A series of 7 cases of patients with narcolepsy with hypocretin deficiency without the HLA DQB1*06:02 allele

STUDY OBJECTIVES

We report data collected from 2 reference European sleep centers on a series of patients with narcolepsy with hypocretin-1 deficiency and absence of the human leukocyte antigens (HLA) DQB1*06:02 allele.

METHODS

Clinical data, HLA DQ markers, and cerebrospinal fluid assessments were collected retrospectively from Caucasian patients with a diagnosis of narcolepsy type 1 with cerebrospinal fluid hypocretin-1 deficiency (< 110 pg/ml) and absence of the HLA DQB1*06:02 allele, with follow-up with at least 1 visit within the last 4 years, consecutively admitted to 2 European sleep centers (Lugano, Switzerland and Montpellier, France).

RESULTS

Seven patients (3 of 29 patients in Lugano and 4 of 328 in Montpellier) were diagnosed with narcolepsy with hypocretin-1 deficiency and absence of HLA DQB1*06:02 (ie, 2% of patients with narcolepsy type 1). Regarding the HLA-DQB1 genotyping, 4 cases were positive for HLA DQB1*03:01, 1 for DQB1*03:02, and 3 for DQB1*02:01. Three patients had atypical cataplexy and 1 had no cataplexy. Only 2 patients had both a mean sleep latency of less than 8 minutes and more than 2 sleep onset rapid eye movement periods on the Multiple Sleep Latency Test, indicative of a less severe condition.

CONCLUSIONS

Although rare, this series of 7 cases confirms that hypocretin-deficient narcolepsy should not be excluded in the absence of HLA DQB1*06:02, especially if patients are carriers of other high-risk HLA-DQB1 alleles (DQB1*03:01, *03:02, *02:01). These data support the hypothesis that narcolepsy type 1 is a wider disease spectrum linked to the loss of hypocretin peptide.

CITATION

Miano S, Barateau L, De Pieri M, et al. A series of 7 cases of patients with narcolepsy with hypocretin deficiency without the HLA DQB1*06:02 allele. J Clin Sleep Med. 2023;19(12):2053-2057.

Progressive narcolepsy: how to deal with intermediate hypocretin-1 values?

According to the International Classification of Sleep Disorders, third edition guidelines, the diagnosis of narcolepsy type 1 is based on the association of excessive daytime sleepiness plus either cataplexy and electrophysiological criteria, or a cerebrospinal fluid hypocretin-1 concentration below 110 pg/mL. This threshold remains debated, and recent works have proposed alternative values in the intermediate (110 to 200 pg/mL) zone. We report the case of a patient who presented with typical clinical symptoms of narcolepsy type 1 developing over six years but in whom initial polysomnography and multiple sleep latency test were negative and cerebrospinal fluid hypocretin-1 was intermediate (132 pg/mL). Cerebrospinal fluid hypocretin-1 reassessment four years later found a dramatic decrease, < 50 pg/mL, and the multiple sleep latency test proved to be abnormal, eventually allowing to confirm the diagnosis. This case highlights the importance of reassessing patients with intermediate hypocretin-1 values and contributes to the debate on the determination of alternative cerebrospinal fluid hypocretin1 thresholds for narcolepsy type 1 diagnosis.

CITATION

Ricordeau F, Bridoux A, Raverot V, Peter-Derex L. Progressive narcolepsy: how to deal with intermediate hypocretin-1 values? J Clin Sleep Med. 2023;19(7):1375-1378.

Pregnancy-specific Adaptations in Leptin and Melanocortin Neuropeptides in Early Human Gestation

INTRODUCTION

Pregnancy is characterized by increased appetitive drive beginning early in gestation, yet the central mechanisms underlying this adaptation are poorly understood in humans. To elucidate central mechanisms underlying appetite regulation in early pregnancy, we examine plasma and cerebrospinal fluid (CSF) leptin and Agouti-related peptide (AgRP) as well as CSF proopiomelanocortin (POMC) as surrogates for brain melanocortin activity.

METHODS

Plasma leptin, soluble leptin receptor, AgRP, and CSF leptin, POMC, and AgRP were collected from pregnant women before cerclage placement (16.6 ± 1.1 weeks; N = 24), scheduled cesarean section (39.2 ± 0.2 weeks; N = 24), and from nonpregnant controls (N = 24), matched for age and body mass index.

RESULTS

Plasma leptin was 1.5 times higher in pregnancy vs controls (P = 0.01), but CSF leptin did not differ. CSF/plasma leptin percentage was lower in early pregnancy vs controls (0.8 ± 0.1 vs 1.7 ± 0.2; P < 0.0001) and remained unchanged at term (0.9 ± 0.1), supporting a decrease in leptin transport into CSF in pregnancy. Plasma AgRP, a peripheral biomarker of the orexigenic hypothalamic neuropeptide, was higher in early pregnancy vs controls (95.0 ± 7.8 vs 67.5 ± 5.3; P = 0.005). In early gestation, CSF AgRP did not differ from controls, but CSF POMC was 25% lower (P = 0.006). In contrast, at term, CSF AgRP was 42% higher vs controls (P = 0.0001), but CSF POMC no longer differed. Overall, the CSF AgRP/POMC ratio was 1.5-fold higher in early pregnancy vs controls, reflecting a decrease in melanocortin tone favoring appetitive drive.

CONCLUSIONS

Pregnancy-specific adaptions in the central regulation of energy balance occur early in human gestation and are consistent with decreased leptin transport into brain and resistance to the effects of leptin on target melanocortin neuropeptides.

Nerve growth factor (NGF) pathway biomarkers in Down syndrome prior to and after the onset of clinical Alzheimer's disease: A paired CSF and plasma study

BACKGROUND

The discovery that nerve growth factor (NGF) metabolism is altered in Down syndrome (DS) and Alzheimer's disease (AD) brains offered a framework for the identification of novel biomarkers signalling NGF deregulation in AD pathology.

METHODS

We examined levels of NGF pathway proteins (proNGF, neuroserpin, tissue plasminogen activator [tPA], and metalloproteases [MMP]) in matched cerebrospinal fluid (CSF)/plasma samples from AD-symptomatic (DSAD) and AD-asymptomatic (aDS) individuals with DS, as well as controls (HC).

RESULTS

ProNGF and MMP-3 were elevated while tPA was decreased in plasma from individuals with DS. CSF from individuals with DS showed elevated proNGF, neuroserpin, MMP-3, and MMP-9. ProNGF and MMP-9 in CSF differentiated DSAD from aDS (area under the curve = 0.86, 0.87). NGF pathway markers associated with CSF amyloid beta and tau and differed by sex.

DISCUSSION

Brain NGF metabolism changes can be monitored in plasma and CSF, supporting relevance in AD pathology. These markers could assist staging, subtyping, or precision medicine for AD in DS.

Relationship between cerebrospinal fluid concentrations of orexin A/hypocretin-1 and body composition in humans

The hypothalamic neuropeptide orexin A (hypocretin-1) is a key signal in sleep/wake regulation and promotes food intake. We investigated the relationship between cerebrospinal fluid orexin A concentrations and body composition in non-narcoleptic human subjects with a wide range of body weight to gain insight into the role of orexin A in human metabolism. We collected cerebrospinal fluid and blood samples and measured body composition by bioelectric impedance analysis in 36 subjects (16 women and 20 men) with body mass indices between 16.24 and 38.10 kg/m² and an age range of 19-80 years. Bivariate Pearson correlations and stepwise multiple regressions were calculated to determine associations between orexin A and body composition as well as biometric variables. Concentrations of orexin A in cerebrospinal fluid averaged 315.6 ± 6.0 pg/ml, were comparable between sexes (p > 0.15) and unrelated to age (p > 0.66); they appeared slightly reduced in overweight/obese compared to normal-weight subjects (p = .07). Orexin A concentrations decreased with body weight (r = -0.38, p = .0229) and fat-free mass (r = -0.39, p = .0173) but were not linked to body fat mass (p > 0.24). They were inversely related to total body water (r = -0.39, p = .0174) as well as intracellular (r = -0.41, p = .0139) and extracellular water (r = -0.35, p = .0341). Intracellular water was the only factor independently associated with cerebrospinal fluid orexin A concentrations (p = .0139). We conclude that cerebrospinal fluid orexin A concentrations do not display associations with body adiposity, but are inversely related to intracellular water content. These cross-sectional findings suggest a link between orexin A signaling and the regulation of water homeostasis in humans.

[Positivity analysis of human leukocyte histocompatibility antigen-DQB1*0602 allele in Chinese patients with narcolepsy]

OBJECTIVE

To explore the association of narcolepsy with human leukocyte histocompatibility antigen (HLA)-DQB1*0602 allele in Chinese narcoleptic patients and examine its relationship with different phenotypes.

METHODS

A total of 1 223 narcoleptic patients (NC, narcolepsy with typical cataplexy, n = 1 132; NWC, narcolepsy without cataplexy, n = 91) diagnosed at Sleep Center of Peking University People's Hospital from August 1998 to July 2011 were recruited into this retrospective study. According to the onset age, they were divided into early-onset group (onset age ≤ 15 y, n = 1 037) and late-onset group (onset age >15 y, n = 181). All of them underwent a polymerase chain reaction with specific sequence primer (PCR-SSP) HLA-DQB1*0602 typing. And the cerebrospinal fluid levels of hypocretin-1 (hcrt-1) were measured in 156 narcoleptic patients and they were divided into hcrt deficiency group (hcrt-1<138 ng/L, n = 115) and hcrt normal group (hcrt-1 ≥ 138 ng/L, n = 41). And 728 healthy volunteers were selected as control group. The expression positivity of HLA-DQB1*0602 gene was analyzed for each group.

RESULTS

There were 1 223 narcoleptic patients including 825 males (67.5%) and 398 females (32.5%) with an average age of (16.6 ± 12.6) years on visiting. There were 728 normal controls including 443 males (60.9%) and 285 females (39.1%) with an average age of (26.6 ± 11.4) years on blood sampling. The positive rate of HLA-DQB1*0602 in narcoleptic, NC and NWC groups was 94.7% (1 158/1 223), 97.0% (1 098/1 132) and 65.9% (60/91) respectively.NC group had a higher rate of HLA-DQB1*0602 positivity (χ² = 155.4, P = 0.000). Both groups were higher than that in control group of 19.5% (142/728). The positive rate of HLA-DQB1*0602 in early-onset group was 95.5% (990/1 037) versus 90.1% (163/181) in late-onset group (χ² = 9.25, P = 0.010). Among those with hcrt-1 measurement, 98.3% (113/115) were HLA-DQB1*0602 positive in hcrt deficiency narcolepsy group versus 25.6% (11/43) in hcrt non-deficiency group (χ² = 94.6, P = 0.001).

CONCLUSIONS

HLA-DQB1* 0602 is an important marker in this large sample of Chinese patients with narcolepsy.Its frequency is much higher in patients with cataplexy, early-onset age and hcrt-1 deficiency.

Humor as a reward mechanism: event-related potentials in the healthy and diseased brain

Humor processing involves distinct processing stages including incongruity detection, emotional response, and engagement of mesolimbic reward regions. Dysfunctional reward processing and clinical symptoms in response to humor have been previously described in both hypocretin deficient narcolepsy-cataplexy (NC) and in idiopathic Parkinson disease (PD). For NC patients, humor is the strongest trigger for cataplexy, a transient loss of muscle tone, whereas dopamine-deficient PD-patients show blunted emotional responses to humor. To better understand the role of reward system and the various contributions of hypocretinergic and dopaminergic mechanisms to different stages of humor processing we examined the electrophysiological response to humorous and neutral pictures when given as reward feedback in PD, NC and healthy controls. Humor compared to neutral feedback demonstrated modulation of early ERP amplitudes likely corresponding to visual processing stages, with no group differences. At 270 ms post-feedback, conditions showed topographical and amplitudinal differences for frontal and left posterior electrodes, in that humor feedback was absent in PD patients but increased in NC patients. We suggest that this effect relates to a relatively early affective response, reminiscent of increased amygdala response reported in NC patients. Later ERP differences, corresponding to the late positive potential, revealed a lack of sustained activation in PD, likely due to altered dopamine regulation in reward structures in these patients. This research provides new insights into the temporal dynamics and underlying mechanisms of humor detection and appreciation in health and disease.

Higher Orexin A levels in lumbar compared to ventricular CSF: a study in idiopathic normal pressure hydrocephalus

Orexin A (ORX-A) is implicated in the regulation of various physiological processes, including sleep/wake cycles and reward/motivation. The hypothalamic ORX-A neurons project throughout the brain and spinal cord. In the present study we established and compared ORX-A levels in lumbar and ventricular cerebrospinal fluid (CSF) samples, drawn from idiopathic normal pressure hydrocephalus (INPH) patients, during respectively, lumbar puncture and shunt placement. Ventricular and lumbar CSF levels of total protein and of the dopamine, serotonin and norepinephrine metabolites HVA, 5-HIAA and MHPG respectively, were also estimated. ORX-A was quantified using a commercially available radioimmunoassay kit. Neurotransmitter metabolites were quantified by high performance liquid chromatography. Expectedly, HVA and 5-HIAA levels were significantly higher and total protein levels lower in ventricular compared to lumbar CSF while there were no differences in MHPG levels. However, in contrast to HVA and 5-HIAA and similar to total protein, lumbar ORX-A levels were significantly higher than ventricular levels. The higher lumbar compared to ventricular ORX-A levels may reflect elevated contributions from the spinal cord. The finding of a ventriculo-lumbar difference for ORX-A should be considered in studies utilizing its CSF levels in assessing Orexin system status.

[Case of herpes simplex encephalitis with hypersomnia and low orexin level in the cerebrospinal fluid]

A 60-year-old woman suffered from high fever (38°C) and abnormal behavior, was admitted to our hospital on the seventh day of the fever. At admission, she was stuporous, and a cerebrospinal fluid (CSF) analysis revealed pleocytosis (55/μl, monocytes). Fluid-attenuated inversion recovery (FLAIR) magnetic resonance (MR) images showed high-intensity signals in the medial temporal lobe, inferior surface of the frontal cortex, right cerebellar vermis, and left thalamus. We diagnosed herpes simplex encephalitis, based on the finding of an elevated titer of herpes simplex virus antibody in the CSF (2.90). She was started on treatment with acyclovir and steroid pulse therapy, which was followed by rapid clinical improvement. After recovering from the stupor, the patient exhibited the symptoms of hypersomnia with low orexin level in the CSF. Thus, we should bear in mind that other than consciousness disturbance, patients with herpes simplex encephalitis can also present with rare complications due to the extent of the lesions.

[Diagnosis and treatment of epilepsy and narcolepsy comorbid]

OBJECTIVE

To analyze the clinical diagnosis and treatment process of narcolepsy and epilepsy co-existence, and thereby to improve awareness of such cases.

METHOD

The clinical manifestations of 2 cases were observed, and video-electroencephalogram (VEEG), multiple sleep latency tests (MSLT) were performed. Hypocretin 1 level in cerebrospinal fluid was examined in one case.

RESULT

The onset of disease of case one was started with epilepsy with myoclonic seizure. After half a year, catalepsy induced by emotion especially laughing and excessive daytime sleepiness appeared. MSLT was positive and hypocretin 1 level decreased. Narcolepsy-cataplexy was definitely diagnosed in this case. Valproate was given and seizure was controlled completely, but the excessive daytime sleepiness was aggravated. Combination of valproate, methylphenidate and clomipramine treatment improved the symptoms of narcolepsy and the patient was still free of epileptic seizures. The onset symptoms of case 2 were catalepsy and excessive daytime sleepiness. MSLT was positive. The treatment was ineffective because of bad compliance. After 2 years, episodes of impairment of consciousness with automatism occurred. VEEG showed slow waves and spikes in right temporal area. Complex partial seizure was determined. Oxcarbazepine was used and then the patients became seizures free, but the symptoms of narcolepsy were still obvious.

CONCLUSION

Comorbidity of narcolepsy and epilepsy is a rare phenomenon. Clinical symptoms, predisposing factor, VEEG and MSLT can help diagnosis and differential diagnosis. The antiepileptic drugs might aggravate drowsiness. Based on therapy of epilepsy by using antiepileptic drugs, low dosage of central nervous system stimulants might improve the drowsiness and catalepsy symptoms of narcolepsy.

[Value of cerebral spinal fluid measurement of hypocretin-1 in the diagnosis of Chinese patients with narcolepsy]

OBJECTIVE

To evaluate the diagnostic value of cerebral spinal fluid (CSF) measurement of hypocretin-1 (hcrt-1) in Chinese patients with narcolepsy.

METHODS

A total of 139 narcoleptic patients, including 111 narcolepsy with typical cataplexy (NC) and 28 narcolepsy without cataplexy (NWC), were diagnosed at the sleep centre of Peking University People's Hospital from April 2003 to March 2012. And 64 non-narcoleptic controls were recruited. CSF hcrt-1 levels were measured in all subjects.Receiver operating characteristic curve (ROC) was applied to determine the cutoff value of hcrt-1 for Chinese narcoleptic patients. The diagnostic utility of hcrt-1 ≤ 110.0 ng/L and hcrt-1 ≤ 30% of mean normal level defined by International Classification of Sleep Disorders-II and the new Chinese cutoff value were evaluated respectively.

RESULTS

The level of hcrt-1 in narcolepsy patients was significantly lower than that of normal controls and the NC group was even lower than NWC group (20 (13, 36) vs 319 (244, 379) and 36 (15, 114) ng/L) (all P < 0.01).Using the international criteria of CSF hcrt-1 ≤ 110.0 ng/L or a level of 1/3 of mean normal control values, a specificity of 100% and sensitivity of 90.6% were generated.ROC curve indicated that CSF hcrt-1 level of 138.0 ng/L was the best cutoff value for the diagnosis of narcolepsy in Chinese narcoleptic patients. There were a specificity of 100%, a sensitivity of 92.8% and the area under the ROC curve of 0.98.

CONCLUSIONS

CSF hcrt-1 measurement with high specificity and sensitivity is a useful diagnostic tool for Chinese narcoleptics. And the level of 138.0 ng/L may be the optimal cutoff for the diagnosis of narcolepsy in this group of patients.

Plasma oxytocin and vasopressin do not predict neuropeptide concentrations in human cerebrospinal fluid

The involvement of the neuropeptides oxytocin (OXT) and vasopressin (AVP) in human socio-emotional behaviours is attracting increasing attention. There is ample evidence for elevated plasma levels upon a wide variety of social and emotional stimuli and scenarios, ranging from romantic love via marital distress up to psychopathology, with cause versus consequence being largely unclear. The present study examined whether plasma levels of both OXT and AVP are reflective of central neuropeptide levels, as assumed to impact upon socio-emotional behaviours. Concomitant plasma and cerebrospinal fluid (CSF) samples were taken from 41 non-neurological and nonpsychiatric patients under basal conditions. Although OXT and AVP levels in the CSF exceeded those in plasma, there was no correlation between both compartments, clearly suggesting that plasma OXT and AVP do not predict central neuropeptide concentrations. Thus, the validity of plasma OXT and AVP as potential biomarkers of human behaviour needs further clarification.

Analysis of adult neurogenesis: evidence for a prominent "non-neurogenic" DCX-protein pool in rodent brain

Here, we have developed a highly sensitive immunoassay for Dcx to characterize expression in brain and cerebrospinal fluid (CSF) of rodents. We demonstrate that Dcx is widely expressed during development in various brain regions and as well can be detected in cerebrospinal fluid of rats (up to 30 days postnatal). While Dcx protein level decline in adulthood and were detectable in neurogenic regions of the adult rodent brain, similar levels were also detectable in brain regions expected to bear no neurogenesis including the cerebral cortex and CA1/CA3 enriched hippocampus. We monitored DCX protein levels after paradigms to increase or severely decrease adult hippocampal neurogenesis, namely physical activity and cranial radiation, respectively. In both paradigms, Dcx protein- and mRNA-levels clearly reflected changes in neurogenesis in the hippocampus. However, basal Dcx-levels are unaffected in non-neurogenic regions (e.g. CA1/CA3 enriched hippocampus, cortex). These data suggest that there is a substantial "non-neurogenic" pool of Dcx- protein, whose regulation can be uncoupled from adult neurogenesis suggesting caution for the interpretation of such studies.

Cerebrospinal fluid melanin-concentrating hormone (MCH) and hypocretin-1 (HCRT-1, orexin-A) in Alzheimer's disease

Ancillary to decline in cognitive abilities, patients with Alzheimer’s disease (AD) frequently suffer from behavioural and psychological symptoms of dementia (BPSD). Hypothalamic polypeptides such as melanin-concentrating hormone (MCH) and hypocretin-1 (HCRT-1, orexin-A) are promoters of sleep-wake regulation and energy homeostasis and are found to impact on cognitive performance. To investigate the role of MCH and HCRT-1 in AD, cerebrospinal fluid (CSF) levels were measured in 33 patients with AD and 33 healthy subjects (HS) using a fluorescence immunoassay (FIA). A significant main effect of diagnosis (F(1,62) = 8.490, p<0.01) on MCH levels was found between AD (93.76±13.47 pg/mL) and HS (84.65±11.40 pg/mL). MCH correlated with T-tau (r = 0.47; p<0.01) and P-tau (r = 0.404; p<0.05) in the AD but not in the HS. CSF-MCH correlated negatively with MMSE scores in the AD (r = −0.362, p<0.05) and was increased in more severely affected patients (MMSE_≤20) compared to HS (p<0.001) and BPSD-positive patients compared to HS (p<0.05). In CSF-HCRT-1, a significant main effect of sex (F(1,31) = 4.400, p<0.05) with elevated levels in females (90.93±17.37 pg/mL vs. 82.73±15.39 pg/mL) was found whereas diagnosis and the sex*diagnosis interaction were not significant. Elevated levels of MCH in patients suffering from AD and correlation with Tau and severity of cognitive impairment point towards an impact of MCH in AD. Gender differences of CSF-HCRT-1 controversially portend a previously reported gender dependence of HCRT-1-regulation. Histochemical and actigraphic explorations are warranted to further elucidate alterations of hypothalamic transmitter regulation in AD.

CSF levels of hypocretin-1 (orexin-A) peak during early infancy in humans

STUDY OBJECTIVES

Hypocretin (orexin) is a unique neuropeptide involved in the consolidation of wakefulness and sleep. Although hypocretin-1 levels in the cerebrospinal fluid (CSF) are stable after infancy, how levels change in preterm and term human infants is unknown.

DESIGN, PATIENTS, AND SETTING

Hypocretin-1 levels were measured in CSF samples, obtained from 284 preterm (25-37 gestational weeks) and full-term infants in the first 4 months of life and 35 older children (ages 0.5-13 years), in a tertiary hospital.

MEASUREMENTS AND RESULTS

Detailed clinical and laboratory data were collected for each of the 319 participants. Based on that data, 108 neurologically intact children were selected (95 infants [43 preterm and 52 term] and 13 older children). CSF hypocretin-1 was measured by direct radioimmunoassay. Hypocretin-1 levels at the first weeks of the 3rd embryonic trimester (gestational age [GA] 28-34 weeks) were 314 ± 65 pg/mL (n = 17). The levels linearly increased during the third trimester and early infancy (r = 0.6), peaking in infants of 2-4 months ages (476 ± 72 pg/mL; n = 16) and decreasing thereafter; hypocretin levels in 2- to 4-month-old infants were significantly higher than those in children 0.5-13 years old (353 ± 78 pg/mL, n = 13; P = 0.0001).

CONCLUSIONS

The present findings indicate that in human infants, CSF hypocretin-1 increases during the third embryonic trimester and is highest at 4 months of life. Thereafter, and consistent with previously published results, hypocretin levels are lower and stable until the geriatric age. This pattern may reflect the role of hypocretin in the dramatic process of sleep and wakefulness consolidation that occurs during early infancy.

Central nervous system lipocalin-type prostaglandin D2-synthase is correlated with orexigenic neuropeptides, visceral adiposity and markers of the hypothalamic-pituitary-adrenal axis in obese humans

Lipocalin-type prostaglandin D2-synthase (L-PGDS) is the main producer of prostaglandin D2 (PGD2) in the central nervous system (CNS). Animal data suggest effects of central nervous L-PGDS in the regulation of food intake and obesity. No human data are available. We hypothesised that a role for CNS L-PGDS in metabolic function in humans would be reflected by correlations with known orexigenic neuropeptides. Cerebrospinal fluid (CSF) and serum samples were retrieved from 26 subjects in a weight loss study, comprising a 3-week dietary lead-in followed by 12-weeks of leptin or placebo treatment. At baseline, CSF L-PGDS was positively correlated with neuropeptide Y (NPY) (ρ = 0.695, P < 0.001, n = 26) and galanin (ρ = 0.651, P < 0.001) as well as visceral adipose tissue (ρ = 0.415, P = 0.035). Furthermore, CSF L-PGDS was inversely correlated with CSF leptin (ρ = -0.529, P = 0.005) and tended to correlate inversely with s.c. adipose tissue (ρ = -0.346, P = 0.084). As reported earlier, leptin treatment had no effect on weight loss and did not affect CSF L-PGDS or NPY levels compared to placebo. After weight loss, the change of CSF L-PGDS was significantly correlated with the change of CSF NPY levels (ρ = 0.604, P = 0.004, n = 21). Because of the correlation between baseline CSF L-PGDS levels and visceral adipose tissue, we examined associations with hypothalamic-pituitary-adrenal (HPA) axis components. Baseline CSF L-PGDS was correlated with corticotrophin-releasing hormone (ρ = 0.764, P < 0.001) and β-endorphin (ρ = 0.491, P < 0.001). By contrast, serum L-PGDS was not correlated with any of the measured variables either at baseline or after treatment. In summary, CSF L-PGDS was correlated with orexigenic neuropeptides, visceral fat distribution and central HPA axis mediators. The importance of these findings is unclear but could suggest a role for CSF L-PGDS in the regulation of visceral obesity by interaction with the neuroendocrine circuits regulating appetite and fat distribution. Further interventional studies will be needed to characterise these interactions in more detail.

Hypocretin (orexin) loss in Alzheimer's disease

Sleep disturbances in Alzheimer's 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.

[Impacts of moxibustion on vascular dementia and neuropeptide substance content in cerebral spinal fluid]

OBJECTIVE

To observe the effects of moxibustion therapy on the improvements of clinical symptom scale score and neuropeptide substance in vascular dementia (VD) and investigate a part of mechanism of moxibustion on Vd.

METHODS

Eighty-seven cases of VD were divided randomly into a moxibustion group (43 cases) and a western medicine group (44 cases). In moxibustion group, the isolated moxibustion with Typhonium Rhizome was applied to Baihui (BL 20), and suspended moxibustion was used on Shenting (BL 24) and Dazhui (GV 14). In western medicine group, Piracetam tablet was taken orally. After 4-session treatment, the scores in Hasegawa's Dementia Scale (HDS), Mini Mental Status Examination (MMSE) and Activity of Daily Living Scale (ADL) as well as the content of active substances, somatostatin (SS) and arginine vasopressin (AVP) in cerebral spinal fluid relevant with learning and memory were compared with those before treatment.

RESULTS

The total effective rate was 81.4% (35/43) in moxibustion group, which was superior to 63.6% (28/44) in western medicine group (P < 0.01). The scores in HDS, MMSE and ADL after treatment were all improved as compared with those before treatment in two groups (P < 0.05, P < 0.01). The improvements of the scores in MMSE and ADL in moxibustion group were superior to those in western medicine group (both P < 0.05). After treatment, SS and AVP content in cerebral spinal fluid increased remarkably as compared with those before treatment in two groups (all P < 0.01), and SS and AVP levels after treatment in moxibustion group were improved significantly as compared with those in western medicine group (P < 0.05, P < 0.01).

CONCLUSION

Moxibustion therapy is superior to oral administration of western medicine no matter in the improvement of symptom scores or in the regulation of neuropeptide substances relevant with learning and memory, which deserves to be promoted in application.

National narcolepsy survey

Narcolepsy is characterised by excessive daytime sleepiness and cataplexy and has a prevalence of 25 per 100,000. We suspect this is higher than presently seen in the Republic of Ireland. We aimed to calculate the Irish prevalence of Narcolepsy and to examine current management practices. We conducted an online survey of respiratory physicians, neurologists, paediatric neurologists, and psychiatrists with an interest in sleep disorders (73% response rate). Of this group, a total of 16 physicians managed 180 patients prior to January 2009. A clinical diagnosis alone was reached in 67 (41%) patients, the remainder by polysomnography or multiple sleep latency testing. No patients were diagnosed by cerebro-spinal fluid analysis of hypocretin levels. While 70 (42%) patients received modafanil, only 7 (4%) were treated with sodium oxybate. Even allowing for missing data it is apparent that Narcolepsy is hugely under-diagnosed in Ireland, however, current practises adhere with new international guidelines.

[Neurophysiological examinations in narcolepsy]

BACKGROUND

Narcolepsy is a chronic hypersomnia of central origin, linked with dysfunction of hypocretin-containing neurons, localized in the lateral hypothalamus. Main symptoms of narcolepsy include excessive daytime sleepiness, cataplexy, hypnagogic hallucinations and sleep paralysis. Establishing the proper diagnosis is very important, because of the negative impact of narcolepsy on patients' functioning in social-life and the possibility of improvement of quality of life with adequate treatment.

AIM OF THE STUDY

Present review describes clinical characteristics of narcolepsy, usefulness of neurophysiological tests in differential diagnosis of narcolepsy and assessing the efficacy of the treatment, as well as the application of novel biological methods in diagnosis of narcolepsy.

METHODS AND RESULTS

According to diagnostic criteria of ICSD-2 the diagnosis of narcolepsy is based on the clinical features and diagnostic examinations and tests. Among them neurophysiological procedures, such as polysomnography (PSG) and Multiple Sleep Latency Test (MSLT) are still recommended as most useful in differential diagnosis of narcolepsy and other hypersomnias. In recent decades novel biochemical and genetic tools have been developed as diagnostic measures in narcolepsy, including the levels of hypocretin in cerebral spinal fluid and HLA DQB1*0602 typing. These both biological markers are strongly associated with the occurrence of cataplexy, therefore do not present considerable diagnostic value in narcolepsy without cataplexy.

CONCLUSIONS

Neurophysiological procedures (MSLT) and biological markers are necessary in the diagnosis of narcolepsy with cataplexy and hypersomnia without cataplexy. Neurophysiological procedures are useful in monitoring of the treatment of hypersomnia also.

Modafinil and γ-hydroxybutyrate have sleep state-specific pharmacological actions on hypocretin-1 physiology in a primate model of human sleep

Hypocretin-1 is a hypothalamic neuropeptide that is important in the regulation of wake and the lack of which results in the sleep disorder narcolepsy. Using a monkey that has consolidated wake akin to humans, we examined pharmacological manipulation of sleep and wake and its effects on hypocretin physiology. Monkeys were given the sleep-inducing γ-hydroxybutyrate (GHB) and the wake-inducing modafinil both in the morning and in the evening. Cerebrospinal fluid hypocretin-1 concentrations changed significantly in response to the drugs only when accompanied by a behavioral change (GHB-induced sleep in the morning or modafinil-induced wake in the evening). We also found that there was a large (180-fold) interindividual variation in GHB pharmacokinetics that explains variability in sleep induction in response to the drug. Our data indicate that the neurochemical concomitants of sleep and wake are capable of changing the physiological output of hypocretin neurons. Sleep independent of circadian timing is capable of decreasing cerebrospinal fluid hypocretin-1 concentrations. Furthermore, hypocretin neurons do not seem to respond to an 'effort' to remain awake, but rather keep track of time spent awake as a wake-promoting counterbalance to extended wakefulness.

[Hypocretin system and narcolepsy]

Narcolepsy is a sleep disorder characterized by excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, and sleep-onset rapid eye movement (REM) sleep periods. It is now identified as a neurodegenerative disease because there is a massive loss of specific neurons in the brain. These neurons contain the neuropeptides hypocretin-1 and hypocretin-2, which are also known as orexin-A and orexin-B. Cerebrospinal fluid hypocretin-1 measurements are diagnostic for primary narcolepsy. The cause of neural loss could be autoimmune since most patients have the HLA DQB1 0602 allele that predisposes to the disorders. The discovery of hypocretin deficiency is redefining the clinical entity of narcolepsy and offering novel diagnostic procedures. This article reviews the current understanding of narcolepsy and discusses the implications of hypocretin discovery.

The link between childhood trauma and depression: insights from HPA axis studies in humans

Childhood trauma is a potent risk factor for developing depression in adulthood, particularly in response to additional stress. We here summarize results from a series of clinical studies suggesting that childhood trauma in humans is associated with sensitization of the neuroendocrine stress response, glucocorticoid resistance, increased central corticotropin-releasing factor (CRF) activity, immune activation, and reduced hippocampal volume, closely paralleling several of the neuroendocrine features of depression. Neuroendocrine changes secondary to early-life stress likely reflect risk to develop depression in response to stress, potentially due to failure of a connected neural circuitry implicated in emotional, neuroendocrine and autonomic control to compensate in response to challenge. However, not all of depression is related to childhood trauma and our results suggest the existence of biologically distinguishable subtypes of depression as a function of childhood trauma that are also responsive to differential treatment. Other risk factors, such as female gender and genetic dispositions, interfere with components of the stress response and further increase vulnerability for depression. Similar associations apply to a spectrum of other psychiatric and medical disorders that frequently coincide with depression and are aggravated by stress. Taken together, this line of evidence demonstrates that psychoneuroendocrine research may ultimately promote optimized clinical care and help prevent the adverse outcomes of childhood trauma.

Detection of elastin derived peptides in cerebrospinal fluid of patients with first ever ischaemic stroke

OBJECTIVE

We have previously reported the optimized methods for the detection of elastin derived peptides (EDP) in the serum, synovial fluid, and bronchoalveolar lavage. The aim of the present study was to investigate whether EDP are detectable in cerebrospinal fluid (CSF) of patients with acute brain ischaemia.

PATIENTS AND METHODS

Twenty-seven first ever ischaemic stroke patients (mean age 61.5+/-10.8 years; age range 47-70 years; 12 women) were studied in acute phase (1-15 days after the onset) with clinical evaluations, radiological assessments, and the analysis of serum and CSF based on Western blot and ELISA for the detection and quantification of EDP.

RESULTS

None of the serum EDP concentrations are significantly higher in stroke patients compared with 25 healthy control individuals. However, EDP levels in CSF are strongly (p<0.0001) elevated compared with healthy subjects. They correlated with total cholesterol (r=0.53; p=0.02), triglycerides (r=0.67; p=0.004) and retinopathy (r=0.24; p=0.03), and with the interval between the stroke onset and the time of lumbar puncture (r=0.35; p=0.02).

CONCLUSION

EDPs are detectable in CSF of healthy subjects and patients with ischaemic stroke. Acute brain infarction is followed by increased levels of EDP in CSF.

Plasma and CSF serpins in Alzheimer disease and dementia with Lewy bodies

OBJECTIVE

Serine protease inhibitors (serpins), the acute phase reactants and regulators of the proteolytic processing of proteins, have been recognized as potential contributors to the pathogenesis of Alzheimer disease (AD). We measured plasma and CSF levels of serpins in controls and patients with dementia.

METHODS

Using rocket immunoelectrophoresis, ELISA, and Luminex xMAP technology, we analyzed plasma levels of alpha(1)-antichymotrypsin and alpha(1)-antitrypsin, and CSF levels of alpha(1)-antichymotrypsin, alpha(1)-antitrypsin, and neuroserpin along with three standard biomarkers (total tau, tau phosphorylated at threonine-181, and the A beta(1-42)) in patients with AD (n = 258), patients with dementia with Lewy bodies (DLB; n = 38), and age-matched controls (n = 37).

RESULTS

The level of CSF neuroserpin was significantly higher in AD compared with controls and DLB, whereas CSF alpha(1)-antichymotrypsin and alpha(1)-antitrypsin were significantly higher in both AD and DLB groups than in controls. Results from logistic regression analyses demonstrate a relationship between higher CSF levels of alpha(1)-antichymotrypsin and neuroserpin and increased predicted probability and odds ratios (ORs) of AD (OR 5.3, 95% CI 1.3 to 20.8 and OR 3.3, CI 1.3 to 8.8). Furthermore, a logistic regression model based on CSF alpha(1)-antichymotrypsin, neuroserpin, and A beta(1-42) enabled us to discriminate between AD patients and controls with a sensitivity of 94.7% and a specificity of 77.8%.

CONCLUSIONS

Higher CSF levels of neuroserpin and alpha(1)-antichymotrypsin were associated with the clinical diagnosis of Alzheimer disease (AD) and facilitated the diagnostic classification of AD vs controls. CSF serpin levels did not improve the diagnostic classification of AD vs dementia with Lewy bodies.

Reduced orexin levels in the cerebrospinal fluid of suicidal patients with major depressive disorder

Orexins are neuropeptides selectively expressed in a small number of neurons in the lateral-posterior hypothalamus. We measured orexin-A in the cerebrospinal fluid (CSF) of 66 patients with major depressive disorder (MDD), dysthymia and adjustment disorder after a suicide attempt. Blood samples confirmed that the patients were free from antidepressive and neuroleptic medication at the time of the lumbar punctures. CSF levels of orexin-A were significantly lower in patients with MDD than in patients with adjustment disorder and dysthymia. Orexin correlated significantly with CSF levels of somatostatin, delta sleep inducing peptide-like immunoreactivity (DSIP-LI) and corticotrophin releasing factor (CRF), but not with leptin or vasopressin. Plasma levels of thyroid-stimulating hormone (TSH) were not reduced in MDD patients, and did not correlate with CSF-orexin. Our results suggest that suicidal patients with MDD have distinct neurobiological features, involving compromised levels of hypothalamic peptides regulating the state of arousal.

CSF orexin-A/hypocretin-1 concentrations in patients with intracerebral hemorrhage (ICH)

Orexins/hypocretins are neuropeptides that have various physiological effects, including the regulation of both the feeding behavior neuroendocrine functions and sleep-wakefulness cycle. Recent studies have suggested that the orexin system may also be involved in neuronal damage in the clinical setting and animal experiments. The aim of this study was to examine the role of the hypothalamic orexin-A/hypocretin-1 system in patients with intracerebral hemorrhage (ICH). The CSF orexin-A/hypocretin-1 levels were measured in 11 ICH patients. CSF orexin-A/hypocretin-1 levels were low in ICH patients during the 13 days following the ICH event. The mean CSF orexin-A/hypocretin-1 levels were 61.1+/-22.3 (S.D.) pg/ml (range 27.5-106.9 pg/ml). The decreasing in the CSF orexin-A/hypocretin-1 levels was not related to the severity of ICH. The CSF orexin-A/hypocretin-1 levels were lower in the thalamic hemorrhage patients than those in other patients (48.5+/-23.3 pg/ml vs. 65.2+/-21.2 pg/ml; p=0.03.) These data indicate that orexin-A/hypocretin-1 may therefore play an important role in the various physiological responses including sleep, feeding, and the overall metabolism in ICH patients.

CSF metabolic and proteomic profiles in patients prodromal for psychosis

BACKGROUND

The initial prodromal state of psychosis (IPS) is defined as an early disease stage prior to the onset of overt psychosis characterized by sub-threshold or more unspecific psychiatric symptoms. Little is known regarding the biochemical changes during this period.

METHODOLOGY/PRINCIPAL FINDINGS

We investigated the metabolic/proteomic profiles of cerebrospinal fluid (CSF) of first-onset drug naïve paranoid schizophrenia patients (n = 54) and individuals presenting with initial prodromal symptoms (n = 24), alongside healthy volunteers (n = 70) using proton nuclear magnetic resonance ((1)H-NMR) spectroscopy and surface enhanced laser desorption ionization (SELDI) mass spectrometry, respectively. Partial least square discriminant analysis (PLS-DA) showed that 36%/29% of IPS patients displayed proteomic/metabolic profiles characteristic of first-onset, drug naïve schizophrenia, i.e., changes in levels of glucose and lactate as well as changes in a VGF-derived peptide (VGF23-62) and transthyretin protein concentrations. However, only 29% (n = 7) of the investigated IPS patients (who to date have been followed up for up to three years) have so far received a diagnosis of schizophrenia. The presence of biochemical alterations in the IPS group did not correlate with the risk to develop schizophrenia.

CONCLUSIONS/SIGNIFICANCE

Our results imply that schizophrenia-related biochemical disease processes can be traced in CSF of prodromal patients. However, the biochemical disturbances identified in IPS patients, at least when measured at a single time point, may not be sufficient to predict clinical outcome.

Increasing length of wakefulness and modulation of hypocretin-1 in the wake-consolidated squirrel monkey

The neuropeptides hypocretins (orexins), the loss of which results in the sleep disorder narcolepsy, are hypothesized to be involved in the consolidation of wakefulness and have been proposed to be part of the circadian-driven alertness signal. To elucidate the role of hypocretins in the consolidation of human wakefulness we examined the effect of wake extension on hypocretin-1 in squirrel monkeys, primates that consolidate wakefulness during the daytime as do humans. Wake was extended up to 7 h with hypocretin-1, cortisol, ghrelin, leptin, locomotion, and feeding, all being assayed. Hypocretin-1 (P < 0.01), cortisol (P < 0.001), and locomotion (P < 0.005) all increased with sleep deprivation, while ghrelin (P = 0.79) and leptin (P = 1.00) did not change with sleep deprivation. Using cross-correlation and multivariate modeling of these potential covariates along with homeostatic pressure (a measure of time awake/asleep), we found that time of day and homeostatic pressure together explained 44% of the variance in the hypocretin-1 data (P < 0.001), while cortisol did not significantly contribute to the overall hypocretin-1 variance. Locomotion during the daytime, but not during the nighttime, helped explain < 5% of the hypocretin-1 variance (P < 0.05). These data are consistent with earlier evidence indicating that in the squirrel monkey hypocretin-1 is mainly regulated by circadian inputs and homeostatic sleep pressure. Concomitants of wakefulness that affect hypocretin-1 in polyphasic species, such as locomotion, food intake, and food deprivation, likely have a more minor role in monophasic species, such as humans.

CSF hypocretin-1 levels and clinical profiles in narcolepsy and idiopathic CNS hypersomnia in Norway

OBJECTIVE

To evaluate the relationship between CSF hypocretin-1 levels and clinical profiles in narcolepsy and CNS hypersomnia in Norwegian patients.

METHOD

CSF hypocretin-1 was measured by a sensitive radioimmunoassay in 47 patients with narcolepsy with cataplexy, 7 with narcolepsy without cataplexy, 10 with idiopathic CNS hypersomnia, and a control group.

RESULTS

Low hypocretin-1 values were found in 72% of the HLA DQB1*0602 positive patients with narcolepsy and cataplexy. Patients with low CSF hypocretin-1 levels reported more extensive muscular involvement during cataplectic attacks than patients with normal levels. Hypnagogic hallucinations and sleep paralysis occurred more frequently in patients with cataplexy than in the other patient groups, but with no correlation to hypocretin-1 levels.

CONCLUSION

About three quarters of the HLA DQB1*0602 positive patients with narcolepsy and cataplexy had low CSF hypocretin-1 values, and appear to form a distinct clinical entity. Narcolepsy without cataplexy could not be distinguished from idiopathic CNS hypersomnia by clinical symptoms or biochemical findings.

HLA-DQB1 genotyping in a family with narcolepsy-cataplexy

Narcolepsy is a unique model for dysfunction in mechanisms that regulate sleep and wakefulness. The narcolepsy syndrome is characterized by excessive daytime sleepiness with recurrent episodes of irresistible sleep, cataplexy, hypnagogic and/or hypnopompic hallucinations and sleep paralysis. The current hypothesis for the etiology of narcolepsy is that it is an autoimmune disorder because of its strong association with the human leukocyte antigen (HLA) system. HLA-DQ alleles are not particularly mutated in narcoleptic patients but they directly influence susceptibility to the disease. DQB10602 homozygote carriers have a two to four times higher risk of developing the disease than heterozygote carriers. In the present study we report a rare multiplex familial case of narcolepsy-cataplexy and show the strong effect of the HLA-DQB10602 allele upon the disease phenotype. In the family studied herein, both the proband and his brother are severely affected and homozygous DQB10602, whereas their sister does not carry the allele and is not affected at all. These data corroborate previous findings proposing DQB10602 homozygous subjects to be far more susceptible to narcolepsy. Insights into the DQB10602 positive family that include homozygous subjects may prove to be an important asset in the investigation of genetic vs. environmental factors predisposing to narcolepsy.

Sleep-wake disturbances 6 months after traumatic brain injury: a prospective study

Sleep-wake disturbances (SWD) are common after traumatic brain injury (TBI). In acute TBI, we recently found decreased CSF levels of hypocretin-1, a wake-promoting neurotransmitter. In the present study, we aimed to delineate the frequency and clinical characteristics of post-traumatic SWD, to assess CSF hypocretin-1 levels 6 months after TBI, and to identify risk factors for posttraumatic SWD. A total of 96 consecutive patients were enrolled within the first 4 days after TBI. Six months later, out of 76 TBI patients, who did not die and who did not move to foreign countries, we included 65 patients (86%, 53 males, mean age 39 years) in our study. Patients were examined using interviews, questionnaires, clinical examinations, computed tomography of the brain, laboratory tests (including CSF hypocretin-1 levels, and HLA typing), conventional polysomnography, maintenance of wakefulness and multiple sleep latency tests (MSLT) and actigraphy. Potential causes of post-traumatic SWD were assessed according to international criteria. New-onset sleep-wake disturbances following TBI were found in 47 patients (72%): subjective excessive daytime sleepiness (EDS; defined by the Epworth Sleepiness Scale > or = 10) was found in 18 (28%), objective EDS (as defined by mean sleep latency < 5 min on MSLT) in 16 (25%), fatigue (daytime tiredness without signs of subjective or objective EDS) in 11 (17%), post-traumatic hypersomnia 'sensu strictu' (increased sleep need of > or = 2 h per 24 h compared to pre-TBI) in 14 (22%) patients and insomnia in 3 patients (5%). In 28 patients (43% of the study population), we could not identify a specific cause of the post-traumatic SWD other than TBI. Low CSF hypocretin-1 levels were found in 4 of 21 patients 6 months after TBI, as compared to 25 of 27 patients in the first days after TBI. Hypocretin levels 6 months after TBI were significantly lower in patients with post-traumatic EDS. There were no associations between post-traumatic SWD and severity or localization of TBI, general clinical outcome, gender, pathological neurological findings and HLA typing. However, post-traumatic SWD correlated with impaired quality of life. These results suggest that sleep-wake disturbances, particularly EDS, fatigue and hypersomnia are common after TBI, and significantly impair quality of life. In almost one out of two patients, post-traumatic SWD appear to be directly related to the TBI. An involvement of the hypocretin system in the pathophysiology of post-traumatic SWD appears possible. Other risk factors predisposing towards the development of post-traumatic SWD were not identified.

The development of hypocretin (orexin) deficiency in hypocretin/ataxin-3 transgenic rats

Narcolepsy is linked to a widespread loss of neurons containing the neuropeptide hypocretin (HCRT), also named orexin. A transgenic (TG) rat model has been developed to mimic the neuronal loss found in narcoleptic humans. In these rats, HCRT neurons gradually die as a result of the expression of a poly-glutamine repeat under the control of the HCRT promoter. To better characterize the changes in HCRT-1 levels in response to the gradual HCRT neuronal loss cerebrospinal fluid (CSF) HCRT-1 levels were measured in various age groups (2-82 weeks) of wild-type (WT) and TG Sprague-Dawley rats. TG rats showed a sharp decline in CSF HCRT-1 level at week 4 with levels remaining consistently low (26%+/-9%, mean+/-S.D.) thereafter compared with WT rats. In TG rats, HCRT-1 levels were dramatically lower in target regions such as the cortex and brainstem (100-fold), indicating decreased HCRT-1 levels at terminals. In TG rats, CSF HCRT-1 levels significantly increased in response to 6 h of prolonged waking, indicating that the remaining HCRT neurons can be stimulated to release more neuropeptide. Rapid eye movement (REM) sleep in TG rats (n=5) was consistent with a HCRT deficiency. In TG rats HCRT immunoreactive (HCRT-ir) neurons were present in the lateral hypothalamus (LH), even in old rats (24 months) but some HCRT-ir somata were in various stages of disintegration. The low output of these neurons is consistent with a widespread dysfunction of these neurons, and establishes this model as a tool to investigate the consequences of partial hypocretin deficiency.

[Comparative analysis of patients with narcolepsy-cataplexy, narcolepsy without cataplexy and idiopathic hypersomnia]

BACKGROUND AND OBJECTIVE

To evaluate the distribution of clinical, electrophysiological and biological variables, and their relationship with the CSF hypocretin-1 levels, in patients with central hypersomnias diagnosed as narcolepsy-cataplexy (NC), narcolepsy without cataplexy (NnC) and idiopathic hypersomnia (IH) based on the ICSD-2 criteria.

PATIENTS AND METHOD

We performed in all patients a clinical interview, a nocturnal polysomnogram and a multiple sleep latency test (MSLT), HLA analysis and measurement of CSF Hcrt-1 levels (low < or = 110 pg/mL).

RESULTS

Out of 51 patients, 31 were classified as NC, 11 as NnC and 8 as IH. 34 patients (66.7%) had low CSF Hcrt-1 levels (29 NC, 3 NnC and 1 IH). In the NC group, 96.1% were HLA DQB1*0602 positive and 91% had low CSF Hcrt-1 levels. The most frequent variables found in NC patients and in those with a low CSF Hcrt-1 levels were cataplexy, fragmented nocturnal sleep, short refreshing naps, automatic behavior, HLA DQB1*0602, and, in the MSLT, a short mean sleep latency, a higher number of REM sleep episodes and a short mean latency of REM sleep episodes. A long nocturnal sleep time and morning sleep drunkenness, 2 variables used in the ICSD-2 for the diagnosis of IH, were not different among the three groups of hypersomnias.

CONCLUSIONS

Central hypersomnias have a superposition of several clinical, electrophysiological and biological variables that makes sometimes difficult the differential diagnosis. The measurement of CSF Hcrt-1 levels may help in the diagnosis of those patients with unclear clinical or electrophysiological forms.

Orexin and psychiatric symptoms in suicide attempters

BACKGROUND

The orexins (hypocretins) are recently discovered hypothalamic peptides that are involved in the regulation of sleep, appetite and state of arousal. In the present study, we investigated the relationship between cerebrospinal fluid (CSF) orexin and specific psychiatric symptoms in suicidal patients.

METHODS

A total of 101 patients were enrolled in the study shortly after a suicide attempt. All patients underwent a lumbar puncture after a wash-out period during which they did not receive any antipsychotic or antidepressive medication. Structured interviews were performed using the Comprehensive Psychopathological Rating Scale (CPRS). CSF-orexin-A was measured and correlated with ratings of psychiatric symptoms.

RESULTS

There were significant and negative correlations between CSF-orexin and the symptoms lassitude (difficulty to initiate activities) and slowness of movement, as well as the ratings of global illness (p<0.005 for all three items, Spearman's rho).

LIMITATIONS

Correlation analysis is an indirect method of investigation and does not demonstrate causal relationships.

CONCLUSION

Low CSF-orexin levels are related to pronounced symptoms of inertia and reduced motor activity in suicidal patients. Interestingly, the lower the orexin levels, the higher were ratings of overall illness, as observed by a specialist in psychiatry. Our results suggest that reduced orexin levels are involved in the etiology of specific psychiatric symptoms.

Hypocretin (orexin) loss in Parkinson's disease

The hypothalamic hypocretin (orexin) system plays a central role in the regulation of various functions, including sleep/wake regulation and metabolism. There is a growing interest in hypocretin function in Parkinson's disease (PD), given the high prevalence of non-motor symptoms such as sleep disturbances in this disorder. However, studies measuring CSF hypocretin levels have yielded contradictory results. In PD patients and matched controls, we (i) estimated the number of hypocretin neurons in post-mortem hypothalami using immunocytochemistry and an image analysis system (ii) quantified hypocretin levels in post-mortem ventricular CSF and (iii) prefrontal cortex using a radioimmunoassay. Furthermore, presence of Lewy bodies was verified in the hypothalamic hypocretin cell area. Data are presented as median (25th-75th percentile). We showed a significant decrease between PD patients and controls in (i) the number of hypocretin neurons (PD: 20 276 (13 821-31 229); controls: 36 842 (32 546-50 938); P = 0.016); (ii) the hypocretin-1 concentration in post-mortem ventricular CSF (PD: 365.5 pg/ml (328.0-448.3); controls: 483.5 (433.5-512.3); P = 0.012) and (iii) the hypocretin-1 concentrations in prefrontal cortex (PD: 389.6 pg/g (249.2-652.2); controls: 676.6 (467.5-883.9); P = 0.043). Hypocretin neurotransmission is affected in PD. The hypocretin-1 concentration in the prefrontal cortex was almost 40% lower in PD patients, while ventricular CSF levels were almost 25% reduced. The total number of hypocretin neurons was almost half compared to controls.

Normal cerebrospinal fluid levels of hypocretin-1 (orexin A) in patients with fibromyalgia syndrome

BACKGROUND

The hypothalamic neuropeptide hypocretin (orexin) modulates sleep-wake, feeding and endocrine functions. Cerebrospinal fluid (CSF) hypocretin-1 (Hcrt-1) concentrations are low in patients with narcolepsy-cataplexy, a sleep disorder characterized by hypersomnolence and rapid eye movement (REM) sleep abnormalities.

METHODS

We determined CSF Hcrt-1 concentrations of patients with the fibromyalgia syndrome (FMS), a condition characterized by fatigue, insomnia and in some cases daytime hypersomnolence.

RESULTS

Basal CSF levels of Hcrt-1 in FMS did not differ from those in healthy normal controls.

CONCLUSIONS

These findings suggest that abnormally low Hcrt-1 is not a likely cause of fatigue in FMS.

Isolated mediotegmental lesion causing narcolepsy and rapid eye movement sleep behaviour disorder: a case evidencing a common pathway in narcolepsy and rapid eye movement sleep behaviour disorder

Narcolepsy is usually an idiopathic disorder, often with a genetic predisposition. Symptomatic cases have been described repeatedly, often as a consequence of hypothalamic lesions. Conversely, REM (rapid eye movement) sleep behaviour disorder (RBD) is usually a secondary disorder, often due to degenerative brain stem disorders or narcolepsy. The case of a hitherto healthy man is presented, who simultaneously developed narcolepsy and RBD as the result of an acute focal inflammatory lesion in the dorsomedial pontine tegmentum in the presence of normal cerebrospinal fluid hypocretin-1 levels and in the absence of human lymphocyte antigen haplotypes typically associated with narcolepsy and RBD (DQB1*0602, DQB1*05). This first observation of symptomatic narcolepsy with RBD underlines the importance of the mediotegmental pontine area in the pathophysiology of both disorders, even in the absence of a detectable hypocretin deficiency and a genetic predisposition.

Narcolepsy without cataplexy: 2 subtypes based on CSF hypocretin-1/orexin-A findings

STUDY OBJECTIVES

Cerebrospinal fluid (CSF) hypocretin-1 levels and their relationship with the clinical characteristics of narcolepsy without cataplexy have not been well elucidated. Our aim was to examine whether clinical characteristics vary with CSF hypocretin-1 levels among narcoleptic patients without cataplexy.

DESIGN

Clinical features, variables on the multiple sleep latency test, and results of HLA typing were correlated with CSF hypocretin-1 levels.

SETTING

University-based sleep laboratories and a sleep disorders center.

PATIENTS

Seventeen patients (5 male, 12 female) who fulfilled the diagnostic criteria of narcolepsy without cataplexy according to the International Classification of Sleep Disorders. INERVENTIONS: Patients underwent lumbar puncture for CSF sampling.

MEASUREMENTS AND RESULTS

Five patients showed a markedly decreased CSF hypocretin-1 level, whereas the remaining 12 patients showed almost normal levels. The mean rapid eye movement (REM) latency was significantly shorter and the age at onset was significantly earlier in the low CSF hypocretin-1 group compared with the normal CSF hypocretin-1 group. HLA-DR2 was positive in all of the patients with low CSF hypocretin-1, whereas only 33.3% of patients with normal CSF hypocretin-1 were DR2 positive.

CONCLUSIONS

Some narcoleptic patients without cataplexy have low CSF hypocretin-1 levels. In patients who have narcolepsy without cataplexy, short mean REM latency, younger age at onset, and HLA-DR2 are associated with CSF hypocretin-1 deficiency. Markedly decreased CSF hypocretin-1 levels could be a significant marker for identifying subgroups of narcolepsy patients without cataplexy.

Narcolepsy with cataplexy

Narcolepsy with cataplexy is a disabling sleep disorder affecting 0.02% of adults worldwide. It is characterised by severe, irresistible daytime sleepiness and sudden loss of muscle tone (cataplexy), and can be associated with sleep-onset or sleep-offset paralysis and hallucinations, frequent movement and awakening during sleep, and weight gain. Sleep monitoring during night and day shows rapid sleep onset and abnormal, shortened rapid-eye-movement sleep latencies. The onset of narcolepsy with cataplexy is usually during teenage and young adulthood and persists throughout the lifetime. Pathophysiological studies have shown that the disease is caused by the early loss of neurons in the hypothalamus that produce hypocretin, a wakefulness-associated neurotransmitter present in cerebrospinal fluid. The cause of neural loss could be autoimmune since most patients have the HLA DQB1*0602 allele that predisposes individuals to the disorder. Treatment is with stimulant drugs to suppress daytime sleepiness, antidepressants for cataplexy, and gamma hydroxybutyrate for both symptoms. Because narcolepsy is an under-recognised disease, it is important that general practitioners and other primary health-care workers identify abnormal daytime sleepiness early.

HLA-DQB1 allele and hypocretin in Korean narcoleptics with cataplexy

Cataplexy is one of the most pathognomonic symptoms in narcolepsy. This study was designed to investigate the frequency of the HLA-DQB1 allele and cerebrospinal fluid (CSF) hypocretin levels in Korean narcoleptics with cataplexy as compared with those who do not have cataplexy. Seventy-two narcoleptics were selected based on polysomnography and multiple sleep latency test as well as their history and clinical symptoms at Sleep Disorders Clinic. The patients were divided into a narcolepsy with cataplexy group (n=56) and a narcolepsy without cataplexy group (n=16). All patients were subjected to HLA typing to determine the frequency of DQB1 allele and to spinal tapping to measure the level of CSF hypocretin. In cataplexy-positive patients, as compared with cataplexy-negative patients, the frequency of HLA-DQB1*0602 was found to be significantly high (89.3% vs. 50.0%) (p=0.003). On the other hand, the frequency of HLA-DQB1*0601 was found to be significantly low (0% vs. 43.8%) (p<0.001). In 48 of 56 cataplexy-positive patients (85.7 %), hypocretin levels were decreased (<or=110 pg/mL). However, only 6 of 16 cataplexy-negative patients (37.5%) exhibited a decreased hyopcretin level (p<0.001). The high frequency of HLA-DQB1*0602, low frequency of HLA-DQB1*0601 and low hypocretin levels in cataplexy-positive groups suggest that cataplexy-positive narcolepsy might be an etiologically different disease entity from the cataplexy-negative.