Exploring the presence of narcolepsy in patients with schizophrenia

Psychotic Episode and Schizophrenia in Slovakian Narcolepsy Database

Narcolepsy type 1 (NT1), a central disorder of hypersomnolence, is associated with mood, anxiety or hyperactivity mental disorders. Association with psychotic episode or schizophrenia is rare and could be the source of diagnostic and therapeutic difficulties. Their frequency in the national narcolepsy database has not been systematically studied. The aim of the presented study was to calculate the frequency of NT1 patients diagnosed with psychosis and/or schizophrenia, to identify clinical characteristics of these cases, and to look for narcoleptic and psychotic symptoms during re-evaluation years later. We identified three (4%) cases diagnosed with a psychotic episode in the course of NT1. They were diagnosed with NT1 by age ≤18 years. In the re-evaluation (mean follow-up 9.8 years), we identified one case with a dual diagnosis of NT1 and schizophrenia; two cases were diagnosed with a solitary psychotic episode in the course of NT1. NT1 patients diagnosed in the age ≤18 years are at higher risk of psychotic episode, and this may be related to higher vulnerability during the ongoing neurodevelopmental period. Comorbid schizophrenia with NT1 in the Slovakian Narcolepsy Database was within the prevalence expected in the general population. The solitary psychotic episode in the course of NT1 did not reduce the possibility of subsequent symptomatic treatment afterwards.

Sleep, cerebrospinal fluid, and the glymphatic system: A systematic review

Current theories of the glymphatic system (GS) hypothesize that it relies on cerebrospinal fluid (CSF) circulation to disseminate growth factors and remove metabolic waste from the brain with increased CSF production and circulation during sleep; thereby, linking sleep disturbance with elements of CSF circulation and GS exchange. However, our growing knowledge of the relations between sleep, CSF, and the GS are plagued by variability in sleep and CSF measures across a wide array of pathologies. Hence, this review aims to summarize the dynamic relationships between sleep, CSF-, and GS-related features in samples of typically developing individuals and those with autoimmune/inflammatory, neurodegenerative, neurodevelopmental, sleep-related, neurotraumatic, neuropsychiatric, and skull atypicalities. One hundred and ninety articles (total n = 19,129 participants) were identified and reviewed for pathology, CSF circulation and related metrics, GS function, and sleep. Numerous associations were documented between sleep problems and CSF metabolite concentrations (e.g., amyloid-beta, orexin, tau proteins) and increased CSF volumes or pressure. However, these relations were not universal, with marked differences across pathologies. It is clear that elements of CSF circulation/composition and GS exchange represent pathways influenced by sleep; however, carefully designed studies and advances in GS measurement are needed to delineate the nuanced relationships.

Narcolepsy and psychosis: A systematic review

OBJECTIVE

Narcolepsy is a rare sleep disorder in which psychotic-like symptoms can present diagnostic and therapeutic challenges. We aimed to review the association between, and medical management of, narcolepsy and psychosis in children and adults.

METHODS

We reviewed the full text of 100 papers from 187 identified by a PubMed search on narcolepsy plus any of these keywords: psychosis, schizophrenia, delusion, side effects, safety, and bipolar disorder.

RESULTS

Three relevant groups are described. (i) In typical narcolepsy, psychotic-like symptoms include predominantly visual hallucinations at the sleep-wake transition (experienced as "not real") and dissociation because of intrusion of rapid eye movement (REM) sleep phenomena into wakefulness. (ii) Atypical patients ("the psychotic form of narcolepsy") experience more severe and vivid, apparently REM-related hallucinations or dream/reality confusions, which patients may rationalize in a delusion-like way. (iii) Some patients have a comorbid schizophrenia spectrum disorder with psychotic symptoms unrelated to sleep. Psychostimulants used to treat narcolepsy may trigger psychotic symptoms in all three groups. We analyzed 58 published cases from groups 2 and 3 (n = 17 and 41). Features that were reported significantly more frequently in atypical patients include visual and multimodal hallucinations, sexual and mystical delusions, and false memories. Dual diagnosis patients had more disorganized symptoms and earlier onset of narcolepsy.

CONCLUSION

Epidemiological studies tentatively suggest a possible association between narcolepsy and schizophrenia only for very early-onset cases, which could be related to the partially overlapping neurodevelopmental changes observed in these disorders. We propose a clinical algorithm for the management of cases with psychotic-like or psychotic features.

Different positron emission tomography findings in schizophrenia and narcolepsy type 1 in adolescents and young adults: a preliminary study

STUDY OBJECTIVES

The association between schizophrenia and narcolepsy has been controversial. We conducted a prospective case control study of schizophrenia and comorbid narcolepsy type 1 in adolescents compared with patients with either diagnosis alone and healthy controls using ¹⁸F-fluorodeoxy glucose positron emission tomography, sleep studies, and neurocognitive tests.

METHODS

We included 11 patients (9-20 years old) with schizophrenia and comorbid narcolepsy type 1, 11 with narcolepsy type 1, 11 with schizophrenia, and 11 controls. All groups were matched for age and sex. Participants were required to submit to clinical interviews for sleep and psychiatric disorders, sleep questionnaires, continuous performance test, Wisconsin card sorting test, sleep studies including polysomnography, multiple sleep latency test and actigraphy, and positron emission tomography studies. All data were analyzed to compare the differences between the 4 groups.

RESULTS

The positron emission tomography results demonstrated significant differences in the dual diagnoses group compared with the 3 other groups. Compared with the controls, the dual diagnoses group had a significant presence of hypometabolism in the right mid-frontal, right orbital inferior frontal, and right posterior cingulum and a significant presence of hypermetabolism in the left amygdala, bilateral striatum, bilateral substantia nigra, bilateral basal ganglia, and bilateral thalamus. Continuous performance tests and Wisconsin card sorting tests showed that the dual diagnoses group had the worst performance.

CONCLUSIONS

Patients with schizophrenia and comorbid narcolepsy type 1 had different positron emission tomography findings than those with either schizophrenia or narcolepsy type 1 alone. They also had more neurocognitive impairments and required additional interventions.

Activating autoantibodies against G protein-coupled receptors in narcolepsy type 1

STUDY OBJECTIVES

Narcolepsy type 1 is a rare hypersomnia of central origin, which is caused by loss of hypothalamic neurons that produce the neuropeptides hypocretin-1 and -2. Hypocretin-containing nerve terminals are found in areas known to play a central role in autonomic control and in pain signaling. Cholinergic M2 receptors are found in brain areas involved with the occurrence of hallucinations and cataplexy. In addition to classical symptoms of narcolepsy, the patients suffer frequently from autonomic dysfunction, chronic pain, and hypnagogic/hypnopompic hallucinations. We aimed to test whether narcolepsy type 1 patients have autoantibodies against autonomic β2 adrenergic receptor, M2 muscarinic receptors, or nociception receptors.

METHODS

We tested the serum of ten narcolepsy type 1 patients (five female) for activating β2 adrenergic receptor autoantibodies, M2 muscarinic receptor autoantibodies, and nociception receptor autoantibodies.

RESULTS

Ten of ten patients were positive for muscarinic M2 receptor autoantibodies (P < 0.001), 9/10 were positive for autoantibodies against nociception receptors (P < 0.001), and 5/10 were positive for β2 adrenergic receptor autoantibodies (P < 0.001).

CONCLUSIONS

Narcolepsy type 1 patients harbored activating autoantibodies against M2 muscarinic receptors, nociception receptors, and β2 adrenergic receptors. M2 receptor autoantibodies may be related to the occurrence of cataplexy and, moreover, hallucinations in narcolepsy since they are found in the same brain areas that are involved with these symptoms. The occurrence of nociception receptor autoantibodies strengthens the association between narcolepsy type 1 and pain. The connection between narcolepsy type 1, autonomic complaints, and the presumed cardiovascular morbidity might be associated with the occurrence of β2 adrenergic receptor autoantibodies. On the other hand, the presence of the autoantibodies may be secondary to the destruction of the hypocretin pathways.

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.

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.

Prevalence and correlates of sleep disorder symptoms in psychiatric disorders

Difficulty falling asleep or maintaining sleep, poor sleep quality, nightmares, and excessive daytime sleepiness are some of the key clinical symptoms of sleep disturbances observed among individuals with psychiatric illnesses. This study aimed to determine the prevalence of symptoms of sleep disorders including parasomnia, narcolepsy, obstructive sleep apnea, circadian rhythm disorder and restless leg syndrome/periodic limb movement (RLS/PLMS) and its correlates in patients with psychiatric diagnoses. Patients aged 21-65 years (n = 400) attending the outpatient clinics with a primary diagnosis of either schizophrenia, mood or anxiety disorder based on ICD-9 criteria were included in this cross-sectional study. Sociodemographic information was collected and screening questions pertaining to specific symptoms of sleep disorders were administered by a study team member. The overall prevalence of symptoms of sleep disorders in the psychiatric outpatient sample was 40.75% (163/400). The prevalence for symptoms of narcolepsy, sleep breathing disorder, PLMS/RLS, circadian rhythm disorder and parasomnia were 12.5%, 14.5%, 14.8%, 4.5%, and 13.8% respectively. These symptoms were associated with age, low physical activity, and anxiety disorder. Results highlight the high prevalence of symptoms of sleep disorders in psychiatric patients. Present study findings should be confirmed using diagnostic interviews and objective measures.

Narcolepsy and emotional experience: a review of the literature

Narcolepsy is a chronic sleep disorder characterized by excessive daytime sleepiness, cataplexy, hypnagogic hallucinations, and sleep paralysis. This disease affects significantly the overall patient functioning, interfering with social, work, and affective life. Some symptoms of narcolepsy depend on emotional stimuli; for instance, cataplectic attacks can be triggered by emotional inputs such as laughing, joking, a pleasant surprise, and also anger. Neurophysiological and neurochemical findings suggest the involvement of emotional brain circuits in the physiopathology of cataplexy, which seems to depending on the dysfunctional interplay between the hypothalamus and the amygdala associated with an alteration of hypocretin levels. Furthermore, behavioral studies suggest an impairment of emotions processing in narcolepsy-cataplexy (NC), like a probable coping strategy to avoid or reduce the frequency of cataplexy attacks. Consistently, NC patients seem to use coping strategies even during their sleep, avoiding unpleasant mental sleep activity through lucid dreaming. Interestingly, NC patients, even during sleep, have a different emotional experience than healthy subjects, with more vivid, bizarre, and frightening dreams. Notwithstanding this evidence, the relationship between emotion and narcolepsy is poorly investigated. This review aims to provide a synthesis of behavioral, neurophysiological, and neurochemical evidence to discuss the complex relationship between NC and emotional experience and to direct future research.

Schizophrenia and sleep disorders: links, risks, and management challenges

Schizophrenia is a major psychiatric disorder that has a massive, long-lasting negative impact on the patients as well as society. While positive symptoms (i.e., delusions and hallucinations), negative symptoms (i.e., anhedonia, social withdrawal), and cognitive impairments are traditionally considered the most prominent features of this disorder, the role of sleep and sleep disturbances has gained increasing prominence in clinical practice. Indeed, the vast majority of patients with schizophrenia report sleep abnormalities, which tend to precede illness onset and can predict an acute exacerbation of psychotic symptoms. Furthermore, schizophrenia patients often have a comorbid sleep disorder, including insomnia, obstructive sleep apnea, restless leg syndrome, or periodic limb movement disorder. Despite accumulating data, the links between sleep disorders and schizophrenia have not been thoroughly examined, in part because they are difficult to disentangle, as numerous factors contribute to their comorbidity, including medication status. Additionally, sleep disorders are often not the primary focus of clinicians treating this population, despite studies suggesting that comorbid sleep disorders carry their own unique risks, including worsening of psychotic symptoms and poorer quality of life. There is also limited information about effective management strategies for schizophrenia patients affected by significant sleep disturbances and/or sleep disorders. To begin addressing these issues, the present review will systematically examine the literature on sleep disorders and schizophrenia, focusing on studies related to 1) links between distinct sleep disorders and schizophrenia; 2) risks unique to patients with a comorbid sleep disorder; and 3) and management challenges and strategies.