Treatment with immunosuppressive and anti-inflammatory agents delays onset of canine genetic narcolepsy and reduces symptom severity

All Doberman pinschers and Labrador retrievers homozygous for a mutation of the hypocretin (orexin) receptor-2 (hcrtr2) gene develop narcolepsy under normal conditions. Degenerative changes and increased display of major histocompatibility complex class II antigens have been linked to symptom onset in genetically narcoleptic Doberman pinschers. This suggests that the immune system may contribute to neurodegenerative changes and narcoleptic symptomatology in these dogs. We therefore attempted to alter the course of canine genetic narcolepsy, as an initial test of principle, by administering a combination of three immunosuppressive and anti-inflammatory drugs chosen to suppress the immune response globally. Experimental dogs were treated with a combination of methylprednisolone, methotrexate and azathioprine orally starting within 3 weeks after birth, and raised in an environment that minimized pathogen exposure. Symptoms in treated and untreated animals were quantified using the food elicited cataplexy test (FECT), modified FECT and actigraphy. With drug treatment, time to cataplexy onset more than doubled, time spent in cataplexy during tests was reduced by more than 90% and nighttime sleep periods were consolidated. Short-term drug administration to control dogs did not reduce cataplexy symptoms, demonstrating that the drug regimen did not directly affect symptoms. Treatment was stopped at 6 months, after which experimental animals remained less symptomatic than controls until at least 2 years of age. This treatment is the first shown to affect symptom development in animal or human genetic narcolepsy. Our findings show that hcrtr2 mutation is not sufficient for the full symptomatic development of canine genetic narcolepsy and suggest that the immune system may play a role in the development of this disorder.

Sodium oxybate demonstrates long-term efficacy for the treatment of cataplexy in patients with narcolepsy

BACKGROUND AND PURPOSE

This study was conducted to demonstrate the long-term efficacy of sodium oxybate for the long-term treatment of cataplexy in patients with narcolepsy.

PATIENTS AND METHODS

Fifty-five (55) narcoleptic patients with cataplexy who had received continuous treatment with sodium oxybate for 7-44 months (mean 21 months) were enrolled in a double-blind treatment withdrawal paradigm. A 2-week single-blind sodium oxybate treatment phase established a baseline for the weekly occurrence of cataplexy. This was followed by a 2-week double-blind phase in which patients were randomized to receive unchanged drug therapy or placebo. Patients recorded the incidence of cataplexy attacks and adverse events in daily diaries.

RESULTS

During the 2-week double-blind phase, the abrupt cessation of sodium oxybate therapy in the placebo patients resulted in a significant increase in the number of cataplexy attacks (median=21; P<0.001 ) compared to patients who remained on sodium oxybate (median=0). Cataplexy attacks returned gradually with placebo patients reporting a median of 4.2 and 11.7 cataplexy attacks during the first and second weeks, respectively. There were no symptoms of frank withdrawal.

CONCLUSIONS

This controlled trial provides evidence supporting the long-term efficacy of sodium oxybate for the treatment of cataplexy. In contrast with antidepressant drug therapy, there is no evidence of rebound cataplexy upon abrupt discontinuation of treatment.

Excessive daytime sleepiness and sleep disturbances in patients with neurological diseases: epidemiology and management

Up to 12% of the general population experience excessive daytime sleepiness (EDS), with increasing prevalence in the elderly. EDS may lead to cognitive impairment, resulting in inattentiveness, poor memory, mood disorders and an increased risk of accidents. As a result, quality of life is reduced in most patients with EDS as well as in their caregiving spouses. There are a variety of causes leading to EDS, including CNS pathology, neurological dysfunction, associated sleep disorders with insufficient or fragmented sleep, and drug therapy. Since EDS accompanies many neurological disorders, such as neurodegenerative and neuromuscular diseases, neurologists should be familiar with the diagnosis, its major causes and with treatment options. The main focus of this article is on movement disorders, neuromuscular diseases, multiple sclerosis, dementia, cerebrovascular diseases, head and brain trauma, pain and epilepsy. General management strategies for EDS in all these neurological diseases include sleep hygiene aspects such as extensions of noctural time in bed and frequent naps during the day. Pharmacological treatment is generally achieved with stimulants such as amphetamine, methylphenidate and pemoline, or newer compounds such as modafinil.

Modafinil: preclinical, clinical, and post-marketing surveillance--a review of abuse liability issues

Modafinil is an agent that is frequently used in the treatment of narcolepsy. More recently it has been used in the treatment of a variety of psychiatric, neurological, and medical illnesses. Due to its ability to improve wakefulness, modafinil has been viewed as a stimulant. Based on the potential for modafinil to become widely used in a variety of syndromes and settings, evidence from preclinical in vitro and in vivo studies, human laboratory studies, and post-marketing experiences examining the potential abuse liability of modafinil were reviewed. Initial evidence suggests that modafinil has limited potential for large-scale abuse.

Schizophrenia and narcolepsy: a review with a case report

Several reports emphasize the importance of differentiating between psychosis in schizophrenia and the psychotic form of narcolepsy. The failure to identify narcolepsy leads to the labeling of patients as refractory to standard treatments for schizophrenia and retards consideration of intervention for narcolepsy in which psychosis can improve with psychostimulant treatment. Psychosis in patients with narcolepsy can occur in three ways: (i) as the psychotic form of narcolepsy with hypnagogic and hypnopompic hallucinations; (ii) as a result of psychostimulant use in a patient with narcolepsy; and (iii) as the concurrent psychosis of schizophrenia in a patient with narcolepsy. The present case report describes a difficult-to-treat patient who likely had concurrent schizophrenia and narcolepsy. It then summarizes the literature related to the treatment of the three types of patients with psychosis associated with narcolepsy.

Effects of IV and ICV hypocretin-1 (orexin A) in hypocretin receptor-2 gene mutated narcoleptic dogs and IV hypocretin-1 replacement therapy in a hypocretin-ligand-deficient narcoleptic dog

STUDY OBJECTIVES

Using two different canine models of narcolepsy, we evaluated the therapeutic effects of hypocretin-1 on cataplexy and sleep.

MEASUREMENTS AND RESULTS

Intracerebroventricular administration of hypocretin-1 (10 and 30 nmol per dog) but not intravenous administration (up to 6 microg/kg) induced significant wakefulness in control dogs. However, hypocretin-1 had no effect on cataplexy or wakefulness in hypocretin receptor-2 gene (Hcrtr2) mutated narcoleptic Dobermans. Only very high intravenously doses of hypocretin-1 (96-384 microg/kg) penetrated the brain, to produce a short-lasting anticataplectic effect in a hypocretin-ligand-deficient animal.

CONCLUSIONS

Hypocretin-1 administration, by central and systemic routes, does not improve narcoleptic symptoms in Hcrtr2 mutated Dobermans. Systemic hypocretin-1 hardly crosses the blood-brain barrier to produce therapeutic effects. The development of more centrally penetrable and longer lasting hypocretin analogs will be needed to further explore this therapeutic pathway in humans.

Modafinil in the treatment of excessive daytime sleepiness in children

BACKGROUND

Modafinil is an alerting agent approved for the treatment of narcolepsy in adults. There are no studies examining the long-term effects and safety profile of modafinil in children with excessive daytime somnolence (EDS).

OBJECTIVES

To determine the effects of modafinil on clinical manifestations of narcolepsy and idiopathic hypersomnia.

METHODS

A systematic chart review was conducted for 13 children (mean age 11.0+/-5.3 years, six males, 10 with narcolepsy and three with idiopathic hypersomnia) receiving modafinil.

RESULTS

The mean modafinil dose was 346+/-119 mg/day, with a mean treatment duration of 15.6+/-7.8 months. For approximately 90% of the children treated, parents reported a favorable response with the reduction in sudden sleep attacks, as documented by sleep-wake diaries. One child failed to improve on 400 mg/day modafinil and was switched to methylphenidate. Two other children showed only partial improvement and required additional stimulant medication to control EDS symptoms. Seven children underwent repeated nocturnal polysomnography and multiple sleep latency tests (MSLT). Compared to baseline MSLT measures (mean sleep latency: 6.6+/-3.7 min), modafinil prolonged mean sleep latency (10.2+/-4.8 min, p=0.02) without significant alteration in nocturnal polysomnographic measures. However, a trend towards REM sleep reduction was noted (16.8+/-5.1%TST vs. 11.8+/-6.2%TST). Exacerbation of seizures and psychotic symptoms was reported with modafinil therapy in two children with preexisting conditions. Hematological and hepatic functions assessed every 3 months remained unaltered.

CONCLUSION

Modafinil has a modest, yet significant effect on EDS in children and appears to be safe and well tolerated.

A putative link between childhood narcolepsy and obesity

BACKGROUND AND PURPOSE

While there have been anecdotal observations of binge eating in childhood-onset narcolepsy, the possible relationship between increased weight gain and childhood-onset narcolepsy has not been evaluated.

PATIENTS AND METHODS

A retrospective, case-control design was used to compare the body mass index (BMI) of 31 narcolepsy children at the time of diagnosis with that of healthy, age- and gender-matched controls.

RESULTS

The median BMI in the narcolepsy subjects was 22.93 as compared to that in controls of 20.36 (P=0.001). BMI did not differ significantly between narcolepsy subjects who had received prior psychotropic medications and those who had not. The mean BMI of 22 of 31 narcolepsy subjects who had not received psychotropic medications prior to diagnosis was also significantly higher than that of controls (25.1, SEM 1.53 versus 21.1, SEM 0.56; P=0.008 ).

CONCLUSION

The tendency for increased weight gain is intrinsic to childhood narcolepsy and is manifested relatively early in the course of the disorder. Correlation of this finding with hypocretin and leptin metabolism may further understanding of the pathogenesis of narcolepsy.

Narcolepsy in the older adult: epidemiology, diagnosis and management

Narcolepsy is a disorder of impaired expression of wakefulness and rapid-eye-movement (REM) sleep. This manifests as excessive daytime sleepiness and expression of individual physiological correlates of REM sleep that include cataplexy and sleep paralysis (REM sleep atonia intruding into wakefulness), impaired maintenance of REM sleep atonia (e.g. REM sleep behaviour disorder [RBD]), and dream imagery intruding into wakefulness (e.g. hypnagogic and hypnopompic hallucinations). Excessive sleepiness typically begins in the second or third decade followed by expression of auxiliary symptoms. Only cataplexy exhibits a high specificity for diagnosis of narcolepsy. While the natural history is poorly defined, narcolepsy appears to be lifelong but not progressive. Mild disease severity, misdiagnoses or long delays in cataplexy expression often cause long intervals between symptom onset, presentation and diagnosis. Only 15-30% of narcoleptic individuals are ever diagnosed or treated, and nearly half first present for diagnosis after the age of 40 years. Attention to periodic leg movements (PLM), sleep apnoea and RBD is particularly important in the management of the older narcoleptic patient, in whom these conditions are more likely to occur. Diagnosis requires nocturnal polysomnography (NPSG) followed by multiple sleep latency testing (MSLT). The NPSG of a narcoleptic patient may be totally normal, or demonstrate the patient has a short nocturnal REM sleep latency, exhibits unexplained arousals or PLM. The MSLT diagnostic criteria for narcolepsy include short sleep latencies (<8 minutes) and at least two naps with sleep-onset REM sleep. Treatment includes counselling as to the chronic nature of narcolepsy, the potential for developing further symptoms reflective of REM sleep dyscontrol, and the hazards associated with driving and operating machinery. Elderly narcoleptic patients, despite age-related decrements in sleep quality, are generally less sleepy and less likely to evidence REM sleep dyscontrol. Nonpharmacological management also includes maintenance of a strict wake-sleep schedule, good sleep hygiene, the benefits of afternoon naps and a programme of regular exercise. Thereafter, treatment is highly individualised, depending on the severity of daytime sleepiness, cataplexy and sleep disruption. Wake-promoting agents include the traditional psychostimulants. More recently, treatment with the 'activating' antidepressants and the novel wake-promoting agent modafinil has been advocated. Cataplexy is especially responsive to antidepressants which enhance synaptic levels of noradrenaline (norepinephrine) and/or serotonin. Obstructive sleep apnoea and PLMs are more common in narcolepsy and should be suspected when previously well controlled older narcolepsy patients exhibit a worsening of symptoms. The discovery that narcolepsy/cataplexy results from the absence of neuroexcitatory properties of the hypothalamic hypocretin-peptidergic system will significantly advance understanding and treatment of the symptom complex in the future.

Efficacy and safety of modafinil for improving daytime wakefulness in patients treated previously with psychostimulants

OBJECTIVES

To assess the efficacy and safety of modafinil for improving wakefulness in narcolepsy patients treated previously with psychostimulants.

BACKGROUND

Modafinil has become a standard therapy for improving daytime wakefulness in narcolepsy patients and may be a useful therapeutic alternative to psychostimulants used to improve waking function in other medical conditions. Modafinil is chemically dissimilar to and has a pharmacological profile that differs from the psychostimulants. Modafinil has a low abuse potential and is well tolerated.

METHODS

Patients (N=151) with narcolepsy who had been unsatisfactorily treated with dextroamphetamine (N=48), methylphenidate (N=66), or pemoline (N=37) were enrolled in this 6-week, open-label, multicenter study. Following a 2-week washout period, patients received modafinil once daily (Week 1, 200 mg; Weeks 2-6, 200 or 400 mg). Efficacy was evaluated at Weeks 1, 2, and 6 using the Epworth Sleepiness Scale and the Clinical Global Impression of Change. Adverse events were monitored throughout the study.

RESULTS

Treatment with modafinil improved daytime wakefulness versus baseline regardless of which psychostimulant was taken previously. Mean ESS scores were improved after 1 week of treatment with modafinil. Improvements were maintained throughout the 6 weeks of treatment (all P<0.001 versus baseline after washout). At Week 6, 79% of all patients were considered to be clinically improved relative to post-washout baseline. The most frequent adverse events were headache, nausea, and insomnia; the majority of adverse events were mild or moderate in nature. Approximately 70% of patients were receiving 400 mg of modafinil once daily at the end of the study.

CONCLUSION

During this 6-week, open-label study, modafinil was an effective and well-tolerated treatment for improving daytime wakefulness in narcolepsy patients previously treated with psychostimulants.

Effect of modafinil on fatigue, mood, and health-related quality of life in patients with narcolepsy

INTRODUCTION

In addition to excessive sleepiness, patients with narcolepsy often have significant fatigue, depressed mood, and decreased quality of life.

OBJECTIVE

To determine whether treatment with modafinil for excessive sleepiness improves fatigue, mood, and health-related quality of life (HRQOL) in patients with narcolepsy.

MATERIALS AND METHODS

Outpatients with narcolepsy underwent a 14-day washout of psychostimulants and then were enrolled in this 6-week, open-label, multicenter study. Patients received modafinil starting at 200 mg once daily for week 1, and then 200 or 400 mg daily for weeks 2 through 6. Efficacy was evaluated using the Medical Outcomes Study 36-Item Short-Form Health Survey (SF-36) and the Profile of Mood States (POMS). Safety was assessed by monitoring adverse events (AE).

RESULTS

At baseline, 151 patients had moderate to severe excessive sleepiness (mean Epworth Sleepiness Scale score=17.8+/-4.4). Most patients (> or =70% of 123 who completed the study) received 400 mg modafinil once daily during weeks 2 through 6. Modafinil significantly improved HRQOL, based on SF-36 measures of mental and physical component summary scores and subdomain scores of role-physical, social functioning, and vitality (each P<0.001). Modafinil treatment was also associated with significantly reduced fatigue and significantly improved vigor and cognition as assessed by the POMS (each P<0.001) from weeks 1 through 6. The most frequent AE with modafinil treatment were headache, nausea, and insomnia; most AE were mild or moderate in nature. Only seven patients (5%) withdrew from the study because of AE.

CONCLUSION

In narcolepsy patients who were switched from psychostimulants, modafinil therapy improved HRQOL and subjective feelings of vigor and cognitive functioning and reduced fatigue.

Melatonin in patients with reduced REM sleep duration: two randomized controlled trials

Recent data suggest that melatonin may influence human physiology, including the sleep-wake cycle, in a time-dependent manner via the body's internal clock. Rapid-eye-movement (REM) sleep expression is strongly circadian modulated, and the impact of REM sleep on primary brain functions, metabolic processes, and immune system function has become increasingly clear over the past decade. In our study, we evaluated the effects of exogenous melatonin on disturbed REM sleep in humans. Fourteen consecutive outpatients (five women, nine men; mean age, 50 yr) with unselected neuropsychiatric sleep disorders and reduced REM sleep duration (25% or more below age norm according to diagnostic polysomnography) were included in two consecutive, randomized, double-blind, placebo-controlled, parallel design clinical trials. Patients received 3 mg melatonin daily, administered between 2200 and 2300 h for 4 wk. The results of the study show that melatonin was significantly more effective than placebo: patients on melatonin experienced significant increases in REM sleep percentage (baseline/melatonin, 14.7/17.8 vs. baseline/placebo, 14.3/12.0) and improvements in subjective measures of daytime dysfunction as well as clinical global impression score. Melatonin did not shift circadian phase or suppress temperature but did increase REM sleep continuity and promote decline in rectal temperature during sleep. These results were confirmed in patients who received melatonin in the second study (REM sleep percentage baseline/placebo/melatonin, 14.3/12.0/17.9). In patients who received melatonin in the first study and placebo in the second, the above mentioned effects outlasted the period of melatonin administration and diminished only slowly over time (REM sleep percentage baseline/melatonin/placebo, 14.7/17.8/16.2). Our findings show that exogenous melatonin, when administered at the appropriate time, seems to normalize circadian variation in human physiology. It may, therefore, have a strong impact on general health, especially in the elderly and in shift workers.

Dosing regimen effects of modafinil for improving daytime wakefulness in patients with narcolepsy

In a multicenter, randomized, double-blind study the authors compared the efficacy of modafinil 400 mg once daily, 400 mg given in a split dose, or 200 mg once daily for maintaining wakefulness throughout the day in patients (N = 32) with narcolepsy reporting a positive daytime response to modafinil but late-afternoon/evening sleepiness. Efficacy evaluations included an extended Maintenance of Wakefulness Test (9:00 am to 9:00 pm), the Clinical Global Impression of Change scale, and the Epworth Sleepiness Scale. Modafinil demonstrated significant improvement in wakefulness as assessed by the Epworth Sleepiness Scale compared with placebo at baseline (all P < 0.001). Modafinil significantly improved patients' ability to sustain wakefulness, as demonstrated by mean sleep latency at week 3 compared with placebo at baseline (all P < 0.001). The 400-mg split-dose regimen improved wakefulness significantly in the evening compared with the 200-mg and 400-mg once-daily regimen (both P < 0.05). The percentage of patients rated as "much improved" or "very much improved" with respect to evening sleepiness was 27%, 82%, and 80% in the 200-mg, 400-mg once-daily, and 400-mg split-dose groups, respectively. Adverse events were mild to moderate in nature and included headache, nausea, nervousness, dyspepsia, pain, and vomiting (all 6%). Some patients may benefit from 400-mg doses of modafinil taken once daily compared with 200-mg doses. A split-dose 400-mg regimen may be superior to once-daily dosing for sustaining wakefulness throughout the entire waking day.

Pharmacological management of narcolepsy

Narcolepsy is a disabling disorder characterised by excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, sleep paralysis and disturbed nocturnal sleep. Traditionally, a wide variety of substances are used in the symptomatic pharmacological treatment of narcolepsy. Several generally more-tolerated substances have been added to the therapeutic repertoire after extensive testing in large patient populations during recent years. This review addresses the state-of-the-art knowledge about the pharmacological treatment of narcolepsy along with the personal view of the authors. The recent discovery that narcolepsy is caused by deficient hypocretin (orexin) transmission opens a perspective on causal therapy.

Report of a Case of Immunosuppression with Prednisone in an 8-Year-Old Boy with an Acute Onset of Hypocretin-deficiency Narcolepsy

OBJECTIVE

To explore whether acute destruction of hypocretin cells in a patient with narcolepsy could be detected and if the course of the disease could be reversed or altered by the use of prednisone for immunosuppression.

DESIGN

Case report.

SETTING

A sleep-clinic population in a tertiary-care hospital.

PATIENT

An 8-year-old boy with a very acute recent (< 2 month) onset of sleepiness.

METHODS

Sleep studies; fluid-attenuated inversion recovery and gadolinium magnetic resonance imaging studies with a focus on the hypothalamus; examinations of cerebrospinal fluid for cytology, protein, and hypocretin-1 levels; and HLA typing were performed.

INTERVENTION

A 3-week regimen of 1 mg x kg(-1) x day(-1) of prednisone was administered in an attempt to modify the course of the disease.

RESULTS AND CONCLUSION

Sleep evaluations were consistent with a diagnosis of narcolepsy. Hypocretin-1 was absent in the cerebrospinal fluid, and HLA-DQB1*0602 was present. All other results were within normal limits, and prednisone did not have any noticeable effects. Clinical manifestation of narcolepsy might occur when the hypocretin cell damage is too advanced to be reversible.

Acquired narcolepsy in an acromegalic patient who underwent pituitary irradiation

The authors report the case of a 60-year-old man with acromegaly, who developed narcolepsy 2 weeks after completing radiotherapy for a pituitary adenoma. Cataplexy and sleepiness were predominant symptoms. Onset of narcolepsy is unusual at this age and the temporal relationship following radiotherapy suggests this treatment was implicated. His CSF hypocretin levels were normal, indicating other factors may be important in his narcolepsy.

Ritanserin improves sleep quality in narcolepsy

A recent study in narcolepsy patients has shown that ritanserin, a 5HT2-antagonist, reduced wake after sleep onset times and subjective sleepiness during daytime. To assess the efficacy of this compound in a statistically sufficient number of narcoleptic patients a double-blind, placebo-controlled, European multi-center study on the effects of ritanserin on daytime sleepiness, the feeling of being refreshed in the morning, number of unwanted sleep periods and slow-wave sleep was performed. All 134 narcolepsy patients were allowed to remain on stable concomitant antidepressant, stimulant and gammahydroxybutyrate medication during the trial. Patients were randomly assigned to treatment with 5 mg or 10 mg ritanserin or placebo given once daily for 28 days. Efficacy was measured by two 40-hour polysomnographic recordings, visual analogue scales and physician, partner, parents and patient-rated sleep-wake behavior tests prior to and after the trial. Patients kept diaries on sleepiness, numbers of wanted and unwanted sleep periods, feeling of being refreshed and frequency of narcoleptic symptoms during the entire treatment period. Treatment with 5 and 10 mg ritanserin significantly improved the 'feeling of being refreshed in the morning,' but no other narcoleptic symptoms as assessed in the diary. Whereas investigators had the impression that the primary efficacy parameters were not improved by ritanserin, patients reported significant improvements in four out of six parameters, and patients partners in two out of six parameters with 5 mg ritanserin compared to placebo. Both ritanserin doses resulted in a significant increase of nocturnal slow-wave sleep (percentage of total sleep time) and a significant, dose-dependent reduction in NREM stage 1 percentage during daytime sleep. The significant polysomnographic findings were not paralleled by changes in the subjective parameters daytime sleepiness or number of unplanned sleep periods. In contrast to the first study on narcoleptic patients, ritanserin only improved one subjective parameter, but did not improve objective sleep quality or number of "sleep attacks" or reduce "wake after sleep onset" during night or daytime sleep. In conclusion, ritanserin may serve as add-on medication for the treatment of impaired sleep quality in narcoleptic patients, but not as a stimulant or hypnotic type of medication.