Sleep disturbances and cognitive impairment in schizophrenia spectrum disorders: a systematic review and narrative synthesis

Conceptualization and characterization of "primary" and "secondary" cognitive impairment in schizophrenia

Cognitive impairment represents one of the core features of schizophrenia, involves both neurocognition and social cognition domains, and has a significant negative impact on real-world functioning. The present review provides a framework for the conceptualization and characterization of "primary" and "secondary" cognitive impairment in schizophrenia. In this conceptualization, primary cognitive impairment can be defined as a consequence of the neurobiological alterations that underlie psychopathological manifestations of the disorder, while secondary cognitive impairment can be defined as the results of a source issue that has a negative impact on cognitive performance. Sources of secondary cognitive impairment are frequent in people with schizophrenia and include several different factors, such as positive and negative symptoms, depressive symptoms, autistic symptoms, pharmacotherapy, substance abuse, metabolic syndrome, social deprivation, and sleep disorders. It can be hypothesized that secondary cognitive impairment may be improved by effectively resolving the source issue, while primary cognitive impairment may benefit from dedicated treatment. Further research is required to confirm this hypothesis, to better characterize the distinction between primary and secondary cognitive impairment in a clinical and in a neurobiological perspective, and to evaluate the impact of systematically assessing and treating secondary cognitive impairment.

Study Protocol: Global Research Initiative on the Neurophysiology of Schizophrenia (GRINS) project

BACKGROUND

Objective and quantifiable markers are crucial for developing novel therapeutics for mental disorders by 1) stratifying clinically similar patients with different underlying neurobiological deficits and 2) objectively tracking disease trajectory and treatment response. Schizophrenia is often confounded with other psychiatric disorders, especially bipolar disorder, if based on cross-sectional symptoms. Awake and sleep EEG have shown promise in identifying neurophysiological differences as biomarkers for schizophrenia. However, most previous studies, while useful, were conducted in European and American populations, had small sample sizes, and utilized varying analytic methods, limiting comprehensive analyses or generalizability to diverse human populations. Furthermore, the extent to which wake and sleep neurophysiology metrics correlate with each other and with symptom severity or cognitive impairment remains unresolved. Moreover, how these neurophysiological markers compare across psychiatric conditions is not well characterized. The utility of biomarkers in clinical trials and practice would be significantly advanced by well-powered transdiagnostic studies. The Global Research Initiative on the Neurophysiology of Schizophrenia (GRINS) project aims to address these questions through a large, multi-center cohort study involving East Asian populations. To promote transparency and reproducibility, we describe the protocol for the GRINS project.

METHODS

The research procedure consists of an initial screening interview followed by three subsequent sessions: an introductory interview, an evaluation visit, and an overnight neurophysiological recording session. Data from multiple domains, including demographic and clinical characteristics, behavioral performance (cognitive tasks, motor sequence tasks), and neurophysiological metrics (both awake and sleep electroencephalography), are collected by research groups specialized in each domain.

CONCLUSION

Pilot results from the GRINS project demonstrate the feasibility of this study protocol and highlight the importance of such research, as well as its potential to study a broader range of patients with psychiatric conditions. Through GRINS, we are generating a valuable dataset across multiple domains to identify neurophysiological markers of schizophrenia individually and in combination. By applying this protocol to related mental disorders often confounded with each other, we can gather information that offers insight into the neurophysiological characteristics and underlying mechanisms of these severe conditions, informing objective diagnosis, stratification for clinical research, and ultimately, the development of better-targeted treatment matching in the clinic.

The effect of education regarding treatment guidelines for schizophrenia and major depressive disorders on psychiatrists' hypnotic medication prescribing behavior: a multicenter study

BACKGROUND

To examine whether the "Effectiveness of Guideline for Dissemination and Education in psychiatric treatment (EGIUDE)" project affects the rate of prescriptions of hypnotic medication and the type of hypnotic medications prescribed among psychiatrists, for schizophrenia and major depressive disorder in Japan.

METHODS

The EGUIDE project is a nationwide prospective study of evidence-based clinical guidelines for schizophrenia and major depressive disorder in Japan. From 2016 to 2021, clinical and prescribing data from patients discharged from hospitals participating in the EGUIDE project were used to examine hypnotic medication prescriptions The prescribing rate of hypnotics and the prescribing rate of each type of hypnotic (benzodiazepine receptor agonist, nonbenzodiazepine receptor agonist, melatonin receptor agonist, and orexin receptor antagonist) were compared among patients who had been prescribed medication by psychiatrists participating in the EGUIDE project and patients who had been prescribed medication by nonparticipating psychiatrists. Multivariate logistic regression analysis was performed to examine the effect of the EGUIDE project on the prescription of hypnotic medications.

RESULTS

A total of 12,161 patients with schizophrenia and 6,167 patients with major depressive disorder were included. Psychiatrists participating in the EGUIDE project significantly reduced the rate of prescribing hypnotic medication and benzodiazepine receptor agonists for both schizophrenia (P < 0.001) and major depressive disorder (P < 0.001) patients.

CONCLUSION

This is the first study to investigate the educational effects of guidelines for the treatment of psychiatric disorders on psychiatrists in terms of prescribing hypnotic medications to patients. The EGUIDE project may play an important role in reducing hypnotic medication prescription rates, particularly with respect to benzodiazepine receptor agonists. The results suggest that the EGUIDE project may result in improved therapeutic behavior.

Effects of cognitive training and behavior modification on aggressive behavior and sleep quality in schizophrenia

Background

Schizophrenia (SCZ) is linked to a heightened risk of impulsive aggression and disturbances in sleep patterns. Cognitive and social cognitive impairments have been connected to aggression, with social cognitive deficits appearing to play a more immediate role. In this investigation, we conducted a retrospective analysis of the impact of cognitive training and sleep interventions on aggressive behavior and the quality of sleep among individuals with SCZ who were hospitalized.

Methods

This study divided 80 hospitalized patients into two groups according to medical advice, namely the normal group and the study group. The control group received routine drug treatment and education; The research group implemented cognitive training and sleep intervention based on the normal group. Collect basic clinical data, aggressive behavior indicators, and sleep quality indicators.

Results

There is no difference in the basic information statistics between the two groups. Both groups can reduce aggressive behavior and improve sleep quality. In the study group, there was a notable decrease in aggressive behavior compared to the control group. Furthermore, the sleep quality in the study group exhibited significant improvement when compared to the control group.

Conclusion

Cognitive training and sleep intervention have been proven to be effective nonpharmacological treatments, effectively reducing aggressive behavior and improving sleep quality.

Influence of White Sound on Sleep Quality, Anxiety, and Depression in Patients with Schizophrenia

BACKGROUND

Patients with schizophrenia frequently experience issues such as poor sleep quality, anxiety, and depression. White sound has been identified as a potential therapeutic strategy to enhance sleep quality and alleviate negative emotions. This study aimed to investigate the effectiveness of white sound in improving sleep quality, anxiety, and depression among patients with schizophrenia.

MATERIALS AND METHODS

This retrospective analysis included clinical data from 212 patients with schizophrenia divided into two groups based on their treatment approach. Group C (control, without white sound, n = 106) received standard pharmacological treatments, while group W (white sound, n = 106) was exposed to white sound (40-50 dB) for 2 hours nightly at 9:00 pm. All patients were assessed using the Pittsburgh Sleep Quality Index (PSQI), Hamilton Depression Scale (HAMD), Hamilton Anxiety Scale (HAMA), and Positive and Negative Syndrome Scale (PANSS) before and after 12 weeks of intervention.

RESULTS

After 12 weeks, group W showed significant improvements in sleep latency, sleep efficiency, and overall PSQI scores compared to group C (P < 0.05). Furthermore, the HAMD and HAMA scores were significantly lower in group W (P < 0.05), indicating reduced levels of anxiety and depression. The negative symptoms score was significantly lower in group W (P < 0.05) after treatment.

CONCLUSION

White sound shows promise in improving sleep quality, and alleviating anxiety and depression in patients with schizophrenia.

Schizophrenia and disruption of circadian rhythms: An overview of genetic, metabolic and clinical signs

A molecular clock in the suprachiasmatic nucleus of the anterior hypothalamus, which is entrained by the dark-light cycle and controls the sleep-wake cycle, regulates circadian rhythms. The risk of developing mental disorders, such as schizophrenia, has long been linked to sleep abnormalities. Additionally, a common aspect of mental disorders is sleep disturbance, which has a direct impact on the intensity of the symptoms and the quality of life of the patient. This relationship can be explained by gene alterations such as CLOCK in schizophrenia which are also important components of the physiological circadian rhythm. The function of dopamine and adenosine in circadian rhythm should also be noted, as these hypotheses are considered to be the most popular theories explaining schizophrenia pathogenesis. Therefore, determining the presence of a causal link between the two can be key to identifying new potential targets in schizophrenia therapy, which can open new avenues for clinical research as well as psychiatric care. We review circadian disruption in schizophrenia at the genetic, metabolic, and clinical levels. We summarize data about clock and clock-controlled genes' alterations, neurotransmitter systems' impairments, and association with chronotype in schizophrenia patients. Our findings demonstrate that in schizophrenia either homeostatic or circadian processes of sleep regulation are disturbed. Also, we found an insufficient number of studies aimed at studying the relationship between known biological phenomena of circadian disorders and clinical signs of schizophrenia.

Positive airway pressure adherence among patients with obstructive sleep apnea and cognitive impairment: A narrative review

Adults with Mild Cognitive Impairment (MCI) and Alzheimer's disease (AD) have increased rates of Obstructive Sleep Apnea (OSA). Positive Airway Pressure (PAP) is the first-line treatment for OSA and may have potential benefits for slowing cognitive decline in these individuals. However, adherence is low in PAP users overall and those with cognitive impairment may have unique challenges. Furthermore, there has been little systematic study of the use of PAP or strategies to enhance PAP adherence among those with AD or MCI. The aim of this review is to examine existing observational, quasi-experimental and experimental studies of the effects of PAP on cognitive function. In addition, our goal was to gather evidence about the adherence rates, and support for PAP among adults with MCI and mild to moderate AD. Through searches of electronic databases (University of Utah Library, SAGE Publishing, PubMed, Wiley, EBSCO, Science Direct, ProQuest, and NCBI), we identified 11 articles that fit our study inclusion criteria. Synthesis of data was performed with a focus on cognitive outcomes of PAP interventions and adherence. Findings from the studies showed that multiple indices of memory improved with PAP use. Adherence in MCI and AD populations was largely comparable to adherence reported in general adult populations, but more research is needed to optimize systems for providing support for PAP users and caregivers. Results support PAP as a promising intervention in this population but more research is needed to make definitive conclusions about the relationship between PAP use and improved cognitive function. Furthermore, research is needed to determine if additional interventions are needed to support patients and caregivers.

Sleep-dependent memory consolidation in schizophrenia: A systematic review and meta-analysis

Sleep disturbances and cognitive impairment are both persistent and common features of schizophrenia. Accumulating evidence indicates that sleep-dependent memory consolidation might be impaired in patients with schizophrenia compared to healthy controls. The current systematic review was performed in accordance with PRISMA guidelines. A random-effects model was used to calculate effect sizes (Hedge's g). In the quantitative review, three separate meta-analyses were conducted for procedural memory in healthy controls, schizophrenia, and comparison between healthy controls and schizophrenia. Additionally, separate meta-analyses were conducted for the studies using finger tapping motor sequence task, as it is the most commonly used task. The current systematic review included 14 studies including 304 patients with schizophrenia and 209 healthy controls. The random-effects model analyses for sleep-dependent procedural memory consolidation resulted in a small effect size in schizophrenia (g = 0.26), a large effect size in healthy controls (g = 0.98), a moderate effect size in healthy controls vs schizophrenia (g = 0.64). For the studies using finger tapping motor sequence task, meta-analyses resulted in a small effect size in schizophrenia (g = 0.19), a large effect size in healthy controls (g = 1.07), a moderate effect size in healthy controls vs schizophrenia (g = 0.70). In the qualitative review, there was also impaired sleep-dependent declarative memory consolidation in schizophrenia compared to healthy controls. Current findings support that sleep improves memory consolidation in healthy adults, but there is a deficit in sleep-dependent memory consolidation in people with schizophrenia. Future studies investigating sleep-dependent consolidation of different memory subtypes with polysomnography in different stages of psychotic disorders are needed.

Nutrition, Sleep, and Exercise as Healthy Behaviors in Schizotypy: A Scoping Review

This scoping review identifies the role of nutrition, sleep, and exercise as healthy behaviors in non-clinical individuals with schizotypy throughout the lifespan.

METHODS

We systematically reviewed the existing literature on these topics through databases including: PsycINFO, Scopus, APA PsycNet, ScienceDirect, Wiley Online Library, and SpringerLink.

RESULTS

Of the 59 studies found, a total of 29 studies met the inclusion criteria on the review topic. Included studies reflect varying study designs (cross-sectional, multiple time-point, intervention, randomized-placebo controlled trials), assessment of schizotypy and associated healthy behaviors, focus on various samples and lifespan (e.g., undergraduates, adolescents, at-risk individuals), and stem from different countries.

CONCLUSION

While a moderate number of studies address the role of nutrition, sleep, and physical exercise in relation to schizotypy, studies intersecting these topics are limited. Of the limited studies that do exist, the majority are correlational with the beginnings of causal support from intervention studies. As such, more research is needed on the topics of nutrition, sleep, and exercise in relation to schizotypy. Specifically, future research should focus on providing a more holistic understanding of schizotypal traits and its subtypes, and which specific or combination of behaviors may reduce levels of schizotypy.

Lateral Habenula Beyond Avoidance: Roles in Stress, Memory, and Decision-Making With Implications for Psychiatric Disorders

In this Perspective review, we highlight some of the less explored aspects of lateral habenula (LHb) function in contextual memory, sleep, and behavioral flexibility. We provide evidence that LHb is well-situated to integrate different internal state and multimodal sensory information from memory-, stress-, motivational-, and reward-related circuits essential for both survival and decision making. We further discuss the impact of early life stress (ELS) on LHb function as an example of stress-induced hyperactivity and dysregulation of neuromodulatory systems within the LHb that promote anhedonia and motivational deficits following ELS. We acknowledge that recent technological advancements in manipulation and recording of neural circuits in simplified and well-controlled behavioral paradigms have been invaluable in our understanding of the critical role of LHb in motivation and emotional regulation as well as the involvement of LHb dysfunction in stress-induced psychopathology. However, we also argue that the use of ethologically-relevant behaviors with consideration of complex aspects of decision-making is warranted for future studies of LHb contributions in a wide range of psychiatric illnesses. We conclude this Perspective with some of the outstanding issues for the field to consider where a multi-systems approach is needed to investigate the complex nature of LHb circuitry interactions with environmental stimuli that predisposes psychiatric disorders.

Associations Between Self-Reported Sleep Disturbances and Cognitive Impairment: A Population-Based Cross-Sectional Study

OBJECTIVE

Cognitive impairment is a rapidly growing global public health problem in China and worldwide. In the recent decades, emerging studies have explored the associations between sleep disturbances and cognitive impairment. However, the variety of the results imply us that further studies should be conducted for the associations.

METHODS

This is a cross-sectional study conducted between August and October 2018 in five cities in Hebei province, China. Subjects were 21,376 community residents. Cognitive impairment was screened by the Chinese version of the Mini-Mental State Examination (MMSE). Scales of Athens Insomnia Scale (AIS), Berlin Questionnaire (BQ), REM (rapid eye movement) Sleep Behavior Disorder Questionnaire (RBDQ-HK), Ullanlinna Narcolepsy Scale (CUNS), and Cambridge-Hopkins Restless Legs Syndrome Questionnaire (CH-RLSq) were used to access insomnia, sleep apnea, REM sleep behavior disorder, narcolepsy, and restless leg syndrome.

RESULTS

The mean ± SD (standard error) of MMSE, AIS, RBDQ-HK, and CUNS were 27.95 ± 4.79, 2.16 ± 3.39, 5.55 ± 7.75, and 3.76 ± 2.31, respectively. Among the participants, 10.6% and 1.5% of the participants were identified as having a high risk of sleep apnea and restless leg syndrome, respectively. The results of multiple linear regression showed that cognitive impairment was associated with insomnia (β = -0.037, p < 0.001) and narcolepsy (β = -0.023, p < 0.001). The association between sleep apnea (β = -0.002, p > 0.05), REM sleep behavior disorder (β = 0.006, p > 0.05), restless leg syndrome (β = -0.007, p > 0.05), and cognitive impairment were not supported. Other factors associated with cognitive impairment were gender, age, education level, married status, and region.

CONCLUSION

This study provides some epidemiological evidence for the association between sleep disturbances and cognitive impairment among community residents in central China. In this study, the associations between insomnia, narcolepsy, and cognitive impairment were identified, but the associations between sleep apnea, REM sleep behavior disorder, narcolepsy, restless leg syndrome, and cognitive impairment were not supported among community residents.

The Impact of Sleep on Neurocognition and Functioning in Schizophrenia—Is It Time to Wake-Up?

People with schizophrenia (SZ) display substantial neurocognitive deficits that have been implicated as major contributors to poor daily functioning and disability. Previous reports have identified a number of predictors of poor neurocognition in SZ including demographics, symptoms, and treatment adherence, as well as body mass index, aerobic fitness, and exercise activity. However, the putative impact of sleep has received relatively limited consideration, despite sleep disturbances, which are pervasive in this population, resulting in symptoms that are strikingly similar to the neurocognitive deficits commonly observed in SZ. Here we argue for the consideration of the impact of sleep on neurocognition in people with SZ and propose recommendations for future research to elucidate the links between sleep parameters, neurocognition and daily functioning.

Hypotic medication use among inpatients with schizophrenia and major depressive disorder: results of a nationwide study

STUDY OBJECTIVES

To investigate the proportion of inpatients with schizophrenia and major depressive disorder prescribed hypnotic medication, and the association between such medication and the use of other antipsychotic agents.

METHODS

This was a nationwide cross-sectional study performed as part of the 'Effectiveness of Guidelines for Dissemination and Education in Psychiatric Treatment' (EGUIDE) project. Data from 2146 inpatients with schizophrenia and 1031 inpatients with major depressive disorder were analyzed. All types and dosages of psychotropic drugs were recorded and the data at the time of discharge were analyzed. Associations between the use of hypnotic medication and other antipsychotic agents were evaluated using multivariate logistic regression analyses.

RESULTS

The proportions of schizophrenia patients who were prescribed any and two or more hypnotic agents were 55.7% and 17.6%, respectively, and the corresponding proportions for patients with major depressive disorder were 63.6% and 22.6%, respectively. In schizophrenia patients, multivariate logistic regression analyses showed that two or more antipsychotics, anticholinergic drugs, anxiolytics, and mood stabilizers/antiepileptic drugs were positively associated with the use of any hypnotic agent. In patients with major depressive disorder, multivariate logistic regression analyses revealed that two or more antidepressants, two or more antipsychotics, anxiolytics, and mood stabilizers/antiepileptic drugs were positively associated with the use of any hypnotic agent.

CONCLUSIONS

Prescription of hypnotic agents was found to be highly frequent among inpatients with psychiatric disorders. Prescription of two or more main antipsychotic agents was commonly associated with the use of hypnotic medication for both schizophrenia and major depressive disorder.