Sleep deprivation disrupts prepulse inhibition and induces psychosis-like symptoms in healthy humans

Association between non-restorative sleep and psychotic-like experiences among Chinese college students: A latent profile and moderated mediation analysis

BACKGROUND

Non-restorative sleep (NRS) is a core symptom of insomnia that has considerable consequences for daily life. However, the association between NRS and psychotic-like experiences (PLEs) remains unclear. The current study was designed to explore the relationship between NRS and PLEs as well as the mediation/moderation role of rumination and resilience among college students in China.

METHODS

3060 college students were recruited from two universities in South China from September 21st to October 26th, 2022. Non-restorative Sleep Scale, 8-item Positive Subscale of the Community Assessment of Psychic Experiences, Ruminative Response Scale, and 10-item Connor-Davidson Resilience Scale were administered. Latent profile analysis and moderated mediation analysis were performed.

RESULTS

11.3 % participants reported frequent PLEs in the past one month. Three profiles of rumination were identified and named as "low rumination" group (27.7 %), "medium rumination" group (55.3 %), and "high rumination" group (16.9 %). NRS directly predicted PLEs, and rumination played a significant mediation role between NRS and PLEs. Resilience significantly moderated the association between NRS and rumination as well as the association between NRS and PLEs.

CONCLUSIONS

NRS, rumination and resilience are important predictors to PLEs. Strategies on increasing restorative sleep, decreasing rumination, and enhancing resilience are of great significance in the prevention of PLEs.

Bidirectional associations between short sleep duration, insomnia symptoms, and psychotic-like experiences in adolescents

This study investigates the prospective associations between short sleep duration, insomnia symptoms, and psychotic-like experiences (PLEs) in a large sample of Chinese adolescents. This study utilized a three-timepoint repeated cross-sectional survey with two nested longitudinal subsamples. A total of 17,722 adolescents were assessed at baseline (April 21 to May 12, 2021) and six months later (December 17 to 26, 2021). Out of these, 15,694 adolescents provided complete responses to the questions at baseline and one year later (May 17 - June 6, 2022). A self-administered questionnaire was used to measure sample characteristics (at baseline), sleep duration, insomnia symptoms, and PLEs (at each assessment), and negative life events (at two follow-ups). Baseline short sleep duration and insomnia symptoms predicted frequent PLEs at both follow-up assessments. Additionally, baseline frequent PLEs also predicted insomnia symptoms at six months and one year later. However, when controlling for confounders, PLEs at baseline only predicted short sleep duration at six months, and not at one year. This study reveals bidirectional prospective relationships between short sleep duration, insomnia symptoms, and PLEs, even after controlling for covariates. Therefore, it is crucial to assess both sleep patterns and PLEs in order to promote optimal sleep and mental health among adolescents.

Baseline prepulse inhibition dependency of orexin A and REM sleep deprivation

RATIONALE

Prepulse inhibition (PPI) impairment reflects sensorimotor gating problems, i.e. in schizophrenia. This study aims to enlighten the role of orexinergic regulation on PPI in a psychosis-like model.

OBJECTIVES

In order to understand the impact of orexinergic innervation on PPI and how it is modulated by age and baseline PPI (bPPI), chronic orexin A (OXA) injections was carried on non-sleep-deprived and sleep-deprived rats that are grouped by their bPPI.

METHODS

bPPI measurements were carried on male Wistar rats on P45 or P90 followed by grouping into low-PPI and high-PPI rats. The rats were injected with OXA twice per day for four consecutive days starting on P49 or P94, while the control groups received saline injections. 72 h REMSD was carried on via modified multiple platform technique on P94 and either OXA or saline was injected during REMSD. PPI tests were carried out 30 min. after the last injection.

RESULTS

Our previous study with acute OXA injection after REMSD without bPPI grouping revealed that low OXA doses might improve REMSD-induced PPI impairment. Our current results present three important conclusions: (1) The effect of OXA on PPI is bPPI-dependent and age-dependent. (2) The effect of REMSD is bPPI-dependent. (3) The effect of OXA on PPI after REMSD also depends on bPPI.

CONCLUSION

Orexinergic regulation of PPI response with and without REMSD can be predicted by bPPI levels. Our findings provide potential insights into the regulation of sensorimotor gating by sleep/wakefulness systems and present potential therapeutic targets for the disorders, where PPI is disturbed.

Role of Inflammation in Short Sleep Duration Across Childhood and Psychosis in Young Adulthood

Importance

Short sleep duration over a prolonged period in childhood could have a detrimental impact on long-term mental health, including the development of psychosis. Further, potential underlying mechanisms of these associations remain unknown.

Objective

To examine the association between persistent shorter nighttime sleep duration throughout childhood with psychotic experiences (PEs) and/or psychotic disorder (PD) at age 24 years and whether inflammatory markers (C-reactive protein [CRP] and interleukin 6 [IL-6]) potentially mediate any association.

Design, Setting, and Participants

This cohort study used data from the Avon Longitudinal Study of Parents and Children. Data analysis was conducted from January 30 to August 1, 2023.

Exposures

Nighttime sleep duration was collected at 6, 18, and 30 months and at 3.5, 4 to 5, 5 to 6, and 6 to 7 years.

Main Outcomes and Measures

PEs and PD were assessed at age 24 years from the Psychosislike Symptoms Interview. CRP level at ages 9 and 15 years and IL-6 level at 9 years were used as mediators. Latent class growth analyses (LCGAs) were applied to detect trajectories of nighttime sleep duration, and logistic regressions were applied for the longitudinal associations between trajectories of nighttime sleep duration and psychotic outcomes at 24 years. Path analyses were applied to test CRP and IL-6 as potential mediators.

Results

Data were available on 12 394 children (6254 female [50.5%]) for the LCGA and on 3962 young adults (2429 female [61.3%]) for the logistic regression and path analyses. The LCGA identified a group of individuals with persistent shorter nighttime sleep duration across childhood. These individuals were more likely to develop PD (odds ratio [OR], 2.50; 95% CI, 1.51-4.15; P < .001) and PEs (OR, 3.64; 95% CI, 2.23-5.95; P < .001) at age 24 years. Increased levels of IL-6 at 9 years, but not CRP at 9 or 15 years, partially mediated the associations between persistent shorter sleep duration and PD (bias-corrected estimate = 0.003; 95% CI, 0.002-0.005; P = .007) and PEs (bias-corrected estimate = 0.002; 95% CI, 0-0.003; P = .03) in young adulthood.

Conclusions and Relevance

Findings of this cohort study highlight the necessity of addressing short sleep duration in children, as persistence of this sleep problem was associated with subsequent psychosis. This study also provides preliminary evidence for future targeted interventions in children addressing both sleep and inflammatory responses.

Associations between disturbed sleep and attenuated psychotic experiences in people at clinical high risk for psychosis

BACKGROUND

Pre-diagnostic stages of psychotic illnesses, including 'clinical high risk' (CHR), are marked by sleep disturbances. These sleep disturbances appear to represent a key aspect in the etiology and maintenance of psychotic disorders. We aimed to examine the relationship between self-reported sleep dysfunction and attenuated psychotic symptoms (APS) on a day-to-day basis.

METHODS

Seventy-six CHR young people completed the Experience Sampling Methodology (ESM) component of the European Union Gene-Environment Interaction Study, collected through PsyMate® devices, prompting sleep and symptom questionnaires 10 times daily for 6 days. Bayesian multilevel mixed linear regression analyses were performed on time-variant ESM data using the brms package in R. We investigated the day-to-day associations between sleep and psychotic experiences bidirectionally on an item level. Sleep items included sleep onset latency, fragmentation, and quality. Psychosis items assessed a range of perceptual, cognitive, and bizarre thought content common in the CHR population.

RESULTS

Two of the seven psychosis variables were unidirectionally predicted by previous night's number of awakenings: every unit increase in number of nightly awakenings predicted a 0.27 and 0.28 unit increase in feeling unreal or paranoid the next day, respectively. No other sleep variables credibly predicted next-day psychotic symptoms or vice-versa.

CONCLUSION

In this study, the relationship between sleep disturbance and APS appears specific to the item in question. However, some APS, including perceptual disturbances, had low levels of endorsement amongst this sample. Nonetheless, these results provide evidence for a unidirectional relationship between sleep and some APS in this population.

Insomnia moderates the association between psychotic-like experiences and suicidal ideation in a non-clinical population: a network analysis

Psychotic-like experiences (PLEs) have been associated with poor sleep quality and increased suicide risk. However, the association between PLEs, insomnia and suicide risk has not been thoroughly investigated in prior studies. In this study, we aimed to explore as to whether insomnia moderates the association between PLEs and suicidal ideation. The study was performed in 4203 young adults (aged 18-35 years, 63.8% females). Data were collected using self-reports. Moderation analysis demonstrated that PLEs are associated with higher levels of the current suicidal ideation only in participants with greater severity of insomnia (B = 0.003, p < 0.001). This analysis included age, gender, education, occupation and depressive symptoms as covariates. Moreover, the network analysis demonstrated that nodes representing PLEs are connected to the node of current suicidal ideation only in participants with greater severity of insomnia. The nodes of PLEs connected to the current suicidal ideation node captured PLEs representing deja vu experiences, auditory hallucination-like experiences and paranoia (edge weights between 0.011 and 0.083). Furthermore, nodes representing PLEs were the three most central nodes in the network analysis of individuals with higher levels of insomnia (strength centrality between 0.96 and 1.10). In turn, the three most central nodes were represented by depressive symptoms in the network analysis of individuals with lower levels of insomnia (strength centrality between 0.67 and 0.79). Findings from this study indicate that insomnia might be an important risk factor of suicide in people with PLEs, especially those reporting deja vu experiences, auditory hallucination-like experiences and paranoia.

Pallidin function in Drosophila surface glia regulates sleep and is dependent on amino acid availability

The Pallidin protein is a central subunit of a multimeric complex called biogenesis of lysosome-related organelles complex 1 (BLOC1) that regulates specific endosomal functions and has been linked to schizophrenia. We show here that downregulation of Pallidin and other members of BLOC1 in the surface glia, the Drosophila equivalent of the blood-brain barrier, reduces and delays nighttime sleep in a circadian-clock-dependent manner. In agreement with BLOC1 involvement in amino acid transport, downregulation of the large neutral amino acid transporter 1 (LAT1)-like transporters JhI-21 and mnd, as well as of TOR (target of rapamycin) amino acid signaling, phenocopy Pallidin knockdown. Furthermore, supplementing food with leucine normalizes the sleep/wake phenotypes of Pallidin downregulation, and we identify a role for Pallidin in the subcellular trafficking of JhI-21. Finally, we provide evidence that Pallidin in surface glia is required for GABAergic neuronal activity. These data identify a BLOC1 function linking essential amino acid availability and GABAergic sleep/wake regulation.

The relationship between subjective sleep disturbance and attenuated psychotic symptoms after accounting for anxiety and depressive symptoms

BACKGROUND AND HYPOTHESES

Sleep disturbances are increasingly recognized as cooccurring with psychotic symptoms. The potential importance of this relationship is complicated when considering the effects of anxiety and depressive symptoms which commonly present in early-stage illness states. This study aimed to investigate the relationship between self-reported sleep disturbance on the development of attenuated psychotic symptoms (APS) cross-sectionally and longitudinally while adjusting for roles of anxiety and depressive symptoms.

DESIGN

Eight-hundred and two help-seeking young people aged 12 to 25 years who engaged with our Australian early intervention services were included in the study (the "Transitions" cohort). Cross sectional mediation and cross-lagged longitudinal (12-month) mediation models were developed with outcomes being different APS domains.

RESULTS

Only baseline excessive daytime sleepiness predicted later APS when accounting for previous APS, anxiety and depressive symptomatology. Cross sectionally, self-reported sleep disturbance showed both direct and indirect predictive relationships with all APS domains. Partial mediation through anxiety and depression was shown for unusual thought content, perceptual abnormalities, and disorganised speech, while full mediation through depression was shown for non-bizarre ideas.

CONCLUSIONS

The specificity of the relationship between self-reported sleep disturbance on APS highlights the potential for different roles in mechanistic models of psychotic symptom expression. This further indicates the need for further experimental research to illuminate potential causal pathways. Future research should continue to use continuous, symptom level approaches across a range of timeframes to more accurately model the complex dynamics present in the sleep-psychosis relationship.

The dynamic relationship between sleep and psychotic experiences across the early stages of the psychosis continuum

BACKGROUND

Psychotic disorders develop gradually along a continuum of severity. Understanding factors associated with psychosis development, such as sleep, could aid in identification of individuals at elevated risk. This study aimed to assess (1) the dynamic relationship between psychotic experiences (PEs) and sleep quality and quantity, and (2) whether this relationship differed between different clinical stages along the psychosis continuum.

METHODS

We used daily diary data (90 days) of individuals (N = 96) at early stages (i.e. before a first diagnosis of psychosis) along the psychosis continuum. Multilevel models were constructed with sleep quality and sleep quantity as predictors of PEs and vice versa. Post-hoc, we constructed a multilevel model with both sleep quality and quantity as predictors of PEs. In addition, we tested whether associations differed between clinical stages.

RESULTS

Within persons, poorer sleep predicted next day PEs (B = -0.02, p = 0.01), but not vice versa. Between persons, shorter sleep over the 90-day period predicted more PEs (B = -0.04, p = 0.002). Experiencing more PEs over 90-days predicted poorer (B = -0.02, p = 0.02) and shorter (B = -1.06, p = 0.008) sleep. We did not find any significant moderation effects for clinical stage.

CONCLUSIONS

We found a bidirectional relationship between sleep and PEs with daily fluctuations in sleep predicting next day PEs and general patterns of more PEs predicting poorer and shorter sleep. Our results highlight the importance of assessing sleep as a risk marker in the early clinical stages for psychosis.

Effects of total sleep deprivation on sensorimotor gating in humans

Sensorimotor gating is a measure of pre-attentional information processing and can be measured by prepulse inhibition (PPI) of the startle reflex. Sleep deprivation has been shown to disrupt PPI in animals and humans, and has been proposed as an early phase 2 model to probe antipsychotic efficacy in heathy humans. To further investigate the reliability and efficacy of sleep deprivation to produce PPI deficits we tested the effects of total sleep deprivation (TSD) on PPI in healthy controls in a highly controlled sleep laboratory environment. Participants spent 4 days and nights in a controlled laboratory environment with their sleep monitored with polysomnography. Participants were randomly assigned to either normal sleep on all 4 nights (N=17) or 36hours of TSD on the 3^rd or 4^th night (N=40). Participants were assessed for sleepiness using the Karolinska Sleepiness Scale (KSS) and underwent a daily PPI task (interstimlulus intervals 30-2000 ms) in the evening. Both within-subject effects (TSD vs. normal sleep in TSD group alone) and between-subject effects (TSD vs. no TSD group) of TSD on PPI were assessed. TSD increased subjective sleepiness measured with the KSS, but did not significantly alter overall startle, habituation or PPI. Sleep measures including duration, rapid eye movement and slow wave sleep duration were also not associated with PPI performance. The current results show that human sensorimotor gating may not be reliably sensitive to sleep deprivation. Further research is required for TSD to be considered a dependable model of PPI disruption for drug discovery in humans.

Sleep Deprivation Induces Dopamine System Maladaptation and Escalated Corticotrophin-Releasing Factor Signaling in Adolescent Mice

Sleep disruption is highly associated with the pathogenesis and progression of a wild range of psychiatric disorders. Furthermore, appreciable evidence shows that experimental sleep deprivation (SD) on humans and rodents evokes anomalies in the dopaminergic (DA) signaling, which are also implicated in the development of psychiatric illnesses such as schizophrenia or substance abuse. Since adolescence is a vital period for the maturation of the DA system as well as the occurrence of mental disorders, the present studies aimed to investigate the impacts of SD on the DA system of adolescent mice. We found that 72 h SD elicited a hyperdopaminergic status, with increased sensitivity to the novel environment and amphetamine (Amph) challenge. Also, altered neuronal activity and expression of striatal DA receptors were noticed in the SD mice. Moreover, 72 h SD influenced the immune status in the striatum, with reduced microglial phagocytic capacity, primed microglial activation, and neuroinflammation. The abnormal neuronal and microglial activity were putatively provoked by the enhanced corticotrophin-releasing factor (CRF) signaling and sensitivity during the SD period. Together, our findings demonstrated the consequences of SD in adolescents including aberrant neuroendocrine, DA system, and inflammatory status. Sleep insufficiency is a risk factor for the aberration and neuropathology of psychiatric disorders.

Pedunculopontine-induced cortical decoupling as the neurophysiological locus of dissociation

Mounting evidence suggests an association between aberrant sleep phenomena and dissociative experiences. However, no wake-sleep boundary theory provides a compelling explanation of dissociation or specifies its physiological substrates. We present a theoretical account of dissociation that integrates theories and empirical results from multiple lines of research concerning the domain of dissociation and the regulation of rapid eye movement (REM) sleep. This theory posits that individual differences in the circuitry governing the REM sleep promoting Pedunculopontine Nucleus and Laterodorsal Tegmental Nucleus determine the degree of similarity in the cortical connectivity profiles of wakefulness and REM sleep. We propose that a latent trait characterized by elevated dissociative experiences emerges from the decoupling of frontal executive regions due to a REM sleep-like aminergic/cholinergic balance. The Pedunculopontine-Induced Cortical Decoupling Account of Dissociation (PICDAD) suggests multiple fruitful lines of inquiry and provides novel insights. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Sleep disturbance is predictive of psychotic-like experiences among adolescents: A two-wave longitudinal survey

PURPOSE

Psychotic-like experiences (PLEs) are prevalent among adolescents and are the most significant predictor of future mental disorders. This study aims to examine the cross-sectional and longitudinal associations between sleep disturbance and PLEs in a large cohort of adolescents.

METHODS

The 17,722 adolescents in our study were assessed from April 21 to May 12, 2021 (Time 1, T1) and again 6 months later from December 17 to 26, 2021 (Time 2, T2). The Youth Self Rating Insomnia Scale and 8-item Positive Subscale of the Community Assessment of Psychic Experiences were used to assess sleep and PLEs, respectively. Sample characteristics and depression were also evaluated at T1, and negative life events were measured at T2. Sleep duration ≤6 h per night was considered as sleep deprivation, and sleep disturbance was defined as having insomnia or poor sleep quality.

RESULTS

The prevalence of sleep disturbance and frequent PLEs at T1 were 14.1% and 14.5%, respectively. Sleep disturbance and sleep deprivation at T1 were significantly associated with increased risk for PLEs at T2 after adjusting for sample characteristics, depression, and negative life events. Furthermore, sleep disturbance and sleep deprivation also predicted the new onset and persistence of PLEs.

CONCLUSION

Sleep disturbance predicts the development and persistence of PLEs. Early assessment and treatment of sleep disturbance may therefore contribute to a comprehensive strategy for the successful prevention and treatment of PLEs in adolescents.

The temporal dynamics of sleep disturbance and psychopathology in psychosis: a digital sampling study

BACKGROUND

Sleep disruption is a common precursor to deterioration and relapse in people living with psychotic disorders. Understanding the temporal relationship between sleep and psychopathology is important for identifying and developing interventions which target key variables that contribute to relapse.

METHODS

We used a purpose-built digital platform to sample self-reported sleep and psychopathology variables over 1 year, in 36 individuals with schizophrenia. Once-daily measures of sleep duration and sleep quality, and fluctuations in psychopathology (positive and negative affect, cognition and psychotic symptoms) were captured. We examined the temporal relationship between these variables using the Differential Time-Varying Effect (DTVEM) hybrid exploratory-confirmatory model.

RESULTS

Poorer sleep quality and shorter sleep duration maximally predicted deterioration in psychosis symptoms over the subsequent 1-8 and 1-12 days, respectively. These relationships were also mediated by negative affect and cognitive symptoms. Psychopathology variables also predicted sleep quality, but not sleep duration, and the effect sizes were smaller and of shorter lag duration.

CONCLUSIONS

Reduced sleep duration and poorer sleep quality anticipate the exacerbation of psychotic symptoms by approximately 1-2 weeks, and negative affect and cognitive symptoms mediate this relationship. We also observed a reciprocal relationship that was of shorter duration and smaller magnitude. Sleep disturbance may play a causal role in symptom exacerbation and relapse, and represents an important and tractable target for intervention. It warrants greater attention as an early warning sign of deterioration, and low-burden, user-friendly digital tools may play a role in its early detection.

Resilience buffers the association between sleep disturbance and psychotic-like experiences in adolescents

BACKGROUND

Sleep disturbance may cause psychotic-like experiences (PLEs). The present study aimed to exam their rate of co-occurrence and investigate whether resilience buffers the association.

METHODS

A total of 50,625 junior high school students were assessed using the self-compiled socio-demographics and sleep questionnaires, 8-item Positive Subscale of the Community Assessment of Psychic Experiences, 10-item Connor-Davidson Resilience Scale, Patient Health Questionnaire and Generalized Anxiety Disorder Questionnaire.

RESULTS

In this sample, 15.8% participants had frequent PLEs in the past month, where 40.1% exhibited comorbid sleep disturbance. Sleep disturbance positively associated with the onset of frequent PLEs, after adjusting for socio-demographics, depression and anxiety. Moderation analysis showed resilience buffers the association between sleep disturbance and PLEs, with a higher level of resilience, the positive effect of sleep disturbance on PLEs would be diminished to a greater extent.

CONCLUSIONS

These findings suggested that early attention should be drawn to adolescents with sleep disturbance. Intervention strategies should be enhancing resilience, increasing sleep duration and improving sleep quality.

Self-Reported Sleep Quality Across Age Modulates Resting-State Functional Connectivity in Limbic and Fronto-Temporo-Parietal Networks: An Exploratory Cross-Sectional fMRI Study

Sleep problems are increasingly present in the general population at any age, and they are frequently concurrent with—or predictive of—memory disturbances, anxiety, and depression. In this exploratory cross-sectional study, 54 healthy participants recruited in Naples (Italy; 23 females; mean age = 37.1 years, range = 20–68) completed the Pittsburgh Sleep Quality Index (PSQI) and a neurocognitive assessment concerning both verbal and visuospatial working memory as well as subjective measures of anxiety and depression. Then, 3T fMRI images with structural and resting-state functional sequences were acquired. A whole-brain seed-to-seed functional connectivity (FC) analysis was conducted by contrasting good (PSQI score <5) vs. bad (PSQI score ≥5) sleepers. Results highlighted FC differences in limbic and fronto-temporo-parietal brain areas. Also, bad sleepers showed an anxious/depressive behavioural phenotype and performed worse than good sleepers at visuospatial working-memory tasks. These findings may help to reveal the effects of sleep quality on daily-life cognitive functioning and further elucidate pathophysiological mechanisms of sleep disorders.

Categorical versus dimensional models of early psychosis

AIM

Early psychosis is typically operationalized as a categorical construct by dividing people into one of three diagnostic statuses: low-risk, clinical high-risk, and first episode psychosis. We empirically assess whether an alternative dimensional approach focused on observed symptom severity may be more desirable for clinical and research purposes.

METHODS

Participants were 152 help-seeking youths ages 12-22 years old. Structured interview for psychosis risk syndromes interviews were used to obtain dimensional psychosis symptom severity ratings, and to classify participants by categorical psychosis risk status. Twenty-five participants were classified as having a diagnosable psychotic disorder, 52 participants as clinical high-risk, and 75 participants as help-seeking controls. We assessed the relation between categorical and dimensional measurements of psychosis severity, and then compared categorical versus dimensional psychosis severity in their ability to predict social and role functioning.

RESULTS

On average, dimensional psychosis symptom severity increased along with categorical risk status (help-seeking control < clinical high-risk < diagnosable psychotic disorder). There was, however, considerable overlap between categories, with people at clinical high-risk being particularly hard to distinguish from people with diagnosable psychotic disorders on the basis of symptom severity. Dimensional symptom severity was more predictive of functioning than categorical risk status.

CONCLUSIONS

Categorical risk status and psychosis symptom severity are related but not interchangeable, and dimensional models of psychosis may be more predictive of functional outcomes. Adopting a dimensional rather than categorical approach to the psychosis risk spectrum may facilitate better predictive models and a richer theoretical understanding of early psychosis.

Examining self-reported social functioning, sleep quality, and psychotic-like experiences in college students

Impairments in social and role functioning have been associated with the prodromal phase of psychosis. Additionally, sleep disturbances impacting daily functioning have been detected across the schizophrenia spectrum. Relationships between social functioning, sleep quality, and psychotic-like experiences (PLEs) in undergraduate-level student populations are less understood. The current project aimed to investigate whether self-reported measures of sleep quality would moderate the relationship between social functioning and PLE endorsement in a community sample of 3042 undergraduate student participants between the ages of 18-35. Participants completed the Social Functioning Scale, the Pittsburgh Sleep Quality Index, and the Prodromal Questionnaire, which indexed PLEs. Bivariate correlations revealed significant associations between social functioning, sleep, and PLEs. As expected, poor sleep and poor social functioning were associated with increased endorsement of PLEs. Contrary to expectation, poor sleep quality was associated with better social functioning. In hierarchical multiple regression models, the interaction between social functioning and sleep was not associated with PLE endorsement. Results indicated that both poor sleep and poor social functioning were significantly associated with PLEs when included in the same model. These findings suggest that poor social functioning and disrupted sleep may act additively to influence PLEs, and that they are both important contributors to psychotic symptoms. Due to deleterious effects of poor sleep on physical and emotional health, these findings provide impetus to further investigate relationships between sleep quality, social functioning, and PLEs using such high-resolution methods as actigraphy, mobile sensing, ecological momentary assessment, and neuroimaging.

Sleep Interventions in the Treatment of Schizophrenia and Bipolar Disorder

Due to the effects of sleep on the central nervous system, it is thought that sleep disorders have a special importance in the onset, course and treatment of psychiatric diseases. Although the negative effects of sleep problems on the occurrence, recurrence and clinical course of psychiatric disorders are well known, it is reported that clinicians do not spend enough time for sleep problems in practice. This may be related to the fact that patients underreport their complaints for various reasons, insufficient examination time, and clinicians' lack of knowledge about the importance of the subject. Pharmacotherapy, psychological and behavioral interventions are options among the therapeutic approaches to sleep problems. But, it seems that clinicians tend to prefer pharmacological approaches for the treatment of sleep problems. However, it is important to choose the appropriate treatment option with considering the method preferred by the patients, who already use many and high doses of pharmacological agents, the nature of the psychiatric disorder and the sleep problem. In this context, chronotherapeutic approaches such as bright light, sleep deprivation, interpersonal relations and social rhythm therapy, and cognitive behavioral therapy techniques adapted for patients with bipolar disorder can be used in the treatment of suitable patients. In this article, the current literature about sleep-related problems observed in patients with schizophrenia and bipolar disorder is reviewed comprehensively with presenting clinical phenotypes and treatment approaches.

Sleep Abnormalities in Schizophrenia: State of the Art and Next Steps

Sleep disturbances are commonly observed in schizophrenia, including in chronic, early-course, and first-episode patients. This has generated considerable interest, both in clinical and research endeavors, in characterizing the relationship between disturbed sleep and schizophrenia. Sleep features can be objectively assessed with EEG recordings. Traditionally, EEG studies have focused on sleep architecture, which includes non-REM and REM sleep stages. More recently, numerous studies have investigated alterations in sleep-specific rhythms, including EEG oscillations, such as sleep spindles and slow waves, in individuals with schizophrenia compared with control subjects. In this article, the author reviews state-of-the-art evidence of disturbed sleep in schizophrenia, starting from the relationship between sleep disturbances and clinical symptoms. First, the author presents studies demonstrating abnormalities in sleep architecture and sleep-oscillatory rhythms in schizophrenia and related psychotic disorders, with an emphasis on recent work demonstrating sleep spindles and slow-wave deficits in early-course and first-episode schizophrenia. Next, the author shows how these sleep abnormalities relate to the cognitive impairments in patients diagnosed with schizophrenia and point to dysfunctions in underlying thalamocortical circuits, Ca+ channel activity, and GABA-glutamate neurotransmission. Finally, the author discusses some of the next steps needed to further establish the role of altered sleep in schizophrenia, including the need to investigate sleep abnormalities across the psychotic spectrum and to establish their relationship with circadian disturbances, which in turn will contribute to the development of novel sleep-informed treatment interventions.

The association between sleep quality and attenuated psychotic symptoms

AIM

To determine if poor sleep makes a unique contribution in predicting the likelihood of experiencing six or more attenuated psychotic symptoms and associated distress, after examining and controlling for sociodemographic factors, depression and drug/alcohol use.

METHOD

An online survey was conducted using Amazon's online crowdsourcing service Mechanical Turk (MTurk). The sample was 1013 adults (18 to 36 years) from the general population in the United States. The survey consisted of the Prodromal Questionnaire 16 (PQ-16), the Pittsburgh Sleep Quality Index, the Patient Health Questionnaire 9, the Drug Abuse Screening Test 10 and the Alcohol Use Disorders Identification Test. Regression analyses were performed with the PQ-16 as the dependent variable, and sleep quality as the predictor variable, holding constant sociodemographic variables, depression, and alcohol/drug abuse.

RESULTS

37% of the sample endorsed six or more PQ-16 items, which may be suggestive of an at-risk mental state, with sleep disturbance significantly increasing the likelihood (Odds ratio 2.09 < .001) of endorsing six or more PQ-16 items. After controlling for sociodemographic variables, depression and drug/alcohol abuse, poor sleep quality made a unique contribution of 5.8% of the variance accounted for in level of distress experienced by attenuated psychotic symptoms.

CONCLUSION

Effective treatment of sleep disturbance may reduce the likelihood ofexperiencing attenuated psychotic symptoms and associated distress.

Neural Mechanism Underlying the Sleep Deprivation-Induced Abnormal Bistable Perception

Quality sleep is vital for physical and mental health. No matter whether sleep problems are a consequence of or contributory factor to mental disorders, people with psychosis often suffer from severe sleep disturbances. Previous research has shown that acute sleep deprivation (SD) can cause transient brain dysfunction and lead to various cognitive impairments in healthy individuals. However, the relationship between sleep disturbance and bistable perception remains unclear. Here, we investigated whether the bistable perception could be affected by SD and elucidated the functional brain changes accompanying SD effects on bistable perception using functional magnetic resonance imaging. We found that the 28-h SD resulted in slower perceptual transitions in healthy individuals. The reduced perceptual transition was accompanied by the decreased activations in rivalry-related frontoparietal areas, including the right superior parietal lobule, right frontal eye field, and right temporoparietal junction. We speculated that SD might disrupt the normal function of these regions crucial for bistable perception, which mediated the slower rivalry-related perceptual transitions in behavior. Our findings revealed the neural changes underlying the abnormal bistable perception following the SD. It also suggested that SD might offer a new window to understand the neural mechanisms underlying the bistable perception.

Home confinement during the COVID-19: day-to-day associations of sleep quality with rumination, psychotic-like experiences, and somatic symptoms

Due to the coronavirus disease 2019 (COVID-19) pandemic, populations from many countries have been confined at home for extended periods of time in stressful environmental and media conditions. Cross-sectional studies already evidence deleterious psychological consequences, with poor sleep as a risk factor for impaired mental health. However, limitations of cross-sectional assessments are response bias tendencies and the inability to track daily fluctuations in specific subjective experiences in extended confinement conditions. In a prospective study conducted across three European countries, we queried participants (N = 166) twice a day through an online interface about their sleep quality and their negative psychological experiences for two consecutive weeks. The focus was set on between- and within-person associations of subjective sleep quality with daytime experiences, such as rumination, psychotic-like experiences, and somatic complaints about the typical symptoms of the coronavirus. The results show that daily reports of country-specific COVID-19 deaths predicted increased negative mood, psychotic-like experiences, and somatic complaints during the same day and decreased subjective sleep quality the following night. Disrupted sleep was globally associated with negative psychological outcomes during the study period, and a relatively poorer night of sleep predicted increased rumination, psychotic-like experiences, and somatic complaints the following day. This temporal association was not paralleled by daytime mental complaints predicting relatively poorer sleep quality on the following night. Our findings show that night-to-night changes in sleep quality predict how individuals cope the next day with daily challenges induced by home confinement.

Sodium valproate improves sensorimotor gating deficit induced by sleep deprivation at low doses

Background/aim

Sleep deprivation disrupts prepulse inhibition of acoustic startle reflex and can be used to mimic psychosis in ex- perimental animals. On the other hand, it is also a model for other disorders of sensory processing, including migraine. This study aims to assess the effects of sodium valproate, a drug that is used in a variety of neuropsychiatric disorders, on normal and disrupted sensorimotor gating in rats.

Materials and methods

Sixty-two Wistar albino rats were randomly distributed into 8 groups. Subchronic and intraperitoneal sodium valproate were administrated to the sleep-deprived and nonsleep-deprived rats by either 50–100 or 200 mg/kg/day. Prepulse inhibition test and locomotor activity test were performed. Sleep deprivation induced by the modified multiple platform method.

Results

Sleep deprivation impaired prepulse inhibition, decreased startle amplitude, and increased locomotor activity. Sodium valpro- ate did not significantly alter prepulse inhibition and locomotor activity in nonsleep-deprived and sleep-deprived groups. On the other hand, all doses decreased locomotor activity in drug-treated groups, and low dose improved sensorimotor gating and startle amplitude after sleep deprivation.

Conclusion

Low-dose sodium valproate improves sleep deprivation-disrupted sensorimotor gating, and this finding may rationalize the use of sodium valproate in psychotic states and other sensory processing disorders. Dose-dependent effects of sodium valproate on sensorimotor gating should be investigated in detail.

Nurr1 deficiency shortens free running period, enhances photoentrainment to phase advance, and disrupts circadian cycling of the dopamine neuron phenotype

Neurological and neuropsychiatric disorders, including addiction, schizophrenia, and Parkinson's disease (PD), involve dysfunction in midbrain dopamine (DA) neurotransmission with severity of disease symptoms and progression associated with disrupted circadian rhythms. The nuclear transcription factor Nurr1, essential for DA neuron (DAN) development, survival, and maintenance, is also known to interact with circadian rhythm regulating clock proteins. In the Nurr1-null heterozygous (+/-) mice, a Nurr1 deficient model which reproduces some of the alterations in DA function found in schizophrenia and PD, we measured, using wheel-running activity, the free running period (tau) and photoperiod entrainment. Because Nurr1 has a role in regulating the DA phenotype, we also measured the circadian fluctuations in the number of DANs using tyrosine hydroxylase (TH) immunofluorescence. In Nurr1 +/- mice, tau was significantly shorter and entrainment to a 6 h earlier shift in the dark cycle was accelerated. The Nurr1 wild-type (+/+) mice cycled DAN numbers across time, with a significantly greater number (∼2-fold increase) of DANs at zeitgeber time (ZT) 0 than ZT12. The +/- mice, however, did not cycle the DA phenotype, as no differences in DAN numbers were observed between ZT0 and ZT12. Additionally, the +/- mice had significantly fewer DANs at ZT0 but not at ZT12 as compared to +/+ mice. Based these data, circadian rhythms and fluctuations in the DA phenotype requires normal Nurr1 function. A better understanding is needed of the mechanisms regulating the DA phenotype and subsequent neurotransmission across the circadian cycle and how this is altered in circadian rhythm and DA neurotransmission-associated disorders.

Head-to-Head Comparison of Sedation and Somnolence Among 37 Antipsychotics in Schizophrenia, Bipolar Disorder, Major Depression, Autism Spectrum Disorders, Delirium, and Repurposed in COVID-19, Infectious Diseases, and Oncology From the FAERS, 2004-2020

Objective: Antipsychotic compounds are known to induce sedation somnolence and have expanded clinical indications beyond schizophrenia to regulatory approval in bipolar disorder, treatment-resistant depression, and is being repurposed in infectious diseases and oncology. However, the medical sciences literature lacks a comprehensive association between sedation and somnolence among a wide-range of antipsychotic compounds. The objective of this study is to assess the disproportionality of sedation and somnolence among thirty-seven typical and atypical antipsychotics.

Materials and Methods: Patient adverse drug reactions (ADR) cases were obtained from the United States Food and Drug Administration Adverse Events Reporting System (FAERS) between January 01, 2004 and September 30, 2020 for a wide-array of clinical indications and off-label use of antipsychotics. An assessment of disproportionality were based on cases of sedation and somnolence and calculated using the case/non-case methodology. Statistical analysis resulting in the reporting odds-ratio (ROR) with corresponding 95% confidence intervals (95% CI) were conducted using the R statistical programming language.

Results: Throughout the reporting period, there were a total of 9,373,236 cases with 99,251 specific ADRs reporting sedation and somnolence. Zuclopenthixol (n = 224) ROR = 13.3 (95% CI, 11.6–15.3) was most strongly associated of sedation and somnolence and haloperidol decanoate long-acting injection (LAI) was not statistically associated sedation and somnolence. Further, among atypical antipsychotic compounds, tiapride and asenapine were the top two compounds most strongly associated with sedation and somnolence. Comprehensively, the typical antipsychotics ROR = 5.05 (95%CI, 4.97–5.12) had a stronger association with sedation and somnolence when compared to atypical antipsychotics ROR = 4.65 (95%CI, 4.47–4.84).

Conclusion: We conducted a head-to-head comparison of thirty-seven antipsychotics and ranked the compounds based on the association of sedation and somnolence from ADR data collected throughout 16 years from the FAERS. The results are informative and with recent interests in repurposing phenothiazine antipsychotics in infectious disease and oncology provides an informative assessment of the compounds during repurposing and in psychopharmacology.

Physiological parameters of mental health predict the emergence of post-traumatic stress symptoms in physicians treating COVID-19 patients

Lack of established knowledge and treatment strategies, and change in work environment, may altogether critically affect the mental health and functioning of physicians treating COVID-19 patients. Thus, we examined whether treating COVID-19 patients affect the physicians' mental health differently compared with physicians treating non-COVID-19 patients. In this cohort study, an association was blindly computed between physiologically measured anxiety and attention vigilance (collected from 1 May 2014 to 31 May 31 2016) and self-reports of anxiety, mental health aspects, and sleep quality (collected from 20 April to 30 June 2020, and analyzed from 1 July to 1 September 2020), of 91 physicians treating COVID-19 or non-COVID-19 patients. As a priori hypothesized, physicians treating COVID-19 patients showed a relative elevation in both physiological measures of anxiety (95% CI: 2317.69-2453.44 versus 1982.32-2068.46; P < 0.001) and attention vigilance (95% CI: 29.85-34.97 versus 22.84-26.61; P < 0.001), compared with their colleagues treating non-COVID-19 patients. At least 3 months into the pandemic, physicians treating COVID-19 patients reported high anxiety and low quality of sleep. Machine learning showed clustering to the COVID-19 and non-COVID-19 subgroups with a high correlation mainly between physiological and self-reported anxiety, and between physiologically measured anxiety and sleep duration. To conclude, the pattern of attention vigilance, heightened anxiety, and reduced sleep quality findings point the need for mental intervention aimed at those physicians susceptible to develop post-traumatic stress symptoms, owing to the consequences of fighting at the forefront of the COVID-19 pandemic.

Sleep problems and worrying precede psychotic symptoms during an online intervention for psychosis

OBJECTIVE

Experience sampling assessments (multiple assessments per day for approximately one week) indicate that positive symptoms fluctuate over time in psychosis. Precursors, such as sleep problems or worrying, predict these fluctuations. To date, it remains unclear whether the same precursors predict symptom variability also during treatment in an online intervention for psychosis, using assessments lying temporally further apart.

METHODS

Participants completed brief intermediate online self-report assessments on their computers (up to every 7 days during a 2-month waiting period and up to twice every 6 days during a 2-month intervention period) within a randomized controlled trial. We monitored the course of paranoia, auditory verbal hallucinations, and their theory-driven precursors worrying, negative affect, self-esteem, self-reported cognitive biases, and quality of sleep in n = 124 participants (M = 10.32 assessments per participant; SD = 6.07). We tested group differences regarding the course of the composite of precursors, group differences regarding the effect of the composite on subsequent momentary psychotic symptoms, and the effect of each individual precursor on subsequent psychotic symptoms, using (lagged) linear mixed models.

RESULTS

The course composite precursors over time and their lagged effect on subsequent momentary psychotic symptoms did not differ between groups. During the intervention, increased worrying and decreased quality of sleep preceded heightened momentary psychotic symptoms.

CONCLUSION

The regression-based design does not allow drawing causal conclusions. However, worrying and sleep problems likely represent underlying mechanisms of psychotic symptom variability during online psychosis treatment, indicating that experience sampling findings from everyday life generalize to interventions with assessments lying several days apart.

PRACTITIONER POINTS

Worrying and sleep problems represent important mechanisms of symptom fluctuations during an online intervention for people with psychosis. Our findings further support the notion that worrying and sleep problems are important treatment targets in psychological interventions for people with psychosis. Momentary levels of worrying and quality of sleep can signal subsequent fluctuations of psychotic symptom severity so practitioners should monitor these variables during treatment. Worrying seems to predict subsequent paranoia specifically during treatment whereas quality of sleep predicts both paranoia and auditory verbal hallucinations.

Troubles psychotiques et troubles du sommeil : revue de la littérature

Contexte La disparition de la nomenclature des troubles du sommeil dits primaires ou secondaires, rendue obsolète par le Manuel diagnostique et statistique des troubles mentaux (DSM-5), représente bien l’engouement académique actuel pour ce domaine de recherche. Il est de plus en plus reconnu que les troubles du sommeil sont plus que de simples conséquences d’un trouble psychiatrique et qu’ils peuvent persister malgré un traitement adéquat de la condition comorbide et même précéder ou exacerber cette dernière. Les troubles du sommeil dans les troubles psychotiques, très fréquents, sont donc devenus un sujet d’actualité, représentant une cible d’intervention jusqu’ici sous-estimée.

Objectif Cet article vise à présenter l’état des connaissances actuelles sur la relation entre les troubles du sommeil et les troubles psychotiques ainsi que sur l’utilisation de la thérapie cognitivo-comportementale (TCC) pour traiter les troubles du sommeil dans ce contexte.

Méthode L’article fait une recension narrative de la littérature pour décrire la relation bidirectionnelle entre la psychose et les troubles du sommeil, les corrélations cliniques et les traitements ciblant l’insomnie chez les patients psychotiques.

Résultats Malgré la présence d’une relation entre les troubles du sommeil et les troubles psychotiques, les mécanismes neuronaux, hormonaux et socioculturels régissant cette relation demeurent encore incertains. Bien que l’association reliant les troubles du sommeil et les troubles psychotiques demeure à clarifier, les études démontrent qu’elle serait bidirectionnelle et peut engendrer un cercle vicieux où ces deux composantes s’aggravent mutuellement. Dans ce contexte de comorbidités, les modèles unifiés en TCC deviennent un traitement de choix, à condition d’adapter les protocoles de TCC pour insomnie (TCC-i) à une population avec trouble psychotique (TCC-ip).

Conclusion Malgré la complexité de la relation entre les troubles psychotiques et ceux du sommeil, la TCC-i a été démontrée efficace pour traiter les troubles du sommeil dans une population psychotique et pourrait, dans certains cas, permettre d’alléger la symptomatologie psychotique. De futures études sur ce domaine pourraient permettre le développement de protocoles de thérapie cognitivo-comportementale pour les troubles du sommeil mieux adaptés à la population avec troubles psychotiques.

Effect of gabapentin on sleep-deprivation-induced disruption of prepulse inhibition

RATIONALE

There are controversial reports on the effects of gabapentin in respect to psychotic symptoms. Prepulse inhibition of the acoustic startle response is an operational measure of sensorimotor gating. In laboratory rodents, deficits in sensorimotor gating are used to model behavioral endophenotypes of schizophrenia. Sleep deprivation disrupts prepulse inhibition and can be used as a psychosis model to evaluate effects of gabapentin.

OBJECTIVES

This study aimed to investigate behavioral effects of gabapentin in both naïve and sleep-deprived rats.

METHODS

Sleep deprivation was induced in male Wistar rats by using the modified multiple platform technique in a water tank for 72 h. The effect of water tank itself was studied in a sham group. The effects of oral acute and subchronic (4.5 days) gabapentin doses (25, 100, or 200 mg/kg/day) on sensorimotor gating and locomotor activity was evaluated by prepulse inhibition test and locomotor activity test, respectively. Plasma gabapentin levels of some groups and body weights of all groups were also assessed.

RESULTS

Sleep deprivation disrupted prepulse inhibition, increased locomotor activity, reduced gabapentin plasma levels, and body weights. Some gabapentin doses disrupted sensorimotor gating irrespective of sleep condition. Some gabapentin doses increased locomotor activity in non-sleep-deprived rats and decreased locomotor activity in sleep-deprived rats. On the contrary, gabapentin did not normalize sleep deprivation-induced disruption in sensorimotor gating.

CONCLUSIONS

Sleep deprivation via modified multiple platform technique could be used as an animal model for psychosis. Gabapentin may have dose- and duration-dependent effects on sensorimotor gating and locomotor activity.

Sleep and schizophrenia: From epiphenomenon to treatable causal target

BACKGROUND

Sleep disturbance is a common clinical issue for patients with psychosis. It has been identified as a putative causal factor in the onset and persistence of psychotic experiences (paranoia and hallucinations). Hence sleep disruption may be a potential treatment target to prevent the onset of psychosis and reduce persistent psychotic experiences. The aim of this review is to describe developments in understanding the nature, causal role, and treatment of sleep disruption in psychosis.

METHOD

A systematic literature search was conducted to identify studies, published in the last five years, investigating subjective sleep disruption and psychotic experiences.

RESULTS

Fifty-eight papers were identified: 37 clinical and 21 non-clinical studies. The studies were correlational (n = 38; 20 clinical, 18 non-clinical), treatment (n = 7; 1 non-clinical), qualitative accounts (n = 6 clinical), prevalence estimates (n = 5 clinical), and experimental tests (n = 2 non-clinical). Insomnia (50%) and nightmare disorder (48%) are the most prevalent sleep problems found in patients. Sleep disruption predicts the onset and persistence of psychotic experiences such as paranoia and hallucinations, with negative affect identified as a partial mediator of this relationship. Patients recognise the detrimental effects of disrupted sleep and are keen for treatment. All psychological intervention studies reported large effect size improvements in sleep and there may be modest resultant improvements in psychotic experiences.

CONCLUSIONS

Sleep disruption is a treatable clinical problem in patients with psychosis. It is important to treat in its own right but may also lessen psychotic experiences. Research is required on how this knowledge can be implemented in clinical services.

Controlled sleep deprivation as an experimental medicine model of schizophrenia: An update

In recent years there has been a surge of interest and corresponding accumulation of knowledge about the role of sleep disturbance in schizophrenia. In this review, we provide an update on the current status of experimentally controlled sleep deprivation (SD) as an experimental medicine model of psychosis, and also consider, given the complexity and heterogeneity of schizophrenia, whether this (state) model can be usefully combined with other state or trait model systems to more powerfully model the pathophysiology of psychosis. We present evidence of dose-dependent aberrations that qualitatively resemble positive, negative and cognitive symptoms of schizophrenia as well as deficits in a range of translational biomarkers for schizophrenia, including prepulse inhibition, smooth pursuit and antisaccades, following experimentally controlled SD, relative to standard sleep, in healthy volunteers. Studies examining the combination of SD and schizotypy, a trait model of schizophrenia, revealed only occasional, task-dependent superiority of the combination model, relative to either of the two models alone. Overall, we argue that experimentally controlled SD is a valuable experimental medicine model of schizophrenia to advance our understanding of the pathophysiology of the clinical disorder and discovery of more effective or novel treatments. Future studies are needed to test its utility in combination with other, especially state, model systems of psychosis such as ketamine.

Effect of repetitive transcranial magnetic stimulation on the cognitive impairment induced by sleep deprivation: a randomized trial

OBJECTIVE

Currently, an efficient method for improving cognitive impairment due to sleep deprivation (SD) is lacking. The aim of this study is to evaluate the effect of high-frequency repetitive transcranial magnetic stimulation (rTMS) during SD on reversing the adverse effects of SD.

METHODS

A total of 66 healthy people were randomized into the rTMS group and sham group. Both groups were deprived of sleep for 24 h. During SD, participants were asked to complete several cognitive tasks and underwent mood assessments. Saliva cortisol levels, plasma concentrations of brain-derived neurotrophic factor (BDNF), precursor BDNF (proBDNF), and tissue-type plasminogen activator (tPA), and frontal blood activation were detected before and after SD. The rTMS group received real rTMS stimulation for 2 sessions of 10 Hz rTMS (40 trains of 50 pulses with a 20-second intertrain interval) to the left dorsolateral prefrontal cortex and the sham group received sham stimulation during SD.

RESULTS

Twenty-four hours of SD induced a reduced accuracy in the n-back task, increases in both anxiety and depression, increased cortisol levels, decreased frontal blood activation and decreased BDNF levels in healthy people. Notably, rTMS improved the hyperactivity of the hypothalamic-pituitary-adrenal axis and decreased frontal blood activation induced by SD, and reduced the consumption of plasma proBDNF.

CONCLUSIONS

Twenty-four hours of SD induced a cognitive impairment. The administration of high-frequency rTMS during sleep deprivation exerted positive effects on HPA axis and frontal activation and might help alleviate cognitive impairment in the long term.

Disrupted Sleep and Circadian Rhythms in Schizophrenia and Their Interaction With Dopamine Signaling

Sleep and circadian rhythm disruption (SCRD) is a common feature of schizophrenia, and is associated with symptom severity and patient quality of life. It is commonly manifested as disturbances to the sleep/wake cycle, with sleep abnormalities occurring in up to 80% of patients, making it one of the most common symptoms of this disorder. Severe circadian misalignment has also been reported, including non-24 h periods and phase advances and delays. In parallel, there are alterations to physiological circadian parameters such as body temperature and rhythmic hormone production. At the molecular level, alterations in the rhythmic expression of core clock genes indicate a dysfunctional circadian clock. Furthermore, genetic association studies have demonstrated that mutations in several clock genes are associated with a higher risk of schizophrenia. Collectively, the evidence strongly suggests that sleep and circadian disruption is not only a symptom of schizophrenia but also plays an important causal role in this disorder. The alterations in dopamine signaling that occur in schizophrenia are likely to be central to this role. Dopamine is well-documented to be involved in the regulation of the sleep/wake cycle, in which it acts to promote wakefulness, such that elevated dopamine levels can disturb sleep. There is also evidence for the influence of dopamine on the circadian clock, such as through entrainment of the master clock in the suprachiasmatic nuclei (SCN), and dopamine signaling itself is under circadian control. Therefore dopamine is closely linked with sleep and the circadian system; it appears that they have a complex, bidirectional relationship in the pathogenesis of schizophrenia, such that disturbances to one exacerbate abnormalities in the other. This review will provide an overview of the evidence for a role of SCRD in schizophrenia, and examine the interplay of this with altered dopamine signaling. We will assess the evidence to suggest common underlying mechanisms in the regulation of sleep/circadian rhythms and the pathophysiology of schizophrenia. Improvements in sleep are associated with improvements in symptoms, along with quality of life measures such as cognitive ability and employability. Therefore the circadian system holds valuable potential as a new therapeutic target for this disorder.

Sex Differences in Subjective Sleep Quality Patterns in Schizophrenia

OBJECTIVE/BACKGROUND

Sleep dysfunction is prevalent among patients with schizophrenia. Although sex differences have been identified in schizophrenia, sex differences in sleep patterns among patients with schizophrenia are not established. Therefore, the current study examined sex differences in subjective sleep quality patterns in people with schizophrenia utilizing a standardized inventory.

PARTICIPANTS

Study sample consisted of 75 patients with schizophrenia and 82 healthy controls (HC).

METHODS

Participants completed the Pittsburgh Sleep Quality Index (PSQI).

RESULTS

Compared to HC, patients with schizophrenia were more likely to report being poor sleepers (PSQI global score > 5), longer sleep duration, more sleep disturbances, longer sleep onset latency, increased daytime dysfunction due to poor sleep, and more frequent use of sleep medications. Regarding sex differences, female patients were more likely to report being poor sleepers and endorsed more sleep disturbances than female HC, while male patients reported longer sleep duration, more daytime dysfunction, and poorer overall sleep quality relative to male HC. Additionally, higher level of sleep dysfunction was linked to higher symptom severity in male patients only.

CONCLUSIONS

Patients with schizophrenia endorsed a range of sleep difficulties, and male and female patients with schizophrenia differ compared to their HC counterparts. Implications for treatment of sleep complaints among patients with schizophrenia are discussed.

Animal Models of Psychosis in Alzheimer Disease

Psychosis in Alzheimer Disease (AD) represents a distinct clinicopathologic variant associated with increased cognitive and functional morbidity and an accelerated disease course. To date, extant treatments offer modest benefits with significant risks. The development of new pharmacologic treatments for psychosis in AD would be facilitated by validated preclinical models with which to test candidate interventions. The current review provides a brief summary of the process of validating animal models of human disease together with a critical analysis of the challenges posed in attempting to apply those standards to AD-related behavioral models. An overview of phenotypic analogues of human cognitive and behavioral impairments, with an emphasis on those relevant to psychosis, in AD-related mouse models is provided, followed by an update on recent progress in efforts to translate findings in the pathophysiology of psychotic AD into novel models. Finally, some future directions are suggested to expand the catalogue of psychosis-relevant phenotypes that may provide a sturdier framework for model development and targets for preclinical treatment outcomes.

Neurobehavioural complications of sleep deprivation: Shedding light on the emerging role of neuroactive steroids

Sleep deprivation (SD) is associated with a broad spectrum of cognitive and behavioural complications, including emotional lability and enhanced stress reactivity, as well as deficits in executive functions, decision making and impulse control. These impairments, which have profound negative consequences on the health and productivity of many individuals, reflect alterations of the prefrontal cortex (PFC) and its connectivity with subcortical regions. However, the molecular underpinnings of these alterations remain elusive. Our group and others have begun examining how the neurobehavioural outcomes of SD may be influenced by neuroactive steroids, a family of molecules deeply implicated in sleep regulation and the stress response. These studies have revealed that, similar to other stressors, acute SD leads to increased synthesis of the neurosteroid allopregnanolone in the PFC. Whereas this up-regulation is likely aimed at counterbalancing the detrimental impact of oxidative stress induced by SD, the increase in prefrontal allopregnanolone levels contributes to deficits in sensorimotor gating and impulse control, signalling a functional impairment of PFC. This scenario suggests that the synthesis of neuroactive steroids during acute SD may be enacted as a neuroprotective response in the PFC; however, such compensation may in turn set off neurobehavioural complications by interfering with the corticolimbic connections responsible for executive functions and emotional regulation.

Sleep problems and attenuated psychotic symptoms in youth at clinical high-risk for psychosis

There has been growing interest on the effect of sleep problems on psychotic and prodromal symptoms. The current study investigated cross-sectional relations between sleep problems and attenuated psychotic symptoms in a large sample of 740 youth at Clinical High Risk (CHR) for psychosis in an attempt to replicate previous findings and assess whether findings from general population samples and psychotic samples extend to this CHR sample. Sleep problems were found to be significantly positively associated with attenuated psychotic symptom severity. Sleep problems were also found to be more closely associated with certain specific prodromal symptoms (e.g., suspiciousness and perceptual abnormalities) than other attenuated psychotic symptoms. Further, we found that depression mediated the cross-sectional association between sleep problems and paranoid symptoms only. This adds to a growing body of evidence suggesting the mediation role of depression is more pronounced for paranoid-type psychotic symptoms as compared to other psychotic symptoms (e.g., hallucinations).

Factors Associated With Delirium in Surgical Intensive Care Unit Patients Treated With Supplemental Melatonin: A Case-Cohort Study

OBJECTIVES

Intensive care unit (ICU) delirium is a common neuropsychiatric syndrome that confers significant morbidity and mortality. Melatonin is an endogenous neurohormone involved with regulating sleep-wake cycles and has been found to be disturbed in ICU delirium. We hypothesized that there are independent factors that predict delirium in a cohort of patients on melatonin in the surgical ICU (SICU).

METHODS

A retrospective, observational case-cohort analysis of adult SICU patients was conducted. Cases were defined by testing positive on the Confusion Assessment Method for the ICU (CAM-ICU). Delirioprotective and deliriogenic factors were assessed prior to the studied melatonin administration.

RESULTS

Forty-one CAM-ICU-positive cases and 59 CAM-ICU-negative controls were included. Higher mean Acute Physiology and Chronic Health Evaluation II scores were associated with delirium in univariable analysis. Stratified analysis found a higher incidence of delirium in baseline CAM-ICU-positive patients who experienced emergency surgery within 24 hours of admission compared with baseline CAM-ICU-negative patients after melatonin administration.

CONCLUSIONS

This study describes the use of melatonin in the SICU and characterizes the patients who receive it. Further research is needed to determine the role of melatonin in deliriogenesis and to clarify its utility as a delirioprotectant for postsurgical, critical care patients.

Hypothalamic-pituitary-adrenal axis responsiveness, startle response, and sensorimotor gating in late pregnancy

During pregnancy, the hypothalamic-pituitary-adrenal (HPA) axis, the main regulator of the stress response, undergoes dramatic changes. The acoustic startle response (ASR) and the prepulse inhibition (PPI) of the startle response are neurophysiological research tools and objective measures of an individual's response to an emotional context or stressor. The ASR and PPI are influenced by psychiatric diseases characterized by anxiety symptoms and are sensitive to cortisol. Hence, the ASR and the PPI can be used to investigate the effects of pregnancy-induced endocrine changes and their contribution to affective disorders. The present study sought to investigate the association between measures of HPA-axis responsiveness, startle reactivity and sensorimotor gating during pregnancy that to date remains unknown. The eye-blink component of the ASR, and its prepulse inhibition, were measured in 107 late third trimester pregnant women. Saliva samples were collected to assess the cortisol awakening response (CAR), a measure of HPA-axis activity. Blood was sampled to measure serum levels of cortisol, cortisone and the cortisone to cortisol ratio. Ongoing anxiety disorders, sleep duration, smoking, and age were considered as potential confounders in the statistical analyses. CAR reactivity, measured as area under the curve (AUC) increase and above baseline, was positively associated with baseline startle magnitude [Cohen's d = 0.27; F (1, 105) = 4.99; p = 0.028, and Cohen's d = 0.30; F (1, 105) = 6.25; p = 0.014, respectively] as well as PPI at 86 dB [Cohen's d = 0.29; F (1, 105) = 5.93; p = 0.017; and Cohen's d = 0.34; F (1, 105) = 8.38; p = 0.005, respectively]. The observed positive correlation between startle magnitude in pregnant women and greater increase in cortisol during the awakening response may be interpreted as heightened neurophysiological reactivity, likely associated with dysregulation of the stress system.

Poor sleep quality predicts psychotic-like symptoms: an experience sampling study in young adults with schizotypal traits

OBJECTIVE

Psychotic-like experiences (PLEs) are unusual experiences such as perceptual abnormalities and delusional-like thoughts that resemble the symptoms of psychosis at the sub-clinical level. PLEs are associated with sleep complaints in healthy and clinical samples; however, evidence for day-to-day associations between poor sleep and subsequent PLEs under naturalistic conditions is scarce. We hypothesized that poor sleep quality would predict next days' PLEs, and vice versa, daytime PLEs would be associated with worse subsequent sleep quality.

METHOD

Seventy-three university students with moderate to high levels of positive schizotypy participated in an experience sampling study. Participants rated their sleep each morning, as well as PLEs and affective states during the day over 3 weeks.

RESULTS

Multilevel regression models indicated that poor sleep quality predicted increased PLEs the following day. Poor sleep was linked to negative daytime mood that partially mediated the associations between sleep quality and next days' PLEs. Furthermore, PLEs were enhanced in the evening as compared to daytime reports. The prediction of poor sleep quality by previous days' PLEs was negligible.

CONCLUSIONS

The results are consistent with the position that sleep-related interventions might reduce the risk of psychosis, especially in individuals that tend to experience psychotic-like phenomena and negative affect.

Insomnia in patients with schizophrenia: current understanding and treatment options

In patients with schizophrenia, insomnia is a common yet often overlooked comorbidity. With sleep disturbances inextricably linked to increased severity of schizophrenia and worsening clinical outcomes, insomnia is an important therapeutic target within this patient population. Thus, through a review of the current literature, this paper reiterates the important etiological link between these two conditions, while evaluating the safety, efficacy, and limitations of current therapeutic options for the treatment of comorbid insomnia in schizophrenia. Despite the continued use of benzodiazepine receptor agonists (BZRAs) for insomnia, the use of other therapies such as Cognitive Behavioral Therapy for Insomnia (CBT-I) and suvorexant warrants increased consideration. More large-scale clinical trials are needed to assess the efficacy of such therapeutic options in the schizophrenia patient population.

Systems Analysis of the 22q11.2 Microdeletion Syndrome Converges on a Mitochondrial Interactome Necessary for Synapse Function and Behavior

Neurodevelopmental disorders offer insight into synaptic mechanisms. To unbiasedly uncover these mechanisms, we studied the 22q11.2 syndrome, a recurrent copy number variant, which is the highest schizophrenia genetic risk factor. We quantified the proteomes of 22q11.2 mutant human fibroblasts from both sexes and mouse brains carrying a 22q11.2-like defect, Df(16)A+/- Molecular ontologies defined mitochondrial compartments and pathways as some of top ranked categories. In particular, we identified perturbations in the SLC25A1-SLC25A4 mitochondrial transporter interactome as associated with the 22q11.2 genetic defect. Expression of SLC25A1-SLC25A4 interactome components was affected in neuronal cells from schizophrenia patients. Furthermore, hemideficiency of the Drosophila SLC25A1 or SLC25A4 orthologues, dSLC25A1-sea and dSLC25A4-sesB, affected synapse morphology, neurotransmission, plasticity, and sleep patterns. Our findings indicate that synapses are sensitive to partial loss of function of mitochondrial solute transporters. We propose that mitoproteomes regulate synapse development and function in normal and pathological conditions in a cell-specific manner.SIGNIFICANCE STATEMENT We address the central question of how to comprehensively define molecular mechanisms of the most prevalent and penetrant microdeletion associated with neurodevelopmental disorders, the 22q11.2 microdeletion syndrome. This complex mutation reduces gene dosage of ∼63 genes in humans. We describe a disruption of the mitoproteome in 22q11.2 patients and brains of a 22q11.2 mouse model. In particular, we identify a network of inner mitochondrial membrane transporters as a hub required for synapse function. Our findings suggest that mitochondrial composition and function modulate the risk of neurodevelopmental disorders, such as schizophrenia.

Intentional inhibition but not source memory is related to hallucination-proneness and intrusive thoughts in a university sample

Proneness to unusual perceptual states - such as auditory or visual hallucinations - has been proposed to exist on a continuum in the general population, but whether there is a cognitive basis for such a continuum remains unclear. Intentional cognitive inhibition (the ability to wilfully control thoughts and memories) is one mechanism that has been linked to auditory hallucination susceptibility, but most evidence to date has been drawn from clinical samples only. Moreover, such a link has yet to be demonstrated over and above relations to other cognitive skills (source monitoring) and cognitive states (intrusive thoughts) that often correlate with both inhibition and hallucinations. The present study deployed two tests of intentional inhibition ability - the Inhibition of Currently Irrelevant Memories (ICIM) task and Directed Forgetting (DF) task - and one test of source monitoring (a source memory task) to examine how cognitive task performance relates to self-reported i) auditory hallucination-proneness and ii) susceptibility to intrusive thoughts in a non-clinical student sample (N = 76). Hierarchical regression analyses were used to assess the independent and combined contributions of task performance to proneness scores. ICIM performance but not DF or source memory scores were significantly related to both hallucination-proneness and intrusive thoughts. Further analysis suggested that intrusive thoughts may mediate the link between intentional inhibition skills and auditory hallucination-proneness, suggesting a potential pathway from inhibition to perception via intrusions in cognition. The implications for studying cognitive mechanisms of hallucination and their role in "continuum" views of psychosis-like experiences are discussed.

Reduced frontal slow wave density during sleep in first-episode psychosis

BACKGROUND

Sleep disturbances are commonly reported in psychotic patients and often contribute to the manifestation and severity of their symptoms. Slow waves characterize the deepest stage of NREM sleep, and their occurrence is critical for restorative sleep. Slow wave abnormalities have been reported in patient with schizophrenia, especially when experiencing an exacerbation of psychosis. However, their presence and delineation, with an emphasis on topography, in first-episode psychosis patients (FEP) have not yet been characterized.

METHODS

We performed sleep high density (hd)-EEG recordings in twenty FEP patients and twenty healthy control subjects (HC). Slow wave activity (SWA) and several other slow wave parameters, e.g. density, amplitude, up- and down-slopes, were calculated at each electrode location and compared across groups. Additionally, the association between slow wave characteristics and clinical symptoms was assessed.

RESULTS

FEP patients showed a reduction selectively in slow-wave density relative to HC, and this reduction was significant in a large frontal area, including channels overlying the prefrontal cortex. Furthermore, slow wave density was inversely correlated with the severity of FEP positive symptoms.

CONCLUSIONS

Abnormalities in slow waves are present at the beginning of psychosis, occur in frontal-prefrontal regions that are highly dysfunctional in psychotic patients, and are associated with their positive symptom severity. Building on these findings, future work will help establish the direction of these associations (i.e., if clinical symptoms precede, coincide, or follow SW deficits), which will determine whether ameliorating slow wave sleep deficits is a viable treatment target in early psychosis.

Combining trait and state model systems of psychosis: The effect of sleep deprivation on cognitive functions in schizotypal individuals

Model systems of psychosis play an important role in pathophysiology and drug development research. Schizotypal individuals display similar cognitive impairments as schizophrenia patients in several domains. Therefore, schizotypy may be interpreted as a trait model system of psychosis. In addition, experimentally controlled sleep deprivation is a putative state psychosis model that evokes subclinical psychosis-like states. We aimed to further validate these model systems by examining them in relation to central cognitive biomarkers of schizophrenia. Most of all, we were interested in investigating, for the first time, effects of their combination on cognitive function. Healthy subjects with high (N = 17) or low (N = 19) levels of schizotypy performed a cognitive task battery after one night of normal sleep and after 24 h of sleep deprivation. Sleep deprivation impaired performance in the go/nogo and n-back tasks relative to the normal sleep control condition. No differences between groups or interactions of group with sleep condition were found. The role of sleep deprivation as a model of psychosis is thus supported to some extent by impairments in inhibitory control. However, classical measures of cognition may be less able to detect deficits in schizotypy, in line with evidence of more basic information processing dysfunctions in schizotypy.