Pharmacotherapy for excessive daytime sleepiness

Differing Behaviors Around Adult Nonmedical Use of Prescription Stimulants and Opioids: Latent Class Analysis

BACKGROUND

The availability of central nervous system stimulants has risen in recent years, along with increased dispensing of stimulants for treatment of, for example, parent-reported attention-deficit/hyperactivity disorder in children and new diagnoses during adulthood. Typologies of drug use, as has been done with opioids, fail to include a sufficient range of behavioral factors to contextualize person-centric circumstances surrounding drug use. Understanding these patterns across drug classes would bring public health and regulatory practices toward precision public health.

OBJECTIVE

The objective of this study was to quantitatively delineate the unique behavioral profiles of adults who currently nonmedically use stimulants and opioids using a latent class analysis and to contrast the differences in findings by class. We further evaluated whether the subgroups identified were associated with an increased Drug Abuse Screening Test-10 (DAST-10) score, which is an indicator of average problematic drug use.

METHODS

This study used a national cross-sectional web-based survey, using 3 survey launches from 2019 to 2020 (before the COVID-19 pandemic). Data from adults who reported nonmedical use of prescription stimulants (n=2083) or prescription opioids (n=6127) in the last 12 months were analyzed. A weighted latent class analysis was used to identify the patterns of use. Drug types, motivations, and behaviors were factors in the model, which characterized unique classes of behavior.

RESULTS

Five stimulant nonmedical use classes were identified: amphetamine self-medication, network-sourced stimulant for alertness, nonamphetamine performance use, recreational use, and nondiscriminatory behaviors. The drug used nonmedically, acquisition through a friend or family member, and use to get high were strong differentiators among the stimulant classes. The latter 4 classes had significantly higher DAST-10 scores than amphetamine self-medication (P<.001). In addition, 4 opioid nonmedical use classes were identified: moderate pain with low mental health burden, high pain with higher mental health burden, risky behaviors with diverse motivations, and nondiscriminatory behaviors. There was a progressive and significant increase in DAST-10 scores across classes (P<.001). The potency of the opioid, pain history, the routes of administration, and psychoactive effect behaviors were strong differentiators among the opioid classes.

CONCLUSIONS

A more precise understanding of how behaviors tend to co-occur would improve efficacy and efficiency in developing interventions and supporting the overall health of those who use drugs, and it would improve communication with, and connection to, those at risk for severe drug outcomes.

Effects of repetitive transcranial magnetic stimulation over right dorsolateral prefrontal cortex on excessive daytime sleepiness in patients with Parkinson's disease

BACKGROUND

Excessive daytime sleepiness (EDS) is a common sleep disorder in Parkinson's disease (PD), which seriously affects patients' quality of life. Repetitive transcranial magnetic stimulation (rTMS) can be used as an add-on therapy to a variety of non-motor symptoms of PD. However, little is known on the treatment of EDS in PD patients.

OBJECTIVE

To explore the effects of low frequency rTMS over right dorsolateral prefrontal cortex (DLPFC) in the treatment of EDS in PD.

METHODS

We conducted a sham-controlled, parallel study including 25 individuals of PD with possible EDS based on Epworth Sleepiness Scale (ESS ≥8 points) and randomly divided them into active group (n = 15) and sham group (n = 10). 1 Hz rTMS was administrated over right DLPFC for 10 consecutive days. In the active group, we further classified them into responsive group and non-responsive group according to change of ESS score in comparison with baseline. Clinical assessments on motor and non-motor symptoms were completed at baseline, at the end of treatment and 1 month after treatment.

RESULTS

Compared to baseline, active group showed significant improvement on ESS score 10 days and 1 month after treatment (P < 0.05 for both). The percentage change of ESS score was positively related to disease duration during follow-up. No significant changes were observed on ESS score change in the sham group. Further analysis of individuals in the active group showed that, relative to those with non-response to rTMS, individuals with therapeutic response exhibited longer disease duration and lower baseline levodopa equivalent dose.

CONCLUSION

Low frequency rTMS over right DLPFC may improve symptoms of EDS in PD.

Circuits and components of delta wave regulation

Sleep is vital and the deepest stages of sleep occur within Non-rapid-eye-movement sleep (NREM), defined by high electroencephalographic power in the delta (~0.5-4Hz) wave frequency range. Delta waves are thought to facilitate a myriad of physical and mental health functions. This review aims to comprehensively cover the historical and recent advances in the understanding of the mechanisms orchestrating NREM delta waves. We discuss a complete neurocircuit - focusing on one leg of the circuit at a time - and delve deeply into the molecular mechanistic components that contribute to NREM delta wave regulation. We also discuss the relatively localized nature in which these mechanisms have been defined, and how likely they might generalize across distinct sensory and higher order modalities in the brain.

A multi-pronged investigation of option generation using depression, PET and modafinil

Option generation is a critical process in decision making, but previous studies have largely focused on choices between options given by a researcher. Consequently, how we self-generate options for behaviour remain poorly understood. Here, we investigated option generation in major depressive disorder and how dopamine might modulate this process, as well as the effects of modafinil (a putative cognitive enhancer) on option generation in healthy individuals. We first compared differences in self-generated options between healthy non-depressed adults [n = 44, age = 26.3 years (SD 5.9)] and patients with major depressive disorder [n = 54, age = 24.8 years (SD 7.4)]. In the second study, a subset of depressed individuals [n = 22, age = 25.6 years (SD 7.8)] underwent PET scans with 11C-raclopride to examine the relationships between dopamine D2/D3 receptor availability and individual differences in option generation. Finally, a randomized, double-blind, placebo-controlled, three-way crossover study of modafinil (100 mg and 200 mg), was conducted in an independent sample of healthy people [n = 19, age = 23.2 years (SD 4.8)] to compare option generation under different doses of this drug. The first study revealed that patients with major depressive disorder produced significantly fewer options [t(96) = 2.68, P = 0.009, Cohen's d = 0.54], albeit with greater uniqueness [t(96) = -2.54, P = 0.01, Cohen's d = 0.52], on the option generation task compared to healthy controls. In the second study, we found that 11C-raclopride binding potential in the putamen was negatively correlated with fluency (r = -0.69, P = 0.001) but positively associated with uniqueness (r = 0.59, P = 0.007). Hence, depressed individuals with higher densities of unoccupied putamen D2/D3 receptors in the putamen generated fewer but more unique options, whereas patients with lower D2/D3 receptor availability were likely to produce a larger number of similar options. Finally, healthy participants were less unique [F(2,36) = 3.32, P = 0.048, partial η2 = 0.16] and diverse [F(2,36) = 4.31, P = 0.021, partial η2 = 0.19] after taking 200 mg versus 100 mg and 0 mg of modafinil, while fluency increased linearly with dosage at a trend level [F(1,18) = 4.11, P = 0.058, partial η2 = 0.19]. Our results show, for the first time, that option generation is affected in clinical depression and that dopaminergic activity in the putamen of patients with major depressive disorder may play a key role in the self-generation of options. Modafinil was also found to influence option generation in healthy people by reducing the creativity of options produced.

Medications for daytime sleepiness in individuals with idiopathic hypersomnia

BACKGROUND

Idiopathic hypersomnia is a disorder of excessive daytime sleepiness, often accompanied by long sleep times or pronounced difficulty in awakening, in the absence of a known cause. The optimal treatment strategy for idiopathic hypersomnia is currently unknown.

OBJECTIVES

To assess the effects of medications for daytime sleepiness and related symptoms in individuals with idiopathic hypersomnia and, in particular, whether medications may: 1. reduce subjective measures of sleepiness; 2. reduce objective measures of sleepiness; 3. reduce symptoms of cognitive dysfunction; 4. improve quality of life; and 5. be associated with adverse events.

SEARCH METHODS

We searched the following databases on 4 February 2021: Cochrane Register of Studies (CRS Web), MEDLINE (Ovid, 1946 to 1 February 2021), and reference lists of articles. CRS Web includes randomized or quasi-randomized controlled trials from PubMed, Embase, ClinicalTrials.gov, the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP), the Cochrane Central Register of Controlled Trials (CENTRAL), and the specialized registers of Cochrane Review Groups, including the Cochrane Epilepsy Group. We previously searched the WHO ICTRP separately when loading of ICTRP records into CRS Web was temporarily suspended.

SELECTION CRITERIA

Randomized studies comparing any medication to placebo, another medication, or a behavioral intervention.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed trial quality. We contacted study authors for additional data. We collected data on adverse events from the included trials.

MAIN RESULTS

We included three trials, with a total of 112 participants. Risk of bias was low for the included studies. Two pharmaceutical company-sponsored trials compared modafinil with placebo, involving 102 participants, nearly all of whom had idiopathic hypersomnia without long sleep time. Modafinil significantly improved self-reported sleepiness on the Epworth Sleepiness Scale by 5.08 points more than placebo (95% confidence interval (CI) 3.01 to 7.16; 2 studies, 101 participants; high-certainty evidence). Modafinil also significantly improved disease severity on the Clinical Global Impression of Severity scale by 1.02 points (95% CI 0.11 to 1.93; 1 study, 30 participants; moderate-certainty evidence) and resulted in a greater proportion of participants who were "much improved" or "very much improved" on the Clinical Global Impression of Change (odds ratio (OR) for improvement 5.14, 95% CI 1.76 to 15.00; 1 study, 70 participants; moderate-certainty evidence). Ability to remain awake on the Maintenance of Wakefulness Test was significantly improved with modafinil, by 4.74 minutes more than with placebo (95% CI 2.46 to 7.01; 2 studies, 99 participants; high-certainty evidence). Ratings of exhaustion and effectiveness/performance were improved with modafinil compared to placebo in one study. Number of naps per week was no different between modafinil and placebo across two studies. Participants receiving modafinil experienced more side effects, although the difference did not reach statistical significance (OR 1.68, 95% CI 0.28 to 9.94; 2 studies, 102 participants; low-certainty evidence). One trial studying 20 participants with different disorders of sleepiness included 10 participants with idiopathic hypersomnia, with or without long sleep time, and compared clarithromycin to placebo. We only included the subset of trial data for those participants with idiopathic hypersomnia, per our protocol. There were no significant differences between clarithromycin and placebo for the Epworth Sleepiness Scale, psychomotor vigilance testing, sleep inertia, other subjective ratings, or side effects.

AUTHORS' CONCLUSIONS

Modafinil is effective for the treatment of several aspects of idiopathic hypersomnia symptomatology, based on studies predominantly including participants with idiopathic hypersomnia without long sleep times, with low risk of bias, and evidence certainty ranging from high to low. There is insufficient evidence to conclude whether clarithromycin is effective for the treatment of idiopathic hypersomnia. There is a clear need for additional studies testing interventions for the treatment of idiopathic hypersomnia.

The Epworth Sleepiness Scale in Service Members with Sleep Disorders

INTRODUCTION

Excessive daytime sleepiness affects an estimated 20% of the general population. While the prevalence of sleepiness in the military is largely unknown, it is well established that short sleep duration is endemic. The reasons for this include: the demanding nature of their duties, shift work and 24-hour duty periods, deployments and exigencies of military service as well as sleep disorders. The Epworth Sleepiness Scale (ESS) is the most widely used sleep questionnaire and provides a self-assessment of daytime sleepiness. To date the clinical utility of this questionnaire in differentiating sleep disorders in military patients with sleep disorders has never been evaluated.

MATERIALS AND METHODS

The primary aim of this manuscript was to assess if Epworth Sleepiness Scale (ESS) scores differed between military personnel with insomnia, obstructive sleep apnea (OSA), comorbid insomnia/obstructive sleep apnea (COMISA), and a group with neither insomnia nor obstructive sleep apnea (NISA). This study assessed the clinical utility of the ESS in differentiating sleep disorders amongst a sample (N = 488) of U.S. military personnel with insomnia (n = 92), OSA (n = 142), COMISA (n = 221), and a NISA group (n = 33) which served as the control population.

RESULTS

In the present sample, 68.4% of service members reported excessive daytime sleepiness (EDS) with an ESS > 10. ESS scores differed between military personnel with COMISA (13.5 ± 4.83) and those with OSA only (11.5 ± 4.08; p < 0.001) and the NISA group (9.46 ± 4.84; p < 0.001). Also, ESS scores differed between patients with insomnia only (13.0 ± 4.84) and the NISA group (p < 0.01).

CONCLUSIONS

Overall, the ESS had poor ability to differentiate sleep disorders. In military personnel, the ESS appears elevated in the most common sleep disorders, likely due to their insufficient sleep, and does not help to differentiate OSA from insomnia. Further studies are required to validate this questionnaire and determine an appropriate threshold value for abnormal sleepiness in the military population.

Enhancement of the rewarding effects of 3,4-methylenedioxymethamphetamine in orexin knockout mice

Orexinergic neurons, which are closely associated with narcolepsy, regulate arousal and reward circuits through the activation of monoaminergic neurons. Psychostimulants as well as 5-HT-related compounds have potential in the treatment of human narcolepsy. Previous studies have demonstrated that orexin receptor antagonists as well as orexin deficiencies affect the pharmacological effects of psychostimulants. However, little information is available on the consequences of psychostimulant use under orexin deficiency. Therefore, the present study was designed to investigate the abuse liability of psychostimulants in orexin knockout (KO) mice. In the present study, conditioned place preferences induced by methamphetamine and methylphenidate were not altered in orexin KO mice. Interestingly, we found that MDMA induced a conditioned place preference in orexin KO mice, but not in wild type (WT) mice. In addition, MDMA produced methylphenidate/methamphetamine-like discriminative stimulus effects in orexin KO mice, but not WT mice. Increases in 5-HT and dopamine release in the nucleus accumbens induced by MDMA were not altered by knockout of orexin; the steady-state level of G protein activation was higher in the limbic forebrain of orexin KO mice. In substitution tests using a drug discrimination procedure, substitution of 5-HT_1A receptor agonist for the discriminative stimulus effects of methylphenidate was enhanced in orexin KO mice. These findings indicate that the orexinergic system is involved the rewarding effects of psychostimulants. However, there is a risk of establishing rewarding effects of psychostimulants even under orexin deficiency. On the other hand, deficiencies in orexin may enhance the abuse liability of MDMA by changing a postsynaptic signal transduction accompanied by changes in discriminative stimulus effects themselves.

Management of Sleep Disturbances Associated with Smith-Magenis Syndrome

Smith-Magenis syndrome is a genetic disorder caused by a microdeletion involving the retinoic acid-induced 1 (RAI1) gene that maps on the short arm of chromosome 17p11.2 or a pathogenic mutation of RAI1. Smith-Magenis syndrome affects patients through numerous congenital anomalies, intellectual disabilities, behavioral challenges, and sleep disturbances. The sleep abnormalities associated with Smith-Magenis syndrome can include frequent nocturnal arousals, early morning awakenings, and sleep attacks during the day. The sleep problems associated with Smith-Magenis syndrome are attributed to haploinsufficiency of the RAI1 gene. One consequence of reduced function of RAI1, and characteristic of Smith-Magenis syndrome, is an inversion of melatonin secretion resulting in a diurnal rather than nocturnal pattern. Treatment of sleep problems in people with Smith-Magenis syndrome generally involves a combination of sleep hygiene techniques, supplemental melatonin, and/or other medications, such as melatonin receptor agonists, β₁-adrenergic antagonists, and stimulant medications, to improve sleep outcomes. Improvement in sleep has been shown to improve behavioral outcomes, which in turn improves the quality of life for both patients and their caregivers.

Clinical and Experimental Human Sleep-Wake Pharmacogenetics

Sleep and wakefulness are highly complex processes that are elegantly orchestrated by fine-tuned neurochemical changes among neuronal and non-neuronal ensembles, nuclei, and networks of the brain. Important neurotransmitters and neuromodulators regulating the circadian and homeostatic facets of sleep-wake physiology include melatonin, γ-aminobutyric acid, hypocretin, histamine, norepinephrine, serotonin, dopamine, and adenosine. Dysregulation of these neurochemical systems may cause sleep-wake disorders, which are commonly classified into insomnia disorder, parasomnias, circadian rhythm sleep-wake disorders, central disorders of hypersomnolence, sleep-related movement disorders, and sleep-related breathing disorders. Sleep-wake disorders can have far-reaching consequences on physical, mental, and social well-being and health and, thus, need be treated with effective and rational therapies. Apart from behavioral (e.g., cognitive behavioral therapy for insomnia), physiological (e.g., chronotherapy with bright light), and mechanical (e.g., continuous positive airway pressure treatment of obstructive sleep apnea) interventions, pharmacological treatments often are the first-line clinical option to improve disturbed sleep and wake states. Nevertheless, not all patients respond to pharmacotherapy in uniform and beneficial fashion, partly due to genetic differences. The improved understanding of the neurochemical mechanisms regulating sleep and wakefulness and the mode of action of sleep-wake therapeutics has provided a conceptual framework, to search for functional genetic variants modifying individual drug response phenotypes. This article will summarize the currently known genetic polymorphisms that modulate drug sensitivity and exposure, to partly determine individual responses to sleep-wake pharmacotherapy. In addition, a pharmacogenetic strategy will be outlined how based upon classical and opto-/chemogenetic strategies in animals, as well as human genetic associations, circuit mechanisms regulating sleep-wake functions in humans can be identified. As such, experimental human sleep-wake pharmacogenetics forms a bridge spanning basic research and clinical medicine and constitutes an essential step for the search and development of novel sleep-wake targets and therapeutics.

[Pharmacotherapy of Sleep-Wake Disorders]

Pharmacotherapy of Sleep-Wake Disorders Abstract. Sleep is a complex behavior, coordinated by many different brain regions and neurotransmitters. These neurochemical systems can be pharmacologically influenced to modulate wakefulness and sleep. Excessive daytime sleepiness (EDS) is often treated with dopaminergic drugs, which in mild cases range from caffeine via (ar)modafinil to amphetamine derivatives. Tricyclic antidepressants and melatonin-based drugs are also used to promote alertness, but to a lesser extent. The drugs used to promote sleep include GABA-ergic drugs such as benzodiazepines and Z-hypnotics as well as histamine H1 receptor antagonists. Exogenous melatonin or a pharmacological combination of melatonin receptor agonists and 5-HT2C receptor antagonists are also used in mild cases. Selective and dual orexin (hypocretin) receptor antagonists (DORA) as well as drugs binding to specific 5-HT receptors are currently being investigated as future sleep-promoting drugs. However, pharmacological treatment is not always the primary treatment option, insomnia is treated first-line with cognitive behavioral therapy, and continuous positive airway pressure is used to treat sleep apnea.

A Practical Approach to Excessive Daytime Sleepiness: A Focused Review

Excessive daytime sleepiness (EDS) is a common problem that is important to recognize and address. Initial steps in management are generally straightforward and only the most advanced cases would require referral to a subspecialist. Of particular concern is that of driving safety. There is a broad differential diagnosis for conditions contributing to EDS but a few common conditions account for the majority of clinical presentations. Subjective self-reporting will often lead to identification of potential problems, but this is often unreliable. Traditional neurophysiologic tests can help in objectively quantifying symptoms but current tests are not always practical clinically and may have little validation in real world situations. There are many treatment options that should generally be able to sufficiently manage most patients presenting with hypersomnolence. This review provides a practical clinical approach to the problem based on current guidelines.

Narcolepsy-like sleep disturbance in orexin knockout mice are normalized by the 5-HT1A receptor agonist 8-OH-DPAT

RATIONALE

Orexin knockout (KO) mice exhibit a phenotype that is similar to human narcolepsy, and monoamine-related compounds, such as psychostimulants and 5-HT uptake inhibitors, have been used for the treatment of narcoleptic disorders. However, little information is available regarding the pathophysiological features of orexin KO mice, particularly with respect to their narcoleptic-like disorder and how it is affected by monoamine-related compounds.

OBJECTIVES

The present study was designed to investigate both the nature of the neuronal changes in orexin KO mice and the therapeutic effects of monoamine-related compounds on the sleep disorder in orexin KO mice.

RESULTS

A decrease in locomotor activity in the dark phase was observed in orexin KO mice, and psychostimulants and 5-HT-related compounds, such as 8-OH-DPAT (5-HT1A receptor agonist) and DOI (5-HT2 receptor agonist), inhibited this hypolocomotion. We also found that 5-HT1A receptor mRNA levels, but not those for 5-HT2 or dopamine receptors, were significantly decreased in the prefrontal cortex of orexin KO mice in the dark period and were accompanied by compromising the increase in 5-HT metabolite levels. In addition, the sleep disorder in orexin KO mice, as analyzed by a polysomnography during the dark period, was completely normalized by 8-OH-DPAT.

CONCLUSION

These results suggest that a dysfunction of 5-HT1A receptors is involved in the narcoleptic-like sleep dysfunction in orexin KO mice, and such dysfunction may participate in orexin deficiency-induced sleep disorders. Further, the use of 5-HT1A receptor agonist could be useful for treating the sleep disorder under a deficiency of orexin.

Pharmacological profiling of zebrafish behavior using chemical and genetic classification of sleep-wake modifiers

Sleep-wake states are impaired in various neurological disorders. Impairment of sleep-wake states can be an early condition that exacerbates these disorders. Therefore, treating sleep-wake dysfunction may prevent or slow the development of these diseases. Although many gene products are likely to be involved in the sleep-wake disturbance, hypnotics and psychostimulants clinically used are limited in terms of their mode of action and are not without side effects. Therefore, there is a growing demand for developing new hypnotics and psychostimulants with high efficacy and few side effects. Toward this end, animal models are indispensable for use in genetic and chemical screens to identify sleep-wake modifiers. As a proof-of-concept study, we performed behavioral profiling of zebrafish treated with chemical and genetic sleep-wake modifiers. We were able to demonstrate that behavioral profiling of zebrafish treated with hypnotics or psychostimulants from 9 to 10 days post-fertilization was sufficient to identify drugs with specific modes of action. We were also able to identify behavioral endpoints distinguishing GABA-A modulators and hypocretin (hcrt) receptor antagonists and between sympathomimetic and non-sympathomimetic psychostimulants. This behavioral profiling can serve to identify genes related to sleep-wake disturbance associated with various neuropsychiatric diseases and novel therapeutic compounds for insomnia and excessive daytime sleep with fewer adverse side effects.

Caffeine increases striatal dopamine D2/D3 receptor availability in the human brain

Caffeine, the most widely consumed psychoactive substance in the world, is used to promote wakefulness and enhance alertness. Like other wake-promoting drugs (stimulants and modafinil), caffeine enhances dopamine (DA) signaling in the brain, which it does predominantly by antagonizing adenosine A2A receptors (A2AR). However, it is unclear if caffeine, at the doses consumed by humans, increases DA release or whether it modulates the functions of postsynaptic DA receptors through its interaction with adenosine receptors, which modulate them. We used positron emission tomography and [(11)C]raclopride (DA D2/D3 receptor radioligand sensitive to endogenous DA) to assess if caffeine increased DA release in striatum in 20 healthy controls. Caffeine (300 mg p.o.) significantly increased the availability of D2/D3 receptors in putamen and ventral striatum, but not in caudate, when compared with placebo. In addition, caffeine-induced increases in D2/D3 receptor availability in the ventral striatum were associated with caffeine-induced increases in alertness. Our findings indicate that in the human brain, caffeine, at doses typically consumed, increases the availability of DA D2/D3 receptors, which indicates that caffeine does not increase DA in the striatum for this would have decreased D2/D3 receptor availability. Instead, we interpret our findings to reflect an increase in D2/D3 receptor levels in striatum with caffeine (or changes in affinity). The association between increases in D2/D3 receptor availability in ventral striatum and alertness suggests that caffeine might enhance arousal, in part, by upregulating D2/D3 receptors.

Modafinil increases the latency of response in the Hayling Sentence Completion Test in healthy volunteers: a randomised controlled trial

Background

Modafinil is a medication licensed for the treatment of narcolepsy. However, it has been reported that healthy individuals without wakefulness disorders are using modafinil off-label to enhance cognitive functioning. Although some studies have reported that modafinil improves cognitive task performance in healthy volunteers, numerous other studies have failed to detect cognitive enhancing effects of modafinil on several well-established neuropsychological tasks. Interestingly, several clinical and preclinical studies have found that improved cognitive task performance by modafinil is accompanied by slower response times. This observation raises the question as to whether this slowing of response time in healthy volunteers is a necessary and sufficient condition for cognitive enhancement with modafinil. The aim of the current experiment was to explore this question by investigating the effects of modafinil on the Hayling Sentence Completion Test (HSCT).

Methodology

Sixty-four healthy volunteers received either a single dose (200 mg) of modafinil (n = 32) or placebo (n = 32) in a randomized, double-blind, placebo-controlled, parallel group study in which the principal outcome measures were response latencies on the response initiation and response inhibition sections of the HSCT.

Principal Findings

Participants dosed with modafinil had significantly longer mean response latencies on the HSCT for both the response initiation and response inhibition compared to participants dosed with placebo. However, participants in both groups made a similar number of errors on each of these measures, indicating that modafinil did not enhance the accuracy of performance of the task relative to placebo.

Conclusions

This study demonstrated that administration of single 200 mg doses of modafinil to healthy individuals increased the latency of responses in the performance of the HSCT, a task that is highly sensitive to prefrontal executive function, without enhancing accuracy of performance. This finding may provide important clues to defining the limitations of modafinil as a putative cognitive enhancer.

Trial Registration

ClinicalTrials.gov NCT02051153

Effects of modafinil on non-verbal cognition, task enjoyment and creative thinking in healthy volunteers

Background

Modafinil, a putative cognitive enhancing drug, has previously been shown to improve performance of healthy volunteers as well as patients with attention deficit disorder and schizophrenia, mainly in tests of executive functions. The aim of this study was to investigate the effects of modafinil on non-verbal cognitive functions in healthy volunteers, with a particular focus on variations of cognitive load, measures of motivational factors and the effects on creative problem-solving.

Methods

A double-blind placebo-controlled parallel design study evaluated the effect of 200 mg of modafinil (N = 32) or placebo (N = 32) in non-sleep deprived healthy volunteers. Non-verbal tests of divergent and convergent thinking were used to measure creativity. A new measure of task motivation was used, together with more levels of difficulty on neuropsychological tests from the CANTAB battery.

Results

Improvements under modafinil were seen on spatial working memory, planning and decision making at the most difficult levels, as well as visual pattern recognition memory following delay. Subjective ratings of enjoyment of task performance were significantly greater under modafinil compared with placebo, but mood ratings overall were not affected. The effects of modafinil on creativity were inconsistent and did not reach statistical significance.

Conclusions

Modafinil reliably enhanced task enjoyment and performance on several cognitive tests of planning and working memory, but did not improve paired associates learning. The findings confirm that modafinil can enhance aspects of highly demanding cognitive performance in non-sleep deprived individuals.

This article is part of a Special Issue entitled ‘Cognitive Enhancers’.

Sleep disorders in children with cancer

Approximately three-fourths of all pediatric cancer patients will be long-term survivors; however, there can be a steep cost for cancer survivorship. Cancer treatment involves exposure to chemotherapy, surgical intervention, and radiation, which can cause lasting long-term toxicities. Children with brain tumors have the highest prevalence of long-term morbidities. These effects can be attributed to direct neurologic damage to the developing brain caused by tumor, hydrocephalus, surgical removal of the tumor, and the effects of irradiation. The late effects experienced by childhood cancer survivors involve multiple domains, one of which is sleep disorders. Sleep dysfunction has an increased prevalence in the pediatric cancer survivor population. These issues are disruptive to patients and cause a decrease in quality of life. This review focuses on sleep disorders that occur in pediatric cancer survivors and discusses the possible causes, the assessments used to determine specific sleep disorders, and treatment modalities used to ameliorate this dysfunction with the hope of improving patient's quality of life.

Effects of modafinil and prazosin on cognitive and physiological functions in healthy volunteers

Previous research has demonstrated cognitive-enhancing effects of modafinil in humans and generated evidence for its therapeutic potential in psychiatric disorders. The neurochemical basis of these effects remains unresolved although a role for α1-adrenoceptors has been hypothesised. In this within-subject, double-blind, placebo-controlled study, 12 healthy male adults received modafinil (300 mg), the α1-adrenoceptor antagonist prazosin (3 mg), both together and placebo on separate occasions at least 5 days apart. Cognitive effects were assessed using a well-validated testing battery focusing on executive and working memory functions. Blood pressure, heart rate and salivary α-amylase (sAA) were measured at hourly intervals. Cognitive effects of modafinil and prazosin were identified at the difficult levels of the One-Touch Stockings of Cambridge (OTSOC) planning task. Prazosin antagonized the error-reducing effect of modafinil when the agents were given together. In contrast, the combined agents acted synergistically to increase time taken to complete OTSOC problems compared with placebo. The tachycardic and sAA-elevating effects of prazosin were also potentiated by concurrent modafinil administration. The current data suggest that the cognitive effects of modafinil on performance accuracy and latency are dissociable in terms of their neurochemical mechanisms. Our findings support the hypothesised involvement of α1-adrenoceptors in some of the cognitive-enhancing effects of modafinil and warrant further investigation.

Good night and good luck: norepinephrine in sleep pharmacology

Sleep is a crucial biological process that is regulated through complex interactions between multiple brain regions and neuromodulators. As sleep disorders can have deleterious impacts on health and quality of life, a wide variety of pharmacotherapies have been developed to treat conditions of excessive wakefulness and excessive sleepiness. The neurotransmitter norepinephrine (NE), through its involvement in the ascending arousal system, impacts the efficacy of many wake- and sleep-promoting medications. Wake-promoting drugs such as amphetamine and modafinil increase extracellular levels of NE, enhancing transmission along the wake-promoting pathway. GABAergic sleep-promoting medications like benzodiazepines and benzodiazepine-like drugs that act more specifically on benzodiazepine receptors increase the activity of GABA, which inhibits NE transmission and the wake-promoting pathway. Melatonin and related compounds increase sleep by suppressing the activity of the neurons in the brain's circadian clock, and NE influences the synthesis of melatonin. Antihistamines block the wake-promoting effects of histamine, which shares reciprocal signaling with NE. Many antidepressants that affect the signaling of NE are also used for treatment of insomnia. Finally, adrenergic receptor antagonists that are used to treat cardiovascular disorders have considerable sedative effects. Therefore, NE, long known for its role in maintaining general arousal, is also a crucial player in sleep pharmacology. The purpose of this review is to consider the role of NE in the actions of wake- and sleep-promoting drugs within the framework of the brain arousal systems.

Treatment of narcolepsy

Narcolepsy is a neurological disorder characterized, in its classical form, by excessive daytime sleepiness (EDS) with irresistible episodes of sleep, cataplexy, disrupted nocturnal sleep, hypnagogic/hypnopompic hallucinations and sleep paralysis. It is often under-diagnosed, however, if it is suitably diagnosed, symptoms can be well treated by means of targeted drugs, such as modafinil to treat EDS, sodium oxybate for cataplexy, as well as EDS and disrupted nocturnal sleep, and tricyclic and newer antidepressants for cataplexy. Hallucinations and sleep paralysis can be treated with the same drugs used for cataplexy. Amphetamines and amphetamine-like stimulants are used less nowadays. Behavioral measures are also important and useful. The discovery of hypocretin deficiency in narcoleptic patients opens new perspectives for the development of newer therapeutic approaches for both EDS and cataplexy. Therapy for narcolepsy is chronic, hence symptomatic. However, the correct use of available drugs enables patients to gain a better quality of life, keeping the symptoms under control, which, mainly from a social point of view, are heavily disabling.

Narcolepsy and depression and the neurobiology of gammahydroxybutyrate

A voluminous literature describes the relationship between disturbed sleep and depression. The breakdown of sleep is one of the cardinal features of depression and often also heralds its onset. Frequent arousals, periods of wakefulness and a short sleep onset REM latency are typical polysomnographic features of depression. The short latency to REM sleep has been attributed to the combination of a monoaminergic deficiency and cholinergic supersensitivity and these irregularities have been proposed to form the biological basis of the disorder. A similar imbalance between monoaminergic and cholinergic neurotransmission has been found in narcolepsy, a condition in which frequent awakenings, periods of wakefulness and short sleep onset REM latencies are also characteristic findings during sleep. In many cases of narcolepsy, this imbalance appears to result from a deficiency of hypocretin but once established, whether in depression or narcolepsy, this disequilibrium sets the stage for the dissociation or premature appearance of REM sleep and for the dissociation of the motor inhibitory component of REM sleep or cataplexy. In the presence of this monoaminergic/cholinergic imbalance, gammahydroxybutyrate (GHB) may acutely further reduce the latency of REM sleep and induce cataplexy, in both patients with narcolepsy or depression. On the other hand, the repeated nocturnal application of GHB in patients with narcolepsy improves the continuity of sleep, prolongs the latency to REM sleep and prevents cataplexy. Evidence to date suggests that GHB may restore the normal balance between monoaminergic and cholinergic neurotransmission. As such, the repeated use of GHB at night and the stabilization of sleep over time makes GHB an effective treatment for narcolepsy and a potentially effective treatment for depression.

Treatment with venlafaxine in six cases of children with narcolepsy and with cataplexy and hypnagogic hallucinations

OBJECTIVE

Narcolepsy with cataplexy is a chronic neuropsychiatric disorder associated with inappropriate control of rapid eye movement (REM) sleep. The main symptoms are excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, and disturbed nocturnal sleep. Cataplexy is marked by episodes of muscular weakness and may cause the patient to collapse to the ground. So far, pharmacotherapy of cataplexy and hypnagogic hallucinations has been predominantly based on tricyclic antidepressants. Recently, new drugs that block the reuptake of norepineprine and serotonin (e.g., venlafaxine) have been suggested as first-line treatment. These drugs have become our choice in treating children with cataplexy and nightmares as a symptom in narcolepsy.

METHODS

We describe clinical case reports of venlafaxine treatment in 6 children aged 7-12 years old when diagnosed with narcolepsy-cataplexy.

RESULTS

In 2 cases with up to 50 daily cataplectic attacks, an initial effect of 37.5 mg of venlafaxine was initially observed. However, during the first year, the dose had to be increased to 112.5 mg daily to avoid cataplexy. A third patient with partial cataplexy was treated with 75 mg of venlafaxine daily. In 2 cases, hypnagogic hallucinations, described by the patients as nightmares, were the most troubling symptom and were successfully treated with only 37.5 mg of venlafaxine daily. Side effects included an increase of disturbed nocturnal sleep when venlafaxine was taken after 2:00 p.m. No major aggressive or suicidal thoughts and no raised blood pressure were recorded.

CONCLUSION

Venlafaxine has proven to be an effective treatment of cataplexy and hypnagogic hallucinations in 6 children with narcolepsy. No severe side effects were observed.

Effects of common medications used for sleep disorders

Sleep disorders are common and their diagnosis is becoming more widespread with improved awareness among clinicians and patients. The armamentarium for the pharmacologic treatment of sleep disorders is rapidly growing, demanding that clinicians be aware of their indications, adverse effects, and interactions. As disorders, such as narcolepsy, shift-work sleep disorder, and RLS are more readily identified, pharmacologic treatments for these conditions will also become more common.

A novel animal model for motion sickness and its first application in rodents

The present work was designed to establish a novel animal model for motion sickness (MS) in rodents and to evaluate the effects of a combination of scopolamine and modafinil on MS with this novel method. It was found that the rats and mice presented several symptoms induced by rotation such as, piloerection, tremble, urinal and fecal incontinence. As the rats and mice are lack of emesis response to rotation, we used a score based on abovementioned symptoms as an index for the severity of MS in rodents. MS index was determined in 260 mice with this novel method. It was found that the distribution of MS index was normal (W=0.99; P=0.23. P>0.05 considered values' normal distribution). The effects of scopolamine on MS were studied in mice and rats. It was found that scopolamine significantly decreased MS index at the dose of 0.3 mg/kg in mice and 1.0 mg/kg in rats. Finally, the effects of a combination of scopolamine and modafinil were observed with this novel method in rats. It was found that the efficacy of the combination (5.0+5.0 mg/kg) was greater than the single drugs (10 mg/kg). Even the smallest dose of the combination (0.5+0.5 mg/kg) had a similar effect to large dose of scopolamine or modafinile when they were used alone. In conclusion, this animal model is suitable for MS study in rats and mice and the combination of scopolamine and modafinil might be a new method to treat or prevent MS.

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.

Psychosocial adjustment following relief of chronic narcolepsy

BACKGROUND AND PURPOSE

No previous research has examined the psychosocial adjustment of chronic narcolepsy patients following efficacious pharmacotherapy. In contrast, considerable research has examined the process of psychosocial adjustment following surgical relief of chronic epilepsy. This process can manifest as a clinical syndrome, the 'burden of normality', comprising psychological, behavioural, affective and sociological features. The aim of the present study was to characterise the process of psychosocial adjustment of patients with successfully treated narcolepsy and to explore the applicability of the burden of normality.

PATIENTS AND METHODS

Thirty-three narcolepsy patients and 31 epilepsy surgery patients were recruited through routine outpatient follow-up at the Austin Hospital in Melbourne. All patients underwent in-depth, qualitative psychosocial assessment using a well-validated semi-structured interview, the Austin CEP Interview. They were also administered quantitative measures of anxiety (State Trait Anxiety Inventory) and depression (Beck Depression Inventory-II).

RESULTS

Narcolepsy patients spontaneously reported similar themes of post-treatment adjustment to successfully treated epilepsy patients, including symptoms of the burden of normality. Chi-squared analyses revealed that the two groups differed only on disease-specific factors, reflecting the later diagnosis and treatment of narcolepsy (P<0.05).

CONCLUSION

The results support a general model of adjustment following successful treatment of chronic neurological illness, as the patient discards perceptions of illness and behaviours associated with being 'sick' and learns to become 'well'. Recognition of the burden of normality has important clinical implications for maximising the post-treatment care and outcome of narcolepsy patients.

Modafinil Occupies Dopamine and Norepinephrine Transporters in Vivo and Modulates the Transporters and Trace Amine Activity in Vitro

2-[(Diphenylmethyl) sulfinyl]acetamide (modafinil), prescribed principally to treat narcolepsy, is undergoing assessment for other neuropsychiatric disorders and medical conditions. The neurochemical substrates of modafinil are unresolved. We postulated that modafinil enhances wakefulness by modulating dopamine (DAT), norepinephrine (NET), or serotonin (SERT) transporter activities. In vivo, we determined DAT and NET occupancy by modafinil by positron emission tomography imaging; in vitro, we determined modafinil activity at the DAT, NET, SERT, and rhesus monkey trace amine receptor 1 (TA1). In rhesus monkey, modafinil occupancy of striatal DAT was detected by [(11)C]2beta-carbomethoxy-3beta-4-(fluorophenyl)tropane and of thalamic NET by [(11)C](S,S)-2-(alpha-(2-methoxyphenoxy)-benzyl)morpholine. In vitro, modafinil effects in DAT-human embryonic kidney (HEK), NET-HEK, and SERT-HEK cells were investigated alone or combined with the TA1 receptor. Modafinil (i.v.) occupied striatal DAT sites (5 mg/kg: 35 +/- 12%, n = 4; 8 mg/kg: 54 +/- 3%, n = 3). In thalamus, modafinil occupied NET sites (5 mg/kg: 16 +/- 7.8%, n = 6; 8 mg/kg: 44 +/- 12%; n = 2). In vitro, modafinil inhibited [(3)H]dopamine (IC(50) = 6.4 microM), [(3)H]norepinephrine (IC(50) = 35.6 microM), and [(3)H]serotonin (IC(50) > 500 microM) transport via the human DAT, NET, and SERT. Modafinil did not activate the TA1 receptor in TA1-HEK cells, but it augmented a monoamine transporter-dependent enhancement of phenethylamine activation of TA1 in TA1-DAT and TA1-NET cells, but not in TA1-SERT cells. The present data provide compelling evidence that modafinil occupies the DAT and NET in living brain of rhesus monkeys and raise the possibility that modafinil affects wakefulness by interacting with catecholamine transporters in brain.

Does methylphenidate reduce the symptoms of chronic fatigue syndrome?

PURPOSE

Chronic fatigue syndrome is a clinical entity consisting of prolonged and debilitating fatigue in which concentration disturbances are very frequent. Until now, no medical treatment has shown any efficacy. The objectives of this study were to investigate the short-term effects of methylphenidate, an amphetamine derivative, on fatigue, concentration disturbances, and quality of life.

SUBJECTS AND METHODS

A double-blind randomized placebo-controlled crossover study was conducted in 60 patients who fulfilled the 1994 Centers for Disease Control criteria for chronic fatigue syndrome and had concentration difficulties. Patients were enrolled between March 2003 and March 2004 at the outpatient department of a university hospital referral center for chronic fatigue syndrome patients. Random assignment to 4 weeks treatment with methylphenidate 2 x 10 mg/day, followed by 4 weeks of placebo treatment, or 4 weeks of placebo treatment, followed by methylphenidate treatment. Fatigue and concentration were measured with a Checklist Individual Strength (CIS) and a Visual Analogue Scale (VAS).

RESULTS

Fatigue scores fell significantly during methylphenidate intake in comparison with baseline (mean difference: -0.7, P = .010 for VAS; mean difference: -11.8, P <.0001 for CIS) and in comparison with placebo (mean difference: -1.0, P = .001 for VAS; mean difference: -9.7, P <.0001 for CIS). Concentration disturbances, measured with a VAS improved significantly under methylphenidate treatment compared with baseline (mean difference: -1.3, P <.0001) and compared with placebo (mean difference: -1.1, P <.0001). A clinical significant effect (> or =33% improvement or CIS < or =76) on fatigue was achieved in 17% of patients, who were considered responders; on concentration in 22% of patients.

CONCLUSIONS

Methylphenidate at a dose of 2 x 10 mg/day is significantly better than placebo in relieving fatigue and concentration disturbances in a minority of chronic fatigue syndrome patients. Further studies are needed to investigate the long-term effects of this treatment.