Life effects of narcolepsy in 180 patients from North America, Asia and Europe compared to matched controls

Emerging treatments for narcolepsy and its related disorders

IMPORTANCE OF THE FIELD

Narcolepsy is a chronic sleep disorder, characterized by excessive daytime sleepiness (EDS), cataplexy, hypnagogic hallucinations, sleep paralysis and nocturnal sleep disruption. Non-pharmacological treatments (i.e., behavioral modification) are often helpful for the clinical management of narcoleptic patients. As these symptoms are often disabling, most patients need life-long treatments. Over 90% of diagnosed narcoleptic patients are currently prescribed medications to control their symptoms; however, available treatments are merely symptomatic.

AREAS COVERED IN THIS REVIEW

This review presents a description of the clinical symptoms of narcolepsy, followed by a discussion of the state-of-the-art knowledge regarding the disorder and related emerging treatments. In preparing this review, an extensive literature search was conducted using Pubmed. Only selected references from 1970 to 2008 are cited.

WHAT THE READER WILL GAIN

This review focuses on emerging treatments for human narcolepsy, and the reader will gain significant knowledge of current and future treatment for this and related disorders. Traditionally, amphetamine-like stimulants (i.e., dopaminergic release enhancers) have been used for clinical management to improve EDS, and tricyclic antidepressants have been used as anticataplectics. However, treatments have recently evolved which utilize better tolerated compounds, such as modafinil (for EDS) and adrenergic/serotonergic selective reuptake inhibitors (as anticataplectics). In addition, night time administration of a short-acting sedative, gamma-hydroxybutyrate, has been used for the treatment for EDS and cataplexy. As a large majority of human narcolepsy is hypocretin peptide deficient, hypocretin replacement therapy may also be a new therapeutic option; yet, this option is still unavailable. In addition to the hypocretin-based therapy, a series of new treatments are currently being tested in animal and/or humans models. These potential options include novel stimulant and anticataplectic drugs as well as immunotherapy, based on current knowledge of the pathophysiology of narcolepsy with cataplexy.

TAKE HOME MESSAGE

We expect that more pathophysiology-based treatments, capable of curing and/or preventing narcolepsy and related diseases, will be available in near future. As cases of EDS, associated with other neurological conditions (i.e., symptomatic narcolepsy or narcolepsy due to medical conditions), are often linked with hypocretin deficiency, these novel therapeutic options may also be applied to treatment of these disabling conditions.

Prevalence of narcolepsy with cataplexy in Norway

OBJECTIVES

Narcolepsy is a lifelong disabling disorder that may be alleviated by relevant treatment. Patients frequently report 10-15 years from the first symptoms to the time they get the diagnosis and treatment can be started. In order to offer a sufficient diagnostic and therapeutic service to this patient group, a reliable estimation of the prevalence of the disorder is important. A study of the prevalence of narcolepsy with cataplexy in Norway was therefore undertaken.

MATERIALS AND METHODS

The Ullanlinna Narcolepsy scale (UNS) was sent to 14548 randomly selected Norwegians between 20 and 60 years. Additionally, the study included telephone interviews and clinical evaluation of responders with >or=14 points on the UNS, and in those with suspected narcolepsy, polygraphic sleep recordings and human leucocyte antigen (HLA)-typing.

RESULTS

A total of 8992 responders answered the questionnaire (response rate 61.8%), 267 had >or=14 points on the UNS, 156 were interviewed and 15 had sleep recordings. In two HLADQB1*0602-positive patients sleep recordings were compatible with narcolepsy.

CONCLUSIONS

The results indicate a prevalence of 0.022% and approximately 1000 patients with narcolepsy with cataplexy in Norway.

Real-time automated neural-network sleep classifier using single channel EEG recording for detection of narcolepsy episodes

Conventional sleep staging and classification methods involve complicated settings to acquire multiple electrophysiological signals for extended recording durations, followed by specialists' analysis which is a time consuming exercise. These procedures need to be carried out in sleep clinics and are not suitable for applications based on real-time sleep monitoring and analysis. In this paper, a real-time sleep staging and classification technique is proposed using single EEG channel based on an artificial neural network classifier. This method is optimized to run on portable processing platforms with limited processing capabilities.

Effect of modafinil on cerebral blood flow in narcolepsy patients

BACKGROUND

To investigate the effects of modafinil on regional cerebral blood flow (rCBF) in narcolepsy, we performed 99mTc-ethylcysteinate dimer single photon emission computed tomography (SPECT) before and after modafinil or placebo medication.

METHODS

Brain SPECT was performed twice during the awake state before and after modafinil or placebo administration for 4 weeks in 43 drug-naive narcoleptics with cataplexy (M/F = 23/20, 29.5 +/- 5.8 years). For SPM analysis, all SPECT images were spatially normalized to the standard SPECT template and then smoothed using a 12-mm full width at half-maximum Gaussian kernel. The paired t-test was used to compare pre- and post-modafinil or placebo SPECT images.

RESULTS

The mean modafinil dose used was 207.8 +/- 62.3 mg/day. Modafinil significantly reduced Epworth Sleepiness Scale scores from 20.3 +/- 2.1 to 5.2 +/- 3.1 (P < 0.01), while placebo did not. Compared to the off-modafinil condition, the on-modafinil condition showed significantly increased rCBF in the right dorsolateral and bilateral medial prefrontal cortices. Conversely, after modafinil administration, rCBF was decreased in bilateral precentral gyri, left hippocampus, left fusiform gyrus, bilateral lingual gyri, and cerebellum. There was no significant rCBF change after placebo administration.

CONCLUSION

By a chronic administration of modafinil in narcoleptic patients, rCBF increased in the bilateral prefrontal cortices, whereas it decreased in left mesio/basal, temporal, bilateral occipital areas, and cerebellum.

Prevalence of narcolepsy-cataplexy in Korean adolescents

BACKGROUND

Narcolepsy typically begins between adolescence and early adulthood causing severe neuropsychiatric impairments, but few prevalence studies are available on adolescent narcoleptics. In the present study, we investigated the prevalence of narcolepsy-cataplexy in adolescents.

METHODS

In total 20,407 students, aged 14-19 years, participated in this study. Ullanlinna Narcolepsy Scale (UNS) was applied to all subjects and those with a UNS score of > or =14 were contacted by phone for semi-structured interview. Subjects then suspected of having narcolepsy participated in a laboratory investigation, which included polysomnography and HLA typing, or were interviewed in detail by telephone.

RESULTS

Three subjects were finally diagnosed as narcolepsy with cataplexy and seven subjects might be diagnosed as narcolepsy without cataplexy. Among three narcoleptics with cataplexy, two subjects were HLA-DQB1*0602 and DRB1*1501 positive, but one subject had no test of HLA typing. The prevalence of narcolepsy with cataplexy in Korean adolescence was thus determined to be 0.015% (95% confidence interval = 0.0-0.0313%).

CONCLUSION

This epidemiologic study is the first of its type on adolescent narcolepsy to use the International Classification of Sleep Disorders, 2nd edition (ICSD-2) diagnostic criteria. Considering those cases with an onset after adolescence were not included, the prevalence of narcolepsy with cataplexy determined in the present study is comparable with that of other studies in adults.

Treatment of narcolepsy and other hypersomnias of central origin

OBJECTIVE

The purpose of this paper is to summarize current knowledge about treatment of narcolepsy and other hypersomnias of central origin.

METHODS

The task force performed a systematic and comprehensive review of the relevant literature and graded the evidence using the Oxford grading system. This paper discusses the strengths and limitations of the available evidence regarding treatment of these conditions, and summarizes key information about safety of these medications. Our findings provide the foundation for development of evidence-based practice parameters on this topic by the Standards of Practice Committee of the American Academy of Sleep Medicine.

RESULTS

The majority of recent papers in this field provide information about use of modafinil or sodium oxybate for treatment of sleepiness associated with narcolepsy. Several large randomized, placebo-controlled studies indicate that modafinil and sodium oxybate are effective for treatment of hypersomnia due to narcolepsy. We identified no studies that report direct comparison of these newer medications versus traditional stimulants, or that indicate what proportion of patients treated initially with these medications require transition to traditional stimulants or to combination therapy to achieve adequate alertness. As with the traditional stimulants, modafinil and sodium oxybate provide, at best, only moderate improvement in alertness rather than full restoration of alertness in patients with narcolepsy. Several large randomized placebo-controlled studies demonstrate that sodium oxybate is effective for treatment of cataplexy associated with narcolepsy, and earlier studies provide limited data to support the effectiveness of fluoxetine and tricyclic antidepressants for treatment of cataplexy. Our findings indicate that very few reports provide information regarding treatment of special populations such as children, older adults, and pregnant or breastfeeding women. The available literature provides a modest amount of information about improvement in quality of life in association with treatment, patient preferences among the different medications, or patient compliance.

CONCLUSION

Several recent studies provide evidence that modafinil and sodium oxybate are effective for treatment of hypersomnia due to narcolepsy. No studies were identified that report direct comparison of these newer medications with traditional stimulants. Despite significant advances in understanding the pathophysiology of narcolepsy, we do not have an ideal treatment to restore full and sustained alertness. Future investigations should be directed toward development of more effective and better tolerated therapies, and primary prevention.

Antidepressant drugs for narcolepsy

BACKGROUND

Narcolepsy is a disorder of the central nervous system, the main symptoms of which are excessive daytime sleepiness (EDS) and cataplexy (an abrupt and reversible decrease in or loss of muscle tone, affecting the limbs or trunk or both, elicited by emotional stimuli). Narcolepsy has an adverse impact on people's quality of life. Together with stimulant drugs (used to control EDS), antidepressants are usually recommended to counteract cataplexy. In addition, some antidepressants are also reported to improve EDS.

OBJECTIVES

To evaluate the effects of antidepressant drugs on EDS, cataplexy, quality of life, and their side effects in people with narcolepsy.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 2, 2007), MEDLINE (1966 to 2007), EMBASE (1980 to 2007), PsycINFO (1872 to 2007), and CINAHL (1981 to 2007). Bibliographies of identified articles were reviewed to find additional references. Unpublished randomised trials were searched for by consulting governmental and non-governmental clinical trial registers, disease-specific websites, investigators and experts in the field, pharmaceutical companies/manufacturers.

SELECTION CRITERIA

Parallel or cross-over randomised or quasi-randomised controlled trials testing the treatment of narcolepsy with any type of antidepressant drug versus no treatment, placebo, or another antidepressant drug.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data.

MAIN RESULTS

Three cross-over and two parallel trials were included with a total of 246 participants. The methodological quality of all studies was unclear. As the trials tested different comparisons, or had a different design or dealt with different outcome measures, meta-analysis was not performed. In one cross-over trial (10 participants) femoxetine had no significant effect in eliminating or reducing EDS but significantly reduced cataplexy. Mild and transient side effects were reported in the femoxetine treatment period by two participants. In a second cross-over trial (56 participants) viloxazine significantly reduced EDS and cataplexy. In a third cross-over trial the authors inappropriately treated the trial design as a parallel study and no conclusions can be reached in favour of either drug. Two more trials with parallel design tested ritanserin versus placebo without finding differences of effectiveness in reducing EDS or cataplexy.

AUTHORS' CONCLUSIONS

There was no good quality evidence that antidepressants are effective for narcolepsy or improve quality of life. Despite the clinical consensus recommending antidepressants for cataplexy there is scarce evidence that antidepressants have a positive effect on this symptom. There is a clear need for well-designed randomised controlled trials to assess the effect of antidepressants on narcolepsy.

Health-related quality of life in patients with narcolepsy

BACKGROUND

To evaluate the health-related quality of life (HRQoL) in patients suffering from narcolepsy.

METHODS

Subjects included 75 narcoleptic patients diagnosed at the Hephata Klinik, Germany, who met the International Classification of Sleep Disorders (ICSD) criteria for narcolepsy. A standardized telephone interview was used to inquire about the disease and its burdens to the patients. HRQoL was recorded using the 36-item short-form Medical Outcomes Study (SF-36) as well as the Euroqol (EQ-5D). Frequency and factors of influence on decreased HRQoL were evaluated by using bivariate and multivariate analyses.

RESULTS

Patients with narcolepsy had considerably lower scores on all eight domains of the SF-36 compared to the general German population. In particular, scores were poor for the dimensions "physical role", "vitality", and "general health perception". Forty-eight percent of the patients reported problems in at least one of the EQ-5D items; most frequent were problems in the dimension "usual activity" (63.8%), "pain/discomfort" (61.7%) and "anxiety/depression" (41.1%). Difficulty maintaining "self-care" was documented only by 6.8%. The mean VAS score was 60.7%. Interestingly, signs and symptoms of narcolepsy, except for irresistible sleep episodes (p<0.03), had only a minor impact on HRQoL. Multivariate analyses confirmed a strong influence of employment status, living with a partner, excessive daytime sleepiness (EDS) and professional advancement.

CONCLUSIONS

HRQoL is considerably reduced in patients, with narcolepsy affecting the different dimensions to various degrees. Factors other than clinical signs and symptoms are associated also with poor HRQoL. Measures should be taken to integrate those factors into healthcare guidelines in order to improve the quality of life in patients with narcolepsy.

Computerized assessment of cognitive impairment in narcoleptic patients

OBJECTIVES - This study was aimed to investigate the comprehensive range of cognitive performance using the objective computerized assessment system in narcolepsy and age, gender, and IQ-matched healthy comparison. MATERIALS AND METHODS - The cognitive functions of 24 patients with narcolepsy and 24 healthy comparison subjects were assessed. RESULTS - Narcoleptics performed more frequent omission and commission errors in the vigilance test, and more frequent omission errors in the continuous performance test. Narcoleptics' response time was slower than healthy volunteers, and the differences were more exaggerated in more complex tasks. The simple repetitious working performance was more impaired in the narcoleptic subjects than in healthy comparison subjects. Narcolepsy group showed worse performances in the determination unit than the comparison group, and this impairment became more salient in faster stimuli relative to slower ones. CONCLUSIONS - Narcoleptics have deficits of efficiency in attention allocation and execution as well as simple vigilance problem.

Clinical and neurobiological aspects of narcolepsy

Narcolepsy is characterized by excessive daytime sleepiness (EDS), cataplexy and/or other dissociated manifestations of rapid eye movement (REM) sleep (hypnagogic hallucinations and sleep paralysis). Narcolepsy is currently treated with amphetamine-like central nervous system (CNS) stimulants (for EDS) and antidepressants (for cataplexy). Some other classes of compounds such as modafinil (a non-amphetamine wake-promoting compound for EDS) and gamma-hydroxybutyrate (GHB, a short-acting sedative for EDS/fragmented nighttime sleep and cataplexy) given at night are also employed. The major pathophysiology of human narcolepsy has been recently elucidated based on the discovery of narcolepsy genes in animals. Using forward (i.e., positional cloning in canine narcolepsy) and reverse (i.e., mouse gene knockout) genetics, the genes involved in the pathogenesis of narcolepsy (hypocretin/orexin ligand and its receptor) in animals have been identified. Hypocretins/orexins are novel hypothalamic neuropeptides also involved in various hypothalamic functions such as energy homeostasis and neuroendocrine functions. Mutations in hypocretin-related genes are rare in humans, but hypocretin-ligand deficiency is found in many narcolepsy-cataplexy cases. In this review, the clinical, pathophysiological and pharmacological aspects of narcolepsy are discussed.

Sleep disorders, sleepiness and traffic safety: a public health menace

Sleep disorders are not uncommon and have been widely reported throughout the world. They have a profound impact on industrialized 24-h societies. Consequences of these problems include impaired social and recreational activities, increased human errors, loss of productivity, and elevated risk of accidents. Conditions such as acute and chronic insomnia, sleep loss, excessive sleepiness, shift-work, jet lag, narcolepsy, and sleep apnea warrant public health attention, since residual sleepiness during the day may affect performance of daily activities such as driving a car. Benzodiazepine hypnotics and zopiclone promote sleep, both having residual effects the following day including sleepiness and reduced alertness. In contrast, the non-benzodiazepine hypnotics zolpidem and zaleplon have no significant next-day residual effects when taken as recommended. Research on the effects of wakefulness-promoting drugs on driving ability is limited. Countermeasures for excessive daytime sleepiness have a limited effect. There is a need for a social awareness program to educate the public about the potential consequences of various sleep disorders such as narcolepsy, sleep apnea, shift-work-related sleep loss, and excessive daytime sleepiness in order to reduce the number of sleep-related traffic accidents.

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.

Low-resolution brain electromagnetic tomography (LORETA) identifies brain regions linked to psychometric performance under modafinil in narcolepsy

Low-resolution brain electromagnetic tomography (LORETA) showed a functional deterioration of the fronto-temporo-parietal network of the right hemispheric vigilance system in narcolepsy and a therapeutic effect of modafinil. The aim of this study was to determine the effects of modafinil on cognitive and thymopsychic variables in patients with narcolepsy and investigate whether neurophysiological vigilance changes correlate with cognitive and subjective vigilance alterations at the behavioral level. In a double-blind, placebo-controlled crossover design, EEG-LORETA and psychometric data were obtained during midmorning hours in 15 narcoleptics before and after 3 weeks of placebo or 400 mg modafinil. Cognitive investigations included the Pauli Test and complex reaction time. Thymopsychic/psychophysiological evaluation comprised drive, mood, affectivity, wakefulness, depression, anxiety, the Symptom Checklist 90 and critical flicker frequency. The Multiple Sleep Latency Test (MSLT) and the Epworth Sleepiness Scale (ESS) were performed too. Cognitive performance (Pauli Test) was significantly better after modafinil than after placebo. Concerning reaction time and thymopsychic variables, no significant differences were observed. Correlation analyses revealed that a decrease in prefrontal delta, theta and alpha-1 power correlated with an improvement in cognitive performance. Moreover, drowsiness was positively correlated with theta power in parietal and medial prefrontal regions and beta-1 and beta-2 power in occipital regions. A less significant correlation was observed between midmorning EEG LORETA and the MSLT; between EEG LORETA and the ESS, the correlation was even weaker. In conclusion, modafinil did not influence thymopsychic variables in narcolepsy, but it significantly improved cognitive performance, which may be related to medial prefrontal activity processes identified by LORETA.

Cognitive deficits in narcolepsy

The aim of the investigations was to explore the nature and the severity of cognitive deficits in narcolepsy patients. In two studies, narcolepsy patients were compared with matched control subjects on a range of attention, memory and executive control tasks. Impairments were only observed on attention and executive function tasks which involved higher demands on inhibition or task management abilities whereas relatively routine memory and attention tasks yielded intact performance in narcolepsy patients. The overall pattern of results indicates an executive control deficit in narcolepsy which might be related to a reduction of available cognitive processing resources because of the need for continuous allocation of resources to monitoring and maintenance of vigilance.

Psychiatric aspects of organic sleep disorders

In recent years, a number of studies have attempted to characterize psychological disturbances related to various sleep disorders. The objective of this type of research is to investigate the possibility that psychopathology may represent an etiological factor, a complication, and/or a target for treatment. In addition, disordered sleep can present itself in a complex and atypical fashion in which the primary sleep-related component may not be immediately apparent. This article reviews the evidence for a relationship between organic sleep disorders and psychiatric morbidity. Generally, it can be concluded that organic sleep disorders have a profound negative impact on most domains of health-related quality of life. Results for the sleep disorders that have been studied (narcolepsy idiopathic hypersomnia, sleep apnea/hypopnea syndrome, restless legs syndrome, periodic limb movement disorder, and circadian sleep disorders) show strong evidence for an association with mood disorders. After treatment, depression scores may or may not improve to the level of population norms, suggesting that this relationship is more complex than one of mere cause and effect.

Antidepressant drugs for narcolepsy

BACKGROUND

Narcolepsy is a disorder of the central nervous system, the main symptoms of which are excessive daytime sleepiness (EDS) and cataplexy (an abrupt and reversible decrease in or loss of muscle tone, affecting the limbs and/or trunk, elicited by emotional stimuli). Narcolepsy has an adverse impact on people's quality of life. Together with stimulant drugs (used to control EDS), antidepressants are usually recommended to counteract cataplexy. In addition, some antidepressants are also reported to improve EDS.

OBJECTIVES

To evaluate the effects of antidepressant drugs on EDS, cataplexy, quality of life, and their side effects in people with narcolepsy.

SEARCH STRATEGY

We searched the Cochrane Central Register of Controlled Trials (The Cochrane Library Issue 3, 2003), MEDLINE (1966 to 2003), EMBASE (1980 to 2003), PsycINFO (1872 to 2003), and CINAHL (1981 to 2003). Bibliographies of identified articles were reviewed to find additional references. Unpublished randomised trials were searched for by consulting governmental and non-governmental clinical trial registers, disease-specific websites, investigators and experts in the field, pharmaceutical companies/manufacturers.

SELECTION CRITERIA

Parallel or cross-over randomised or quasi-randomised controlled trials testing the treatment of narcolepsy with any type of antidepressant drug versus no treatment, placebo, or another antidepressant drug.

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected trials for inclusion and extracted data. Outcomes were: (a) elimination of EDS; (b) mean reduction of EDS; (c) elimination of cataplexy; (d) 50% or greater reduction in cataplexy frequency; (e) mean reduction of cataplexy; (f) mean improvement in quality of life; (g) adverse events; (h) withdrawal from treatment.

MAIN RESULTS

Two cross-over trials were included. The methodological quality of both studies was unclear and so the influence of common biases was impossible to define. As the trials tested two different comparisons (one femoxetine versus placebo, the other fluvoxamine versus clomipramine) meta-analysis was not performed. In the first trial (10 participants) femoxetine had no significant effect in eliminating or reducing EDS; a significant reduction of cataplexy was in favour of femoxetine. Mild and transient side effects were reported in the femoxetine treatment period by two participants. In the second trial the authors inappropriately treated the trial design as a parallel study and no conclusions can be reached in favour of either drug.

AUTHORS' CONCLUSIONS

There was no good quality evidence that antidepressants are effective for narcolepsy or improve quality of life. Despite the clinical consensus recommending antidepressants for cataplexy there is scarce evidence that antidepressants have a positive effect on this symptom. There is a clear need for well-designed randomised controlled trials to assess the effect of antidepressants on narcolepsy.

Modafinil: a novel stimulant for the treatment of narcolepsy

Excessive daytime sleepiness (EDS) is a common and debilitating symptom of narcolepsy and other sleep disorders. Modafinil is a novel stimulant which effectively treats EDS, yet lacks many of the undesirable side-effects commonly encountered with currently available compounds. The specific mode of action of modafinil is not well understood, but it may promote sleep by indirectly influencing adrenergic or GABAergic neurotransmission. Modafinil-induced wakefulness is not associated with rebound hypersomnolence or the potential for abuse as is often encountered with other stimulants such as amphetamines. At typical therapeutic doses, modafinil may produce dry mouth but generally has a low incidence of minor side-effects. Many preclinical and clinical studies have demonstrated the effectiveness of modafinil in promoting wakefulness and vigilance in normal subjects and in those with EDS. Modafinil significantly improves the EDS of narcolepsy and also may improve the EDS of idiopathic hypersomnia and obstructive sleep apnoea. Modafinil's low prevalence of side-effects, minimal potential for abuse, and lack of rebound hypersomnia indicate that it has potential to become a widely prescribed drug for the treatment of narcolepsy.

Excessive sleepiness in adolescents and young adults: causes, consequences, and treatment strategies

Adolescents and young adults are often excessively sleepy. This excessive sleepiness can have a profound negative effect on school performance, cognitive function, and mood and has been associated with other serious consequences such as increased incidence of automobile crashes. In this article we review available scientific knowledge about normal sleep changes in adolescents (13-22 years of age), the factors associated with chronic insufficient sleep, the effect of insufficient sleep on a variety of systems and functions, and the primary sleep disorders or organic dysfunctions that, if untreated, can cause excessive daytime sleepiness in this population.

Narcolepsy and Disorders of Excessive Somnolence

Recent studies provide valid criteria that help differentiate idiopathic narcolepsy from other disorders of excessive daytime somnolence [3]. Research to date suggests that idiopathic narcolepsy might properly be considered a disorder of excessive sleepiness with dysfunctional REM-sleep mechanisms, clinically evidenced as cataplexy and electrophysiologically recognized as SOREMPs. Given these criteria, a diagnosis can generally be made using a combination of history, PSG, and MSLT. Traditionally, the medical treatment of idiopathic narcolepsy has centered on a two-drug regimen (stimulants for sleepiness and TCAs for cataplexy and auxiliary symptoms). Some newer medications are proving efficacious for sleepiness with minimal adverse effects, whereas others may provide a single-drug regimen that simultaneously addresses sleepiness and cataplexy [18]. New research has allowed some experts to hypothesize that idiopathic narcolepsy may be the result of a genetic predisposition to autoimmune disease [176]. It is possible that aberrant genetic coding of elements in the hypocretin/orexin systems allows a sensitivity to inducible and possibly virally mediated changes, which leave cells in the lateral hypothalamus susceptible to autoimmune attack [96]. As such, genetic screening of high-risk individuals might eventually rationalize the prophylactic use of immunosuppressants in some instances. In the future, for atypical cases(poorly responsive to therapy), genetic, CSF, and brain imaging studies, and possibly even neuronal transplantation may prove beneficial in the assessment and treatment of idiopathic narcolepsy.

Comparison of driving simulator performance and neuropsychological testing in Narcolepsy

Daytime sleepiness and cataplexy can increase automobile accident rates in narcolepsy. Several countries have produced guidelines for issuing a driving license. The aim of the study was to compare driving simulator performance and neuropsychological test results in narcolepsy in order to evaluate their predictive value regarding driving ability. Thirteen patients with narcolepsy (age: 41.5+/-12.9 years) and 10 healthy control patients (age: 55.1+/-7.8 years) were investigated. By computer-assisted neuropsychological testing, vigilance, alertness and divided attention were assessed. In a driving simulator patients and controls had to drive on a highway for 60 min (mean speed of 100 km/h). Different weather and daytime conditions and obstacles were presented. Epworth Sleepiness Scale-Scores were significantly raised (narcolepsy patients: 16.7+/-5.1, controls: 6.6+/-3.6, P < or = 0.001). The accident rate of the control patients increased (3.2+/-1.8 versus 1.3+/-1.5, P < or = 0.01). Significant differences in concentration lapses (e.g. tracking errors and deviation from speed limit) could not be revealed (9.8+/-3.5 versus 7.1+/-3.2, pns). Follow-up investigation in five patients after an optimising therapy could demonstrate the decrease in accidents due to concentration lapses (P < or = 0.05). Neuropsychological testing (expressed as percentage compared to a standardised control population) revealed deficits in alertness (32.3+/-28.6). Mean percentage scores of divided attention (56.9+/-25.4) and vigilance (58.7+/-26.8) were in a normal range. There was, however, a high inter-individual difference. There was no correlation between driving performance and neuropsychological test results or ESS Score. Neuropsychological test results did not significantly change in the follow-up. The difficulties encountered by the narcolepsy patient in remaining alert may account for sleep-related motor vehicle accidents. Driving simulator investigations are closely related to real traffic situations than isolated neuropsychological tests. At the present time the driving simulator seems to be a useful instrument judging driving ability especially in cases with ambiguous neuropsychological results.

Functional status in patients with narcolepsy

OBJECTIVE

To describe health and functional status in treated narcolepsy patients and to compare it with normative data and with patients with another cause of sleepiness, the obstructive sleep apnea/hypopnea syndrome (OSAHS) patients.

METHODS

A functional status survey in narcolepsy patients and in symptomatic untreated and CPAP treated OSAHS patients with an apnea-hypopnea index (AHI) >5 was assessed using the UK Short Form 36 (SF-36) questionnaire, the Functional Outcomes of Sleep Questionnaire (FOSQ) and the Epworth Sleepiness Scale (ESS). SF-36 scores in narcoleptics were compared to age and sex matched controls. Narcolepsy patients also replied to a psychosocial aspects questionnaire. Health history and demographic data were obtained via a review of medical records and postal survey.

RESULTS

Forty-nine treated narcolepsy patients, 56 untreated OSAHS and 48 CPAP treated OSAHS patients attending the sleep disorders clinic were recruited for this study. Narcoleptics presented significantly lower scores in all SF-36 domains compared to normative data. No difference in SF-36 scores was found between narcoleptics and untreated OSAHS patients but narcoleptics were sleepier and had lower FOSQ scores. These treated narcolepsy patients had lower scores in two dimensions of the SF-36 and in all FOSQ domains compared to CPAP-treated OSAHS patients.

CONCLUSIONS

Functional status in treated narcoleptics is poor.

Quality of life in sleep disorders

Quality of life is a major outcome variable in choosing and evaluating treatment alternatives for sleep disorders. However, the number of well validated and sufficiently responsive quality of life measures for use with this population is limited. The SF-36, Nottingham Health Profile (NHP) and Sickness Impact Profile (SIP) are the most frequently used generic measures. The Functional Outcomes of Sleep Questionnaire (FOSQ) and Sleep Apnoea Quality of Life Index (SAQLI) are useful as condition/disease specific measures. However there are not yet specific measures in common use for other sleep disorders. Results across the sleep disorders that have been studied, primarily sleep apnea, narcolepsy, restless legs and insomnia, have consistently shown poorer quality of life than population norms prior to treatment, particularly in those dimensions related to sleep, energy and fatigue. Before treatment scorespes typically are of similar magnitude to those found among individuals with other chronic diseases such as hypertension and chronic obstructive pulmonary disease. With treatment quality of life scores may or may not improve to the level of population norms, suggesting that currently available treatments may not fully reverse the effects of the common sleep disorders.

Clinical aspects and pathophysiology of narcolepsy

Narcolepsy is a chronic debilitating sleep disorder first described in the late 19th century. It is characterized by two major symptoms, excessive daytime sleepiness and cataplexy, and two so-called auxiliary symptoms, hypnagogic hallucinations and sleep paralysis. The final diagnosis relies on polysomnography showing the presence of sleep onset rapid eye movement periods (SOREMPs) during the multiple sleep latency test. The presence of HLA DQA1*0102-DQB1*0602 is supportive of the diagnosis. The pathophysiology of the disorder is still unknown but an imbalance between monoamines and acetylcholine is generally accepted. Recent findings in narcoleptic dogs, a natural model of narcolepsy, and in knockout mice revealed that a mutation of type 2 hypocretin receptor plays a major role in the etiology of narcolepsy. Up to now, no mutation has been found in humans except a case of early onset and atypical narcolepsy. However, a marked reduction of hypocretin type 1 has been found in the cerebrospinal fluid (CSF) of a majority of patients and a global loss of hypocretins was noted in post-mortem brain tissue of narcoleptic subjects. Conversely, no hypocretin neuron degeneration has been observed in the genetic form of narcolepsy in dogs but no trace of hypocretin was seen in the brain or the CSF in cases of sporadic canine narcolepsy. This suggests that different hypocretinergic mechanisms are involved in sporadic and genetic forms of canine narcolepsy. Treatment has not evolved significantly over the last few years. However, new drugs, such as hypocretin agonists, are currently being developed.

SIGNIFICANCE

After the discovery of the type 2 hypocretin receptor mutation in canine narcolepsy and the finding of a CSF hypocretin-1 deficiency in human narcolepsy, the major stream of research has involved the hypocretinergic system. However, other lines of research deserve to be pursued simultaneously, in view of comprehensive advancements in the understanding of narcolepsy.

Factors associated with a delay in the diagnosis of narcolepsy

BACKGROUND

There can be a long interval from the onset of symptoms before a diagnosis of narcolepsy is made. There are no multivariate analyses reported in the literature of factors that may contribute to this delay. The aims of this study were to describe the delay in diagnosis of people with narcolepsy living in the UK and to identify associated factors.

METHODS

The study comprised a postal survey of 500 members of the Narcolepsy Association UK, which included questions regarding age of onset of symptoms, year of diagnosis and subject demographics. Cox's proportional hazards regression was performed.

RESULTS

A total of 313 questionnaires were returned of which 219 had been completed sufficiently for analysis. The interval between symptom onset and diagnosis ranged from within 1 to 61 years with a median of 10.5 years. Multivariate analysis showed that the presence of cataplexy as one of the initial symptoms and a more recent year of symptom onset were the only factors associated with time to diagnosis.

CONCLUSIONS

We have confirmed that the diagnosis of narcolepsy can be delayed for many years particularly when cataplexy is absent initially. The delay in diagnosis in the UK appears to be decreasing, probably through greater doctor and patient awareness of the clinical manifestations of narcolepsy.

Narcolepsy

Narcolepsy is a chronic disorder of EDS. All patients experience EDS. Other symptoms include cataplexy, sleep paralysis, hypnagogic hallucinations, and disrupted nocturnal sleep. Treatment, usually with stimulants and low-doses of antidepressant medications, can dramatically improve the patient's quality of life. Although only advanced practice nurses may be actively involved in the diagnosis and treatment of this disorder, all nurses can encourage their patients who complain of EDS to consult a specialist in sleep disorders medicine, provide emotional support after diagnosis, and educate patients and their families about narcolepsy and its treatment.

Benefits and risks of pharmacotherapy for narcolepsy

Narcolepsy is a life-long central nervous system (CNS) syndrome characterised by excessive sleepiness, cataplexy, sleep paralysis, hypnagogic hallucinations and disturbed night-time sleep. Unsuccessfully treated narcolepsy confers increased risks on patients and on society due to the patient's increased chance of becoming involved in vehicle crashes and workplace mishaps. The syndrome may be diagnosed by a clinical history positive for cataplexy and excessive daytime sleepiness and negative for other more common sleep disorders such as sleep apnoea and sleep deprivation. Night-time polysomnography and multiple sleep latency testing are helpful in differentiating narcolepsy from other sleep problems. Recent data from canine, murine, and human forms of narcolepsy indicate that genetically or developmentally mediated deficits in the hypocretin neurotransmitter system may cause some, but not all, forms of narcolepsy. Pharmacotherapy for narcolepsy is required to control symptoms and involves the use of CNS stimulants or modafinil to control sleepiness and antidepressant medications or sodium oxybate to control cataplexy. Modafinil and sodium oxybate have been developed and approved specifically for the indication of narcolepsy based on large, double-blind, placebo-controlled, parallel group efficacy and safety studies. The efficacy of drugs in the treatment of narcolepsy is variable from patient to patient and usually associated with adverse effects that can limit patient compliance and, therefore, symptom control. Nevertheless, the benefits of pharmacotherapy are judged to outweigh the risks to the patient. The favourable benefit-risk ratio of pharmacotherapy is greater if one considers the reduced risk to society of vehicle crashes and workplace mishaps that might be precipitated by attentional lapses or sleep attacks in the untreated or under-treated patient with narcolepsy.

Narcolepsy and psychopathology: is there an association?

BACKGROUND

It is widely believed that patients with narcolepsy show high rates of associated psychiatric disturbance, especially schizophrenia and depression. However, surveys have produced conflicting findings and have not addressed the potential confounding effects of stimulant drug treatment.

METHOD

Forty-five patients with narcolepsy attending a sleep disorder clinic and 50 matched normal controls underwent structured psychiatric interview. Using a 'lifetime' approach, psychiatric symptoms and diagnoses were established for both groups.

RESULTS

Four of the narcolepsy patients but none of the controls had experienced psychotic symptoms. All four patients were taking amphetamines, and the symptoms resolved when the dose was lowered or treatment was changed to modafinil. The lifetime frequency of various depressive syndromes did not differ significantly between the groups.

CONCLUSIONS

Contrary to previous claims this study found little to suggest that narcolepsy is associated with schizophrenia. Nor, despite its serious social and occupational consequences, does narcolepsy appear to be associated with an increased frequency of diagnosable depressive disorders.

Cognitive dysfunction in sleep disorders

Fifty-six studies were reviewed that explored cognitive dysfunctions in people with sleep-related breathing disorders (SRBD, 24 studies), insomnia (18 studies), or narcolepsy (14 studies). Individual study outcomes were grouped according to neuropsychological functions. Available evidence was reviewed separately for SRBD, insomnia and narcolepsy. Consistent evidence was found for impaired driving simulation performance in SRBD patients (92.9% of comparisons with control subjects). Other neuropsychological functions with less pronounced impairment included (i) attention span, divided attention and sustained attention for SRBD patients; (ii) attention span, verbal immediate memory and vigilance for insomniac patients, and (iii) sustained attention, vigilance and driving simulation performance for narcoleptic patients. Reduced performance in tasks measuring attention was found to be higher for SRBD and narcoleptic patients (35.9% and 44.2% of all comparisons, respectively) while this rate was lower for insomniac patients (22.8%). Impairment of memory performance in comparison with control subjects was less pronounced for all three groups, with 20.0% for insomnia, 17.1% for SRBD and 15.6% for narcolepsy. In other areas of cognitive functioning, the data did not allow definite conclusions for any of the patient groups.

Attentive and preattentive processing in narcolepsy as revealed by event-related potentials (ERPs)

Narcolepsy is a neurological disorder, characterised by excessive daytime sleepiness, sleep attacks, cataplexy and abnormal manifestations of rapid eye movement sleep. Recent studies suggest that neuropsychological impairments in narcolepsy may include memory and attention deficits due to a monoaminergic or cholinergic transmitter dysfunction. To explore the nature of cognitive problems, the P300 and mismatch negativity (MMN) event-related potentials were investigated in narcoleptic patients and matched controls. Narcoleptics showed significantly increased P300 amplitudes relative to controls, especially at frontal recording sites. While control subjects exhibited typically larger MMN over the right than the left hemisphere, in particular at frontal and central electrodes, narcoleptics did not show this asymmetry. These results are interpreted as possible alterations in cognitive preattentive and attentive processing associated with altered functioning of the prefrontal cortex in narcolepsy.

The impact of narcolepsy on psychological health and role behaviours: negative effects and comparisons with other illness groups

OBJECTIVES

The study sought to (i) assess psychosocial adjustment, disruption due to symptoms, and medication problems in narcolepsy, (ii) determine how these variables changed with gender, age and medication status, and (iii) compare narcolepsy adjustment with three other illness groups.

BACKGROUND

Psychosocial adjustment to an illness can be conceptualized in terms of people's ability to function in their life roles and assessed using the Psychosocial Adjustment to Illness Scale-Self Report (PAIS-SR) questionnaire.

METHODS

Participants (n=129) were recruited via a support group using posted questionnaires. The PAIS-SR was supplemented with additional questionnaire material.

RESULTS

Males were more vulnerable than females in terms of adjustment (notably health care orientation and sexual relationships) and younger narcoleptics may have particular vocational problems. Unmedicated narcoleptics were least inclined to participate in social/leisure activities. Reported disruption due to symptoms was strongly associated with both psychological distress and overall psychosocial adjustment and was most notable in those taking both stimulants and tricyclic antidepressants. Narcoleptics reported more adjustment problems in comparison to three other illness groups (cardiac, mixed cancer and diabetes). A table of normative PAIS-SR values for narcolepsy was developed.

CONCLUSIONS

Poor adjustment in terms of health care orientation and psychological distress are of particular concern. Health care that can reduce the disruption due to symptoms is especially important for adjustment.

Narcolepsy: clinical features, new pathophysiologic insights, and future perspectives

Narcolepsy is characterized by excessive daytime sleepiness and abnormal manifestations of rapid eye movement sleep such as cataplexy. The authors review the clinical features of narcolepsy, including epidemiology, symptoms, diagnosis, and treatment, in detail. Recent findings show that a loss of hypocretin-producing neurons lies at the root of the signs and symptoms of narcolepsy. The authors review the current state of knowledge on hypocretin anatomy, physiology, and function with special emphasis on the research regarding the hypocretin deficiency in narcolepsy, which may also explain associated features of the disorder, such as obesity. Lastly, they discuss some future perspectives for research into the pathophysiology of sleep/wake disorders, and the potential impact of the established hypocretin deficiency on the diagnosis and treatment of narcolepsy.

Current concepts in the etiology, diagnosis and treatment of narcolepsy

Background and purpose: Narcolepsy is the most common neurologic cause of excessive daytime sleepiness. Rapid eye movement (REM) sleep phenomena such as cataplexy, sleep paralysis and hypnagogic hallucinations can also occur. Cataplexy, a sudden bilateral loss of muscle tone usually brought on by emotional reactions such as excitement, is essentially unique to narcolepsy. Narcolepsy, which has a prevalence of 0.02-0.05% in the US, has a profound influence on the quality of life and safety of affected individuals.Patients and methods: The most characteristic and striking physiological abnormality observed in narcolepsy is the sleep-onset REM, or the occurrence of REM sleep at, or within 20 min of, the onset of sleep. The diagnosis is established by nocturnal polysomnography, and the Multiple Sleep Latency Test (MSLT).Results: Familial cases of narcolepsy have been reported, with the risk to first-degree relatives estimated at 1-2%; however, most cases are sporadic and the syndrome is generally believed to involve environmental factors acting on a specific genetic background. The observation of an HLA association in narcolepsy suggests that autoimmunity may play a role in the disorder. However, extensive studies have failed to find convincing evidence of an autoimmune process. Patients with narcolepsy have recently been shown to be deficient in hypocretin, also called orexin, in the cerebrospinal fluid and have a reduction in hypocretin cells in the lateral hypothalamus. This suggests that hypocretins could potentially provide a novel therapeutic approach to the treatment of narcolepsy.Conclusions: Although non-pharmacologic measures can be helpful in treating narcolepsy, most patients require pharmacotherapy that includes psychostimulants or modafinil. Cataplexy is controlled by tricyclic antidepressants or selective serotonin reuptake inhibitors.

Long-term efficacy and safety of modafinil (PROVIGIL((R))) for the treatment of excessive daytime sleepiness associated with narcolepsy

Objectives: To assess the long-term efficacy and safety of modafinil in patients with excessive daytime sleepiness (EDS) associated with narcolepsy.Background: Modafinil has been shown to be effective and well tolerated for treating EDS associated with narcolepsy in two large-scale, well-controlled, 9-week clinical trials.Methods: Four hundred and seventy eight adult patients with a diagnosis of narcolepsy who had completed one of two 9-week, double-blind, placebo-controlled, multicenter, clinical trials of modafinil were enrolled in two 40-week, open-label, extension studies. A flexible-dose regimen (i.e. 200, 300, or 400 mg daily) was followed in one study. In the second study, patients received 200 mg/day for 1 week, followed by 400 mg/day for 1 week. Investigators then prescribed either 200- or 400-mg doses for the duration of the study. Efficacy was evaluated using Clinical Global Impression of Change (CGI-C) scores, the Epworth Sleepiness Scale (ESS), and the 36-item Medical Outcomes Study health survey (SF-36). Adverse events were recorded. Data from the two studies were combined.Results: The majority of patients ( approximately 75%) received 400 mg of modafinil daily. Disease severity improved in >80% of patients throughout the 40-week study. At weeks 2, 8, 24, and 40, disease severity was 'much improved' or 'very much improved' in 49, 58, 59, and 58% of patients, respectively. The mean (+/-SEM) ESS score improved significantly from 16.5+/-0.2 at open-label baseline to 12.4+/-0.2 at week 2 and remained at that level through week 40 (P<0.001). Quality of life scores at weeks 4, 8, 24, and 40 were significantly improved versus open-label baseline scores for six of the eight SF-36 domains (P<0.001). The most common treatment-related adverse events were headache (13%), nervousness (8%), and nausea (5%). Most adverse events were mild to moderate in nature. A total of 341 patients (71%) completed the studies. Forty-three patients (9.0%) discontinued treatment because of adverse events.Conclusions: Modafinil is effective for the long-term treatment of EDS associated with narcolepsy and significantly improves perceptions of general health. Modafinil is well tolerated, with no evidence of tolerance developing during 40 weeks of treatment.

[Prevalence of sleep disorders in Madrid, Spain]

INTRODUCTION

Sleep disorders are among the clinical entities with a great health and socioeconomic impact. So far, in Spain there are isolated epidemiologic data, lacking from studies that cover the full spectrum of sleep disorders in the general adult population.

METHODS

A sample of 1,500 adult subjects from Madrid were interviewed during the first semester of 1990, using a clinical questionnaire including sociodemographic data, habits, sleep disorders, and information regarding somatic and psychiatric pathology. A detailed analysis of the influence of sex, age and occupational status on the prevalence of the different disorders is presented.

RESULTS

1,131 persons (75.4%) completed the interview. 22.8% (95% confidence interval, CI: 20.4-25.4) referred at least one sleep difficulty, 11.3% (9.5-13.3) of the sample complained of insomnia, this being more common in women, older individuals and unemployed. Daytime sleepiness was reported by 11.6% (9.8-13.7) of the sample, and 3.2% (2.2-4.4) referred hypersomnia, with sleep attacks and sleep paralysis being rarely found. Regarding parasomnias, 12.3% (10.4-14.4) had nightmares, with the prevalence of sonambulism, night terrors and enuresis being near 1%. Daily snoring was present in 11.9% (10.1-14.0) of the sample, whereas 1.1% (0.6-2.0) reported respiratory pauses during the night.

CONCLUSIONS

A high prevalence of sleep disorders is estimated in the adult population of the city of Madrid, Spain. Our data are in general similar to those found in other countries, and differences found are discussed.

Sleep problems in emergency department patients with injuries

OBJECTIVES

To assess trauma patients' frequency of sleep problems, to evaluate their injuries in the context of their sleep habits, and to determine how often ED health care workers (HCWs) inquire about sleep complaints.

METHODS

This was a prospective observational study of patients evaluated in the ED for unintentional trauma. Patients answered a "sleep survey" that was reviewed for the amount and timing of sleep in the preinjury period and for indications of a sleep problem. Preinjury sleep characteristics were compared with the individual's usual habits, and the group's sleep features were compared with "normal" sleep and the prevalence of sleep problems in historical controls.

RESULTS

Seventy patients were surveyed. Mechanisms and types of injury included motor vehicle collisions (MVCs), falls, lacerations, bruises, sprains, and fractures. The mean total sleep time in the preinjury period (6.9 hours) was significantly shorter than that obtained during usual weekday and weekend sleep. Twenty-four patients (34.3%) were at high risk for a sleep problem. Few patients thought a sleep problem contributed to the injury. No other ED HCW asked about the patient's sleep habits.

CONCLUSIONS

Acute sleep deprivation in the preinjury period, and chronic sleep deprivation with a variety of other sleep problems are found in this patient population. Despite the association of sleep problems and certain types of injury (e.g., MVC), ED HCWs do not inquire about sleep in their initial ED evaluations. This important issue may be overlooked in trauma risk assessment and prevention.

Medical-legal aspects of sleep medicine

Sleepiness and sleep disorders are increasingly raising interesting and important medical-legal issues in three areas: violent or injurious behavior arising from the sleep period, accidents or errors in judgment caused by sleepiness behind the wheel or in the workplace, and disability determinations caused by sleepiness-induced work impairment. Sleep-related violence may be caused by many conditions, most of which are diagnosable and treatable. Legal issues raised by these behaviors are usually enigmatic. The nature of such behaviors may be extremely complex, and documenting that a given violent act was caused by such a behavior, after the fact, may be difficult. Guidelines for the medical-legal evaluation of such behaviors have been developed and are evolving. Culpability determination in sleepiness-related industrial or motor vehicle accidents is in the developmental stage, and varies by jurisdiction. Disability determination for workplace sleepiness caused by sleep disorders is in its infancy, and poses a challenge, given the erroneous but pervasive societal attitude that sleepiness is a manifestation of laziness, depression, sloth, work-avoidance behavior, or a defect of character.

Genetic studies in the sleep disorder narcolepsy

Narcolepsy is a chronic neurologic disorder characterized by excessive daytime sleepiness and abnormal manifestations of REM sleep including cataplexy, sleep paralysis, and hypnagogic hallucinations. Narcolepsy is both a significant medical problem and a unique disease model for the study of sleep. Research in human narcolepsy has led to the identification of specific HLA alleles (DQB1*0602 and DQA1*0102) that predispose to the disorder. This has suggested the possibility that narcolepsy may be an autoimmune disorder, a hypothesis that has not been confirmed to date. Genetic factors other than HLA are also likely to be involved. In a canine model of narcolepsy, the disorder is transmitted as a non-MHC single autosomal recessive trait with full penetrance (canarc-1). A tightly linked marker for canarc-1 has been identified, and positional cloning studies are under way to isolate canarc-1 from a newly developed canine genomic BAC library. The molecular cloning of this gene may lead to a better understanding of sleep mechanisms, as has been the case for circadian rhythms following the cloning of frq, per, and Clock.

Epworth Sleepiness Scale outcome in 616 Brazilian medical students

The Epworth Sleepiness Scale (ESS) measures daytime sleepiness in adults. This paper reports the following data in 616 medical students: 1-ESS scores, 2-its correlation with the declared night sleep time, 3-comparison with ESS values obtained from Australia, 4-comparison of ESS values in a sub-population of 111 students tested early and late 1995. There were 387 males, 185 females and 4 not specified. Age = 20.16 +/- 2.23 (SD), ESS score = 10.00 +/- 3.69 (SD), declared sleep time = 7.04 +/- 1.03 (SD). ESS scores did not statistically correlate with sleep time. Average ESS score was statistically higher than in the Australian sample. Retesting of the medical students showed an increase in ESS values from March to November 1995. Sleep time difference was non-significant. Higher ESS scores in this sample seem to be related to shorter sleep time, but fatigue effects can not be ruled out.

Pharmacological aspects of human and canine narcolepsy

Narcolepsy-cataplexy is a disabling neurological disorder that affects 1/2000 individuals. The main clinical features of narcolepsy, excessive daytime sleepiness and symptoms of abnormal REM sleep (cataplexy, sleep paralysis, hypnagogic hallucinations) are currently treated using amphetamine-like compounds or modafinil and antidepressants. Pharmacological research in the area is facilitated greatly by the existence of a canine model of the disorder. The mode of action of these compounds involves presynaptic activation of adrenergic transmission for the anticataplectic effects of antidepressant compounds and presynaptic activation of dopaminergic transmission for the EEG arousal effects of amphetamine-like stimulants. The mode of action of modafmil is still uncertain, and other neurochemical systems may offer interesting avenues for therapeutic development. Pharmacological and physiological studies using the canine model have identified primary neurochemical and neuroanatomical systems that underlie the expression of abnormal REM sleep and excessive sleepiness in narcolepsy. These involve mostly the pontine and basal forebrain cholinergic, the pontine adrenergic and the mesolimbic and mesocortical dopaminergic systems. These studies confirm a continuing need for basic research in both human and canine narcolepsy, and new treatments that act directly at the level of the primary defect in narcolepsy might be forthcoming.

Etiologies and sequelae of excessive daytime sleepiness

Excessive daytime sleepiness (EDS), the primary complaint of patients seen in sleep clinics, affects up to 12% of the general population. The effects of EDS can be debilitating and even life threatening. Patients with EDS may exhibit psychosocial distress, decreased work or school performance, and increased risk for accidents. The differential diagnosis of EDS requires objective assessments, such as polysomnography and the Multiple Sleep Latency Test. There are four major causes of EDS: (1) central nervous system (CNS) pathologic abnormalities, such as narcolepsy and idiopathic CNS hypersomnia; (2) qualitative or quantitative sleep deficiencies, such as sleep apnea and insufficient nocturnal sleep; (3) misalignments of the body's circadian pacemaker with the environment (eg. jet lag or shift work); and (4) drugs, which can increase sleepiness either therapeutically or as a side effect. Depending on etiology, management strategies for EDS include extension of time in bed, naps, surgery, various medical devices (eg, oral appliances, continuous positive airway pressure), and pharmacotherapy. Pharmacotherapy is generally achieved with stimulants, such as amphetamine sulfate, methylphenidate, and pemoline or newer, safer compounds like modafinil.

Acute mood improvement after dextroamphetamine and methylphenidate in narcolepsy

Mood changes following ingestion of dextroamphetamine (D-AMP) or methylphenidate (MPH) were examined in 40 narcoleptic patients. The Profile of Mood Status (POMS) and eight additional adjectives describing feelings were used to quantify changes in mood before taking stimulant medication and approximately 90 minutes after ingestion of medication. No significant differences were found between the effects of the two stimulants. When the data from D-AMP and MPH were combined, significantly higher ratings on the POMS factor of Vigour-Activity and the adjectives of 'confident', 'talkative' and 'competitive' were found. Lower ratings after medication were noted for the POMS factors of Fatigue-Inertia, Depression-Dejection and Confusion-Bewilderment (all P < 0.001). These effects are similar to those previously reported in normal subjects as well as in certain other patient populations. The findings indicate a possible therapeutic role of stimulant medication not only for the treatment of excessive sleepiness but also for improving affect, motor and mental vigour, and aspects of cognition.