Comparing neural correlates of REM sleep in posttraumatic stress disorder and depression: a neuroimaging study

Prevalence and influencing factors of sleep disorders in medical students after the COVID-19 pandemic

BACKGROUND

The prevalence of sleep disorders among medical students was high during the COVID-19 pandemic. However, fewer studies have been conducted on sleep disorders among medical students after the COVID-19 pandemic. This study investigated the prevalence and factors influencing sleep disorders among Chinese medical students after COVID-19.

METHODS

A total of 1,194 Chinese medical students were included in this study from 9th to 12th July 2023. We used the Self-administered Chinese scale to collect the demographic characteristics. In addition, we used the Chinese versions of the Self-rating Depression Scale (SDS), the Self-rating Anxiety Scale (SAS), and the Pittsburgh Sleep Quality Index (PSQI) to assess subjects' depression, anxiety, and sleep disorders, respectively. The chi-square test and binary logistic regression were used to identify factors influencing sleep disorders. The receiver operating characteristic (ROC) curve was utilized to assess the predictive value of relevant variables for sleep disorders.

RESULTS

We found the prevalence of sleep disorders among medical students after COVID-19 was 82.3%. According to logistic regression results, medical students with depression were 1.151 times more likely to have sleep disorders than those without depression (OR = 1.151, 95% CI 1.114 to 1.188). Doctoral students were 1.908 times more likely to have sleep disorders than graduate and undergraduate students (OR = 1.908, 95% CI 1.264 to 2.880).

CONCLUSION

The prevalence of sleep disorders among medical students is high after COVID-19. In addition, high academic levels and depression are risk factors for sleep disorders. Therefore, medical colleges and administrators should pay more attention to sleep disorders in medical students after the COVID-19 pandemic. Regular assessment of sleep disorders and depression is essential.

Regulation of dendritic spines in the amygdala following sleep deprivation

The amygdala is a hub of emotional circuits involved in the regulation of cognitive and emotional behaviors and its critically involved in emotional reactivity, stress regulation, and fear memory. Growing evidence suggests that the amygdala plays a key role in the consolidation of emotional memories during sleep. Neuroimaging studies demonstrated that the amygdala is selectively and highly activated during rapid eye movement sleep (REM) and sleep deprivation induces emotional instability and dysregulation of the emotional learning process. Regulation of dendritic spines during sleep represents a morphological correlate of memory consolidation. Several studies indicate that dendritic spines are remodeled during sleep, with evidence for broad synaptic downscaling and selective synaptic upscaling in several cortical areas and the hippocampus. Currently, there is a lack of information regarding the regulation of dendritic spines in the amygdala during sleep. In the present work, we investigated the effect of 5 h of sleep deprivation on dendritic spines in the mouse amygdala. Our data demonstrate that sleep deprivation results in differential dendritic spine changes depending on both the amygdala subregions and the morphological subtypes of dendritic spines. We observed decreased density of mushroom spines in the basolateral amygdala of sleep deprived mice, together with increased neck length and decreased surface area and volume. In contrast, we observed greater densities of stubby spines in sleep deprived mice in the central amygdala, indicating that downscaling selectively occurs in this spine type. Greater neck diameters for thin spines in the lateral and basolateral nuclei of sleep deprived mice, and decreases in surface area and volume for mushroom spines in the basolateral amygdala compared to increases in the cental amygdala provide further support for spine type-selective synaptic downscaling in these areas during sleep. Our findings suggest that sleep promotes synaptic upscaling of mushroom spines in the basolateral amygdala, and downscaling of selective spine types in the lateral and central amygdala. In addition, we observed decreased density of phosphorylated cofilin immunoreactive and growth hormone immunoreactive cells in the amygdala of sleep deprived mice, providing further support for upscaling of dendritic spines during sleep. Overall, our findings point to region-and spine type-specific changes in dendritic spines during sleep in the amygdala, which may contribute to consolidation of emotional memories during sleep.

Clarifying sleep characteristics and analyzing risk factors of sleep disorders to promote a predictive, preventive, and personalized medicine in patients with burn scars

Purpose

This study assessed sleep quality in patients with burn scars and investigated risk factors of sleep disorders to guide clinical therapy. From the strategy of predictive, preventive, and personalized medicine (PPPM/3PM), we proposed that risk assessment based on clinical indicators could prompt primary prediction, targeted prevention, and personalized interventions to improve the management of sleep disorders present in patients with burn scars.

Methods

This retrospective study recruited patients with burn scars and healthy volunteers from the Shanghai Burn Treatment Center between 2017 and 2022. Relevant information and data, including demographic characteristics, scar evaluation, and sleep quality, were obtained through the hospital information system, classical scar scale, and self-report questionnaires. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI) and monitored using a cardiopulmonary-coupled electrocardiograph. Pain and pruritus were assessed using the visual analog scale (VAS). Scar appearance was assessed using the modified Vancouver scar scale (mVSS).

Results

The sample was comprised of 128 hypertrophic scar (HS) patients, with 61.7% males, a mean age of 41.1 ± 11.6 years, and burn area of 46.2 ± 27.9% total body surface area (TBSA). Patients with PSQI ≥ 7 accounted for 76.6%, and the global PSQI score was 9.4 ± 4.1. Objective sleep data showed that initial enter deep sleep time, light sleep time, awakening time, light sleep efficiency, and sleep apnea index were higher but deep sleep time, sleep efficiency, and deep sleep efficiency were lower in HS patients than that in healthy controls. Preliminary univariate analysis showed that age, hyperplasia time of scar, narrow airway, microstomia, VAS for pain and pruritus, and mVSS total (comprised of pigmentation, vascularity, height and pliability) were associated with the PSQI score (p < 0.1). Multivariable linear regression showed narrow airway, VAS for pain and pruritus, and mVSS specifically height, were the risk factors for PSQI score (p < 0.1).

Conclusions

This study model identified that narrow airway, pain, pruritus and scar appearance specifically height may provide excellent predictors for sleep disorders in HS patients. Our results provided a basis for the predictive diagnostics, targeted prevention, and individualized therapy of somnipathy predisposition and progression of HS patients in the setting of PPPM/3PM health care system, which contributed to a paradigm shift from reactive cure to advanced therapy.

The influence of sleep on fear extinction in trauma-related disorders

In Posttraumatic Stress Disorder (PTSD), fear and anxiety become dysregulated following psychologically traumatic events. Regulation of fear and anxiety involves both high-level cognitive processes such as cognitive reattribution and low-level, partially automatic memory processes such as fear extinction, safety learning and habituation. These latter processes are believed to be deficient in PTSD. While insomnia and nightmares are characteristic symptoms of existing PTSD, abundant recent evidence suggests that sleep disruption prior to and acute sleep disturbance following traumatic events both can predispose an individual to develop PTSD. Sleep promotes consolidation in multiple memory systems and is believed to also do so for low-level emotion-regulatory memory processes. Consequently sleep disruption may contribute to the etiology of PTSD by interfering with consolidation in low-level emotion-regulatory memory systems. During the first weeks following a traumatic event, when in the course of everyday life resilient individuals begin to acquire and consolidate these low-level emotion-regulatory memories, those who will develop PTSD symptoms may fail to do so. This deficit may, in part, result from alterations of sleep that interfere with their consolidation, such as REM fragmentation, that have also been found to presage later PTSD symptoms. Here, sleep disruption in PTSD as well as fear extinction, safety learning and habituation and their known alterations in PTSD are first briefly reviewed. Then neural processes that occur during the early post-trauma period that might impede low-level emotion regulatory processes through alterations of sleep quality and physiology will be considered. Lastly, recent neuroimaging evidence from a fear conditioning and extinction paradigm in patient groups and their controls will be considered along with one possible neural process that may contribute to a vulnerability to PTSD following trauma.

Individuals with and without military-related PTSD differ in subjective sleepiness and alertness but not objective sleepiness

Posttraumatic stress disorder-related sleep disturbances may increase daytime sleepiness and compromise performance in individuals with posttraumatic stress disorder. We investigated nighttime sleep predictors of sleepiness in Veterans with and without posttraumatic stress disorder. Thirty-seven post-9/11 Veterans with posttraumatic stress disorder and 47 without posttraumatic stress disorder (Control) completed a 48-h lab stay. Nighttime quantitative EEG and sleep architecture parameters were collected with polysomnography. Data from daytime sleepiness batteries assessing subjective sleepiness (global vigor questionnaire), objective sleepiness (Multiple Sleep Latency Tests) and alertness (psychomotor vigilance task) were included in analyses. Independent samples t-tests and linear regressions were performed to identify group differences in sleepiness and nighttime sleep predictors of sleepiness in the overall sample and within each group. Participants with posttraumatic stress disorder had higher subjective sleepiness (t = 4.20; p < .001) and lower alertness (psychomotor vigilance task reaction time (t = -3.70; p < .001) and lapses: t = -2.13; p = .04) than the control group. Objective daytime sleepiness did not differ between groups (t = -0.79, p = .43). In the whole sample, higher rapid eye movement delta power predicted lower alertness quantified by psychomotor vigilance task reaction time (β = 0.372, p = .013) and lapses (β = 0.388, p = .013). More fragmented sleep predicted higher objective sleepiness in the posttraumatic stress disorder group (β = -.467, p = .005) but no other nighttime sleep measures influenced the relationship between group and sleepiness. Objective measures of sleep and sleepiness were not associated with the increased subjective sleepiness and reduced alertness of the posttraumatic stress disorder group.

The Effect of Self-Reported REM Behavior Disorder Symptomology on Intrusive Memories in Post-Traumatic Stress Disorder

Background: PTSD is characterised by severe sleep disturbances, which is increasingly recognised to in many cases consist of similar symptomology to sleep disorders such as REM Behaviour Disorder (RBD). The present study aimed to investigate whether different aspects of sleep quality influence intrusive memory development and whether PTSD status moderates this relationship. Participants and Methods: 34 PTSD, 52 trauma-exposed (TE) and 42 non-trauma exposed (NTE) participants completed an emotional memory task, where they viewed 60 images (20 positive, 20 negative and 20 neutral) and, two days later, reported how many intrusive memories they had of each valence category. Participants also completed three measures of sleep quality: the Pittsburgh Sleep Quality Index, the REM Behaviour Disorder Screening Questionnaire and total hours slept before each session. Results: The PTSD group reported poorer sleep quality than both TE and NTE groups on all three measures, and significantly more negative intrusive memories than the NTE group. Mediation analyses revealed that self-reported RBD symptomology before the second session mediated the relationship between PTSD status and intrusive memories. Follow-up moderation analyses revealed that self-reported RBD symptomology before the second session was only a significant predictor of intrusion in the PTSD group, though with a small effect size. Conclusions: These findings suggest that RBD symptomology is an indicator of consolidation of intrusive memories in PTSD but not trauma-exposed or healthy participants, which supports the relevance of characterising RBD in PTSD.

Increased risk for sleep disorders in burn patients: A 14-year nationwide, population-based cohort study

BACKGROUND

Burn is a major trauma that causes physical and psychosocial impairments, leading to sleep disorders. However, the data about risks for sleep disorders in patients over 3 years following burn injury are limited.

AIM

To investigate the long-term risks for sleep disorders in patients after burn injury and identify the high-risk population.

METHODS

A 14-year population-based cohort study was performed using data from the 2000-2013 Taiwan National Health Insurance Research Database (NHIRD) which was a valid representative sample of the total population. All diagnoses of medical records in NHIRD were made by physicians and coded according to the ICD-9-CM. Cases diagnosed with burns (ICD-9 CM: N-code 940-949 and E-code 890-899) were included. The control group (non-burn injury group) was comprised quadruple the number of cases matched by index date, sex and age.

RESULTS

In 2000-2013, among the 10,289 burn patients included and followed-up after the index year, burn injury significantly increased the risks for sleep disorders (Hazard Ratio; HR = 1.36, p = 0.044), including insomnia (HR = 1.41, p = 0.036), sleep disturbance (HR = 2.39, p = 0.005) and sleep apnoea (HR = 1.38, p = 0.029). Compared with the control group, those who were women (HR = 1.73, p = 0.021), adolescents (HR = 5.45, p < 0.001), aged 19-24 years (HR = 1.36, p = 0.034), aged 25-44 years (HR = 1.67, p = 0.007), had low income (HR = 2.14, p = 0.001), and without a history of mental disorders (HR = 1.41, p = 0.024) had significantly higher risks for developing sleep disorders when suffered burn injury.

CONCLUSION

Burn had long-term negative effects on sleep during both the first year of burn injury and the subsequent follow-up 14 years. It is important for physicians to long-term assess the sleep quality of burn patients regardless of the number of years after burn injury.

Posttraumatic stress disorder diagnosis is associated with reduced parasympathetic activity during sleep in US veterans and military service members of the Iraq and Afghanistan wars

Study Objectives

To determine whether high-frequency heart rate variability (HF-HRV) during sleep differs between those with and without posttraumatic stress disorder (PTSD) as a function of sleep type (non-rapid eye movement [NREM] vs. rapid eye movement [REM]), and to explore this relationship across successive sleep cycles. Participants with PTSD were hypothesized to have lower HF-HRV across both REM and NREM sleep.

Methods

Sixty-two post-9/11 military veterans and service members completed self-report measures of sleep quality, insomnia severity, and disruptive nocturnal behaviors. Participants then completed a laboratory-based polysomnographic study night with concurrent HRV assessment.

Results

Participants with PTSD (N = 29) had lower HF-HRV in overall NREM sleep relative to those without PTSD (N = 33) (F(1, 54) = 4.24, p = .04). Groups did not differ on overall HF-HRV during REM sleep. HF-HRV increased over the night for the sample as a whole during both NREM and REM sleep. PTSD status did not moderate the association between HF-HRV and sleep cycles. However, the PTSD group had lower HF-HRV in the first t(155) = 2.67, p = .008, and fourth NREM cycles, t(155) = 2.11, p = .036, relative to participants without PTSD.

Conclusions

Findings suggest blunted parasympathetic modulation during NREM sleep in a young cohort of military veterans and service-members with PTSD. Findings are concerning considering the increased risk of incident cardiovascular events associated with impaired parasympathetic nervous system function. Reduced parasympathetic modulation may be one mechanism underlying the increased prevalence of cardiovascular disease (CVD) among veterans with PTSD.

Trauma Associated Sleep Disorder: Clinical Developments 5 Years After Discovery

PURPOSE OF REVIEW

We review recent and growing evidence that provides support for a novel parasomnia, trauma associated sleep disorder (TASD). Based on these findings, we further develop the clinical and polysomnographic (PSG) characteristics of TASD. We also address factors that precipitate TASD, develop a differential diagnosis, discuss therapy, and propose future directions for research.

RECENT FINDINGS

Nightmares, classically a REM phenomenon, are prevalent and underreported, even in individuals with trauma exposure. When specifically queried, trauma-related nightmares (TRN) are frequently associated with disruptive nocturnal behaviors (DNB), consistent with TASD. Capture of DNB in the lab is rare but ambulatory monitoring reveals dynamic autonomic concomitants associated with disturbed dreaming. TRN may be reported in NREM as well as REM sleep, though associated respiratory events may confound this finding. Further, dream content is more distressing in REM. Therapy for this complex disorder likely requires addressing not only the specific TASD components of TRN and DNB but comorbid sleep disorders. TASD is a unique parasomnia developing after trauma. Trauma-exposed individuals should be specifically asked about their sleep and if they have nightmares with or without DNB. Patients who report TRN warrant in-lab PSG as part of their evaluation.

Investigating the Correspondence of Clinical Diagnostic Grouping With Underlying Neurobiological and Phenotypic Clusters Using Unsupervised Machine Learning

Many brain-based disorders are traditionally diagnosed based on clinical interviews and behavioral assessments, which are recognized to be largely imperfect. Therefore, it is necessary to establish neuroimaging-based biomarkers to improve diagnostic precision. Resting-state functional magnetic resonance imaging (rs-fMRI) is a promising technique for the characterization and classification of varying disorders. However, most of these classification methods are supervised, i.e., they require a priori clinical labels to guide classification. In this study, we adopted various unsupervised clustering methods using static and dynamic rs-fMRI connectivity measures to investigate whether the clinical diagnostic grouping of different disorders is grounded in underlying neurobiological and phenotypic clusters. In order to do so, we derived a general analysis pipeline for identifying different brain-based disorders using genetic algorithm-based feature selection, and unsupervised clustering methods on four different datasets; three of them-ADNI, ADHD-200, and ABIDE-which are publicly available, and a fourth one-PTSD and PCS-which was acquired in-house. Using these datasets, the effectiveness of the proposed pipeline was verified on different disorders: Attention Deficit Hyperactivity Disorder (ADHD), Alzheimer's Disease (AD), Autism Spectrum Disorder (ASD), Post-Traumatic Stress Disorder (PTSD), and Post-Concussion Syndrome (PCS). For ADHD and AD, highest similarity was achieved between connectivity and phenotypic clusters, whereas for ASD and PTSD/PCS, highest similarity was achieved between connectivity and clinical diagnostic clusters. For multi-site data (ABIDE and ADHD-200), we report site-specific results. We also reported the effect of elimination of outlier subjects for all four datasets. Overall, our results suggest that neurobiological and phenotypic biomarkers could potentially be used as an aid by the clinician, in additional to currently available clinical diagnostic standards, to improve diagnostic precision. Data and source code used in this work is publicly available at https://github.com/xinyuzhao/identification-of-brain-based-disorders.git.

Sleep Disturbance in Posttraumatic Stress Disorder: Epiphenomenon or Causal Factor?

PURPOSE OF REVIEW

The goal of this review is to integrate recent findings on sleep disturbance and PTSD, examine sleep disturbance as a causal factor in the development of PTSD, and identify future directions for research, treatment, and prevention.

RECENT FINDINGS

Recent research highlights a relationship between both objective and subjective sleep disturbance and PTSD across diverse samples. Sleep disturbance also predicts PTSD over time. Finally, treatments targeting sleep disturbance lead to decreased PTSD symptoms, while standard PTSD treatments conclude with residual sleep disturbance. Sleep disturbance may be more than a mere epiphenomenon of PTSD. Future research examining the causal role of sleep disturbance in the development of PTSD, as well as the utility of targeting sleep disturbance in prevention and treatment, is necessary to fully understand the likely bidirectional relationship between sleep disturbance and PTSD.

Sleep-dependent memory consolidation and its implications for psychiatry

Both sleep disturbance and memory impairment are very common in psychiatric disorders. Since sleep has been shown to play a role in the process of transferring newly acquired information into long-term memory, i.e., consolidation, it is important to highlight this link in the context of psychiatric disorders. Along these lines, after providing a brief overview of healthy human sleep, current neurobiological models on sleep-dependent memory consolidation and resultant opportunities to manipulate the memory consolidation process, recent findings on sleep disturbances and sleep-dependent memory consolidation in patients with insomnia, major depression, schizophrenia, and post-traumatic stress disorder are systematically reviewed. Furthermore, possible underlying neuropathologies and their implications on therapeutic strategies are discussed. This review aims at sensitizing the reader for recognizing sleep disturbances as a potential contributor to cognitive deficits in several disorders, a fact which is often overlooked up to date.

Sleep and REM sleep disturbance in the pathophysiology of PTSD: the role of extinction memory

Post-traumatic stress disorder (PTSD) is accompanied by disturbed sleep and an impaired ability to learn and remember extinction of conditioned fear. Following a traumatic event, the full spectrum of PTSD symptoms typically requires several months to develop. During this time, sleep disturbances such as insomnia, nightmares, and fragmented rapid eye movement sleep predict later development of PTSD symptoms. Only a minority of individuals exposed to trauma go on to develop PTSD. We hypothesize that sleep disturbance resulting from an acute trauma, or predating the traumatic experience, may contribute to the etiology of PTSD. Because symptoms can worsen over time, we suggest that continued sleep disturbances can also maintain and exacerbate PTSD. Sleep disturbance may result in failure of extinction memory to persist and generalize, and we suggest that this constitutes one, non-exclusive mechanism by which poor sleep contributes to the development and perpetuation of PTSD. Also reviewed are neuroendocrine systems that show abnormalities in PTSD, and in which stress responses and sleep disturbance potentially produce synergistic effects that interfere with extinction learning and memory. Preliminary evidence that insomnia alone can disrupt sleep-dependent emotional processes including consolidation of extinction memory is also discussed. We suggest that optimizing sleep quality following trauma, and even strategically timing sleep to strengthen extinction memories therapeutically instantiated during exposure therapy, may allow sleep itself to be recruited in the treatment of PTSD and other trauma and stress-related disorders.

Schizophrenia and Depression: A systematic Review of the Effectiveness and the Working Mechanisms Behind Acupuncture

OBJECTIVE

This systematic review assessed clinical evidence for the use of acupuncture as an add-on treatment in patients with depression and schizophrenia and for its underlying working mechanisms.

DATA SOURCES

Four databases (Medline, Scopus, ERIC, and the Cochrane Library) were searched with a cutoff date of March 31, 2014.

STUDY SELECTION

Systematic reviews and meta-analyses of acupuncture treatment for depression and schizophrenia were considered for inclusion. The scarcity of acupuncture research involving schizophrenia led to the inclusion of randomized controlled trials and case studies.

DATA EXTRACTION

The primary and secondary aims of this study were to evaluate the effects of acupuncture in treating patients with depression or schizophrenia and the possible working mechanisms underlying acupuncture through a systematic literature review.

DATA SYNTHESIS

The overall clinical results on using acupuncture to treat depression are promising, but only limited evidence for its effectiveness in treating schizophrenia was found. Acupuncture improves the quality of life, particularly that of sleep, in psychiatric patients. Brain research has revealed that acupuncture has a modulating and normalizing effect on the limbic-paralimbic-neocortical network (LPNN), including the default mode network. Because the LPNN is related to sleep and emotions, this might explain the improved qualities of life and sleep after acupuncture.

CONCLUSIONS

From the evidence found in this study, acupuncture seems to be an effective add-on treatment in patients with depression and, to a lesser degree, in patients with schizophrenia, but large well-designed studies are needed to confirm that evidence.

The Neurobiological Mechanisms and Treatments of REM Sleep Disturbances in Depression

Most depressed patients suffer from sleep abnormalities, which are one of the critical symptoms of depression. They are robust risk factors for the initiation and development of depression. Studies about sleep electroencephalograms have shown characteristic changes in depression such as reductions in non-rapid eye movement sleep production, disruptions of sleep continuity and disinhibition of rapid eye movement (REM) sleep. REM sleep alterations include a decrease in REM sleep latency, an increase in REM sleep duration and REM sleep density with respect to depressive episodes. Emotional brain processing dependent on the normal sleep-wake regulation seems to be failed in depression, which also promotes the development of clinical depression. Also, REM sleep alterations have been considered as biomarkers of depression. The disturbances of norepinephrine and serotonin systems may contribute to REM sleep abnormalities in depression. Lastly, this review also discusses the effects of different antidepressants on REM sleep disturbances in depression.

Neurobiology of Sleep Disturbances in PTSD Patients and Traumatized Controls: MRI and SPECT Findings

OBJECTIVE

Sleep disturbances such as insomnia and nightmares are core components of post-traumatic stress disorder (PTSD), yet their neurobiological relationship is still largely unknown. We investigated brain alterations related to sleep disturbances in PTSD patients and controls by using both structural and functional neuroimaging techniques.

METHOD

Thirty-nine subjects either developing (n = 21) or not developing (n = 18) PTSD underwent magnetic resonance imaging and a symptom-provocation protocol followed by the injection of 99mTc-hexamethylpropyleneamineoxime. Subjects were also tested with diagnostic and self-rating scales on the basis of which a Sleep Disturbances Score (SDS; i.e., amount of insomnia/nightmares) was computed.

RESULTS

Correlations between SDS and gray matter volume (GMV)/regional cerebral blood flow (rCBF) were computed in the whole sample and separately in the PTSD and control groups. In the whole sample, higher sleep disturbances were associated with significantly reduced GMV in amygdala, hippocampus, anterior cingulate, and insula; increased rCBF in midbrain, precuneus, and insula; and decreased rCBF in anterior cingulate. This pattern was substantially confirmed in the PTSD group, but not in controls.

CONCLUSION

Sleep disturbances are associated with GMV loss in anterior limbic/paralimbic, PTSD-sensitive structures and with functional alterations in regions implicated in rapid eye movement-sleep control, supporting the existence of a link between PTSD and sleep disturbance.