Decreased nocturnal growth hormone secretion and sleep fragmentation in combat-related posttraumatic stress disorder; potential predictors of impaired memory consolidation

Narrative review: The role of circadian rhythm on sports performance, hormonal regulation, immune system function, and injury prevention in athletes

Objectives

This study was a narrative review of the importance of circadian rhythm (CR), describes the underlying mechanisms of CR in sports performance, emphasizes the reciprocal link between CR, endocrine homeostasis and sex differences, and the unique role of the circadian clock in immune system function and coordination.

Method

As a narrative review study, a comprehensive search was conducted in PubMed, Scopus, and Web of Science (core collection) databases using the keywords "circadian rhythm", "sports performance", "hormonal regulation", "immune system", and "injury prevention". Inclusion criteria were studies published in English and peer-reviewed journals until July 2023. Studies that examined the role of CR in sports performance, hormonal status, immune system function, and injury prevention in athletes were selected for review.

Results

CR is followed by almost all physiological and biochemical activities in the human body. In humans, the superchiasmatic nucleus controls many daily biorhythms under solar time, including the sleep-wake cycle. A body of literature indicates that the peak performance of essential indicators of sports performance is primarily in the afternoon hours, and the evening of actions occurs roughly at the peak of core body temperature. Recent studies have demonstrated that the time of day that exercise is performed affects the achievement of good physical performance. This review also shows various biomarkers of cellular damage in weariness and the underlying mechanisms of diurnal fluctuations. According to the clock, CR can be synchronized with photonic and non-photonic stimuli (i.e., temperature, physical activity, and food intake), and feeding patterns and diet changes can affect CR and redox markers. It also emphasizes the reciprocal links between CR and endocrine homeostasis, the specific role of the circadian clock in coordinating immune system function, and the relationship between circadian clocks and sex differences.

Conclusion

The interaction between insufficient sleep and time of day on performance has been established in this study because it is crucial to balance training, recovery, and sleep duration to attain optimal sports performance.

Hypothalamus and Post-Traumatic Stress Disorder: A Review

Humans have lived in a dynamic environment fraught with potential dangers for thousands of years. While fear and stress were crucial for the survival of our ancestors, today, they are mostly considered harmful factors, threatening both our physical and mental health. Trauma is a highly stressful, often life-threatening event or a series of events, such as sexual assault, war, natural disasters, burns, and car accidents. Trauma can cause pathological metaplasticity, leading to long-lasting behavioral changes and impairing an individual's ability to cope with future challenges. If an individual is vulnerable, a tremendously traumatic event may result in post-traumatic stress disorder (PTSD). The hypothalamus is critical in initiating hormonal responses to stressful stimuli via the hypothalamic-pituitary-adrenal (HPA) axis. Linked to the prefrontal cortex and limbic structures, especially the amygdala and hippocampus, the hypothalamus acts as a central hub, integrating physiological aspects of the stress response. Consequently, the hypothalamic functions have been attributed to the pathophysiology of PTSD. However, apart from the well-known role of the HPA axis, the hypothalamus may also play different roles in the development of PTSD through other pathways, including the hypothalamic-pituitary-thyroid (HPT) and hypothalamic-pituitary-gonadal (HPG) axes, as well as by secreting growth hormone, prolactin, dopamine, and oxytocin. This review aims to summarize the current evidence regarding the neuroendocrine functions of the hypothalamus, which are correlated with the development of PTSD. A better understanding of the role of the hypothalamus in PTSD could help develop better treatments for this debilitating condition.

Acute sleep interventions as an avenue for treatment of trauma-associated disorders

Scientific evidence that acute, posttrauma sleep disturbances (eg, nightmares and insomnia) can contribute significantly to the pathogenesis of trauma-induced disorders is compelling. Sleep disturbances precipitating from trauma are uniquely predictive of daytime posttrauma symptom occurrence and severity, as well as subsequent onset of mental health disorders, including post-traumatic stress disorder. Conversely, adequate sleep during the acute posttrauma period is associated with reduced likelihood of adverse mental health outcomes. These findings, which are broadly consistent with what is known about the role of sleep in the regulation of emotion, suggest that the acute posttrauma period constitutes a "window of opportunity" during which treatment of sleep disturbances may be especially effective for preventing or mitigating progression of aberrant psychophysiological processes. At this point, the weight of the scientific evidence supporting this possibility warrants initiation of clinical trials to confirm the benefits of targeted prophylactic sleep enhancement, and to establish treatment guidelines as appropriate.

CITATION

Swift KM, Thomas CL, Balkin TJ, Lowery-Gionta EG, Matson LM. Acute sleep interventions as an avenue for treatment of trauma-associated disorders. J Clin Sleep Med. 2022;18(9):2291-2312.

Effects of Sleep Deficiency on Risk, Course, and Treatment of Psychopathology

This article reviews the literature on the relationship between sleep deficiency and unipolar and bipolar depression, anxiety disorders, and posttraumatic stress disorder. We consider the evidence for sleep as a contributory causal factor in the development of psychiatric disorders, as well as sleep as an influential factor related to the outcome and recurrence of psychopathology. A case for sleep deficiency being an important treatment target when sleep and psychiatric disorders are comorbid is also made. Our recommendation is that sleep deficiency is recognized as a means to positively impact the development and course of psychopathology and, as such, is routinely assessed and treated in clinical practice.

Impaired episodic memory in PTSD patients - A meta-analysis of 47 studies

Episodic memory impairments beyond the traumatic event might be a characteristic hallmark of post-traumatic stress disorder (PTSD). Although several studies support such a claim, empirical findings are inconsistent. Therefore, we performed a random-effects meta-analysis including data from a total of 47 studies and 3,062 subjects. As main finding, we can show that PTSD patients show episodic memory deficits compared to all controls. This effect was significantly stronger for PTSD vs. non-traumatized healthy controls as compared to PTSD vs. traumatized controls without PTSD. Finally, episodic memory impairments in PTSD were most pronounced in verbal memory tests as compared to non-verbal memory tests. Our results provide new evidence that PTSD is characterized by impaired episodic long-term memory beyond the traumatic event, and these deficits are particularly pronounced in verbal memory. We will discuss our findings in the context of physiological, psychological and trauma related memory models. From a broader perspective, our findings may have implications for the treatment of PTSD by suggesting that the assessment and, if necessary, training of memory deficits could be included as part of diagnostics and psychotherapeutic treatment.

Sleep and PTSD in the Military Forces: A Reciprocal Relationship and a Psychiatric Approach

Sleep disturbances are well-recognised symptoms of Post-Traumatic Stress Disorder (PTSD). This review updates knowledge regarding the relationship between sleep during deployment, combat-related trauma, and PTSD in military personnel, from which the importance of restorative sleep results. The description of the characteristics of sleep in military forces with the considerable roles of the operational and training contexts highlights the important consequences of degraded sleep. Indeed, a lot of data suggest a dynamic link between sleep and the onset and chronicity of PTSD. We propose a reciprocal relationship model with strategies strongly recommended or already adopted by the military to promote restorative sleep before and after combat exposure. Among the alterations in a variety of sleep architecture and sleep patterns described in PTSD, the physiological hypothesis of REM sleep fragmentation in the development of PTSD symptoms may be important because REM sleep is generally associated with emotional memory. Finally, we address clinical and research perspectives that could be used to detect or restore sleep continuity before and during military deployment to possibly alleviate nightmares and insomnia related to combat exposure and PTSD occurrence and improve our understanding of sleep in PTSD.

Sleep Quality Improvements After MDMA-Assisted Psychotherapy for the Treatment of Posttraumatic Stress Disorder

Sleep disturbances (SDs) are among the most distressing and commonly reported symptoms in posttraumatic stress disorder (PTSD). Despite increased attention on sleep in clinical PTSD research, SDs remain difficult to treat. In Phase 2 trials, 3,4-methylenedioxymethamphetamine (MDMA)-assisted psychotherapy has been shown to greatly improve PTSD symptoms. We hypothesized that MDMA-assisted psychotherapy would improve self-reported sleep quality (SQ) in individuals with PTSD and be associated with declining PTSD symptoms. Participants in four studies (n = 63) were randomized to receive 2-3 sessions of active MDMA (75-125 mg; n = 47) or placebo/control MDMA (0-40 mg, n = 16) during all-day psychotherapy sessions. The PSQI was used to assess change in SQ from baseline to the primary endpoint, 1-2 months after the blinded sessions. Additionally, PSQI scores were measured at treatment exit (TE) and 12-month follow-up. Symptoms of PTSD were measured using the CAPS-IV. At the primary endpoint, CAPS-IV total severity scores dropped more after active MDMA than after placebo/control (-34.0 vs. -12.4), p = .003. Participants in the active dose group showed more improvement in SQ compared to those in the control group (PSQI total score ΔM = -3.5 vs. 0.6), p = .003. Compared to baseline, SQ had improved at TE, p < .001, with further significant gains reported at 12-month follow-up (TE to 12-months ΔM = -1.0), p = .030. Data from these randomized controlled double-blind studies provide evidence for the beneficial effects of MDMA-assisted psychotherapy in treating SDs in individuals with PTSD.

Mechanism for the Increase in Human Growth Hormone with Administration of a Novel Test Supplement and Results Indicating Improved Physical Fitness and Sleep Efficiency

An oral test supplement increases serum human growth hormone (hGH) levels after acute administration in healthy adults. We investigated the mechanism for the increase in hGH and the effect of continued daily administration of the test supplement on measures of physical fitness and sleep efficiency. In Study 1, serum triiodothyronine (T3) was measured in samples from a prior placebo-controlled, double-blind study in which 16 healthy participants received both placebo and the test supplement in a crossover design; treatment order was randomized, and treatments were separated by a 1-week washout. In Study 2, physical fitness (VO₂ max) was measured at baseline and after 2 weeks of daily administration of the test supplement (N = 12 healthy participants). Study 3 assessed daily sleep onset latency and time awake during 3 weeks of daily administration of the test supplement (N = 15 healthy participants). A fall from baseline in T3 was observed with placebo (-6.1 ± 8.5 ng/dL, P = .01). Of note, the change in T3 was smaller with the test supplement (-3.3 ± 10.7 ng/dL, P = not significant) but was not statistically different from placebo. Mean VO₂ max increased by 6% from baseline after 2 weeks (P = .02). Sleep-onset latency and time awake during the night were reduced from baseline to week 3 by 22% and 65%, respectively (P = .01 and P = .02). The conservation of T3 levels suggests that the mechanism for increased hGH secretion by the test supplement is through somatostatin inhibition. Furthermore, pilot studies indicated that daily administration of the supplement improved physical fitness and sleep efficiency from baseline, effects consistent with increased endogenous hGH release. Clinical Trial Registration No. NCT02987868.

Sleep in the anxiety-related disorders: A meta-analysis of subjective and objective research

Although sleep disturbance is implicated in psychopathology, its role in anxiety-related disorders remains unclear. The present meta-analysis characterizes sleep disturbance in anxiety-related disorders collectively and individually. Subjective measures of total sleep time and sleep continuity were included with objective measures. Results indicate a large effect for increased subjective sleep disturbance (g = 2.16), medium effects for decreased total sleep time (g = -.40) and sleep continuity (g = -.49), and a small effect for decreased sleep depth (g = -.20) in anxiety-related disorders compared to healthy controls. Each anxiety-related disorder exhibited a distinct sleep disturbance pattern, suggesting that sleep may facilitate identification of unique biopsychological underpinnings. Effects were not moderated by comorbid depression and were similar in magnitude to those found for depression. Sleep disturbances, particularly decreased sleep continuity, may be a key pathology in the anxiety-related disorders that could highlight novel etiological mechanisms and intervention targets.

Sleep continuity, stability and organization in good and bad sleepers

The relationship between objective and subjective sleep quality is still debated. Here, we investigate differences in objective sleep parameters in habitual subjective good sleepers and bad sleepers with the aim of evaluating sleep continuity, stability and organization as possible determinants of subjective sleep quality. In total, 38 subjects (good sleepers, N = 18; bad sleepers, N = 20) underwent two nights of sleep recording. Traditional sleep parameters displayed no between-groups differences. Conversely, bad sleepers showed lower sleep continuity (awakenings frequency), stability (e.g. arousals and state transitions frequency) and organization (e.g. number of sleep cycles and time spent in cycles). Our findings point to the involvement of these measures in determining habitual sleep quality perception and suggest the possibility to include them in standard sleep assessments.

Changes in chronic neck pain following the introduction of a visco-elastic polyurethane foam pillow and/or chiropractic treatment

Background

Sleep ergonomics are increasingly prescribed as an adjunct treatment to chronic neck pain. Postulated benefits to maintaining the ideal sleeping posture are improved tissue repair in and around the facet joints, decrease in tension of associated musculature and better quality sleep.

Aim

The purpose of this study was to determine if the inclusion of a visco-elastic polyurethane (VEP) pillow could benefit the chiropractic treatment of chronic neck pain.

Setting

The study took place at a chiropractic training clinic in Johannesburg.

Method

Participants were randomly assigned to either a chiropractic treatment only group (CHI) (n = 15) or a chiropractic treatment with a VEP pillow group (CHI+P) (n = 15). Both groups underwent six chiropractic treatments spaced at 3-4-day intervals and the CHI+P were provided with a VEP pillow. Baseline and post-test measurements consisted of the initial Numerical Pain Rating Scale (NRS) and the Vernon-Mior Neck Pain and Disability Index (NDI).

Results

Both the CHI and CHI+P groups significantly (p ≤ 0.05) improved their NRS (p = 0.001 for both groups) and NDI (p = 0.001 and p = 0.000, respectively) scores. Furthermore, post hoc analysis indicated a significant difference at post-test between the two groups for NRS (p = 0.015), but not for NDI (p = 0.195). The CHI+P demonstrated an improved minimum clinically important difference (MCID) (43% vs. 73% for NRS and 59% vs. 71% for the NDI).

Conclusion

Findings of this study suggest that a VEP pillow could be included as an adjunct management tool to chiropractic treatment of chronic neck pain.

The Effect of Cognitive Activity on Sleep Maintenance in a Subsequent Daytime Nap

Background/Objective: The aim of this study is to assess the effects of a learning task on the characteristics of a subsequent daytime nap. Participants and Methods: Thirty-eight subjects were administered a control nap (C) and one preceded by a cognitive training session (TR). Results: Relative to C, TR naps showed significantly increased sleep duration with decreased sleep latency, as well as significantly increased sleep efficiency due to reduced awakening frequency. Meaningful trends were also found toward an increase of Stage 2 sleep proportion and a reduction of Stage 1 sleep, percentage of wake after sleep onset (WASO), and frequency of state transitions. Conclusions: Our results indicate that presleep learning favors sleep propensity and maintenance, offering the possibility to explore planned cognitive training as a low-cost treatment for sleep impairments.

Rapid eye movement fragmentation, not slow-wave sleep, predicts neutral declarative memory consolidation in posttraumatic stress disorder

Individuals diagnosed with posttraumatic stress disorder (PTSD) experience disruption at both slow-wave sleep (SWS) and rapid-eye movement (REM) sleep stages and demonstrate marked memory impairment. A small group of studies suggests that, within the disorder, there is a mechanistic relation between these sleep and memory impairments. This study sought to extend that literature by examining whether, in PTSD-diagnosed individuals, memory-retention deficits are present after a sleep-filled (but not after a wake-filled) delay (i.e., whether memory deficits can be traced to interruptions of sleep-dependent memory consolidation). Moreover, we investigated whether SWS- or REM-based disturbances, or both, contribute to retention deficits. We recruited participants into three groups: PTSD (n = 21), trauma-exposed non-PTSD (TE; n = 19) and healthy control (HC; n = 20). Using a crossover design, we assessed memory recall before and after an 8-hr period of polysomnography-monitored sleep and an 8-hr period of regular waking activity. PTSD-diagnosed participants retained less information than controls over the sleep-filled (but not wake-filled) delay. Furthermore, increased REM fragmentation predicted postsleep memory retention in PTSD-diagnosed individuals only. No SWS parameter was associated with or predictive of the amount of information retained postsleep. We conclude that specific REM-related changes in PTSD-diagnosed individuals affected sleep-dependent neutral declarative memory consolidation. Generally, these findings extend the literature suggesting that the co-occurrence of sleep and memory difficulties in PTSD is not accidental, but that these two symptom clusters are meaningfully related. Specifically, the study illustrates that subtle REM-related disruptions contribute most strongly to memory impairment in PTSD.

Modelling PTSD diagnosis using sleep, memory, and adrenergic metabolites: An exploratory machine-learning study

OBJECTIVE

Features of posttraumatic stress disorder (PTSD) typically include sleep disturbances, impaired declarative memory, and hyperarousal. This study evaluated whether these combined features may accurately delineate pathophysiological changes associated with PTSD.

METHOD

We recruited a cohort of PTSD-diagnosed individuals (N = 20), trauma survivors without PTSD (TE; N = 20), and healthy controls (HC; N = 20). Analyses of between-group differences and support vector machine (SVM)-learning were applied to participant features.

RESULTS

Analyses of between-group differences replicated previous findings, indicating that PTSD-diagnosed individuals self-reported poorer sleep quality, objectively demonstrated less sleep depth, and evidenced declarative memory deficits in comparison to HC. Integrative SVM-learning distinguished HC from trauma participants with 80% accuracy using a combination of five features, including subjective and objective sleep, neutral declarative memory, and metabolite variables. PTSD and TE participants could be distinguished with 70% accuracy using a combination of subjective and objective sleep variables but not by metabolite or declarative memory variables.

CONCLUSION

From among a broad range of sleep, cognitive, and biochemical variables, sleep characteristics were the primary features that could differentiate those with PTSD from those without. Our exploratory SVM-learning analysis establishes a framework for future sleep- and memory-based PTSD investigations that could drive improvements in diagnostic accuracy and treatment.

The interplay between neuroendocrine and sleep alterations following traumatic brain injury

BACKGROUND

Sleep and endocrine disruptions are prevalent after traumatic brain injury (TBI) and are likely to contribute to morbidity.

OBJECTIVE

To describe the interaction between sleep and hormonal regulation following TBI and elucidate the impact that alterations of these systems have on cognitive responses during the posttraumatic chronic period.

METHODS

Review of preclinical and clinical literature describing long-lasting endocrine dysregulation and sleep alterations following TBI. The bidirectional relationship between sleep and hormones is described. Literature describing co-occurrence between sleep-wake disturbances and hormonal dysregulation will be presented. Review of literature describing cognitive effects of seep and hormones. The cognitive and functional impact of sleep disturbances and hormonal dysregulation is discussed within the context of TBI.

RESULTS/CONCLUSIONS

Sleep and hormonal alterations impact cognitive and functional outcome after TBI. Diagnosis and treatment of these disturbances will impact recovery following TBI and should be considered in the post-acute rehabilitative setting.

Untangling PTSD and TBI: Challenges and Strategies in Clinical Care and Research

PURPOSE OF REVIEW

Traumatic brain injury (TBI) and post-traumatic stress disorder (PTSD) can result from similar injuries and can result in similar symptoms, such as problems with sleep, concentration, memory, and mood. Although PTSD and persistent sequelae due to a TBI (PST) have generally been viewed as pragmatically confounded but conceptually separable entities, we examine emerging evidence emphasizing the breadth of overlap in both clinical presentation and underlying pathophysiology between PST and PTSD.

RECENT FINDINGS

New evidence underscores the poor specificity of symptoms to etiology and emphasizes the potential, after both physical brain injury and traumatic stress, for changes in each of the three interacting systems that coordinate the body's response to the experience or expectation of major injury-the immune, endocrine, and neuromodulatory neurotransmitter systems. A view of PTSD and PST sharing common pathophysiologic elements related to the CNS response to acute injury or threat carries important implications for research and clinical care.

Poor Sleep Quality Is Associated with Higher Hemoglobin A1c in Pregnant Women: A Pilot Observational Study

We hypothesized that poor sleep quality exacerbates glucose intolerance manifested as elevated glycosylated hemoglobin (HbA1c), which increases the risk for gestational diabetes. To test this, 38 pregnant and 22 non-pregnant (age, 18–35 years; body-mass index, 20–35 kg/m²) otherwise healthy women were enrolled in the study. Sleep quality was assessed during gestational week 24 (pregnant), or outside of the menstrual period (non-pregnant), using qualitative (Pittsburgh Sleep Quality Index) and objective (actigraphic wrist-watch) measures. Blood glucose, total cortisol, and depression status were evaluated. Eight pregnant and one non-pregnant women were lost to follow-up, or withdrew from the study. There was a higher incidence of poor sleep quality in pregnant (73%) relative to non-pregnant women (43%). Although actigraphic data revealed no differences in actual sleep hours between pregnant and non-pregnant women, the number of wake episodes and sleep fragmentation were higher in pregnant women. Poor sleep quality was positively correlated with higher HbA1c in both pregnant (r = 0.46, n = 26, p = 0.0151) and non-pregnant women (r = 0.50, n = 19, p = 0.0217), reflecting higher average blood glucose concentrations. In contrast, poor sleep was negatively correlated with cortisol responses in pregnant women (r = −0.46, n = 25, p = 0.0167). Three pregnant women had elevated one-hour oral glucose tolerance test results (>153 mg/dL glucose). These same pregnant women exhibited poor sleep quality. These results support the suggestion that poor sleep quality is an important risk factor that is associated with glucose intolerance and attendant health complications in pregnancy.

REM deprivation but not sleep fragmentation produces a sex-specific impairment in extinction

REM sleep is essential for learning and memory processes, particularly emotional learning. Manipulations of REM sleep impair learning and memory and sleep architecture is often altered following a learning experience; for example, short term REM deprivation immediately after fear conditioning results in impaired extinction. In light of research demonstrating sex-dependent differences in fear conditioning as well as differences in sleep architecture, the present study investigated the effects of short term REM deprivation on the extinction of conditioned fear in male and female rats. In addition, given evidence that sleep fragmentation, which is a consequence of REM deprivation, can negatively impact learning and memory, this manipulation was compared to REM deprivation and a control condition. Male and female rats were exposed to fear conditioning followed by 6 h of REM deprivation, sleep fragmentation, or a control condition. Two extinction sessions were conducted at 48 h intervals after conditioning. REM deprivation, but not sleep fragmentation or the control condition, impaired extinction of conditioned fear. However, this effect was seen only in male rats. This study is the first to explore the effects of sleep manipulations on memory in female rats and suggests that female rats are more resilient to the deleterious effects of REM deprivation. In addition, it demonstrates that REM deprivation but not fragmentation of sleep is responsible for impairment in extinction of conditioned fear.

Medial temporal lobe atrophy relates more strongly to sleep-wake rhythm fragmentation than to age or any other known risk

Atrophy of the medial temporal lobe of the brain is key to memory function and memory complaints in old age. While age and some morbidities are major risk factors for medial temporal lobe atrophy, individual differences remain, and mechanisms are insufficiently known. The largest combined neuroimaging and whole genome study to date indicates that medial temporal lobe volume is most associated with common polymorphisms in the GRIN2B gene that encodes for the 2B subunit (NR2B) of the NMDA receptor. Because sleep disruption induces a selective loss of NR2B from hippocampal synaptic membranes in rodents, and because of several other reports on medial temporal lobe sensitivity to sleep disruption, we hypothesized a contribution of the typical age-related increase in sleep-wake rhythm fragmentation to medial temporal lobe atrophy. Magnetic resonance imaging and actigraphy in 138 aged individuals showed that individual differences in sleep-wake rhythm fragmentation accounted for more (19%) of the variance in medial temporal lobe atrophy than age did (15%), or any of a list of health and brain structural indicators. The findings suggest a role of sleep-wake rhythm fragmentation in age-related medial temporal lobe atrophy, that might in part be prevented or reversible.

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.

Neuroendocrine Regulation of Growth Hormone Secretion

This article reviews the main findings that emerged in the intervening years since the previous volume on hormonal control of growth in the section on the endocrine system of the Handbook of Physiology concerning the intra- and extrahypothalamic neuronal networks connecting growth hormone releasing hormone (GHRH) and somatostatin hypophysiotropic neurons and the integration between regulators of food intake/metabolism and GH release. Among these findings, the discovery of ghrelin still raises many unanswered questions. One important event was the application of deconvolution analysis to the pulsatile patterns of GH secretion in different mammalian species, including Man, according to gender, hormonal environment and ageing. Concerning this last phenomenon, a great body of evidence now supports the role of an attenuation of the GHRH/GH/Insulin-like growth factor-1 (IGF-1) axis in the control of mammalian aging.

Bone Age and Serum Osteocalcin Levels in Children With Obstructive Sleep Apnea Hypopnea Syndrome Before and After Adenotonsillectomy

Our aim was to study the changes in bone age and serum osteocalcin levels before and after adenotonsillectomy (AT) in children with obstructive sleep apnea hypopnea syndrome (OSAHS). A total of 58 OSAHS children (37 males and 21 females) with the mean age of 6.68 ± 1.11 years were enrolled and assessed by x-ray-based bone age estimation and enzyme-linked immunosorbent assay-based measurement of serum osteocalcin levels, before surgery and 6 months after AT. SPSS 19.0 software was used for statistical analysis. Our results revealed that bone age and serum osteocalcin levels in OSAHS patients were significantly lower than normal controls before AT (P < 0.05). Within 6 months after surgery, the bone age and the serum osteocalcin levels were significantly elevated in OSAHS patients (P < 0.05), compared with those before surgery. Serum osteocalcin levels and bone age are negatively correlated with apnea-hypopnea index, oxygen desaturation index, the percentage of the total recorded time spent below 90% oxygen saturation, and Epworth sleepiness scale scores (all P < 0.05). Our findings suggested that bone age and serum osteocalcin levels may be correlated with the development of OSAHS in children. AT may improve bone age and serum osteocalcin levels in OSAHS children.

Altered gene expression of the innate immune, neuroendocrine, and nuclear factor-kappa B (NF-κB) systems is associated with posttraumatic stress disorder in military personnel

Whole transcriptome analysis provides an unbiased examination of biological activity, and likely, unique insight into the mechanisms underlying posttraumatic stress disorder (PTSD) and comorbid depression and traumatic brain injury. This study compared gene-expression profiles in military personnel with PTSD (n=28) and matched controls without PTSD (n=27) using HG-U133 Plus 2.0 microarrays (Affymetrix), which contain 54,675 probe sets representing more than 38,500 genes. Analysis of expression profiles revealed 203 differentially expressed genes in PTSD, of which 72% were upregulated. Using Partek Genomics Suite 6.6, differentially expressed transcription clusters were filtered based on a selection criterion of ≥1.5 relative fold change at a false discovery rate of ≤5%. Ingenuity Pathway Analysis (Qiagen) of the differentially expressed genes indicated a dysregulation of genes associated with the innate immune, neuroendocrine, and NF-κB systems. These findings provide novel insights that may lead to new pharmaceutical agents for PTSD treatments and help mitigate mental and physical comorbidity risk.

A systematic review of sleep disturbance in anxiety and related disorders

Recent research suggests that sleep disturbance may be a transdiagnostic process, and there is increasing interest in examining how sleep disturbance may contribute to anxiety and related disorders. The current review summarizes and synthesizes the extant research assessing sleep in anxiety and related disorders. The findings suggest that sleep disturbance exacerbates symptom severity in the majority of anxiety and related disorders. However, the nature of sleep disturbance often varies as a function of objective versus subjective assessment. Although sleep disturbance is a correlate of most anxiety and related disorders, a causal role for sleep disturbance is less clear. A model of potential mechanisms by which sleep disturbance may confer risk for the development of anxiety and related disorders is discussed. Future research integrating findings from basic sleep research with current knowledge of anxiety and related disorders may facilitate the development of novel treatments for comorbid sleep disturbance and clinical anxiety.

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.

Growth hormone deficiency after mild combat-related traumatic brain injury

OBJECTIVE

Traumatic brain injury (TBI) has been recognized as a cause of growth hormone deficiency (GHD) in civilians. However, comparable data are sparse in veterans who incurred TBI during combat. Our objective was to determine the prevalence of GHD in veterans with a history of combat-related TBI, and its association with cognitive and psychosocial dysfunction.

DESIGN

Single center prospective study.

PATIENTS

Twenty male veterans with mild TBI incurred during combat 8-72 months prior to enrollment.

MEASUREMENTS

GHD was defined by a GH peak <3 μg/L during glucagon stimulation test. Differences in neuropsychological, emotional, and quality of life of the GHD Veterans were described using Cohen's d. Large effect sizes were considered meaningful.

RESULTS

Mean age was 33.7 years (SD 7.8) and all subjects had normal thyroid hormone and cortisol levels. Five (25%) exhibited a subnormal response to glucagon. Sixteen participants (80%) provided sufficient effort for valid neuropsychological assessment (12 GH-sufficient, 4 GHD). There were large effect size differences in self-monitoring during memory testing (d = 1.46) and inhibitory control (d = 0.92), with worse performances in the GHD group. While fatigue and post-traumatic stress disorder were comparable, the GHD group reported more depression (d = 0.80) and lower quality of life (d = 0.64).

CONCLUSIONS

Our study found a 25% prevalence of GHD in veterans with mild TBI as shown by glucagon stimulation. The neuropsychological findings raise the possibility that GHD has adverse effects on executive abilities and mood. Further studies are needed to determine whether GH replacement is an effective treatment in these patients.

Sleep disturbances, TBI and PTSD: Implications for treatment and recovery

Post-Traumatic Stress Disorder (PTSD), traumatic brain injury (TBI), and sleep problems significantly affect recovery and functional status in military personnel and Veterans returning from combat. Despite recent attention, sleep is understudied in the Veteran population. Few treatments and rehabilitation protocols target sleep, although poor sleep remains at clinical levels and continues to adversely impact functioning even after the resolution of PTSD or mild TBI symptoms. Recent developments in non-pharmacologic sleep treatments have proven efficacious as stand-alone interventions and have potential to improve treatment outcomes by augmenting traditional behavioral and cognitive therapies. This review discusses the extensive scope of work in the area of sleep as it relates to TBI and PTSD, including pathophysiology and neurobiology of sleep; existing and emerging treatment options; as well as methodological issues in sleep measurements for TBI and PTSD. Understanding sleep problems and their role in the development and maintenance of PTSD and TBI symptoms may lead to improvement in overall treatment outcomes while offering a non-stigmatizing entry in mental health services and make current treatments more comprehensive by helping to address a broader spectrum of difficulties.

The role of rapid eye movement sleep for amygdala-related memory processing

Over the years, rapid eye movement (REM) sleep has been associated with general memory consolidation, specific consolidation of perceptual, procedural, emotional and fear memories, brain maturation and preparation of waking consciousness. More recently, some of these associations (e.g., general and procedural memory consolidation) have been shown to be unlikely, while others (e.g., brain maturation and consciousness) remain inconclusive. In this review, we argue that both behavioral and neurophysiological evidence supports a role of REM sleep for amygdala-related memory processing: the amygdala-hippocampus-medial prefrontal cortex network involved in emotional processing, fear memory and valence consolidation shows strongest activity during REM sleep, in contrast to the hippocampus-medial prefrontal cortex only network which is more active during non-REM sleep. However, more research is needed to fully understand the mechanisms.

The impact of sleep and circadian disturbance on hormones and metabolism

The levels of several hormones fluctuate according to the light and dark cycle and are also affected by sleep, feeding, and general behavior. The regulation and metabolism of several hormones are influenced by interactions between the effects of sleep and the intrinsic circadian system; growth hormone, melatonin, cortisol, leptin, and ghrelin levels are highly correlated with sleep and circadian rhythmicity. There are also endogenous circadian mechanisms that serve to regulate glucose metabolism and similar rhythms pertaining to lipid metabolism, regulated through the actions of various clock genes. Sleep disturbance, which negatively impacts hormonal rhythms and metabolism, is also associated with obesity, insulin insensitivity, diabetes, hormonal imbalance, and appetite dysregulation. Circadian disruption, typically induced by shift work, may negatively impact health due to impaired glucose and lipid homeostasis, reversed melatonin and cortisol rhythms, and loss of clock gene rhythmicity.

Sleep fragmentation and false memories during pregnancy and motherhood

Pregnant women, both before and after childbirth, frequently experience memory deficits and disrupted sleep. In the present study we assessed the relationship between false memory generation and fragmented sleep during pregnancy and motherhood. We tested 178 pregnant women and 58 female non-pregnant childless controls, during pregnancy (15-35th week of gestation) and again after childbirth (8-13th month). False memories were defined as memories of gist words that were semantically related to studied word lists but were not presented during learning of these lists in the Deese-Roediger-McDermott (DRM) paradigm. Sleep was monitored by actigraphy in the home environment for seven consecutive nights. Compared to the controls, the group of pregnant women produced more false memories and displayed more fragmented sleep both during pregnancy and after childbirth. However, false memory generation was not correlated to measures of sleep fragmentation. These results show that pregnant women suffer from sleep fragmentation and a higher susceptibility to false memories, but leave open the question as to whether both phenomena are related.

Disrupted rapid eye movement sleep predicts poor declarative memory performance in post-traumatic stress disorder

Successful memory consolidation during sleep depends on healthy slow-wave and rapid eye movement sleep, and on successful transition across sleep stages. In post-traumatic stress disorder, sleep is disrupted and memory is impaired, but relations between these two variables in the psychiatric condition remain unexplored. We examined whether disrupted sleep, and consequent disrupted memory consolidation, is a mechanism underlying declarative memory deficits in post-traumatic stress disorder. We recruited three matched groups of participants: post-traumatic stress disorder (n = 16); trauma-exposed non-post-traumatic stress disorder (n = 15); and healthy control (n = 14). They completed memory tasks before and after 8 h of sleep. We measured sleep variables using sleep-adapted electroencephalography. Post-traumatic stress disorder-diagnosed participants experienced significantly less sleep efficiency and rapid eye movement sleep percentage, and experienced more awakenings and wake percentage in the second half of the night than did participants in the other two groups. After sleep, post-traumatic stress disorder-diagnosed participants retained significantly less information on a declarative memory task than controls. Rapid eye movement percentage, wake percentage and sleep efficiency correlated with retention of information over the night. Furthermore, lower rapid eye movement percentage predicted poorer retention in post-traumatic stress disorder-diagnosed individuals. Our results suggest that declarative memory consolidation is disrupted during sleep in post-traumatic stress disorder. These data are consistent with theories suggesting that sleep benefits memory consolidation via predictable neurobiological mechanisms, and that rapid eye movement disruption is more than a symptom of post-traumatic stress disorder.

Pituitary dysfunction after blast traumatic brain injury: The UK BIOSAP study

OBJECTIVE

Pituitary dysfunction is a recognized consequence of traumatic brain injury (TBI) that causes cognitive, psychological, and metabolic impairment. Hormone replacement offers a therapeutic opportunity. Blast TBI (bTBI) from improvised explosive devices is commonly seen in soldiers returning from recent conflicts. We investigated: (1) the prevalence and consequences of pituitary dysfunction following moderate to severe bTBI and (2) whether it is associated with particular patterns of brain injury.

METHODS

Nineteen male soldiers with moderate to severe bTBI (median age = 28.3 years) and 39 male controls with moderate to severe nonblast TBI (nbTBI; median age = 32.3 years) underwent full dynamic endocrine assessment between 2 and 48 months after injury. In addition, soldiers had structural brain magnetic resonance imaging, including diffusion tensor imaging (DTI), and cognitive assessment.

RESULTS

Six of 19 (32.0%) soldiers with bTBI, but only 1 of 39 (2.6%) nbTBI controls, had anterior pituitary dysfunction (p = 0.004). Two soldiers had hyperprolactinemia, 2 had growth hormone (GH) deficiency, 1 had adrenocorticotropic hormone (ACTH) deficiency, and 1 had combined GH/ACTH/gonadotrophin deficiency. DTI measures of white matter structure showed greater traumatic axonal injury in the cerebellum and corpus callosum in those soldiers with pituitary dysfunction than in those without. Soldiers with pituitary dysfunction after bTBI also had a higher prevalence of skull/facial fractures and worse cognitive function. Four soldiers (21.1%) commenced hormone replacement(s) for hypopituitarism.

INTERPRETATION

We reveal a high prevalence of anterior pituitary dysfunction in soldiers suffering moderate to severe bTBI, which was more frequent than in a matched group of civilian moderate to severe nbTBI subjects. We recommend that all patients with moderate to severe bTBI should routinely have comprehensive assessment of endocrine function.

Animal models of post-traumatic stress disorder: face validity

Post-traumatic stress disorder (PTSD) is a debilitating condition that develops in a proportion of individuals following a traumatic event. Despite recent advances, ethical limitations associated with human research impede progress in understanding PTSD. Fortunately, much effort has focused on developing animal models to help study the pathophysiology of PTSD. Here, we provide an overview of animal PTSD models where a variety of stressors (physical, psychosocial, or psychogenic) are used to examine the long-term effects of severe trauma. We emphasize models involving predator threat because they reproduce human individual differences in susceptibility to, and in the long-term consequences of, psychological trauma.

Sympathetic activity and hypothalamo-pituitary-adrenal axis activity during sleep in post-traumatic stress disorder: a study assessing polysomnography with simultaneous blood sampling

BACKGROUND

Nightmares and insomnia in PTSD are hallmark symptoms, yet poorly understood in comparison to the advances toward a biological framework for the disorder. According to polysomnography (PSG), only minor changes in sleep architecture were described. This warrants alternative methods for assessing sleep regulation in PTSD.

METHODS

After screening for obstructive sleep apnea and period limb movement disorder, veterans with PTSD (n=13), trauma controls (TCs, n=17) and healthy controls (HCs, n=15) slept in our sleep laboratory on two consecutive nights with an IV catheter out of which blood was sampled every 20min from 22:00h to 08:00h. Nocturnal levels of plasma adrenocorticotropic hormone (ACTH), cortisol, melatonin were assessed in conjunction with PSG registration, as well as subjective sleep parameters.

RESULTS

PTSD patients showed a significant increase in awakenings during sleep in comparison to both control groups. These awakenings were correlated with ACTH levels during the night, and with the subjective perception of sleep depth. Also, heart rate (HR) was significantly increased in PTSD patients as compared with both control groups. The diurnal regulation of ACTH, cortisol and melatonin appeared undisturbed. PTSD patients exhibited lower cortisol levels at borderline significance (p=0.056) during the first half of the night. ACTH levels and cortisol levels during the first half of the night were inversely related to slow wave sleep (SWS).

CONCLUSION

This study suggests that hypothalamo-pituitary-adrenal (HPA) axis activity is related to sleep fragmentation in PTSD. Also, activity of the sympathetic nervous system (SNS) is increased during sleep in PTSD. Further research is necessary to explore the potential causal relationship between sleep problems and the activity of the HPA-axis and SNS in PTSD.

The effects of pre-sleep learning on sleep continuity, stability, and organization in elderly individuals

Several studies have consistently shown that pre-sleep learning is associated to changes of sleep structure. Whereas previous research has mainly focused on sleep states, namely REM and NREM amount, very little attention has been paid to the hypothesis that pre-sleep learning might improve sleep continuity, stability, and cyclic organization, which are often impaired in aging. Thus, aim of this research was to assess, in a sample of 18 healthy elderly subjects, whether a memory task administered at bedtime would determine changes in any sleep parameter, with special regard to sleep continuity, stability, and organization. To this purpose, a baseline sleep (BL), i.e., a normal sleep with 9-h time in bed (TIB), was compared to a post-training sleep (TR), with the same TIB but preceded by an intensive training session. For the latter, a verbal declarative task was used, consisting in learning paired-word lists, rehearsed, and recalled for three times in a row. To control for individual learning abilities, subjects were administered several sets of lists with increasing difficulty, until they reached an error rate ≥20% at third recall. Relative to BL, TR shows a significant reduction in the frequency of brief awakenings, arousals, state transitions, "functional uncertainty" (FU) periods, and in the percentage of time in FU over total sleep time (TST). A significant increase in the number of complete cycles, total cycle time (TCT), and TCT/TST proportion was also found. All these changes are evenly distributed over the sleep episode. No sleep stage measure display significant changes, apart from a slight reduction in the percentage of Stage 1. Scores at retest are negatively correlated with both the frequency of arousals and of state transitions. Our data suggest that pre-sleep learning can yield a beneficial re-organizing effect on elderlies' sleep quality. The inverse correlation between recall scores and the measures of sleep continuity and stability provides further support to the role of these features in memory processes.

Obstructive sleep apnea in combat-related posttraumatic stress disorder: a controlled polysomnography study

BACKGROUND

Obstructive sleep apnea (OSA) may be highly prevalent in posttraumatic stress disorder (PTSD) and may exacerbate PTSD complaints.

OBJECTIVE

Our objective was to determine whether the prevalence of OSA was high in a sample of Dutch veterans with PTSD as compared to age- and trauma-matched controls, and whether OSA was associated with more severe PTSD complaints.

METHODS

We determined the apnea hypopnea indices (AHI) with polysomnographic registrations in 20 veterans with PTSD, 24 veterans without PTSD, and 17 healthy controls. PTSD severity and nightmare complaints were assessed with the Clinician-Administered PTSD Scale (CAPS).

RESULTS

The prevalence of an AHI>10 was 29% in PTSD, 21% in trauma controls, and 29% in healthy controls (χ(2)= 0.60, df=2, p=n.s.). The mean CAPS score in patients with OSA (n=6) was significantly higher than in patients without OSA (p<0.05), while nightmare severity was similar in PTSD patients with OSA as compared to PTSD patients without OSA (p=n.s.). Furthermore, there was a significant correlation between AHI and CAPS score in PTSD patients (r=0.46, p<0.05, df=14).

CONCLUSIONS

Our results indicate that PTSD is not necessarily associated with a higher prevalence of OSA. However, PTSD severity was related to OSA, which may possibly mean that comorbid OSA leads to an increase in PTSD complaints. However, future research should indicate whether OSA exerts a negative influence on PTSD, and treatment of OSA alleviates PTSD symptoms.