The effect of modafinil on cortical excitability in patients with narcolepsy: A randomized, placebo-controlled, crossover study

Treatment of central disorders of hypersomnolence: an American Academy of Sleep Medicine systematic review, meta-analysis, and GRADE assessment

INTRODUCTION

This systematic review provides supporting evidence for the accompanying clinical practice guideline on the treatment of central disorders of hypersomnolence in adults and children. The review focuses on prescription medications with U.S. Food & Drug Administration approval and nonpharmacologic interventions studied for the treatment of symptoms caused by central disorders of hypersomnolence.

METHODS

The American Academy of Sleep Medicine commissioned a task force of experts in sleep medicine to perform a systematic review. Randomized controlled trials and observational studies addressing pharmacological and nonpharmacological interventions for central disorders of hypersomnolence were identified. Statistical analyses were performed to determine the clinical significance of all outcomes. Finally, the Grading of Recommendations Assessment, Development and Evaluation (GRADE) process was used to assess the evidence for the purpose of making specific treatment recommendations.

RESULTS

The literature search identified 678 studies; 144 met the inclusion criteria and 108 provided data suitable for statistical analyses. Evidence for the following interventions is presented: armodafinil, clarithromycin, clomipramine, dextroamphetamine, flumazenil, intravenous immune globulin (IVIG), light therapy, lithium, l-carnitine, liraglutide, methylphenidate, methylprednisolone, modafinil, naps, pitolisant, selegiline, sodium oxybate, solriamfetol, and triazolam. The task force provided a detailed summary of the evidence along with the quality of evidence, the balance of benefits and harms, patient values and preferences, and resource use considerations.

CITATION

Maski K, Trotti LM, Kotagal S, et al. Treatment of central disorders of hypersomnolence: an American Academy of Sleep Medicine systematic review, meta-analysis, and GRADE assessment. J Clin Sleep Med. 2021;17(9):1895-1945.

Doping detection in animals: A review of analytical methodologies published from 1990 to 2019

Despite the impressive innate physical abilities of horses, camels, greyhounds, or pigeons, doping agents might be administered to these animals to improve their performance. To control these illegal practices, anti-doping analytical methodologies have been developed. This review compiles the analytical methods that have been published for the detection of prohibited substances administered to animals involved in sports over 30 years. Relevant papers meeting the search criteria that discussed analytical methods aiming to detect and/or quantify doping substances in animal biological matrices published from 1990 to 2019 were considered. A total of 317 studies were included, of which 298 were related to horses, demonstrating significant advances toward the development of doping detection methods for equine sports. However, analytical methods for the detection of doping agents in sports involving other species are lacking. Due to enhanced accuracy and specificity, chromatographic analysis coupled to mass spectrometry detection is preferred over immunoassays. Regarding biological matrices, blood and urine remain the first choice, although alternative biological matrices, such as hair and feces, have been considered. With the increasing number and type of drugs used as doping agents, the analytes addressed in the published papers are diverse. It is very important to continue to detect and quantify these drugs, recognizing those that are most frequently used, in order to punish the abusers, protect animals' health, and ensure a healthier and genuine competition.

Fluctuation of primary motor cortex excitability during cataplexy in narcolepsy

Objective

Cataplexy is a complicated and dynamic process in narcolepsy type 1 (NT1) patients. This study aimed to clarify the distinct stages during a cataplectic attack and identify the changes of the primary motor cortex (PMC) excitability during these stages.

Methods

Thirty-five patients with NT1 and 29 healthy controls were recruited to this study. Cataplectic stages were distinguished from a cataplectic attack by video-polysomnogram monitoring. Transcranial magnetic stimulation motor-evoked potential (TMS-MEP) was performed to measure the excitability of PMC during quiet wakefulness, laughter without cataplexy, and each cataplectic stage.

Results

Based on the video and electromyogram observations, a typical cataplectic attack (CA) process is divided into four stages: triggering (CA1), resisting (CA2), atonic (CA3), and recovering stages (CA4). Compared with healthy controls, NT1 patients showed significantly decreased intracortical facilitation during quiet wakefulness. During the laughter stage, both patients and controls showed increased MEP amplitude compared with quiet wakefulness. The MEP amplitude significantly increased even higher in CA1 and 2, and then dramatically decreased in CA3 accompanied with prolonged MEP latency compared with the laughter stage and quiet wakefulness. The MEP amplitude and latency gradually recovered during CA4.

Interpretation

This study identifies four stages during cataplectic attack and reveals the existence of a resisting stage that might change the process of cataplexy. The fluctuation of MEP amplitude and MEP latency shows a potential participation of PMC and motor control pathway during cataplexy, and the increased MEP amplitude during CA1 and 2 strongly implies a compensatory mechanism in motor control that may resist or avoid cataplectic attack.

Effective treatment of narcolepsy-like symptoms with high-frequency repetitive transcranial magnetic stimulation: A case report

RATIONALE

Narcolepsy is a rare sleep disorder with disrupted sleep-architecture. Clinical management of narcolepsy lies dominantly on symptom-driven pharmacotherapy. The treatment role of repetitive transcranial magnetic stimulation (rTMS) for narcolepsy remains unexplored.

PATIENT CONCERNS

In this paper, we present a case of a 14-year-old young girl with excessive daytime sleepiness (EDS), cataplexy and hypnagogic hallucinations.

DIAGNOSES

After excluding other possible medical conditions, this patient was primarily diagnosed with narcolepsy.

INTERVENTIONS

The patient received 25 sessions of high-frequency rTMS over the left dorsolateral prefrontal cortex (DLPFC).

OUTCOMES

The symptoms of EDS and cataplexy significantly improved after rTMS treatment. Meanwhile, her score in the Epworth sleep scale (ESS) also remarkably decreased.

LESSONS

This case indicates that rTMS may be selected as a safe and effective alternative strategy for treating narcolepsy-like symptoms. Well-designed researches are warranted in future investigations on this topic.

Disharmony between wake- and respiration-promoting activities: effects of modafinil on ventilatory control in rodents

Background

Modafinil is a wake-promoting drug and has been widely used for daytime sleepiness in patients with narcolepsy and other sleep disorders. A recent case series reported that daily oral modafinil alleviated hypercapnic respiratory failure in patients with COPD. However, the precise action of modafinil on respiration such as hypercapnic and/or hypoxic ventilatory responses remains unclear. The aim of this study is to clarify the effect of modafinil on the ventilatory control.

Methods

We investigated the hypothesis that modafinil enhances resting ventilation as well as the stimulatory ventilatory responses to hypercapnia and hypoxia. We addressed the issue by examining minute ventilation, respiratory rate and volume components using plethysmography, combined with a concurrent EEG monitoring of the level of wakefulness before and after administration of modafinil in two doses of 100 mg/kg and 200 mg/kg in unanesthetized mice. In addition, we monitored the effect of the lower dose of modafinil on mice locomotor activity in a freely moving condition by video-recording.

Results

Wakefulness, locomotor activity and variability of the breathing pattern in tidal volume were promoted by both doses of modafinil. Neither dose of modafinil increased the absolute values of resting ventilation or promoted the ventilatory responses to hypercapnia and hypoxia. Rather, higher dose of modafinil slightly suppressed respiratory rate in room air condition.

Conclusions

Modafinil is conducive to the state of wakefulness but does not augment resting ventilation or the hyperventilatory responses to chemical stimuli in unanesthetized rodents.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-016-0466-9) contains supplementary material, which is available to authorized users.

Pharmacological treatment of sleep disorders and its relationship with neuroplasticity

Sleep and wakefulness are regulated by complex brain circuits located in the brain stem, thalamus, subthalamus, hypothalamus, basal forebrain, and cerebral cortex. Wakefulness and NREM and REM sleep are modulated by the interactions between neurotransmitters that promote arousal and neurotransmitters that promote sleep. Various lines of evidence suggest that sleep disorders may negatively affect neuronal plasticity and cognitive function. Pharmacological treatments may alleviate these effects but may also have adverse side effects by themselves. This chapter discusses the relationship between sleep disorders, pharmacological treatments, and brain plasticity, including the treatment of insomnia, hypersomnias such as narcolepsy, restless legs syndrome (RLS), obstructive sleep apnea (OSA), and parasomnias.

Modafinil augments oscillatory power in middle frequencies during rule selection

Control-related cognitive processes are associated with cortical oscillations and modulated by catecholamine neurotransmitters. It remains unclear how catecholamine systems modulate control-related oscillations. We tested modafinil effects on rule-related 4-30 Hz oscillations, with double-blind, placebo-controlled (within-subjects) testing of 22 healthy adults, using EEG during cognitive control task performance. EEG data underwent time-frequency decomposition with Morlet wavelets to determine power of 4-30 Hz oscillations. Modafinil enhanced oscillatory power associated with high-control rule selection in theta, alpha, and beta ranges, with a frontotemporal topography and minimal effects during rule maintenance. Augmentation of catecholamine signaling enhances middle-frequency cortical oscillatory power associated with rule selection, which may subserve diverse subcomponent processes in proactive cognitive control.

Transcranial magnetic stimulation and sleep disorders: pathophysiologic insights

The neural mechanisms underlying the development of the most common intrinsic sleep disorders are not completely known. Therefore, there is a great need for noninvasive tools which can be used to better understand the pathophysiology of these diseases. Transcranial magnetic stimulation (TMS) offers a method to noninvasively investigate the functional integrity of the motor cortex and its corticospinal projections in neurologic and psychiatric diseases. To date, TMS studies have revealed cortical and corticospinal dysfunction in several sleep disorders, with cortical hyperexcitability being a characteristic feature in some disorders (i.e., the restless legs syndrome) and cortical hypoexcitability being a well-established finding in others (i.e., obstructive sleep apnea syndrome narcolepsy). Several research groups also have applied TMS to evaluate the effects of pharmacologic agents, such as dopaminergic agent or wake-promoting substances. Our review will focus on the mechanisms underlying the generation of abnormal TMS measures in the different types of sleep disorders, the contribution of TMS in enhancing the understanding of their pathophysiology, and the potential diagnostic utility of TMS techniques. We also briefly discussed the possible future implications for improving therapeutic approaches.

Is High IQ Protective Against Cognitive Dysfunction in Narcoleptic Patients?

BACKGROUND AND PURPOSE

The aims of this study were to elucidate the cognitive functions of narcoleptics and determine whether intelligence protects against cognitive dysfunction and depressive mood in these patients.

METHODS

Sixty-six subjects (33 narcoleptics, 33 controls) were administered a battery of neuropsychological tests and an individual standardized intelligence test. The cognitive functions of the narcoleptic patients and the healthy controls were compared, as were those of high-IQ and mid-to-low-IQ narcoleptic patients.

RESULTS

Narcoleptics exhibited significantly lower scores in the Corsi Block-Tapping Test forward and backward, and the digit symbol tests, and significantly higher Beck Depression Inventory scores than the controls. However, verbal attention, verbal-visual long-term memory, and executive function task scores did not differ significantly between patients and controls. The mid-to-low-IQ patient group had lower mean digit span backward test, phonemic and semantic fluency Controlled Oral Word Association Test and Korean version of the Boston Naming Test scores, and a higher total score and general depressive symptoms subscales Beck Depression Inventory score than the high-IQ patient group. However, controls exhibited no IQ-related differences in cognitive performance or depressive mood. Patients in the high-IQ group exhibited impaired visual attention and working memory as compared with controls.

CONCLUSIONS

The findings of the present study show that narcolepsy patients have deficits in visual attention and visual working memory, and tend to feel more general depressive symptoms but not somatic symptoms than their control, nonnarcoleptic counterparts. In addition, it appears that higher intelligence protects against cognitive dysfunction and depressive mood.

Can transcranial magnetic stimulation be used to evaluate patients with narcolepsy?

Narcolepsy is a rare, chronic sleep disorder characterized by excessive daytime sleepiness, cataplexy and other manifestations of dissociated rapid eye movement in sleep. We assessed the utility of transcranial magnetic stimulation (TMS) as an objective tool to elucidate the cortical excitability changes and also to analyze its role in assessing the treatment efficacy in narcolepsy. Eight patients with narcolepsy under our regular follow-up from 2000 to 2009 at our Sleep disorder clinic were chosen. All of them underwent polysomnography, multiple sleep latency tests and TMS. Resting motor threshold (RMT), cortical silent period (CSP) and central motor conduction time (CMCT) were assessed using TMS in both drug-naïve and post-treatment states. Eight controls were also subjected to all the three investigations. Appropriate statistical methods were used. The mean RMT (%) pre-treatment was higher in narcolepsy patients than that in controls, and it normalized following treatment. CSP and CMCT were unaffected in narcolepsy patients as compared to controls. This study shows that the cortical excitability is significantly low in narcolepsy patients. This motor cortex hypoexcitability becomes normal with the institution of treatment, pari passu with the control of symptoms. In future, TMS may be considered as an effective tool for documenting the treatment efficacy in patients with narcolepsy.