Comorbidity of narcolepsy and depressive disorders: a nationwide population-based study in Taiwan

Development and validation of a machine learning model for prediction of comorbid major depression disorder among narcolepsy type 1

BACKGROUND

Major depression disorder (MDD) forms a common psychiatric comorbidity among patients with narcolepsy type 1 (NT1), yet its impact on patients with NT1 is often overlooked by neurologists. Currently, there is a lack of effective methods for accurately predicting MDD in patients with NT1.

OBJECTIVE

This study utilized machine learning (ML) algorithms to identify critical variables and developed the prediction model for predicting MDD in patients with NT1.

METHODS

The study included 267 NT1 patients from four sleep centers. The diagnosis of comorbid MDD was based on Diagnostic and Statistical Manual of Mental Disorders fifth edition (DSM-5). ML models, including six full models and six compact models, were developed using a training set. The performance of these models was compared in the testing set, and the optimal model was evaluated in the testing set. Various evaluation metrics, such as Area under the receiver operating curve (AUC), precision-recall (PR) curve and calibration curve were employed to assess and compare the performance of the ML models. Model interpretability was demonstrated using SHAP.

RESULT

In the testing set, the logistic regression (LG) model demonstrated superior performance compared to other ML models based on evaluation metrics such as AUC, PR curve, and calibration curve. The top eight features used in the LG model, ranked by feature importance, included social impact scale (SIS) score, narcolepsy severity scale (NSS) score, total sleep time, body mass index (BMI), education years, age of onset, sleep efficiency, sleep latency.

CONCLUSION

The study yielded a straightforward and practical ML model for the early identification of MDD in patients with NT1. A web-based tool for clinical applications was developed, which deserves further verification in diverse clinical settings.

The Changed Nocturnal Sleep Structure and Higher Anxiety, Depression, and Fatigue in Patients with Narcolepsy Type 1

Purpose

This study aimed to evaluate nocturnal sleep structure and anxiety, depression, and fatigue in patients with narcolepsy type 1 (NT1).

Methods

Thirty NT1 patients and thirty-five healthy controls were enrolled and evaluated using the Epworth sleepiness scale (ESS), Generalized Anxiety Disorder-7, Patient Health Questionnaire-9, Fatigue Severity Scale (FSS), polysomnography, multiple sleep latency test, and brain function state monitoring. Statistical analyses were performed using SPSS Statistics for Windows, version 23.0. Benjamini-Hochberg correction was performed to control the false discovery rate.

Results

Apart from typical clinical manifestations, patients with NT1 are prone to comorbidities such as nocturnal sleep disorders, anxiety, depression, and fatigue. Compared with the control group, patients with NT1 exhibited abnormal sleep structure, including increased total sleep time (P adj=0.007), decreased sleep efficiency (P adj=0.002), shortening of sleep onset latency (P adj<0.001), elevated wake after sleep onset (P adj=0.002), increased N1% (P adj=0.006), and reduced N2%, N3%, and REM% (P adj=0.007, P adj<0.001, P adj=0.013). Thirty-seven percent of patients had moderate to severe obstructive sleep apnea-hypopnea syndrome. And sixty percent of patients were complicated with REM sleep without atonia. Patients with NT1 displayed increased anxiety propensity (P adj<0.001), and increased brain fatigue (P adj=0.020) in brain function state monitoring. FSS scores were positively correlated with brain fatigue (P adj<0.001) and mean sleep latency was inversely correlated with FSS scores and brain fatigue (P adj=0.013, P adj=0.029). Additionally, ESS scores and brain fatigue decreased after 3 months of therapy (P=0.012, P=0.030).

Conclusion

NT1 patients had abnormal nocturnal sleep structures, who showed increased anxiety, depression, and fatigue. Excessive daytime sleepiness and fatigue improved after 3 months of treatment with methylphenidate hydrochloride prolonged-release tablets in combination with venlafaxine.

Narcolepsy and psychiatric disorders: A bidirectional Mendelian randomization study

Since the introduction of the concept of narcolepsy, there has been a proliferation of discussions about its association with psychiatry. To elucidate the causal role of narcolepsy in the three psychiatric disorders [i.e., schizophrenia (SCZ), major depressive disorder (MDD), and attention-deficit hyperactivity disorder (ADHD)], we applied a bidirectional Mendelian randomization study using two stages (discovery stage and validation stage) and data from three different genome-wide association studies of narcolepsy. The estimates from different stages were combined using fixed-effects meta-analysis. Our findings suggest that narcolepsy is associated with an increased risk of SCZ. Conversely, MDD may be causally related to narcolepsy. A causal relationship between narcolepsy and ADHD was excluded.

Differences in psychosocial factors and sleep study findings between delayed sleep-wake phase disorder and hypersomnia in teenagers

Central hypersomnia (HS) and delayed sleep-wake phase disorder (DSWPD) appear commonly in adolescents, and they severely reduce quality of life and have an enormous impact on academic performance and other aspects of development. Although these disorders are thought to be considerably different in etiology, it is sometimes difficult to distinguish them because of their similar clinical features. This study aimed to compare psychosocial factors and sleep study findings between HS and DSWPD in teenagers. The clinical data of 89 teenagers who visited the psychiatric section of the Sleep Medicine Center of Nihon University Itabashi Hospital from January 2013 to December 2019 were analyzed. Psychosocial factors were evaluated at the first visit, and polysomnography (PSG) and the multiple sleep latency test (MSLT) were performed for patients deemed to require definitive diagnosis. Compared with patients with HS, those with DSWPD had a higher rate of mother's employment, introversion, adjustment problems, events that triggered the disorder, concurrent mental disorders, habitual lateness, and difficulty attending school or work. PSG did not show any differences in sleep parameters between the two disorders, except for sleep latency. On the MSLT, sleep latency was shorter in those with HS on the second, third, and fourth tests. The present results suggest that focusing on psychosocial factors could be useful for differential diagnosis of the two disorders that appear commonly in adolescents.

Sleep function: an evolutionary perspective

Prospective epidemiological studies in industrial societies indicate that 7 h of sleep per night in people aged 18 years or older is optimum, with higher and lower amounts of sleep predicting a shorter lifespan. Humans living a hunter-gatherer lifestyle (eg, tribal groups) sleep for 6-8 h per night, with the longest sleep durations in winter. The prevalence of insomnia in hunter-gatherer populations is low (around 2%) compared with the prevalence of insomnia in industrial societies (around 10-30%). Sleep deprivation studies, which are done to gain insights into sleep function, are often confounded by the effects of stress. Consideration of the duration of spontaneous daily sleep across species of mammals, which ranges from 2 h to 20 h, can provide important insights into sleep function without the stress of deprivation. Sleep duration is not related to brain size or cognitive ability. Rather, sleep duration across species is associated with their ecological niche and feeding requirements, indicating a role for wake-sleep balance in food acquisition and energy conservation. Brain temperature drops from waking levels during non-rapid eye movement (non-REM) sleep and rises during REM sleep. Average daily REM sleep time of homeotherm orders is negatively correlated with average body and brain temperature, with the largest amount of REM sleep in egg laying (monotreme) mammals, moderate amounts in pouched (marsupial) mammals, lower amounts in placental mammals, and the lowest amounts in birds. REM sleep might, therefore, have a key role in the regulation of temperature and metabolism of the brain during sleep and in the facilitation of alert awakening.

Narcolepsy: Comorbidities, complexities and future directions

Patients with narcolepsy live with a lifelong sleep-wake disorder, impairing their quality of life, productivity, educational and employment outcomes. Clinicians are becoming aware that a significant aspect of the burden of this disease relates to frequent comorbid conditions, including aspects of the patient's emotional, metabolic, sleep and immune health. This review explores the literature describing the comorbidities seen in patients with narcolepsy, to enhance understanding of these often complex presentations. It hopes to encourage a multidisciplinary approach, to collaborate with patients and a broad clinical team, and to maximise clinical and quality of life outcomes, for those living with narcolepsy.

Case report: Cases of narcolepsy misdiagnosed as other psychiatric disorders

Narcolepsy is characterized by uncontrollable excessive daytime sleepiness, paroxysmal cataplexy, sleep paralysis, and hallucinations. It is often misdiagnosed as psychiatric disorders such as depression and schizophrenia, resulting from the overlap in symptoms and a lack of understanding of narcolepsy. In the present study, three cases of narcolepsy misdiagnosed as depression, dissociative disorder, and schizophrenia are presented to emphasize the high occurrence of the misdiagnosis of narcolepsy in clinical practice. The main reasons for this dilemma are attributed to the lack of adequate sleep, medicine, education, as well as specialized professional technicians. A multi-disciplinary team composed of psychiatrists and sleep specialists should be established to deal with this problem.

Factors Associated with Depression and Sub-Dimension Symptoms in Adolescent Narcolepsy

OBJECTIVE

We evaluate the association between depression symptoms, clinical features (disease onset-age, disease duration, sleep-related hallucination), sleepiness, and polysomnography parameters in adolescent narcolepsy type 1 patients.

METHODS

Eighty-three adolescent narcolepsy type 1 patients were involved in this cross-sectional study. Patients completed questionnaires evaluating depression symptoms (Center for Epidemiologic Studies Depression Scale) and sleepiness (Epworth Sleepiness Scale). Parameters from polysomnography and multiple sleep latency test were also collected.

RESULTS

Patients with depression symptoms (62.7%) have later disease onset-age. Depression symptoms were associated with sleep-related hallucination (OR = 2.75). Six independent variables were associated with sub-dimensional depression symptoms, including sleep latency, sleep efficiency, sleep-related hallucination, Epworth sleepiness scale, disease duration, and disease onset-age.

CONCLUSION

Sleep-related hallucination is associated with total depression symptoms in adolescent narcolepsy. Subjective sleepiness is associated with depressed affect, somatic symptoms, and interpersonal problems. Lower sleep efficiency is associated with a lack of positive affect.

2018 worldwide survey of health-care providers caring for patients with narcolepsy: WSS narcolepsy task force

BACKGROUND

There are limited data available on regional differences in the diagnosis and management of narcolepsy. In order to better understand worldwide trends in clinical assessment and management of narcolepsy, a survey of health-care providers was conducted by the World Sleep Society Narcolepsy task force.

METHODS

A total of 146 surveys that included items on the diagnosis and management of narcolepsy were completed by practitioners representing 37 countries.

RESULTS

Most of the participants were from Europe, North America, Oceania, Asia and Latin America. A consistent approach to applying the diagnostic criteria of Narcolepsy was documented with the exception of measurement of CSF hypocretin-1, which has limited availability. While the majority of practitioners (58%) reported not using the test, 1% indicated always evaluating CSF hypocretin-1 levels. There was much variability in the availability of currently recommended medications such as sodium oxybate and pitolisant; modafinil and antidepressants were the most commonly used medications. Amphetamines were unavailable in some countries.

CONCLUSION

The results of the study highlight clinical and therapeutic realities confronted by worldwide physicians in the management of narcolepsy. While the diagnostic criteria of narcolepsy rely in part on the quantification of CSF hypocretin-1, few physicians reported having incorporated this test into their routine assessment of the condition. Regional differences in the management of narcolepsy appeared to be related to geographic availability and expense of the therapeutic agents.

Recognizing the Symptom Spectrum of Narcolepsy to Improve Timely Diagnosis: A Narrative Review

Narcolepsy is a chronic sleep disorder with a strong negative impact on quality of life, especially when untreated. Diagnostic delay is a persistent problem, with obvious detrimental effects on patients. A diagnosis of narcolepsy may be delayed because of its broad symptom presentation which is much more encompassing than the classical "tetrad" of sleepiness, cataplexy, hallucinations, and sleep paralysis. Furthermore, symptoms can vary over time. Presentation of symptoms can also be markedly different between children and adults. Finally, common sleep-related comorbidities increase the risk of narcolepsy being masked by overlapping symptoms or treatment. In this review, we provide a detailed description of the broad and dynamic symptom spectrum of narcolepsy, with specific attention to the different manifestations in both adults and children. The overarching goal is to help not only sleep specialists, but general practitioners, pediatricians, and other caregivers with early recognition and prompt diagnosis of this severe but treatable disorder.

Pleasure, addiction, and hypocretin (orexin)

The hypocretins/orexins were discovered in 1998. Within 2 years, this led to the discovery of the cause of human narcolepsy, a 90% loss of hypothalamic neurons containing these peptides. Further work demonstrated that these neurons were not simply linked to waking. Rather these neurons were active during pleasurable behaviors in waking and were silenced by aversive stimulation. This was seen in wild-type mice, rats, cats, and dogs. It was also evident in humans, with increased Hcrt release during pleasurable activities and decreased release, to the levels seen in sleep, during pain. We found that human heroin addicts have, on average, an increase of 54% in the number of detectable Hcrt neurons compared to "control" human brains and that these Hcrt neurons are substantially smaller than those in control brains. We found that in mice, chronic morphine administration induced the same changes in Hcrt neuron number and size. Our studies in the mouse allowed us to determine the specificity, dose response relations, time course of the change in the number of Hcrt neurons, and that the increased number of Hcrt neurons after opiates was not due to neurogenesis. Furthermore, we found that it took a month or longer for these anatomical changes in the mouse brain to return to baseline. Human narcoleptics, despite their prescribed use of several commonly addictive drugs, do not show significant evidence of dose escalation or substance use disorder. Similarly, mice in which the peptide has been eliminated are resistant to addiction. These findings are consistent with the concept that an increased number of Hcrt neurons may underlie and maintain opioid or cocaine use disorders.

Quality of life and procrastination in post-H1N1 narcolepsy, sporadic narcolepsy and idiopathic hypersomnia, a Swedish cross-sectional study

OBJECTIVE/BACKGROUND

A cross-sectional study of health-related quality of life (HRQoL), procrastination and the relation to sleepiness, depression and fatigue in post-H1N1 narcolepsy type 1 (NT1), sporadic NT1 and idiopathic hypersomnia (IH).

PATIENTS/METHODS

Participants with NT1 and IH were enrolled from the Department of Neurology, Sahlgrenska University Hospital in Gothenburg (Sweden). All participants completed questionnaires about medication, employment, studies, transfer income, sleepiness, HRQoL, depression, fatigue and three questionnaires for procrastination.

RESULTS

Post-H1N1, sporadic NT1 and IH all scored higher than healthy controls on Epworth Sleepiness Scale (ESS), Patient Health Questionnaire (PHQ-9) and Fatigue Severity Scale (FSS), whereas EQ-5D-5L index and VAS was lower than for healthy individuals, but with no difference between groups. Post-H1N1 NT1 had a larger proportion of participants prescribed with sodium oxybate (44% vs. 9%, p = 0.003) and dexamphetamine (62% vs. 17%, p = 0.03) compared to sporadic NT1. The latter also in significantly higher doses than in sporadic NT1 (46 ± 12 vs. 25 ± 10 and 47.5 ± 21 mg, p < 0.0001). Post-H1N1 NT1 also had significantly higher scores on Pure Procrastination Scale (PPS), Irrational Procrastination Scale (IPS) and Susceptibility to Temptation Scale (STS), indicating a higher degree of procrastination. Multivariate analysis showed that depression, and to some extent fatigue, were predictors in NT1 for both HRQoL and procrastination.

CONCLUSIONS

The results show that health-related quality of life is impaired and tendency to procrastinate is higher in patients suffering from NT1 and both attributes can in part be explained by depressive symptoms. These findings highlight the impact of symptoms other than sleep and wakefulness regulation in patients with NT1.

Association between selective serotonin reuptake inhibitors and kidney cancer risk: A nationwide population-based cohort study

The association between selective serotonin reuptake inhibitor (SSRI) exposure and cancer incidence has been investigated; however, no epidemiological study has investigated the association between exposure to individual SSRIs and kidney cancer incidence. The aim of this study is to examine whether SSRI use affected the risk of kidney cancer. We conducted a population-based retrospective cohort study using data from Taiwan's National Health Insurance Research Database. After adjusting for sex, age, urbanization level, comorbidity and medication use through propensity score matching, we identified 222 024 SSRI users and 221 361 SSRI nonusers. A robust Cox proportional hazards model was used to examine the associations between use of individual SSRIs and the risk of kidney cancer with 1- and 2-year induction periods. The result showed that SSRI users tended to be associated with a lower risk of kidney cancer with a 2-year induction period than nonusers; however, the association was not statistically significant (adjusted hazards ratio [aHR] = 0.88, 95% confidence interval [CI] = 0.77-1.01). We further examined the effects of individual SSRIs and observed a significantly lower risk of kidney cancer associated with the use of citalopram (aHR = 0.67, 95% CI = 0.47-0.96) and paroxetine (aHR = 0.75, 95% CI = 0.58-0.97) with the 2-year induction period. These findings support that SSRIs are associated with decreased kidney cancer risk and indicate that citalopram and paroxetine have protective effects in depressed patients with kidney cancer.

Methylphenidate and the risk of burn injury among children with attention-deficit/hyperactivity disorder

AIMS

Attention-deficit/hyperactivity disorder (ADHD) is associated with a higher risk of burn injury than in the normal population. Nevertheless, the influence of methylphenidate (MPH) on the risk of burn injury remains unclear. This retrospective cohort study analysed the effect of MPH on the risk of burn injury in children with ADHD.

METHOD

Data were from Taiwan's National Health Insurance Research Database (NHIRD). The sample comprised individuals younger than 18 years with a diagnosis of ADHD (n = 90 634) in Taiwan's NHIRD between January 1996 and December 2013. We examined the cumulative effect of MPH on burn injury risk using Cox proportional hazards models. We conducted a sensitivity analysis for immortal time bias using a time-dependent Cox model and within-patient comparisons using the self-controlled case series model.

RESULTS

Children with ADHD taking MPH had a reduced risk of burn injury, with a cumulative duration of treatment dose-related effect, compared with those not taking MPH. Compared with children with ADHD not taking MPH, the adjusted hazard ratio for burn injury was 0.70 in children taking MPH for <90 days (95% confidence interval (CI) 0.64-0.77) and 0.43 in children taking MPH for ≥90 days (95% CI 0.40-0.47), with a 50.8% preventable fraction. The negative association of MPH was replicated in age-stratified analysis using time-dependent Cox regression and self-controlled case series models.

CONCLUSION

This study showed that MPH treatment was associated with a lower risk of burn injury in a cumulative duration of treatment dose-related effect manner.

Prevalence of Depression or Depressive Symptoms in Patients with Narcolepsy: a Systematic Review and Meta-Analysis

A meta-analysis was conducted to review the prevalence and associated moderators of depression or depressive symptoms in patients with narcolepsy. An extensive search of the literature yielded 1104 articles and abstracts, of which 31 studies were included in the meta-analysis. Meta-analysis revealed that the overall pooled prevalence of depression or depressive symptoms in patients with narcolepsy was 32% (95% Confidence Interval, 28-36%) with high between-study heterogeneity (Q = 249.77, df = 30, p < 0.001, τ² = 0.0087, I² = 88%). An analysis of 13 studies with healthy control groups indicated that narcolepsy was associated with a significantly increased risk of depression or depressive symptoms (Odds Ratio 3.48, 95% Confidence Interval 2.73-4.45; Q = 41.23, df = 12, p < 0.001, τ² = 0.0087, I² = 70.9%). The prevalence of depression or depressive symptoms in patients with narcolepsy was significantly affected by study design (Q = 5.05, p = 0.02) and recruitment setting (Q = 5.98, p = 0.01), and was marginally affected by age group (Q = 3.44, p = 0.06). The results indicate that narcolepsy patients should be closely monitored for depression and depressive symptoms and that early screening should be considered. However, these conclusions should be tempered because of high variability between studies. The estimates across studies are very inconsistent, indicating the need for larger, multicenter studies, with stringent case definitions.

Neuropsychiatric Correlates of Narcolepsy

PURPOSE OF REVIEW

The complex nature of narcolepsy symptoms, along with the use of stimulants and anticataplectic medications, poses diagnostic difficulties in terms of underlying neuropsychiatric comorbidities. This study reviews recent evidence for the association between narcolepsy and neuropsychiatric disorders. We also critically analyze studies that have addressed the neuropsychiatric correlates of patients with narcolepsy, with a discussion of the possible pathophysiological mechanisms linking narcolepsy and neuropsychiatric disorders.

RECENT FINDINGS

Neuropsychiatric manifestations are common among patients with narcolepsy as narcolepsy and some neuropsychiatric disorders share common clinical features. This may create challenges in making the correct diagnosis, and hence result in a delay in starting appropriate treatment. Comorbid neuropsychiatric manifestations in patients with narcolepsy include depression, anxiety, psychosis, rapid eye movement (REM) sleep behavior disorder, and cognitive impairment. Although hypocretin deficiency has been proposed as a pathophysiological mechanism underlying both narcolepsy and neuropsychiatric disorders, further research is necessary to identify the exact mechanisms. Narcolepsy patients often manifest comorbid neuropsychiatric symptoms, which makes the diagnosis difficult. Therefore, it is essential to address neuropsychiatric symptoms in the clinical care of patients with narcolepsy.

Risk of Burn Injury in Patients With Narcolepsy: A Nationwide Population-Based Cohort Study

Narcolepsy is a rare brain disorder characterized by excessive daytime sleepiness (EDS), cataplexy, hypnagogic hallucinations, and sleep paralysis. Stimulants have been used to relieve the symptoms of EDS. Narcolepsy symptoms may pose a risk to burn injury. The study aimed to investigate the risk of burn injury in narcolepsy patients and to examine the relationship between the use of stimulants and the risk of burn injury. In all, 507 narcolepsy patients and 504 controls matched by gender, age, index year, and Charlson Comorbidity Index (CCI) score were enrolled between 1998 and 2012, then followed until the end of 2013 using Taiwan's National Health Insurance Research Database. During the follow-up period, participants who developed burn injury were identified. Cox regression analysis was used to calculate the hazard ratio (HR) with 95% confidence interval (CI) of the burn incidence rate between narcolepsy patients and unaffected controls. Narcolepsy patients had a significantly increased risk of burn injury compared to unaffected controls (5.37 versus 2.69 per 1,000 person-years, HR: 2.04, 95% CI: 1.13-3.67) after adjusting for gender, age, CCI score, urbanization degree, and duration of stimulants use. Also, the use of stimulants in narcolepsy patients was associated with a lower incidence rate of developing burn injury, but the risk estimate was not statistically significant after adjusting for the above-mentioned variables. This study shows narcolepsy patients have an increased risk of burn injury and the use of stimulants may reduce the burn incidence rate, providing a reference for developing prevention interventions.

Sex and age differences in the association between anxiety disorders and narcolepsy: A nationwide population-based case control study

BACKGROUND

To examine the association between narcolepsy and anxiety disorders.

METHODS

This population-based, retrospective case-control study analyzed Taiwan's National Health Insurance Research Database between 2000 and 2013. We included narcoleptic patients aged at least 12 years, diagnosed according to the International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) code 347. The cases and the propensity score-matched controls were selected in a 1:4 ratio. Each subject with anxiety disorders (ICD-9-CM code 300) was required to visit the outpatient clinic at least three times within a year. Multivariate logistic regression and interaction analyses were used to calculate the association between anxiety disorders and narcolepsy.

RESULTS

This study enrolled 478 and 1912 subjects with and without narcolepsy, respectively. After adjusting for covariates, patients with anxiety disorders had an approximately 2.7 odds ratio of developing narcolepsy when compared to the control subjects (adjusted odds ratio [aOR)] = 2.7; 95% confidence interval [CI] = 1.699-4.344). Interaction analysis and subgroup analysis showed a higher incidence of previously diagnosed anxiety disorders in narcoleptic patients aged 12 to 17 years and female patients (aOR = 25.9; 95% CI = 15.194-42.896; aOR = 3.6; 95% CI = 1.818-7.062, respectively).

LIMITATIONS

The narcolepsy and anxiety disorders were not distinguished by validated structural diagnostic instruments.

CONCLUSIONS

The results of this study revealed higher comorbidity rates of anxiety disorders in narcoleptic patients. The incidence of previously diagnosed anxiety disorders was higher in narcoleptic patients aged 12 to 17 years and female patients.

Comorbidity of Narcolepsy and Psychotic Disorders: A Nationwide Population-Based Study in Taiwan

BACKGROUND

Narcolepsy is a chronic sleep disorder that is likely to have neuropsychiatric comorbidities. Psychotic disorders are characterized by delusion, hallucination, and reality impairments. This study investigates the relationship between narcolepsy and psychotic disorders.

DESIGN AND METHODS

This study involves patients who were diagnosed with narcolepsy between January 2002 and December 2011 (n = 258) and age- and gender-matched controls (n = 2580) from Taiwan's National Health Insurance database. Both the patients and the controls were monitored from January 1, 2002 to December 31, 2011 to identify any occurrence of a psychotic disorder. Drugs that have been approved for treating narcolepsy: immediate-release methylphenidate (IR-MPH), osmotic controlled-release formulations of methylphenidate (OROS-MPH), and modafinil, were analyzed. A multivariate logistic regression model was used to evaluate the potential comorbidity of narcolepsy with psychotic disorders.

RESULTS

During the study period, 8.1% of the narcoleptic patients exhibited comorbidity with a psychotic disorder, whereas only 1.5% of the control subjects (1.5%) had psychotic disorders (aOR, 4.07; 95% CI, 2.21-7.47). Of the narcolepsy patients, 41.5, 5.4, and 13.2% were treated with MPH-IR, MPH-OROS, and modafinil, accordingly. Pharmacotherapy for narcolepsy did not significantly affect the risk of exhibiting a psychotic disorder.

CONCLUSIONS

This nationwide study revealed that narcolepsy and psychotic disorders commonly co-occur. Pharmacotherapy for narcolepsy was not associated with the risk of psychotic disorders. Our findings serve as a reminder that clinicians must consider the comorbidity of narcolepsy and psychosis.

Association Between Attention Deficit Hyperactivity Disorder and Risk of Burn Injury: A Propensity-Matched Cohort Study

PURPOSE

Literature suggests that attention deficit hyperactivity disorder (ADHD) is associated with a high risk of unintentional injury. However, few studies have focused on whether risk of burn injury is relatively high among patients with ADHD. The aim of this study was to investigate whether ADHD affects the risk of burn injury.

MATERIALS AND METHODS

Individuals aged <18 years with a current diagnosis of ADHD (N = 52,705) and age-, sex-, and other comorbidity-matched controls were selected from Taiwan's National Health Insurance Research Database for the period of January 1996 to December 2013. Burn injury was identified in both groups, and risk was evaluated using Cox proportional hazards models. We also explored the effects of age and sex on the association.

RESULTS

We determined that patients with ADHD had an increased probability of burn injury compared with the control group (ADHD vs controls, 4.6% vs 2.6%; adjusted hazard ratio [aHR] = 1.78; 95% confidence interval [CI] = 1.66-1.90). The effect of ADHD on burn injury was more prominent among those aged <6 years (aHR = 1.96; 95% CI = 1.75-2.20) relative to those aged ≥6 years (aHR = 1.69; 95% CI = 1.56-1.83). Both sexes had similar risk profiles.

CONCLUSION

The study findings contribute to the increasing body of evidence that ADHD is associated with proneness to burn injury, particularly in children aged <6 years.

Academic and professional paths of narcoleptic patients: the Narcowork study

OBJECTIVE/BACKGROUND

To study educational and professional pathways of narcoleptic patients and examine demographic, disease-related and environmental factors associated with a better academic and professional prognosis.

PATIENTS/METHODS

In sum, 69 narcoleptic patients (51 narcolepsy type 1 and 18 narcolepsy type 2, age 42.5 ± 18.2 years) were enrolled in this pilot monocentric cross-sectional study with a comparison group (80 age- and sex-matched controls) between October 2017 and July 2018 in Lyon Center for Sleep Medicine. They completed questionnaires about their academic and professional trajectories and specific scales of quality of life (EuroQol quality of life scale EQ-5D-3L), depression (beck depression inventory, BDI), sleepiness (Epworth Sleepiness Scale, ESS) and narcoleptic symptoms severity (narcolepsy severity scale, NSS).

RESULTS

No difference in grade repetition or final obtained diploma was observed between patients and controls, but patients evaluated their academic curricula as more difficult (45.5% vs 16.9%, p = 0.0007), complained for more attentional deficits (75% vs 22.1%, p < 0.0001), and had needed more educational reorientation (28.6% vs 9.9%, p = 0.01). Even if no difference was observed in occupational category and professional status, patients expressed significantly less satisfaction about their work. Patients had more signs of depression [OR severe depression = 4.4 (1.6-12.6), p = 0.02] and their quality of life was significantly decreased (67.3 ± 18.4 vs 80.6 ± 13.2, p = 0.0007) as compared to controls. Multivariate analysis showed that a more favorable professional career was associated with a better quality of life.

CONCLUSIONS

Educational and professional pathways do not seem to be significantly impaired in narcoleptic patients, but their experience and quality of life are affected. These findings may allow to reassure patients and should lead to a more comprehensive management of the disease.

CLINICAL TRIAL REGISTRATION

Narcowork, https://clinicaltrials.gov/ct2/show/NCT03173378, N° NCT03173378.

Comorbid psychiatric disorders among patients with narcolepsy

PURPOSE

This case-control study assessed the prevalence of psychiatric disorders in Arab (Saudi) patients with narcolepsy using a structured clinical interview.

METHODS

The study included 74 adult patients with narcolepsy and 265 controls matched for age and sex. Narcolepsy diagnosis was made according to the International Classification of Sleep Disorders-Third Edition. Psychiatric disorders were diagnosed via using a validated Arabic version of the Mini International Neuropsychiatric Interview DSM-IV (MINI version 6). A multivariate logistic regression model was used to assess the potential influence of narcolepsy on the comorbidity of psychiatric disorders.

RESULTS

The mean age of the patients was 29.4 ± 10.2 years, and males accounted for 81% of the study sample. Forty-four patients (60%) were diagnosed with narcolepsy type-1 (NT1) and 30 (40%) with narcolepsy type-2 (NT2). Psychiatric disorders were diagnosed in 45% of patients with narcolepsy compared with 15% of the controls (p < 0.001). The multivariate logistic regression models demonstrated that compared with the controls, patients with narcolepsy were more likely to have major depressive disorders (OR, 4.3 [CI, 2.2-8.2]), and generalized anxiety disorders (OR, 9.5 [CI, 1.8-50.2]). No difference was detected between the prevalence of various psychiatric disorders in patients with NT1 and NT2.

CONCLUSION

Comorbid psychiatric disorders are common among Arab (Saudi) patients with narcolepsy compared with the general population. Therefore, clinicians should be aware of the comorbidity of narcolepsy and psychiatric disorders, particularly depression.

The neurobiological basis of narcolepsy

Narcolepsy is the most common neurological cause of chronic sleepiness. The discovery about 20 years ago that narcolepsy is caused by selective loss of the neurons producing orexins (also known as hypocretins) sparked great advances in the field. Here, we review the current understanding of how orexin neurons regulate sleep-wake behaviour and the consequences of the loss of orexin neurons. We also summarize the developing evidence that narcolepsy is an autoimmune disorder that may be caused by a T cell-mediated attack on the orexin neurons and explain how these new perspectives can inform better therapeutic approaches.

A false alarm of narcolepsy: obstructive sleep apnea masquerading as narcolepsy and depression

PURPOSE

We report a case with symptoms and signs of obstructive sleep apnea (OSA), depression, and narcolepsy. Polysomnographic (PSG) and multiple sleep latency test (MSLT) findings, clinical characteristics, and diagnostic challenges in this case are discussed.

METHODS

A 23-year-old single male presented with excessive daytime sleepiness, low mood, lack of energy, and snoring for 3 years. In addition, he reported excessive weight gain, lack of interest in work, partial loss of muscle tone during excitations, and sleep attacks during work and driving. He had experienced three episodes of sleep paralysis. The patient underwent a sleep study including PSG and MSLT.

RESULTS

On baseline PSG, he had an apnea/hypopnea index (AHI) of 72.8/h. The MSLT showed a mean sleep latency of 3.8 min and two sleep-onset rapid eye movement periods (SOREMPs). On admission, he had an Epworth Sleepiness Scale (ESS) score of 21, and positive findings for depression in the clinical interview and psychometric scales. He was treated with continuous positive airway pressure without any medication. Follow-up PSG and MSLT were performed after 1 week, which showed an AHI of 0/h without SOREMPs. After 1 month, there was no sign of depression.

CONCLUSIONS

This study reflects that OSA can present with cataplexy-like features and false positive MSLT results for narcolepsy, as well as depressive symptoms. The case highlights the complexity in which OSA can present to physicians, and emphasizes that clinicians should be aware that OSA can mimic narcolepsy and present with depressive symptoms.

Sleep-Wake Cycling and Energy Conservation: Role of Hypocretin and the Lateral Hypothalamus in Dynamic State-Dependent Resource Optimization

The hypocretin (Hcrt) system has been implicated in a wide range of physiological functions from sleep-wake regulation to cardiovascular, behavioral, metabolic, and thermoregulagtory control. These wide-ranging physiological effects have challenged the identification of a parsimonious function for Hcrt. A compelling hypothesis suggests that Hcrt plays a role in the integration of sleep-wake neurophysiology with energy metabolism. For example, Hcrt neurons promote waking and feeding, but are also sensors of energy balance. Loss of Hcrt function leads to an increase in REM sleep propensity, but a potential role for Hcrt linking energy balance with REM sleep expression has not been addressed. Here we examine a potential role for Hcrt and the lateral hypothalamus (LH) in state-dependent resource allocation as a means of optimizing resource utilization and, as a result, energy conservation. We review the energy allocation hypothesis of sleep and how state-dependent metabolic partitioning may contribute toward energy conservation, but with additional examination of how the loss of thermoregulatory function during REM sleep may impact resource optimization. Optimization of energy expenditures at the whole organism level necessitates a top-down network responsible for coordinating metabolic operations in a state-dependent manner across organ systems. In this context, we then specifically examine the potential role of the LH in regulating this output control, including the contribution from both Hcrt and melanin concentrating hormone (MCH) neurons among a diverse LH cell population. We propose that this hypothalamic integration system is responsible for global shifts in state-dependent resource allocations, ultimately promoting resource optimization and an energy conservation function of sleep-wake cycling.

Narcolepsy and Psychiatric Disorders: Comorbidities or Shared Pathophysiology?

Narcolepsy and psychiatric disorders have a significant but unrecognized relationship, which is an area of evolving interest, but unfortunately, the association is poorly understood. It is not uncommon for the two to occur co-morbidly. However, narcolepsy is frequently misdiagnosed initially as a psychiatric condition, contributing to the protracted time to accurate diagnosis and treatment. Narcolepsy is a disabling neurodegenerative condition that carries a high risk for development of social and occupational dysfunction. Deterioration in function may lead to the secondary development of psychiatric symptoms. Inversely, the development of psychiatric symptoms can lead to the deterioration in function and quality of life. The overlap in pharmaceutical intervention may further enhance the difficulty to distinguish between diagnoses. Comprehensive care for patients with narcolepsy should include surveillance for psychiatric illness and appropriate treatment when necessary. Further research is necessary to better understand the underlying pathophysiology between psychiatric disease and narcolepsy.