Sleep polygraphy in schizophrenia: methodological issues

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.

Sleep EEG and spindle characteristics after combination treatment with clozapine in drug-resistant schizophrenia: a pilot study

PURPOSE

Clozapine is an atypical neuroleptic agent, effective in treating drug-resistant schizophrenia. The aim of this work was to investigate overall sleep architecture and sleep spindle morphology characteristics, before and after combination treatment with clozapine, in patients with drug-resistant schizophrenia who underwent polysomnography.

METHODS

Standard polysomnographic techniques were used. To quantify the sleep spindle morphology, a modeling technique was used that quantifies time-varying patterns in both the spindle envelope and the intraspindle frequency.

RESULTS

After combination treatment with clozapine, the patients showed clinical improvement. In addition, their overall sleep architecture and, more importantly, parameters that quantify the time-varying sleep spindle morphology were affected. Specifically, the results showed increased stage 2 sleep, reduced slow-wave sleep, increased rapid eye movement sleep, increased total sleep time, decreased wake time after sleep onset, as well as effects on spindle amplitude and intraspindle frequency parameters. However, the above changes in overall sleep architecture were statistically nonsignificant trends.

CONCLUSIONS

The findings concerning statistically significant effects on spindle amplitude and intraspindle frequency parameters may imply changes in cortical sleep EEG generation mechanisms, as well as changes in thalamic pacing mechanisms or in thalamo-cortical network dynamics involved in sleep EEG generation, as a result of combination treatment with clozapine.

SIGNIFICANCE

Sleep spindle parameters may serve as metrics for the eventual development of effective EEG biomarkers to investigate treatment effects and pathophysiological mechanisms in schizophrenia.

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.

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.

Slow wave sleep deficits as a trait marker in patients with schizophrenia

BACKGROUND

Among the sleep abnormalities found in schizophrenia, slow wave sleep deficits have been found to persist even after the resolution of active psychotic symptoms. Further, such abnormalities are observed in young healthy individuals at high risk of schizophrenia, which suggest that slow wave sleep deficits might be trait marker in schizophrenia.

METHODS

Sleep EEG was recorded in 20 right handed patients aged 18-45 years with ICD-10 DCR diagnosis of schizophrenia, 14 first degree relatives and 20 age and sex matched controls. Patients were rated on Positive and Negative Syndrome Scale (PANSS) and Brief Psychiatric Rating Scale (BPRS) for assessment of psychopathology.

RESULTS

There was significant difference between the three groups in total sleep period (p<.01), total sleep time (p<.01), stage shifts (p<.05), stage 1 percentage of total sleep time (p<.05), stage 2 duration (p<.05), stage 3 latency (p<.05), stage 4 duration (p<.01) and stage 4 percentage of total sleep time (p<.01). There was significant positive correlation of REM percentage of total sleep time with BPRS total score (r(s) = .488, p = .029) and PANSS positive score (r(s) = .583, p = .007), whereas significant negative correlation of REM latency was found with BPRS total score (r(s) = -.640, p = .002) and PANSS positive score (r(s) = -.657, p = .002) in the patients.

CONCLUSIONS

Slow wave sleep deficits are a possible trait marker in patients with schizophrenia, which needs replication in further studies.

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 onset REM periods in obsessive compulsive disorder

Sleep studies in patients with obsessive compulsive disorder (OCD) are sparse and results inconsistent. Moreover, in 3 out of 4 published studies up to 50% of patients suffered from secondary major depression. In this study, 10 inpatients with a DSM-IV diagnosis of OCD without comorbid major depression (Yale-Brown Obsessive Compulsive Scale (Y-BOCS) score >15; Hamilton Depression Rating Scale (HAMD)-21 total score <17) and 10 healthy matched controls were included. Polysomnography of patients (7 males, 3 females, 34.5+/-12.7 years, Y-BOCS: 27.8+/-4.6, HAMD-21: 13.3+/-1.9) and controls (7 males, 3 females, 34.4+/-12.8 years) was recorded, following an adaptation night. Sleep variables did not significantly differ in both groups except that stage 4 sleep was reduced in patients. Three of the patients with OCD, however, exhibited sleep onset REM periods (SOREMPs), i.e. rapid-eye-movement (REM) latencies <10 min. Obsessive compulsive symptoms were significantly (P<0.05) more severe in these patients (Y-BOCS: 32+/-2.0) compared to those without SOREMPs (Y-BOCS 26+/-4.2). This is, to our knowledge, the first report of sleep onset REM periods in OCD.

Sleep and EEG profile in neonatal hippocampal lesion model of schizophrenia

Sleep architecture, EEG power pattern and locomotor activity were investigated in a putative animal model of schizophrenia. The model was prepared by excitotoxic damage of the ventral hippocampus on postnatal day 7 (PD 7), after which locomotor activity and electroencephalographic (EEG) sleep profile were compared between lesioned and sham operated animals respectively, at prepuberty (postnatal day PD 35) and postpuberty (PD 56). An enhancement of locomotor activity was observed in lesioned adult PD 56, but not in juvenile PD 35 rats. Spontaneous EEG/EMG recordings during 24 h showed no major differences between both groups at PD 35 and at PD 56. However, quantitative analysis of the EEG revealed an enhancement of power in delta (delta), theta (theta) and alpha (alpha) activities in lesioned animals at PD 35 during wakefulness in both light and dark phases. At PD 56, the power in the delta and theta bands was increased during the light and dark periods in both wakefulness and non-REM sleep. These findings suggest that ventral hippocampus lesion is not associated with disturbance of sleep architecture in rats, while consistent changes were observed in the dynamic of EEG slow wave frequency domain. Thus, the data indicate that neonatal lesion of ventral hippocampus did not mimic sleep abnormalities observed in schizophrenia, however this rodent model may model some EEG features seen in schizophrenia such as a frontally pronounced slowing of the slow EEG activity in delta and theta frequency bands.

Sleep in schizophrenia: impairments, correlates, and treatment

In untreated schizophrenia, psychotic decompensation is associated with profound insomnia, one of the prodromal symptoms associated with psychotic relapse. First- and second-generation antipsychotic medication can ameliorate this insomnia, but side effects may include sedation or residual insomnia. Patients who are clinically stable and medicated may continue to experience disturbed sleep, including long sleep-onset latencies, poor sleep efficiency, slow wave sleep deficits, and short rapid eye movement latencies. Schizophrenia also can be associated with comorbid sleep disorders, which may be enhanced or induced by antipsychotic medication. Sleep disorders in schizophrenia should be treated vigorously because normalized sleep and its restorative processes may be essential for a positive clinical outcome.

Sleep in schizophrenia patients and the effects of antipsychotic drugs

Insomnia is a common feature in schizophrenia. However, it seldom is the predominant complaint. Nevertheless, severe insomnia is often seen during exacerbations of schizophrenia, and may actually precede the appearance of other symptoms of relapse. The sleep disturbances of either never-medicated or previously treated schizophrenia patients are characterized by a sleep-onset and maintenance insomnia. In addition, stage 4 sleep, slow wave sleep (stages 3 and 4), non-REM (NREM) sleep in minutes and REM latency are decreased. The atypical antipsychotics olanzapine, risperidone, and clozapine significantly increase total sleep time and stage 2 sleep. Moreover, olanzapine and risperidone enhance slow wave sleep. On the other hand, the typical antipsychotics haloperidol, thiothixene, and flupentixol significantly reduce stage 2 sleep latency and increase sleep efficiency. Future research should address: (1) the sleep patterns in subtypes of schizophrenia patients; (2) the role of neurotransmitters other than dopamine in the disruption of sleep in schizophrenia; (3) the functional alterations in CNS areas related to the pathophysiology of schizophrenia during NREM sleep and REM sleep (brain imaging studies); (4) the short-term, intermediate-term, and long-term effects of atypical antisychotics on sleep variables.

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.

Sensory gating impairment associated with schizophrenia persists into REM sleep

Physiological measures of sensory gating are increasingly used to study biological factors associated with attentional dysfunction in psychiatric and neurologic patient populations. The present study was designed to assess sensory gating during rapid eye movement (REM) sleep in patients with schizophrenia, a population bearing a genetic load for gating impairment. Auditory event-related potentials (ERPs) were recorded in response to paired clicks during separate waking and overnight sleep recording sessions in controls and schizophrenia patients. Suppression of ERP component P50 was significantly impaired in the patient group during both waking and REM sleep, whereas the difference between groups for N100 gating was dependent on state. These results suggest that REM sleep is an appropriate state during which to assess P50 gating in order to disentangle the effects of state and trait on sensory gating impairment in other clinical populations.

Sleep and depression--results from psychobiological studies: an overview

Disturbances of sleep are typical for most depressed patients and belong to the core symptoms of the disorder. Polysomnographic sleep research has demonstrated that besides disturbances of sleep continuity, in depression sleep is characterized by a reduction of slow wave sleep and a disinhibition of REM sleep, with a shortening of REM latency, a prolongation of the first REM period and increased REM density. These findings have stimulated many sleep studies in depressive patients and patients with other psychiatric disorders. In the meantime, several theoretical models, originating from basic research, have been developed to explain sleep abnormalities of depression, like the two-process-model of sleep and sleep regulation, the GRF/CRF imbalance model and the reciprocal interaction model of non-REM and REM sleep regulation. Interestingly, most of the effective antidepressant agents suppress REM sleep. Furthermore, manipulations of the sleep-wake cycle, like sleep deprivation or a phase advance of the sleep period, alleviate depressive symptoms. These data indicate a strong bi-directional relationship between sleep, sleep alterations and depression.

BPRS symptom factors and sleep variables in schizophrenia

To examine the relationship of clinical symptoms to sleep architecture, polysomnography and clinical ratings were carried out in 20 male psychiatric in-patients who met Research Diagnostic Criteria for schizophrenia. Clinical symptoms were assessed by the Brief Psychiatric Rating Scale (BPRS). Four BPRS sub-factors, i.e., 'Thinking Disturbance', 'Withdrawal/Retardation', 'Hostility/Suspiciousness', and 'Anxiety/Depression' were correlated with five components of sleep architecture, namely, sleep onset latency, total sleep time, total slow wave sleep minutes (the summation of visually scored stages 3 and 4), total REM minutes, and REM latency. Partial correlations were computed to control for the effects of age. Of the 20 correlation coefficients computed, only one was statistically significant after Bonferroni correction, namely, sleep onset latency was positively correlated with the 'Thinking Disturbance' factor. This finding is consistent with studies showing that psychotic exacerbation is associated with reduced sleep efficiency. In contrast to this cross-sectional design, longitudinal studies are more likely to clarify the relationship of sleep architecture to changes in clinical state.

Cholinergic REM induction test: muscarinic supersensitivity underlies polysomnographic findings in both depression and schizophrenia

Disinhibition of rapid eye movement (REM) sleep (e.g. shortening of REM latency, heightened REM density) is frequently encountered in patients with a major depressive disorder (MDD). Administration of cholinomimetics prior to or during sleep leads to a more pronounced advance of REM sleep in depressed patients compared to healthy controls and patients with other psychiatric disorders. The present study tested whether the cholinergic REM induction test (CRIT) with 1.5 mg RS 86 (an orally acting muscarinic agonist) differentiates patients with MDD (n = 40) from those with schizophrenia (n = 43) and healthy controls (n = 36). The most pronounced shortening of REM latency after cholinergic stimulation occurred in patients with MDD. However, a significant number of patients with schizophrenia also displayed short REM latencies (REM latency < 25 minutes) under placebo conditions and after cholinergic stimulation. REM density measures more clearly differentiated patients with MDD from those with schizophrenia. It is concluded that a subgroup of patients suffering from schizophrenia displays signs of a muscarinic receptor supersensitivity.

Symposium: Normal and abnormal REM sleep regulation: REM sleep in depression-an overview

Abnormalities of REM sleep, i.e. shortening of REM latency, lengthening of the duration of the first REM period and heightening of REM density, which are frequently observed in patients with a major depressive disorder (MDD), have attracted considerable interest. Initial hopes that these aberrant patterns of sleep constitute specific markers for the primary/endogenous sub-type of depression have not been fulfilled. The specificity of REM sleep disinhibition for depression in comparison with other psychopathological groups is challenged as well. Demographic variables like age and sex exert strong influences on sleep physiology and must be controlled when searching for specific markers of depressed sleep. It is still an open question whether abnormalities of sleep are state- or trait-markers of depression. Beyond baseline studies, the cholinergic REM induction test (CRIT) indicated a heightened responsitivity of the REM sleep system to cholinergic challenge in depression compared with healthy controls and other psychopathological groups, with the exception of schizophrenia. A special role for REM sleep in depression is supported by the well-known REM sleep suppressing effect of most antidepressants. The antidepressant effect of selective REM deprivation by awakenings stresses the importance of mechanisms involved in REM sleep regulation for the understanding of the pathophysiology of depressive disorders. The positive effect of total sleep deprivation on depressive mood which can be reversed by daytime naps, furthermore emphasizes relationships between sleep and depression. Experimental evidence as described above instigated several theories like the REM deprivation hypothesis, the 2-process model and the reciprocal interaction model of nonREM-REM sleep regulation to explain the deviant sleep pattern of depression. The different models will be discussed with reference to empirical data gathered in the field.

Electroencephalographic sleep in clinically stable schizophrenic patients: two-weeks versus six-weeks neuroleptic-free

EEG sleep studies in schizophrenic patients are influenced by alterations in clinical state and medication status. The current study defines longitudinal alterations in electroencephalographic (EEG) sleep for 10 healthy men who were schizophrenic patients who remained relatively clinically stable during a double-blind neuroleptic withdrawal study. Clinical assessments and EEG sleep studies were performed at baseline on haloperidol, and then at 2-week and 6-week drug-free periods. Sleep continuity and rapid eye movement (REM) sleep measures declined not only between the haloperidol baseline and 2-week drug-free conditions, but continued to decline from 2-week to 6-weeks neuroleptic-free. Alterations in EEG sleep from the 2-week to 6-week haloperidol-free assessments did not correlate with changes in clinical symptoms suggesting effects related to drug-withdrawal or subclinical state changes. These results show that despite relative clinical stability over time, the EEG sleep of schizophrenic patients continues to change following withdrawal of a neuroleptic and is dependent on the duration of the drug-free interval.

Human sleep, sleep loss and behaviour. Implications for the prefrontal cortex and psychiatric disorder

The prefrontal cortex (PFC) consists of the cortex lying in front of the primary and secondary motor cortex, and includes the dorsolateral and orbital areas, frontal eye fields, and Broca's area. Not all of the functions of the PFC are known, but key ones are the maintenance of wakefulness and non-specific arousal, and the recruiting of various cortical areas required to deal with tasks in hand (Luria, 1973; Stuss & Benson, 1986; Fuster, 1989). Other roles include (Kolb & Whishaw, 1985) planning, sensory comparisons, discrimination, decisions for action, direction and maintenance of attention at a specific task, execution of associated scanning eye movements, and initiation and production of novel goal-directed behaviour (especially with speech). Of the senses, vision makes a particular demand of the PFC, and this is reflected by the frontal eye fields.

Human slow wave sleep: a review and appraisal of recent findings, with implications for sleep functions, and psychiatric illness

Recent findings concerning human slow wave sleep (hSWS-stages 3 + 4; delta EEG activity) are critically reviewed. Areas covered include the significance of the first hSWS cycle; hSWS in extended sleep; relationship between hSWS, prior wakefulness and sleep loss; hSWS influence on sleep length; problems with hSWS deprivation; influence of the circadian rhythm; individual differences in hSWS, especially, age, gender and constitutional variables such as physical fitness and body composition. Transient increases in hSWS can be produced by increasing both the quality and quantity of prior wakefulness, with an underlying mechanism perhaps relating to the waking level of brain metabolism. Whilst there may also be thermoregulatory influences on hSWS, hypotheses that energy conservation and brain cooling are major roles for hSWS are debatable. hSWS seems to offer some form of cerebral recovery, with the prefrontal cortex being particularly implicated. The hSWS characteristics of certain forms of major psychiatric disorders may well endorse this prefrontal link.