -6·9 (6·2) in the modafinil group. Our primary analysis of between-group differences in mean ESS score at endpoint (adjusted for baseline) showed pitolisant to be superior to placebo (difference -3·0, 95% CI -5·6 to -0·4; p=0·024), but not non-inferior to modafinil (difference 0·12, 95% CI -2·5 to 2·7; p=0·250). We recorded 22 adverse events with pitolisant, 26 with modafinil, and ten with placebo. Six severe adverse events were treatment-related: one with pitolisant (abdominal discomfort) and five with modafinil (abdominal pain, abnormal behaviour, amphetamine-like withdrawal symptoms, lymphoadenopathy, and inner ear disorders). INTERPRETATION Pitolisant at doses up to 40 mg was efficacious on EDS compared with placebo and well tolerated compared with modafinil. If these findings are substantiated in further studies, pitolisant could offer a new treatment option for patients with narcolepsy. FUNDING Bioprojet, France.

Genome-wide association study identifies new HLA class II haplotypes strongly protective against narcolepsy

Narcolepsy is a rare sleep disorder with the strongest human leukocyte antigen (HLA) association ever reported. Since the associated HLA-DRB1*1501-DQB1*0602 haplotype is common in the general population (15–25%), it has been suggested that it is almost necessary but not sufficient for developing narcolepsy. To further define the genetic basis of narcolepsy risk, we performed a genome-wide association study (GWAS) in 562 European individuals with narcolepsy (cases) and 702 ethnically matched controls, with independent replication in 370 cases and 495 controls, all heterozygous for DRB1*1501-DQB1*0602. We found association with a protective variant near HLA-DQA2 (rs2858884; P < 3 × 10−8). Further analysis revealed that rs2858884 is strongly linked to DRB1*03-DQB1*02 (P < 4 × 10−43) and DRB1*1301-DQB1*0603 (P < 3 × 10−7). Cases almost never carried a trans DRB1*1301-DQB1*0603 haplotype (odds ratio = 0.02; P < 6 × 10−14). This unexpected protective HLA haplotype suggests a virtually causal involvement of the HLA region in narcolepsy susceptibility.

ImmunoChip Study Implicates Antigen Presentation to T Cells in Narcolepsy

Recent advances in the identification of susceptibility genes and environmental exposures provide broad support for a post-infectious autoimmune basis for narcolepsy/hypocretin (orexin) deficiency. We genotyped loci associated with other autoimmune and inflammatory diseases in 1,886 individuals with hypocretin-deficient narcolepsy and 10,421 controls, all of European ancestry, using a custom genotyping array (ImmunoChip). Three loci located outside the Human Leukocyte Antigen (HLA) region on chromosome 6 were significantly associated with disease risk. In addition to a strong signal in the T cell receptor alpha (TRA@), variants in two additional narcolepsy loci, Cathepsin H (CTSH) and Tumor necrosis factor (ligand) superfamily member 4 (TNFSF4, also called OX40L), attained genome-wide significance. These findings underline the importance of antigen presentation by HLA Class II to T cells in the pathophysiology of this autoimmune disease.

Hypocretin (orexin) loss in Alzheimer's disease.

Sleep disturbances in Alzheimers disease (AD) patients are associated with the severity of dementia and are often the primary reason for institutionalization. These sleep problems partly resemble core symptoms of narcolepsy, a sleep disorder caused by a general loss of the neurotransmitter hypocretin. AD is a neurodegenerative disorder targeting different brain areas and types of neurons. In this study, we assessed whether the neurodegenerative process of AD also affects hypothalamic hypocretin/orexin neurons. The total number of hypocretin-1 immunoreactive neurons was quantified in postmortem hypothalami of AD patients (n = 10) and matched controls (n = 10). In addition, the hypocretin-1 concentration was measured in postmortem ventricular cerebrospinal fluid of 24 AD patients and 25 controls (including the patients and controls in which the hypothalamic cell counts were performed). The number of hypocretin-1 immunoreactive neurons was significantly decreased by 40% in AD patients (median [25th-75th percentiles]); AD 12,935 neurons (9972-19,051); controls 21,002 neurons (16,439-25,765); p = 0.049). Lower cerebrospinal fluid (CSF) hypocretin-1 levels were found in AD patients compared with controls (AD: 275 pg/mL [197-317]; controls: 320 pg/mL [262-363]; p = 0.038). Two AD patients with documented excessive daytime sleepiness showed the lowest CSF hypocretin-1 concentrations (55 pg/mL and 76 pg/mL). We conclude that the hypocretin system is affected in advanced AD. This is reflected in a 40% decreased cell number, and 14% lower CSF hypocretin-1 levels.

Narcolepsy: immunological aspects.

Narcolepsy with cataplexy is a debilitating sleep disorder with an estimated prevalence of about 0.05%. Narcolepsy is caused by a selective loss of hypocretin (orexin) producing neurons in the perifornical hypothalamus. Based on the very strong association with the HLA subtype DQB1*0602, it is currently hypothesized narcolepsy is caused by an autoimmune-mediated process directed at the hypocretin neurons. So far however, studies focusing on general markers of (auto)immune activation, as well as humoral immunity against the hypocretin system have not yielded consistent results supporting this hypothesis.

DQB1 locus alone explains most of the risk and protection in narcolepsy with cataplexy in Europe

STUDY OBJECTIVE Prior research has identified five common genetic variants associated with narcolepsy with cataplexy in Caucasian patients. To replicate and/or extend these findings, we have tested HLA-DQB1, the previously identified 5 variants, and 10 other potential variants in a large European sample of narcolepsy with cataplexy subjects. DESIGN Retrospective case-control study. SETTING A recent study showed that over 76% of significant genome-wide association variants lie within DNase I hypersensitive sites (DHSs). From our previous GWAS, we identified 30 single nucleotide polymorphisms (SNPs) with P < 10(-4) mapping to DHSs. Ten SNPs tagging these sites, HLADQB1, and all previously reported SNPs significantly associated with narcolepsy were tested for replication. PATIENTS AND PARTICIPANTS For GWAS, 1,261 narcolepsy patients and 1,422 HLA-DQB1*06:02-matched controls were included. For HLA study, 1,218 patients and 3,541 controls were included. MEASUREMENTS AND RESULTS None of the top variants within DHSs were replicated. Out of the five previously reported SNPs, only rs2858884 within the HLA region (P < 2x10(-9)) and rs1154155 within the TRA locus (P < 2x10(-8)) replicated. DQB1 typing confirmed that DQB1*06:02 confers an extraordinary risk (odds ratio 251). Four protective alleles (DQB1*06:03, odds ratio 0.17, DQB1*05:01, odds ratio 0.56, DQB1*06:09 odds ratio 0.21, DQB1*02 odds ratio 0.76) were also identified. CONCLUSION An overwhelming portion of genetic risk for narcolepsy with cataplexy is found at DQB1 locus. Since DQB1*06:02 positive subjects are at 251-fold increase in risk for narcolepsy, and all recent cases of narcolepsy after H1N1 vaccination are positive for this allele, DQB1 genotyping may be relevant to public health policy.