Electroencephalographic sleep in schizophrenia: a critical review

The importance of covert memory consolidation in schizophrenia: Dysfunctional network profiles of the hippocampus and the dorsolateral prefrontal cortex

Altered brain network profiles in schizophrenia (SCZ) during memory consolidation are typically observed during task-active periods such as encoding or retrieval. However active processes are also sub served by covert periods of memory consolidation. These periods are active in that they allow memories to be recapitulated even in the absence of overt sensorimotor processing. It is plausible that regions central to memory formation like the dlPFC and the hippocampus, exert network signatures during covert periods. Are these signatures altered in patients? The question is clinically relevant because real world learning and memory is facilitated by covert processing, and may be impaired in schizophrenia. Here, we compared network signatures of the dlPFC and the hippocampus during covert periods of a learning and memory task. Because behavioral proficiency increased non-linearly, functional connectivity of the dlPFC and hippocampus [psychophysiological interaction (PPI)] was estimated for each of the Early (linear increases in performance) and Late (asymptotic performance) covert periods. During Early periods, we observed hypo-modulation by the hippocampus but hyper-modulation by dlPFC. Conversely, during Late periods, we observed hypo-modulation by both the dlPFC and the hippocampus. We stitch these results into a conceptual model of network deficits during covert periods of memory consolidation.

Electroencephalography Microstate Class D is a Brain Marker of Subjective Sleep Quality for College Students with High Habitual Sleep Efficiency

Subjective sleep quality is an individual's subjective sleep feeling, and its effective evaluation is the premise of improving sleep quality. However, people with autism or mental disorders often experience difficulties in verbally expressing their subjective sleep quality. To solve the above problem, this study provides a non-verbal and convenient brain feature to assess subjective sleep quality. Reportedly, microstates are often used to characterize the patterns of functional brain activity in humans. The occurrence frequency of microstate class D is an important feature in the insomnia population. We therefore hypothesize that the occurrence frequency of microstate class D is a physiological indicator of subjective sleep quality. To test this hypothesis, we recruited college students from China as participants [N = 61, mean age = 20.84 years]. The Chinese version of the Pittsburgh Sleep Quality Index scale was used to measure subjective sleep quality and habitual sleep efficiency, and the state characteristics of the brain at this time were assessed using closed eyes resting-state brain microstate class D. The occurrence frequency of EEG microstate class D was positively associated with subjective sleep quality (r = 0.32, p < 0.05). Further analysis of the moderating effect showed that the occurrence frequency of microstate class D was significantly and positively correlated with subjective sleep quality in the high habitual sleep efficiency group. However, the relationship was not significant in the low sleep efficiency group (βsimple = 0.63, p < 0.001). This study shows that the occurrence frequency of microstate class D is a physiological indicator of assessing subjective sleep quality levels in the high sleep efficiency group. This study provides brain features for assessing subjective sleep quality of people with autism and mental disorders who cannot effectively describe their subjective feelings.

Investigating sleep spindle density and schizophrenia: A meta-analysis

Sleep abnormalities are an early feature of schizophrenia (SZ) characterized by reductions in sleep spindles that are associated with deficits in brain connectivity and cognitive function. This study investigated sleep spindle density (SSD) differences between SZ, first episode psychosis (FEP), and family high-risk (FHR) populations and matched healthy controls (HC) by investigating recent studies via a meta-analysis. We collected experimental, demographic, and methodological metrics from eligible studies across multiple online databases. 14 total studies survived the inclusion and exclusion criteria for a total of 337 patients and relatives and 339 HC. R-Studio was used to run the meta-analysis via the meta and metaphor packages. A heterogeneity score of I² = 80% was calculated and thus a random effects model was chosen. We report a large effect size for SSD in patients compared to controls. Furthermore, illness duration was significantly associated with SSD. Our next step to understanding sleep spindles would be to investigate SSD's use as a predictor for SZ or attempt to normalize SSD deficits as a therapeutic option.

Smartphone-Based Tracking of Sleep in Depression, Anxiety, and Psychotic Disorders

PURPOSE OF REVIEW

Sleep is an important feature in mental illness. Smartphones can be used to assess and monitor sleep, yet there is little prior application of this approach in depressive, anxiety, or psychotic disorders. We review uses of smartphones and wearable devices for sleep research in patients with these conditions.

RECENT FINDINGS

To date, most studies consist of pilot evaluations demonstrating feasibility and acceptability of monitoring sleep using smartphones and wearable devices among individuals with psychiatric disorders. Promising findings show early associations between behaviors and sleep parameters and agreement between clinic-based assessments, active smartphone data capture, and passively collected data. Few studies report improvement in sleep or mental health outcomes. Success of smartphone-based sleep assessments and interventions requires emphasis on promoting long-term adherence, exploring possibilities of adaptive and personalized systems to predict risk/relapse, and determining impact of sleep monitoring on improving patients' quality of life and clinically meaningful outcomes.

Sleep-endocrine effects of growth hormone-releasing hormone (GHRH) in patients with schizophrenia

Changes in sleep-EEG after endocrine stimulation tests in patients with schizophrenia include reduced sleep efficiency, prolonged sleep latency and increased awaking after sleep onset Findings on sleep associated growth hormone (GH) secretion were ambiguous. The aim of this study was to elucidate the sleep-endocrine activity especially in the GH system of patients with schizophrenia after repeated administration of GHRH. The effect of repetitive injections of 4 × 50 μg GHRH between 22.00 and 01.00 h on sleep endocrine parameters was investigated in 9 patients diagnosed for schizophrenia. Patients did not receive any medication for one week. Concentrations of ACTH, cortisol, prolactin and GH were determined. Patients spent three consecutive nights in the sleep laboratory. Blood was taken every 20min. Results were compared with matched healthy controls. A non-significant prolonged sleep onset latency and increased time awake was found in patients compared to controls. Sleep stage 2 was significantly reduced in patients. No significant difference in ACTH and cortisol was detected, whereas the GH secretion in patients following GHRH stimulation was significantly elevated compared to controls. Our results in drug free patients confirm already known changes in sleep-EEG in these patients. The GH response to GHRH-stimulation indicates a different regulatory sensitivity of the system between daytime and night-time.

Beta and Gamma Oscillations in Prefrontal Cortex During NMDA Hypofunction: An In Vitro Model of Schizophrenia Features

NMDA receptor (NMDAr) hypofunction has been widely used as a schizophrenia model. Decreased activation of NMDAr is associated with a disrupted excitation/inhibition balance in the prefrontal cortex and with alterations in gamma synchronization. Our aim was to investigate whether this phenomenon could be reproduced in the spontaneous oscillatory activity generated by the local prefrontal network in vitro and, if so, to explore the effects of antipsychotics on the resulting activity. Extracellular recordings were obtained from prefrontal cortex slices bathed in in vivo-like ACSF solution. Slow (<1 Hz) oscillations consisting of interspersed Up (active) and Down (silent) states spontaneously emerged. Fast-frequency oscillations (15-90 Hz) occurred during Up states. We explored the effects of the NMDAr antagonist MK-801 on the spontaneously generated activity. Bath-applied MK-801 induced a dose-dependent decrease in Up-state duration and in the frequency of Up states. However, the beta/gamma power during Up states significantly increased; this increase was in turn prevented by the antipsychotic drug clozapine. The increased beta/gamma power with NMDAr blockade implies that NMDAr activation in physiological conditions prevents hypersynchronization in this frequency range. High-frequency hypersynchronization following NMDAr blockade occurring in cortical slices suggests that-at least part of-the underlying mechanisms of this schizophrenia feature persist in the local cortical circuit, even in the absence of long-range cortical or subcortical inputs. The observed action of clozapine decreasing hypersynchronization in the local circuit may be one of the mechanisms of action of clozapine in preventing schizophrenia symptoms derived from NMDA hypofunction.

Aberrant Network Activity in Schizophrenia

Brain dynamic changes associated with schizophrenia are largely equivocal, with interpretation complicated by many factors, such as the presence of therapeutic agents and the complex nature of the syndrome itself. Evidence for a brain-wide change in individual network oscillations, shared by all patients, is largely equivocal, but stronger for lower (delta) than for higher (gamma) bands. However, region-specific changes in rhythms across multiple, interdependent, nested frequencies may correlate better with pathology. Changes in synaptic excitation and inhibition in schizophrenia disrupt delta rhythm-mediated cortico-cortical communication, while enhancing thalamocortical communication in this frequency band. The contrasting relationships between delta and higher frequencies in thalamus and cortex generate frequency mismatches in inter-regional connectivity, leading to a disruption in temporal communication between higher-order brain regions associated with mental time travel.

Reduced sleep spindle activity point to a TRN-MD thalamus-PFC circuit dysfunction in schizophrenia

Sleep disturbances have been reliably reported in patients with schizophrenia, thus suggesting that abnormal sleep may represent a core feature of this disorder. Traditional electroencephalographic studies investigating sleep architecture have found reduced deep non-rapid eye movement (NREM) sleep, or slow wave sleep (SWS), and increased REM density. However, these findings have been inconsistently observed, and have not survived meta-analysis. By contrast, several recent EEG studies exploring brain activity during sleep have established marked deficits in sleep spindles in schizophrenia, including first-episode and early-onset patients, compared to both healthy and psychiatric comparison subjects. Spindles are waxing and waning, 12-16Hz NREM sleep oscillations that are generated within the thalamus by the thalamic reticular nucleus (TRN), and are then synchronized and sustained in the cortex. While the functional role of sleep spindles still needs to be fully established, increasing evidence has shown that sleep spindles are implicated in learning and memory, including sleep dependent memory consolidation, and spindle parameters have been associated to general cognitive ability and IQ. In this article we will review the EEG studies demonstrating sleep spindle deficits in patients with schizophrenia, and show that spindle deficits can predict their reduced cognitive performance. We will then present data indicating that spindle impairments point to a TRN-MD thalamus-prefrontal cortex circuit deficit, and discuss about the possible molecular mechanisms underlying thalamo-cortical sleep spindle abnormalities in schizophrenia.

Sleep Disturbances in Schizophrenia

Sleep disturbances are prevalent in patients with schizophrenia and play a critical role in the morbidity and mortality associated with the illness. Subjective and objective assessments of sleep in patients with schizophrenia have identified certain consistent findings. Findings related to the sleep structure abnormalities have shown correlations with important clinical aspects of the illness. Disruption of specific neurotransmitter systems and dysregulation of clock genes may play a role in the pathophysiology of schizophrenia-related sleep disturbances. Antipsychotic medications play an important role in the treatment of sleep disturbances in these patients and have an impact on their sleep structure.

Abnormalities in sleep patterns in individuals at risk for psychosis and bipolar disorder

AIM

To compare patterns of sleep and the presence of sleep disturbances in individuals in at-risk mental states (ARMS) for psychosis and bipolar disorder (BD) with a healthy control (HC) group.

METHODS

This was a comparative study involving 20 individuals in ARMS for psychosis or BD, according to the Comprehensive Assessment of At-Risk Mental States, and 20 age- and sex-matched healthy controls. Quality of sleep in the previous month was assessed using the Pittsburgh Sleep Quality Index, diurnal somnolence was evaluated using The Epworth Sleepiness Scale, and chronotype was determined using the Questionnaire of Morningness/Eveningness (QME). All of the participants underwent polysomnography (PSG) during the entire night for two consecutive nights. The first night aimed to adapt the subject to the environment, and only the data from the second night were used for the analysis.

RESULTS

Compared with the HC group, individuals in the ARMS group reported significantly worse sleep quality, as measured by the Pittsburgh Sleep Quality Index. Both groups had scores consistent with daytime sleepiness on the Epworth Sleepiness Scale, and there were no differences with regard to chronotype between the groups, with a predominance of the indifferent type in both groups. In the PSG assessment, we observed increased Sleep Latency (SL) and increased Rapid Eye Movement Sleep Onset Latency (REMOL) in the ARMS group, compared to the HC group.

CONCLUSION

The results of this study indicated that sleep abnormalities could be found early in the course of mental diseases, even in at-risk stages, and support the further investigation of their predictive value in the transition to psychosis and BD.

Targeting modulation of noradrenalin release in the brain for amelioration of REMS loss-associated effects

Rapid eye movement sleep (REMS) loss affects most of the physiological processes, and it has been proposed that REMS maintains normal physiological processes. Changes in cultural, social, personal traits and life-style severely affect the amount and pattern of sleep, including REMS, which then manifests symptoms in animals, including humans. The effects may vary from simple fatigue and irritability to severe patho-physiological and behavioral deficits such as cognitive and behavioral dysfunctions. It has been a challenge to identify a molecule(s) that may have a potential for treating REMS loss-associated symptoms, which are very diverse. For decades, the critical role of locus coeruleus neurons in regulating REMS has been known, which has further been supported by the fact that the noradrenalin (NA) level is elevated in the brain after REMS loss. In this review, we have collected evidence from the published literature, including those from this laboratory, and argue that factors that affect REMS and vice versa modulate the level of a common molecule, the NA. Further, NA is known to affect the physiological processes affected by REMS loss. Therefore, we propose that modulation of the level of NA in the brain may be targeted for treating REMS loss-related symptoms. Further, we also argue that among the various ways to affect the release of NA-level, targeting α₂ adrenoceptor autoreceptor on the pre-synaptic terminal may be the better option for ameliorating REMS loss-associated symptoms.

Biomarkers and clinical staging in psychiatry

Personalized medicine is rapidly becoming a reality in today's physical medicine. However, as yet this is largely an aspirational goal in psychiatry, despite significant advances in our understanding of the biochemical, genetic and neurobiological processes underlying major mental disorders. Preventive medicine relies on the availability of predictive tools; in psychiatry we still largely lack these. Furthermore, our current diagnostic systems, with their focus on well-established, largely chronic illness, do not support a pre-emptive, let alone a preventive, approach, since it is during the early stages of a disorder that interventions have the potential to offer the greatest benefit. Here, we present a clinical staging model for severe mental disorders and discuss examples of biological markers that have already undergone some systematic evaluation and that could be integrated into such a framework. The advantage of this model is that it explicitly considers the evolution of psychopathology during the development of a mental illness and emphasizes that progression of illness is by no means inevitable, but can be altered by providing appropriate interventions that target individual modifiable risk and protective factors. The specific goals of therapeutic intervention are therefore broadened to include the prevention of illness onset or progression, and to minimize the risk of harm associated with more complex treatment regimens. The staging model also facilitates the integration of new data on the biological, social and environmental factors that influence mental illness into our clinical and diagnostic infrastructure, which will provide a major step forward in the development of a truly pre-emptive psychiatry.

Psychophysiology-informed (multimodal) imaging

Electroencephalography (EEG) and magnetic resonance imaging are two popular methodologies for brain research. While EEG has a high temporal resolution, yet a low spatial resolution, MRI has the complete opposite, a high spatial resolution, yet a low temporal resolution. Obviously therefore, researchers have been searching for ways combining the two methodologies, for more than two decades. However, there are many issues that have to be solved before the methodologies can be successfully and, more importantly reliably, combined. Here, we give an overview of these issues, and present strategies that have been used over the past two decades to overcome them. We start with a general description of EEG and (f)MRI methodology, then present the difficulties involved in combining both methodologies, and lastly present and discuss the most popular strategies that have been used over the past two decades to solve these problems. We conclude that in spite of the many issues, the two methodologies can be combined successfully, provided that the correct procedures are followed.

A microstructural study of sleep instability in drug-naive patients with schizophrenia and healthy controls: sleep spindles, rapid eye movements, and muscle atonia

This study aimed at characterizing the functional stability of sleep in schizophrenia by quantifying dissociated stages of sleep (DSS), and to explore their correlation with psychopathology. The sleep of 10 first-break, drug-naive young adults with schizophrenia and 10 controls was recorded. Four basic DSS patterns were scored: 1) the transitional EEG-mixed intermediate stage (EMIS); 2) Rapid-eye-movement (REM) sleep without rapid eye movement (RSWR); 3) REM sleep without atonia (RSWA); and 4) non-REM sleep with rapid eye movements. An intermediate sleep (IS) score was calculated by summing EMIS and RSWR scores, and the durations of intra-REM sleep periods IS (IRSPIS) and IS scored "at the expense" of REM sleep (ISERS) were determined. Patients were administered the Brief Psychiatric Rating Scale (BPRS) at the time of recording. Proportions of each DSS variables over total sleep time and proportions of IRSPIS and ISERS over REM sleep duration were compared between patients and controls. Correlation coefficients between DSS variables and BPRS total scores were calculated. The proportion of total DSS did not differ between patients and controls. Among DSS subtypes, RSWA was significantly increased in patients while other comparisons showed no significant differences. Significant positive correlations were found between BPRS scores and proportions of DSS, IS, RSWR, IRSPIS and ISERS over total sleep and REM sleep durations. These results demonstrate the functional instability of REM sleep in first-break, drug naive young adults with schizophrenia and unveil a pattern reminiscent of REM sleep behavior disorder. The significant correlation suggests that schizophrenia and REM sleep share common neuronal control mechanisms.

Genome-wide study of association and interaction with maternal cytomegalovirus infection suggests new schizophrenia loci

Genetic and environmental components as well as their interaction contribute to the risk of schizophrenia, making it highly relevant to include environmental factors in genetic studies of schizophrenia. This study comprises genome-wide association (GWA) and follow-up analyses of all individuals born in Denmark since 1981 and diagnosed with schizophrenia as well as controls from the same birth cohort. Furthermore, we present the first genome-wide interaction survey of single nucleotide polymorphisms (SNPs) and maternal cytomegalovirus (CMV) infection. The GWA analysis included 888 cases and 882 controls, and the follow-up investigation of the top GWA results was performed in independent Danish (1396 cases and 1803 controls) and German-Dutch (1169 cases, 3714 controls) samples. The SNPs most strongly associated in the single-marker analysis of the combined Danish samples were rs4757144 in ARNTL (P=3.78 × 10(-6)) and rs8057927 in CDH13 (P=1.39 × 10(-5)). Both genes have previously been linked to schizophrenia or other psychiatric disorders. The strongest associated SNP in the combined analysis, including Danish and German-Dutch samples, was rs12922317 in RUNDC2A (P=9.04 × 10(-7)). A region-based analysis summarizing independent signals in segments of 100 kb identified a new region-based genome-wide significant locus overlapping the gene ZEB1 (P=7.0 × 10(-7)). This signal was replicated in the follow-up analysis (P=2.3 × 10(-2)). Significant interaction with maternal CMV infection was found for rs7902091 (P(SNP × CMV)=7.3 × 10(-7)) in CTNNA3, a gene not previously implicated in schizophrenia, stressing the importance of including environmental factors in genetic studies.

Insomnia comorbid to severe psychiatric illness

In psychiatric illness, there is a growing body of evidence indicating that sleep disturbances exert a detrimental influence on the course of these disorders and contribute to impaired function. Even when psychiatric disorders are successfully treated or stabilized, insomnia and other sleep disturbances often fail to remit. The present review focuses on sleep in two severe mental illnesses, namely bipolar disorder and schizophrenia. This article discusses the role of sleep disturbances and altered sleep architecture in relation to symptom status, functional impairment, quality of life, and the course of these disorders. Current evidence regarding pharmacological and psychological treatment approaches for insomnia in these populations is presented. This review also notes considerations for adapting Cognitive Behavioral Therapy for insomnia (CBT-I) procedures for severe mental illness and proposes directions for future research.

Sleep and circadian rhythm dysregulation in schizophrenia

Sleep-onset and maintenance insomnia is a common symptom in schizophrenic patients regardless of either their medication status (drug-naive or previously treated) or the phase of the clinical course (acute or chronic). Regarding sleep architecture, the majority of studies indicate that non-rapid eye movement (NREM), N3 sleep and REM sleep onset latency are reduced in schizophrenia, whereas REM sleep duration tends to remain unchanged. Many of these sleep disturbances in schizophrenia appear to be caused by abnormalities of the circadian system as indicated by misalignments of the endogenous circadian cycle and the sleep-wake cycle. Circadian disruption, sleep onset insomnia and difficulties in maintaining sleep in schizophrenic patients could be partly related to a presumed hyperactivity of the dopaminergic system and dysfunction of the GABAergic system, both associated with core features of schizophrenia and with signaling in sleep and wake promoting brain regions. Since multiple neurotransmitter systems within the CNS can be implicated in sleep disturbances in schizophrenia, the characterization of the neurotransmitter systems involved remains a challenging dilemma.

Decoupling of sleep-dependent cortical and hippocampal interactions in a neurodevelopmental model of schizophrenia

Rhythmic neural network activity patterns are defining features of sleep, but interdependencies between limbic and cortical oscillations at different frequencies and their functional roles have not been fully resolved. This is particularly important given evidence linking abnormal sleep architecture and memory consolidation in psychiatric diseases. Using EEG, local field potential (LFP), and unit recordings in rats, we show that anteroposterior propagation of neocortical slow-waves coordinates timing of hippocampal ripples and prefrontal cortical spindles during NREM sleep. This coordination is selectively disrupted in a rat neurodevelopmental model of schizophrenia: fragmented NREM sleep and impaired slow-wave propagation in the model culminate in deficient ripple-spindle coordination and disrupted spike timing, potentially as a consequence of interneuronal abnormalities reflected by reduced parvalbumin expression. These data further define the interrelationships among slow-wave, spindle, and ripple events, indicating that sleep disturbances may be associated with state-dependent decoupling of hippocampal and cortical circuits in psychiatric diseases.

Sleep correlates of cognition in early course psychotic disorders

BACKGROUND

Slow waves and sleep spindles, the main oscillations during non-rapid eye movement sleep, have been thought to be related to cognitive processes, and are impaired in psychotic disorders. Cognitive impairments, seen early in the course of psychotic disorders, may be related to alterations in these oscillations, but few studies have examined this relationship.

METHOD

Twenty seven untreated patients with a recently diagnosed psychotic disorder had polysomnographic sleep studies and neuro-cognitive testing.

RESULTS

Reduced power in the sigma range, which reflects spindle density, was associated with impaired attention, and reasoning, but not intelligence quotient (IQ). Slow wave sleep measures were not significantly associated with any cognitive measures.

CONCLUSIONS

Impairments in sleep spindles may be associated with cognitive deficits in the early course of psychotic disorders. These observations may help clarify neuro-biologic mechanisms of cognitive deficits in psychotic disorders such as schizophrenia.

Schizophrenia patients with predominantly positive symptoms have more disturbed sleep-wake cycles measured by actigraphy

Sleep disturbances are widespread in schizophrenia, and one important concern is to determine the impact of this disruption on self-reported sleep quality and quality of life (QoL). Our aim was to evaluate the sleep-wake cycle in a sample of patients with schizophrenia (SZ), and whether sleep patterns differ between patients with predominantly negative versus predominantly positive symptoms, as well as its impact on sleep quality and QoL. Twenty-three SZ outpatients were studied with 24 h continuous wrist-actigraphy during 7 days. The quality of sleep was assessed with the Pittsburgh Sleep Quality Index (PSQI), and the self-reported QoL was evaluated with the World Health Organization Quality of Life - Abbreviated version (WHOQOL-Bref). About half of the studied population presented an irregular sleep-wake cycle. We found a trend for more disrupted sleep-wake patterns in patients with predominantly positive symptoms, who also had a trend self-reported worse quality of sleep and worse QoL in all domains. Overall, patients with worse self-reported QoL demonstrated worse sleep quality. Our findings suggest that SZ patients are frequently affected with sleep and circadian rhythm disruptions; these may have a negative impact on rehabilitation strategies. Moreover, poor sleep may play a role in sustaining poor quality of life in SZ patients.

Off-line memory consolidation impairments in multiple sclerosis patients receiving high-dose corticosteroid treatment mirror consolidation impairments in depression

BACKGROUND

Sleep supports the consolidation of procedural memory, however patients with major depression show impaired motor memory performance after a night of sleep. It was hypothesized that this impairment is related to hypothalamic-pituitary-adrenal (HPA) axis dysfunction. We tested if high-dose administration of corticosteroids impairs off-line motor memory consolidation in patients with multiple sclerosis (MS).

METHODS

Nine patients with MS receiving high-dose corticosteroid therapy (methylprednisolone) and nine MS patients receiving alternative therapy (mitoxantrone) were assessed using a sequential finger tapping task before and after a night with polysomnography. In addition, nine patients with major depression (MD) receiving antidepressants and nine healthy controls were assessed.

RESULTS

Although the four groups did not differ in practice-dependent learning, healthy subjects and MS patients receiving mitoxantrone showed markedly overnight-improvements in tapping performance of 17% and 24% while MS patients receiving high-dose corticosteroid therapy and depressed patients showed -9% and -10% overnight decrease. MS patients with and without corticosteroid therapy did not differ in their amount of REM sleep, nor did MD patients and healthy controls. In addition, we did not find any correlation between REM sleep and memory consolidation.

CONCLUSION

Our results show that a strong intervention into the HPA system like in MS high-dose corticosteroid therapy impairs off-line motor memory consolidation comparable to the impairments seen in depressed patients. We propose therefore that depression-related changes in plasma corticosteroid levels rather than in sleep per se underlie off-line memory consolidation impairments in MD.

Impaired off-line memory consolidation in depression

Sleep is critically involved in the consolidation of procedural memory. In major depression (MD) and during antidepressant pharmacotherapy, changes in sleep EEG are well documented. Here, we test if off-line motor memory consolidation is impaired in MD. 50 medicated patients with an acute episode of MD, 50 normal controls and 12 patients with a remitted episode of MD were assessed using a sequential finger tapping task before and after a night of sleep. Although depressed patients and control subjects did not differ in practice-dependent learning, healthy subjects showed markedly overnight improvements in tapping performance of 18% while patients failed to show any improvement. This pattern became even more striking when the subjects were divided by an age threshold of 30years: In the 30+yrs group the healthy subjects showed 16% overnight increase in motor performance, whereas the patients showed -10% overnight decrease. In contrast, patients and controls in the </=30yrs group showed virtually the same motor performance, as well as remitted patients and controls in the 30+yrs group. In addition, the younger controls showed stronger overnight improvements than the older controls. This pattern might be interpreted as a synergistic interaction between age and depression: Off-line motor memory consolidation is not affected in young patients, but severely impaired in older patients with an acute episode of MD. This impairment seems to recover after remission from depression.

Does abnormal sleep impair memory consolidation in schizophrenia?

Although disturbed sleep is a prominent feature of schizophrenia, its relation to the pathophysiology, signs, and symptoms of schizophrenia remains poorly understood. Sleep disturbances are well known to impair cognition in healthy individuals. Yet, in spite of its ubiquity in schizophrenia, abnormal sleep has generally been overlooked as a potential contributor to cognitive deficits. Amelioration of cognitive deficits is a current priority of the schizophrenia research community, but most efforts to define, characterize, and quantify cognitive deficits focus on cross-sectional measures. While this approach provides a valid snapshot of function, there is now overwhelming evidence that critical aspects of learning and memory consolidation happen offline, both over time and with sleep. Initial memory encoding is followed by a prolonged period of consolidation, integration, and reorganization, that continues over days or even years. Much of this evolution of memories is mediated by sleep. This article briefly reviews (i) what is known about abnormal sleep in schizophrenia, (ii) sleep-dependent memory consolidation in healthy individuals, (iii) recent findings of impaired sleep-dependent memory consolidation in schizophrenia, and (iv) implications of impaired sleep-dependent memory consolidation in schizophrenia. This literature suggests that abnormal sleep in schizophrenia disrupts attention and impairs sleep-dependent memory consolidation and task automation. We conclude that these sleep-dependent impairments may contribute substantially to generalized cognitive deficits in schizophrenia. Understanding this contribution may open new avenues to ameliorating cognitive dysfunction and thereby improve outcome in schizophrenia.

Effects of Quetiapine on Sleep in Nonpsychiatric and Psychiatric Conditions

Objective:

To evaluate the use of immediate-release quetiapine for the treatment of insomnia.

Data Sources:

Pre-MEDLINE and MEDLINE were searched (1966 to October 2008) using the terms quetiapine, sleep, insomnia, and antipsychotics.

Study Selection and Data Extraction:

All studies and case reports evaluating insomnia as a primary endpoint were reviewed.

Data Synthesis:

The role of quetiapine for improving sleep in various patient populations is uncertain. Quetiapine has moderately sedative properties, and closes used in treatment of insomnia have ranged from 12.5 to 800 mg. Results of clinical trials and observations in case studies have revealed possible beneficial effects of quetiapine on several subjective and objective sleep parameters. In most studies, significant improvements in sleep were found in areas of total sleep time, sleep efficiency, and subjective sleep scores. However, some of these results may not be clinically significant. Also, quetiapine has been found to have adverse effects such as periodic leg movements, akathisia, and metabolic complications. Additionally, changes in rapid eye movement (REM) and percentage of REM sleep have been noted in different populations and need further study. Despite quetiapine's sedative properties, current data do not appear to support its use as first-line treatment for sleep complications. However, it may be useful for treatment of insomnia in patients with psychiatric disorders (eg, bipolar, schizophrenia) who do not respond to primary or secondary treatments.

Conclusions:

Further studies are needed to define the placement, dose, and adverse effects of quetiapine for the treatment of sleep problems.

Sleep deprivation disrupts prepulse inhibition of the startle reflex: reversal by antipsychotic drugs

Sleep deprivation (SD) is known to induce perceptual impairments, ranging from perceptual distortion to hallucinatory states. Although this phenomenon has been extensively described in the literature, its neurobiological underpinnings remain elusive. In rodents, SD induces a series of behavioural patterns that might be reflective of psychosis and mania, such as hyperlocomotion and sensitization to psychotogenic drugs. Notably, such changes are accompanied by transitory alterations of dopaminergic signalling. Based on the hypothesis that both psychotic and manic disorders reflect gating impairments, the present study was aimed at the assessment of the impact of SD on the behavioural model of prepulse inhibition (PPI) of the startle reflex, a reliable paradigm for the study of informational filtering. Rats subjected to SD (24 h, 48 h, 72 h) exhibited a time-dependent increase in startle reflex and a dramatic deficit in PPI. Both alterations were reversed 24 h after termination of the SD period. Interestingly, PPI disruption was efficiently prevented by haloperidol (0.1 mg/kg i.p.) clozapine (5 mg/kg i.p.) and risperidone (1 mg/kg i.p.). Conversely, neither the anxiolytic diazepam (5 mg/kg i.p.) nor the antidepressant citalopram (5 mg/kg i.p) affected the PPI disruption mediated by SD, although diazepam reversed the enhancement in startle reflex magnitude induced by this manipulation. Our data suggest that SD induces gating deficits that might be relevant to the hallucinatory phenomena observed in humans, and provide a novel reliable animal model where such relationship can be studied.

Sleep disturbances in childhood-onset schizophrenia

Sleep disturbances in psychiatric disease have long been reported. However, research on sleep disturbances in child and adolescent psychiatric disorders is limited. We examined the relationship of sleep disturbance to clinical severity and co-morbid diagnoses (e.g. anxiety), for a population with childhood-onset schizophrenia (COS). Sixty-one COS patients underwent a medication-free inpatient observation period as part of an NIMH study of COS. Sleep quantity during the last 5-7 days of a patient's medication-free period was measured using safety records and daily nursing notes. Subjects were divided into two groups: "good sleepers" (>6 h) and "poor sleepers" (<6 h) based on the average of total hours slept per night. Comparisons between groups were made with respect to clinical ratings at both admission and during washout period, co-morbid diagnosis of generalized anxiety disorder (GAD) and a susceptibility gene (G72) for COS. The median average sleep score for the entire group was 6.1 (S.D.=2.01) h. The good and poor sleep groups differed significantly in terms of severity of positive symptoms (SAPS) and negative symptoms at admission (SANS) both on admission and during the medication-free period. There was no significant relationship between G72 genotypes and a past and/or present diagnosis of GAD. COS patients suffer from significant sleep disturbances and the sleep disturbance is highly related to the symptom severity. As there are numerous health implications of poor sleep, clinicians should have a low threshold for treating sleep disturbances in this population.

Decreased coherence in higher frequency ranges (beta and gamma) between central and frontal EEG in patients with schizophrenia: A preliminary report

Schizophrenia is associated with a dysfunction of cognitive integration that may be due to abnormalities in inhibitory neural circuitry. A previous study found a failure of gamma band (25-45 Hz) synchronization in patients with schizophrenia compared to controls. Another recent study also stressed the importance of investigating high frequencies in the scalp-recorded sleep electroencephalogram (EEG). In this study, we compared coherence between first episode drug-naïve patients with schizophrenia (n=8) and age- and sex-matched normal controls (n=8) using two 32-s epochs of C4 and F4 EEG. The coherence was obtained using 4096 data points (128 Hz signal) using cross-spectral analysis with Blackman-Tukey window in beta (15.25-24.75 Hz) and gamma (25-44.75 Hz) frequency bands. We used wake, non-rapid eye movement (NREM) and rapid eye movement (REM) sleep periods for the analyses. Our results show a significant decrease in coherence in both beta and gamma frequency bands in patients. Post-hoc 't' tests revealed a significantly lower coherence only during the wake stage in patients with schizophrenia in beta as well as gamma frequency bands. These results further support the importance of the analyses of high-frequency bands in the EEG and support previous findings of abnormal neural synchrony in patients with schizophrenia. These results have been discussed further in relation to wake and sleep stages.

Sleep disturbance in schizophrenia

Insomnia is a common symptom in schizophrenia, although it is seldom the predominant complaint. Sleep-onset and maintenance insomnia is a characteristic feature of schizophrenic patients regardless of either their medication status (drug-naive or previously treated) or the phase of the clinical course (acute or chronic). Regarding sleep architecture, the majority of studies indicate that stage 4 sleep and rapid eye movement (REM) latency are reduced in schizophrenia, whereas REM sleep duration tends to remain unchanged. Insomnia in schizophrenic patients could be partly related to the presumed over-activity of the dopaminergic system. However, there is a possibility that the GABAergic system is also involved in sleep disturbance in schizophrenia. Since many signal transmission systems within the CNS can be implicated in the reduction of REM latency in schizophrenia, the characterization of the neurotransmitter systems involved remains a challenging dilemma.

A failure of sleep-dependent procedural learning in chronic, medicated schizophrenia

BACKGROUND

Schizophrenia patients have difficulty mastering even rote procedural tasks in rehabilitation settings. Although most studies demonstrate intact procedural learning in schizophrenia, recent findings demonstrate that a critical component of procedural learning is dependent on sleep. This study tested the hypothesis that patients with schizophrenia have a deficit in sleep-dependent procedural learning.

METHODS

Using a simple, well-characterized test of motor skill learning, the finger tapping motor sequence task (MST), 26 patients with chronic, medicated schizophrenia and 14 demographically matched healthy control subjects were tested on two occasions, 24 hours apart. The main outcome measures were learning of the MST on day 1 (practice-dependent learning) and overnight, sleep-dependent improvement in performance.

RESULTS

Although schizophrenia patients and control subjects did not differ in practice-dependent learning, patients failed to show overnight improvement (4% deterioration) and differed significantly from control subjects who showed a significant 11% improvement.

CONCLUSIONS

We present here the first demonstration of a failure of sleep-dependent consolidation of procedural learning in chronic, medicated schizophrenia. This deficit occurred in the context of normal practice-dependent learning within a training session. This behavioral dissociation is consistent with evidence that practice- and sleep-dependent motor learning reflect independent processes and suggests that they are differentially affected in schizophrenia.

Decreased nonlinear complexity and chaos during sleep in first episode schizophrenia: a preliminary report

Schizophrenia is characterized by disturbed sleep architecture. It has been thought that sleep abnormalities may underlie information processing deficits associated with this disorder. Nonlinear analyses of sleep data can provide valuable information on sleep characteristics that may be relevant to the functions of sleep. This study examined the predictability and nonlinear complexity of sleep EEG time series in two EEG channels (C4 and F4) using measures of nonlinearity, such as symbolic dynamics and the largest Lyapunov exponent (LLE) in schizophrenia. A series of antipsychotic naive patients with first episode of schizophrenia or schizoaffective disorder and age-matched healthy controls were studied during awake period, stage 1/2, slow wave sleep (stage 3/4) and rapid eye movement (REM) sleep. Nonlinearity scores were significantly lower during awake stage in patients compared to controls suggesting that there may be a diminished interplay between various parameters for the genesis of waking EEG. Symbolic dynamics and LLE were significantly lower in patients during REM compared to healthy controls, suggesting decreased nonlinear complexity of the EEG time series and diminished chaos in schizophrenia. Decreased nonlinear complexity was also correlated with neurocognitive deficits as assessed by the Wisconsin card sorting test. Diminished complexity of EEG time series during awake and REM sleep in patients with schizophrenia may underlie the impaired ability to process information in psychotic disorders such as schizophrenia.

Sleep quality in schizophrenia and the effects of atypical antipsychotic medication

BACKGROUND

Sleep disorders are widespread among patients with schizophrenia and contribute to adverse clinical outcomes. Antipsychotic drugs exert varying effects on sleep, and the effects of atypical agents may differ from those of conventional neuroleptics.

OBJECTIVE

To review the literature on the effects of atypical medication on subjective and objective sleep quality in patients with schizophrenia.

METHODS

A non-systematic literature review of Medline was performed in August 2003 searching the period from January 1985 to August 2003 for studies of the effects of atypical antipsychotics on sleep.

RESULTS

We found published studies of clozapine, olanzapine, and risperidone, but none on quetiapine or ziprasidone. Studies with clozapine showed that it increased total sleep time, sleep efficiency, stage-2 non-rapid eye movement sleep and rapid eye movement (REM) sleep density, and decreased stage-4 sleep, slow wave sleep (SWS) and stage-1 sleep. Single-dose studies with olanzapine have shown that it increases SWS, sleep continuity, total sleeping time, subjective sleep quality, and delta sleep. Long-term studies with risperidone have shown improvements in total sleep, sleep efficiency, sleep continuity, SWS, and stage-2 sleep, and reductions in sleep latency, number of awakenings, and proportion of time awake. These benefits were paralleled by improvements in subjective sleep assessment and psychopathology, and psychosocial functioning.

CONCLUSIONS

The evidence presented in this review suggests that atypical antipsychotics exert favorable effects on sleep profile compared with conventional agents, including improvement of subjective sleep quality and modification of specific sleep stages known to be associated with better clinical outcome.

Sleep architecture and its clinical correlates in first episode and neuroleptic-naive patients with schizophrenia

The goal of the present study was to characterize sleep organization in first episode and neuroleptic-naive patients with schizophrenia and to evaluate relationships between those sleep parameters and clinical symptoms. Eleven patients with acute schizophrenia never treated with neuroleptics were compared to 11 healthy controls. Sleep stages and phasic events (sleep spindles and rapid-eye-movements during REM sleep (REMs) were visually identified. Clinical symptoms were assessed using the Brief Psychiatric Rating Scale (BPRS). Compared to controls, patients with schizophrenia had difficulty initiating sleep, decreased stage 4 duration, reduced rapid eye movement (REM) sleep latency, and normal sleep spindles and REMs densities. Positive symptoms correlated negatively with REM sleep latency. The BPRS total score correlated negatively with REM sleep duration and REMs density. The present results indicate that first episode and neuroleptic-naive patients with schizophrenia have difficulties initiating, but not maintaining, sleep. These results also confirm that the duration of stage 4 and REM sleep latency are reduced in first episode and neuroleptic-naive patients with schizophrenia. The fact that measures of REM sleep correlate with clinical scales of schizophrenia suggests that REM sleep physiology shares common substrates with symptoms of this disease.

Anesthesia with ketamine, propofol, and fentanyl decreases the frequency of postoperative psychosis emergence and confusion in schizophrenic patients

STUDY OBJECTIVE

To investigate whether total IV anesthesia with ketamine, propofol, and fentanyl affects the frequency of postoperative psychosis emergence or confusion in schizophrenic patients.

DESIGN

Prospective, controlled study.

SETTING

Hirosaki National Hospital and Hakodate Watanabe Hospital.

PATIENTS

76 ASA physical status I and II schizophrenic patients taking chronic antipsychotic drugs and schedule for orthopedic surgery of extremities.

INTERVENTIONS

In Group A (n = 38) patients, anesthesia was maintained with sevoflurane, nitrous oxide, and fentanyl. In Group B (n = 38) patients, anesthesia was maintained with ketamine, propofol, and fentanyl.

MEASUREMENTS AND MAIN RESULTS

The frequency of psychosis emergence or confusion (54%) in Group A during the first 48 hours after surgery was significantly higher than the 30% figure in Group B.

CONCLUSION

Ketamine, when combined with propofol and fentanyl, is an appropriate anesthetic drug for schizophrenic patients.

Phasic and enduring negative symptoms in schizophrenia: biological markers and relationship to outcome

Negative symptoms have been associated with poor response to neuroleptics, enlarged ventricles, cognitive impairment, and poor outcome in schizophrenia. These associations appear, however, to be dependent on the phase of study, suggesting that acute-phase (phasic) negative symptoms may be pathophysiologically distinct from enduring negative symptoms that persist through the residual phase. To compare correlates of enduring and phasic negative symptoms, we studied 60 drug-free schizophrenic patients (DSM-III-R and SADS/RDC) at baseline, 4 weeks after neuroleptic treatment, and assessed the 1 year outcome. We rated positive and negative symptoms at baseline and 4 weeks after treatment. At baseline, premorbid function, neuropsychological function, ventricle-brain ratio (VBR) and symptom response to an anticholinergic agent were assessed, and a two-night sleep EEG and 1mg dexamethasone suppression test (DST) were conducted. Phasic negative symptoms were defined as the change in negative symptoms (baseline to 4 weeks) and enduring negative symptoms as severity of negative symptoms at 4 weeks. Patients had varying proportions of phasic and enduring symptoms; the two did not define distinct subgroups. Phasic negative symptoms were significantly correlated with global treatment response, positive symptom treatment response, response to anticholinergic agent, baseline post-dexamethasone cortisol, and shortened REM latency. Enduring negative symptoms were significantly correlated with residual positive symptoms and global psychopathology, VBR, poor performance on neuropsychological testing, decreased slow-wave sleep, poor premorbid function, and poor 1 year outcome. These data suggest that phasic negative symptoms and enduring negative symptoms may be caused by different pathophysiological mechanisms.

Slow-wave activity during non-REM sleep in men with schizophrenia and major depressive disorders

Both major depressive disorders (MDD) and schizophrenia (SZ) have been associated with reductions in slow-wave (Stages 3 and 4) sleep, although these findings are controversial. The present study compared quantitative EEG measures of slow-wave activity (0.5-4 Hz) during non-REM (NREM) sleep among age-matched, symptomatic but unmedicated, depressed, schizophrenic and healthy control men (n=13/group). The amplitude of slow-wave activity (SWA) in the first NREM sleep period was significantly lower in both the MDD and SZ groups compared with controls. However, the time course of SWA, its accumulation and dissipation over all NREM sleep time, was abnormal in the MDD group but not in those with SZ. These findings suggest that the regulation of SWA is impaired in men with MDD but not in SZ. Thus, although those with SZ show reduced amplitude SWA in the first NREM period, there is no evidence that homeostatic regulation of SWA is impaired in this psychiatric group.

Can chronic neuroleptic treatment promote sleep disturbances in elderly schizophrenic patients?

It has been proposed that sleep disturbances, especially reduced delta sleep, are related to a poor outcome in schizophrenia. To determine whether long-term treatment with neuroleptics can promote sleep disturbances by increasing the risk of a nocturnal myoclonus syndrome (NMS) (=periodic movements in sleep) related insomnia, we performed all-night polysomnography in 10 chronically ill schizophrenic patients who had been under neuroleptic therapy for a mean of 27 years. NMS-related insomnia was detected in all 10 patients. Potential pathophysiological relationships between long-term neuroleptic therapy and NMS occurrence are discussed. Our findings suggest that long-term administration of neuroleptics favours the appearance of insomnia.

Olanzapine acute administration in schizophrenic patients increases delta sleep and sleep efficiency

BACKGROUND

A delta sleep deficit has been observed in schizophrenic patients. Olanzapine is a novel atypical antipsychotic agent with affinity at dopaminergic, serotonergic, muscarinic, adrenergic and histaminergic binding sites. The present study was designed to analyze a sleep promoting effect reported for olanzapine.

METHODS

Twenty schizophrenic patients (DSM-IV) were studied, who were drug free and inpatients. Patients slept for 5 consecutive nights in the sleep unit as follows: one acclimatization night; two baseline nights (the first for sleep disorder screenings); and two olanzapine nights (10 mg olanzapine, one hour before sleep onset).

RESULTS

Sleep continuity variables and total sleep time showed an overall improvement with olanzapine. Waking time was reduced since the first night of olanzapine administration. The main sleep architecture changes were: reduction in sleep stage 1, while sleep stage 2 and delta were significantly enhanced. Rapid eye movement density was also increased by the second olanzapine night.

CONCLUSIONS

Total sleep improvement was due to the increase in sleep stages 2 and delta sleep. This may be related to serotonergic antagonistic properties of olanzapine. Olanzapine seems to have a sleep promoting effect in schizophrenic patients.

REM sleep disinhibition at sleep onset: a comparison between narcolepsy and depression

Shortened REM latency and increased REM density are frequently observed in both narcolepsy and depression, suggesting a common mechanism of REM sleep disinhibition in these disorders. We compared night sleep recordings of 24 depressive and 24 narcoleptic patients. The amount of REM sleep and REM density did not differ between the patient groups; however, REM latency distributions differed significantly. Whereas in narcoleptic patients REM episodes started either immediately at sleep onset or following at least 60 min of non-REM sleep, in depressives two thirds of REM latencies were in the range from 1 to 60 min. In narcoleptic patients, short as compared to long REM latencies were associated with longer total sleep time, greater sleep efficiency, reduced amounts of wakefulness, and increased amounts of slow-wave sleep. In depressive subjects the reverse pattern was seen. We conclude that a common mechanism of REM sleep disinhibition in narcolepsy and depression is very unlikely.

Plasma interleukin-1 beta and sleep architecture in schizophrenia and other nonaffective psychoses

OBJECTIVE

It has been reported that sleep deprivation may enhance interleukin (IL)-1 beta production of healthy subjects. Furthermore, patients with acute psychoses have been reported to exhibit higher levels of IL-1 beta than healthy controls. The present study examined polysomnographic sleep and morning IL-1 beta plasma values in 20 drug-free patients with acute nonaffective psychoses.

METHODS

Ten patients with DSM-III diagnosis of schizophrenia, five with delusional disorder, and five with atypical psychosis underwent polysomnographic sleep registrations and their morning blood levels of IL-1 beta were measured.

RESULTS

IL-1 beta values correlated negatively with the length of the sleep period (p = 0.010) and the relative time of rapid eye movement (REM) sleep (p = 0.038), and positively with REM latency (p = 0.043).

CONCLUSIONS

It is concluded that reduced sleep, possibly especially reduced REM sleep, may be a reason for increased morning IL-1 beta values in these patients. Additional studies on IL-1 beta in psychiatric patients should consider the possibility of sleep disturbances as a possible explanation for deviations in IL-1 beta levels.

Sleep in psychiatric disorders

Psychiatric disorders are some of the most common causes of sleep-related complaints, particularly insomnia. Sleep abnormalities may be caused by CNS abnormalities associated with psychiatric illnesses as well as by accompanying behavioral disturbances. Although sleep patterns are not necessarily diagnostic of particular psychiatric disorders, there are relationships between certain sleep abnormalities and categories of psychiatric disorders. Sleep disturbances associated with psychiatric disorders and general approaches to treatment are reviewed.

Biological predictors of 1-year outcome in schizophrenia in males and females

This paper describes a prospective study designed to ascertain the predictive value of biological factors associated with schizophrenia in males and females. In a sample of 59 medication-free schizophrenic inpatients (41 males; 18 females), we assessed the correlation of four factors--rapid eye movement (REM) sleep latency, delta (slow-wave) sleep, dexamethasone suppression test (DST) cortisol levels, and ventricle-brain ratio (VBR)--with several dimensions of outcome at 1-year post-discharge. In the total sample, shorter REM latency was associated with poor outcome on all dimensions measured: rehospitalization, employment, social activity, symptomatology, and global functioning. However, none of the other biological factors were associated with any measure of outcome. The predictive value of REM latency appeared to be gender-specific; in general, the relationships between reduced REM latency and poor outcome were consistently noted in females, but were not significant in males. These results suggest that a common, possibly gender-related, pathophysiological mechanism might underlie both abnormal REM latency and poor outcome. The findings underscore the importance of considering gender differences in studies of schizophrenia.

A longitudinal study of EEG sleep in schizophrenia

Several abnormalities in sleep architecture have been described in schizophrenia. However, the question of whether sleep electroencephalographic (EEG) changes are influenced by treatment and phase of illness remains unclear. To examine the longitudinal stability of sleep data, we compared baseline sleep measures with measures obtained approximately 4 weeks and 1 year after the beginning of treatment in a series of schizophrenic patients. At the 4-week assessment, sleep continuity measures improved significantly; a modest increase in rapid eye movement (REM) latency was seen, but no other changes were found in sleep architecture. At the 1-year assessment, REM latency, REM time, and average automated REM counts increased. No significant changes were seen for slow-wave sleep (SWS) parameters at 1-year follow-up. These findings suggest that SWS parameters are relatively stable during follow-up, while REM parameters seem to change, perhaps in relation to phase of illness and treatment. SWS alterations may, at least in part, reflect more invariant, perhaps trait-related alterations in schizophrenia.

Sequential analysis of the brain's transfer properties during consecutive REM episodes

Classical analysis of the spontaneous sleep EEG has revealed alterations of REM sleep in psychiatric diseases and under the influence of drugs. In order to elucidate possible functional differences between different REM episodes even in healthy subjects we investigated in 10 volunteers the transfer properties of the brain by measuring auditory (AEP) and visual evoked potentials (VEP) from scalp positions Fz, Cz and Pz during the night. According to linear system theory we computed the so-called amplitude-frequency characteristics (AFC) from averaged AEPs and VEPs during the first and each of the following 3 REM episodes. These functions describe the relationship between the input and output of the investigated system. A 3-factorial analysis of variances with the independent factors frequency band, REM episode and electrode position revealed a statistically significant main effect for the factor REM episode under auditory stimulation (P = 0.05), whereas no significant main effect for REM episode was found under visual stimulation (P = 0.88). Applying a 2-factorial analysis of variance with the independent factors REM episode and electrode position in the case of auditory stimulation we could demonstrate a statistically significant main effect (P = 0.029) for the factor REM episode in the beta range (12.5-20 Hz). A subsequent analysis of contrasts revealed that the first REM episodes could be differentiated from each other. For auditory stimulation the beta resonance during the first REM episode appears enhanced compared to each of the later REM episodes. These findings point to a functional difference of the brain's transfer functions between the first and the 3 following REM episodes, indicating different information processing during consecutive paradoxical sleep.

Biological correlates of slow wave sleep deficits in functional psychoses: 31P-magnetic resonance spectroscopy

Deficits in slow wave sleep (SWS) are consistently seen in schizophrenia and related psychotic disorders. However, the pathophysiological significance of this finding is uncertain. In 19 patients with psychotic illness, sleep and 31P-magnetic resonance spectroscopy (MRS) studies were carried out before the patients began medication treatment. Polysomnographic studies were carried out in 2-3 consecutive nights. MRS studies were performed with a surface coil and a depth-resolved pulse sequence focusing on the dorsal prefrontal cortex. Phosphomonoesters were correlated with visually scored delta and Stage 4 sleep, as well as with automated delta wave counts. An inverse relation was also seen between negative symptoms scores and SWS. The association between decreases brain anabolic processes (reflected by decreased PME) and decreased SWS may be related either to processes of accelerated aging or to developmentally mediated alterations in cortical synaptic pruning, postulated to underlie the pathophysiology of functional psychoses.

Slow-wave sleep and symptomatology in schizophrenia and related psychotic disorders

Deficits in slow-wave sleep (SWS), or delta sleep, are frequently seen in schizophrenia, but their relationship with schizophrenic symptomatology remains unclear. We examined the association between visually scored and automated measures of SWS and positive and negative symptoms in a series of unmedicated patients with schizophrenia and related psychotic disorders. Total and average automated delta wave counts were significantly inversely associated with negative symptoms overall, and the psychomotor poverty syndrome in particular. Total delta counts were also inversely related to the disorganization syndrome. No relation was seen between reality distortion or the Brief Psychiatric Rating Scale (BPRS) positive symptoms and SWS. These findings support the view that SWS deficits may be related to negative symptoms of schizophrenia and may perhaps be mediated by impaired functioning of frontothalamic neural circuits.

Slow-wave sleep deficits and outcome in schizophrenia and schizoaffective disorder

Schizophrenia is associated with altered sleep architecture, particularly in regard to delta sleep. We examined the relation between the baseline polysomnographic measures in schizophrenic and schizoaffective patients and psychosocial outcome as measured by the Strauss & Carpenter scale at 1 (n = 20) and 2 (n = 7) years. The percentages of delta sleep at baseline were significantly correlated with total outcome scores at 1 and at 2 years. These preliminary findings suggest that delta sleep deficits may be associated with relatively poor outcome in this disorder.

A quantitative sleep-EEG study on the effects of benzodiazepine and zopiclone in schizophrenic patients

Polysomnographic examinations (PSG) were performed on 6 male schizophrenic outpatients who were being treated with benzodiazepine (BZD) hypnotics in combination with neuroleptics and 6 healthy male volunteers. In schizophrenic subjects, zopiclone (ZPC), 15 mg/day, was substituted for the BZD hypnotics, and PSGs were recorded again during ZPC therapy. All-night sleep stage scoring was carried out by visual analysis, and computerized period-amplitude analysis of sleep EEG was also performed. The schizophrenics showed marked reduction in the amount of slow-wave sleep (SWS) and in the number of delta half-waves during all-night sleep, especially those with higher amplitude, as compared to the normals. The number of delta half-waves in the patients was markedly reduced during the first sleep cycle. The average amplitude of delta half-waves during all-night sleep in the schizophrenics was significantly lower than that in the normals. The half-wave count of total delta waves in the schizophrenics was higher during treatment with ZPC than with BZDs, although no significant differences were observed in the amount of SWS between the two treatments. Soundness of sleep in the subjective sleep assessment was better evaluated during treatment with ZPC than BZDs. These results suggest that reduction of SWS in schizophrenia may be attributable mainly to the decrease in the number of delta waves with higher amplitude and that ZPC may induce deeper sleep in schizophrenics than BZDs.