The interplay of hypoxic and mental stress: Implications for anxiety and depressive disorders

Therapeutic targeting of hypoxia inducible factor in acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is characterized by bilateral chest infiltration and acute hypoxic respiratory failure. ARDS carries significant morbidity and mortality despite advancements in medical management, calling for the development of novel therapeutic targets. Hypoxia-inducible factor (HIF) is a heterodimeric protein involved in various essential pathways, including metabolic reprogramming, immune modulation, angiogenesis and cell cycle regulation. HIF is routinely degraded in homeostasis conditions via the prolyl hydroxylase domain/von Hippel-Lindau protein pathway. However, HIF is stabilized in ARDS via various mechanisms (oxygen-dependent and independent) as an endogenous protective pathway and plays multifaceted roles in different cell populations. This review focuses on the functional role of HIF and its target genes during ARDS, as well as how HIF has evolved as a therapeutic target in current medical management.

Mechanisms underlying the health benefits of intermittent hypoxia conditioning

Intermittent hypoxia (IH) is commonly associated with pathological conditions, particularly obstructive sleep apnoea. However, IH is also increasingly used to enhance health and performance and is emerging as a potent non-pharmacological intervention against numerous diseases. Whether IH is detrimental or beneficial for health is largely determined by the intensity, duration, number and frequency of the hypoxic exposures and by the specific responses they engender. Adaptive responses to hypoxia protect from future hypoxic or ischaemic insults, improve cellular resilience and functions, and boost mental and physical performance. The cellular and systemic mechanisms producing these benefits are highly complex, and the failure of different components can shift long-term adaptation to maladaptation and the development of pathologies. Rather than discussing in detail the well-characterized individual responses and adaptations to IH, we here aim to summarize and integrate hypoxia-activated mechanisms into a holistic picture of the body's adaptive responses to hypoxia and specifically IH, and demonstrate how these mechanisms might be mobilized for their health benefits while minimizing the risks of hypoxia exposure.

Long-Term Mental Health Outcomes of Bronchopulmonary Dysplasia in Neonates: An 18-Year National Cohort Study

OBJECTIVE

To evaluate the association between neonatal bronchopulmonary dysplasia and the subsequent development of mental health conditions in children and adolescents.

STUDY DESIGN

This was a retrospective cohort study, utilizing data from individuals born in South Korea between 2002 and 2005 and followed up until 2021, using the National Health Insurance Database. The cohort included 1,893,314 participants born during that period, with 927 diagnosed with bronchopulmonary dysplasia during the neonatal period (the exposed cohort). They were matched 1:10 with 9,270 unexposed individuals (the unexposed cohort) based on key demographic factors.

RESULTS

The median age at the first mental health disorder diagnosis was 9 years (interquartile range, 5-15 years), with 5,698 individuals (55.9%) being male. During an average follow-up of 15.2 years, the incidence rate was 481/10,000 person-years in the exposed and 138/10,000 person-years in the unexposed cohort. By the age of 18 years, the cumulative incidence in the exposed cohort was 54% (95% confidence interval [CI]; 50%-57%), with an adjusted hazard ratio of 3.18 (95% CI; 2.81-3.60) compared with the unexposed cohort, and adjusted hazard ratios for early- and late-onset mental health disorders of 4.48 (95% CI; 3.84-5.22) and 1.89 (95% CI; 1.61-2.22), respectively. Sensitivity analyses confirmed these findings, and a subgroup analysis revealed a higher risk among individuals with bronchopulmonary dysplasia who required prolonged respiratory support or oxygen.

CONCLUSIONS

Half of children with bronchopulmonary dysplasia in our cohort developed mental health disorders by the age of 18 years, emphasizing the need for interventions and support for such individuals.

Brain-derived neurotrophic factor modulation in response to oxidative stress and corticosterone: role of scopolamine and mirtazapine

Major Depressive Disorder (MDD) is a very complex disease, challenging to study and manage. The complexities of MDD require extensive research of its mechanisms to develop more effective therapeutic approaches. Crucial in the context of this disease is the role of brain-derived neurotrophic factor (BDNF) signaling pathway.

AIM

This manuscript aims to explore the complex relationship between MDD and BDNF signaling pathway, focusing on how BDNF is modulated in response to oxidative stress and corticosterone, known to be altered in MDD and contributing to the pathology of the disorder, when treated with scopolamine and mirtazapine.

METHODS

To assess BDNF levels after the different treatment conditions, rat hippocampal slices and mice primary hippocampus and cortical cell culture were analyzed by immunofluorescence and Western blot.

KEY FINDINGS

Both mirtazapine and scopolamine under stress conditions induced by hydrogen peroxide (H2O2) and corticosterone, had a significant impact on BDNF levels, and this was distinct in different neuronal models. Mirtazapine, especially when combined with H2O2, altered BDNF expression. Scopolamine when combined with both stressors also altered BDNF levels. However, its effects varied depending on the specific neuronal model and stress condition. In accordance with BDNF results, phosphorylated tropomyosin receptor kinase B (pTrkB) presented increased activation when neuronal cells subjected to stress were treated with mirtazapine or scopolamine.

SIGNIFICANCE

Collectively, this study highlights the complex connection between these compounds, stress conditions, and BDNF/TrkB modulation, supporting the potential therapeutic effects of scopolamine and mirtazapine in modulating BDNF levels, even in stressful conditions.

Is it Possible for Individuals with Pre-Existing Mental Disorders to Perform Mountain Sports at High Altitude-First Evidence from a Pilot Cross-Sectional Questionnaire Study

Gstir, Claudia, Timo Schurr, Roxana Ehlers, Johannes Burtscher, Barbara Sperner-Unterweger, and Katharina Hüfner. Is it possible for individuals with pre-existing mental disorders to perform mountain sports at high altitude-First evidence from a pilot cross-sectional questionnaire study. High Alt Med Biol. 00:00-00, 2024. Introduction: Mountain sports at high altitude (HA) are gaining increasing popularity, but little is known about the effect of such activities on mental health, despite a great prevalence of mental disorders. Methods: Data were collected using an online self-report questionnaire assessing mental and somatic disorders in individuals performing mountain sports at HA (>2,500 m above sea level [ASL]) as well as their symptom change. Nonparametric tests were used for analyses. Results: 251 individuals without pre-existing disorders (noD), 34 with somatic disorders (somaD), and 38 with mental disorders (mentalD; mainly depressive, eating, and anxiety disorders) participated in this study. Overall, 44.7% of the mentalD group compared with 14.7% of somaD experienced ameliorated symptoms during mountain sports at HA, while 2.6% and 8.8%, respectively, reported a worsening (χ2[2] =8.13, p = 0.017). People in the mentalD compared with somaD group significantly less frequently inform tour partners (41.9% vs. 90.9%; χ2[2]=16.69, p < 0.001) about their condition or consult their physician (2.6% vs. 26.5%; χ2[1]=8.53, p = 0.003) regarding their plans to perform mountain sports at HA. 14.5% of all participants reported mental symptoms at 2,500-3,500 m ASL, 23.5% between >3,500-5,500 m ASL and 31.8% >5,500 m ASL. Conclusion: Individuals with mental disorders often report improved mental health during mountain sports at HA, possibly due to a combination of physical activity, the alpine natural environment, and/or moderate hypoxia. The fact that tour partners and physicians are rarely informed shows the need to reduce the stigma of mental disorders in the mountain sports community. The study was prospectively registered with the German Clinical Trials Registry (DRKS00024949).

Network Pharmacology and Molecular Docking Analysis of Morinda citrifolia Fruit Metabolites Suggest Anxiety Modulation through Glutamatergic Pathways

The fruit of Morinda citrifolia, also known as the noni tree, has been extensively used in Polynesian culture as an alternative medicine to various diseases. Recent studies have pointed out its anxiolytic activity in vitro and in mouse models. Despite the effectiveness of developed anxiolytic drugs in the market, the potential side effects of these medications have led people to resort to traditional medicine such as M. citrifolia. However, evidence regarding its anti-anxiety characteristics is still lacking to this day. Hence, this preliminary study implemented combined network pharmacology and molecular docking to validate its anti-anxiety claims. This study highlighted the bioactive compounds of the M. citrifolia fruit part to have excellent absorption, distribution, metabolism, excretion, and toxicity (ADMET) properties, particularly their outstanding oral bioavailability and blood-brain barrier penetration, both of which are essential considerations to ensure the effectiveness of anxiolytic drugs to arrive at the site of action. Moreover, noni fruit metabolites target genes involved in glutamatergic synapse pathways, which have been significantly associated with anxiety. Through molecular docking, selected compounds exhibited a strong binding affinity towards GRIA2 and PRKCA, both of which have connections with glutamatergic pathways. With all things considered, the results established that the noni fruit potentially contains therapeutic agents that elicit anti-anxiety potential. Through this, the promotion of a more sustainable, accessible, and affordable treatment of anxiety could be developed.

Adrenergic C1 neurons enhance anxiety via projections to PAG

Anxiety is an emotional state precipitated by the anticipation of real or potential threats. Anxiety disorders are the most prevalent psychiatric illnesses globally and increase the risk of developing comorbid conditions that negatively impact the brain and body. The etiology of anxiety disorders remains unresolved, limiting improvement of therapeutic strategies to alleviate anxiety-related symptoms with increased specificity and efficacy. Here, we applied novel intersectional tools to identify a discrete population of brainstem adrenergic neurons, named C1 cells, that promote aversion and anxiety-related behaviors via projections to the periaqueductal gray matter (PAG). While C1 cells have traditionally been implicated in modulation of autonomic processes, rabies tracing revealed that they receive input from brain areas with diverse functions. Calcium-based in vivo imaging showed that activation of C1 cells enhances excitatory responses in vlPAG, activity that is exacerbated in times of heightened stress. Furthermore, inhibition of C1 cells impedes the development of anxiety-like behaviors in response to stressful situations. Overall, these findings suggest that C1 neurons are positioned to integrate complex information from the brain and periphery for the promotion of anxiety-like behaviors.

The effects of long-term high-altitude exposure on cognition: A meta-analysis

Long-term high altitudes (HA) exposure's impact on cognition has yielded inconsistent findings in previous research. To address this, we conducted a meta-analysis of 49 studies (6191 individuals) to comprehensively evaluate this effect. Moderating factors such as cognitive task type, altitude (1500-2500 m, 2500-4000 m, and above 4000 m), residential type (chronic and lifelong), adaptation level and demographic factors were analyzed. Cognitive tasks were classified into eight categories: perceptual processes, psychomotor function, long-term memory, working memory, inhibitory control, problem-solving, language, and others. Results revealed a moderate negative effect of HA on cognitive performance (g = -.40, SE =.18, 95% CI = -.76 to -.05). Psychomotor function and long-term memory notably experience the most pronounced decline, while working memory and language skills show moderate decreases due to HA exposure. However, perceptual processes, inhibitory control, and problem-solving abilities remain unaffected. Moreover, residing at altitudes above 4000 m and being a HA immigrant are associated with significant cognitive impairment. In summary, our findings indicate a selective adaptation of cognitive performance to HA conditions.

Mitochondrial dysfunction: mechanisms and advances in therapy

Mitochondria, with their intricate networks of functions and information processing, are pivotal in both health regulation and disease progression. Particularly, mitochondrial dysfunctions are identified in many common pathologies, including cardiovascular diseases, neurodegeneration, metabolic syndrome, and cancer. However, the multifaceted nature and elusive phenotypic threshold of mitochondrial dysfunction complicate our understanding of their contributions to diseases. Nonetheless, these complexities do not prevent mitochondria from being among the most important therapeutic targets. In recent years, strategies targeting mitochondrial dysfunction have continuously emerged and transitioned to clinical trials. Advanced intervention such as using healthy mitochondria to replenish or replace damaged mitochondria, has shown promise in preclinical trials of various diseases. Mitochondrial components, including mtDNA, mitochondria-located microRNA, and associated proteins can be potential therapeutic agents to augment mitochondrial function in immunometabolic diseases and tissue injuries. Here, we review current knowledge of mitochondrial pathophysiology in concrete examples of common diseases. We also summarize current strategies to treat mitochondrial dysfunction from the perspective of dietary supplements and targeted therapies, as well as the clinical translational situation of related pharmacology agents. Finally, this review discusses the innovations and potential applications of mitochondrial transplantation as an advanced and promising treatment.

Recommendations for Women in Mountain Sports and Hypoxia Training/Conditioning

The (patho-)physiological responses to hypoxia are highly heterogeneous between individuals. In this review, we focused on the roles of sex differences, which emerge as important factors in the regulation of the body's reaction to hypoxia. Several aspects should be considered for future research on hypoxia-related sex differences, particularly altitude training and clinical applications of hypoxia, as these will affect the selection of the optimal dose regarding safety and efficiency. There are several implications, but there are no practical recommendations if/how women should behave differently from men to optimise the benefits or minimise the risks of these hypoxia-related practices. Here, we evaluate the scarce scientific evidence of distinct (patho)physiological responses and adaptations to high altitude/hypoxia, biomechanical/anatomical differences in uphill/downhill locomotion, which is highly relevant for exercising in mountainous environments, and potentially differential effects of altitude training in women. Based on these factors, we derive sex-specific recommendations for mountain sports and intermittent hypoxia conditioning: (1) Although higher vulnerabilities of women to acute mountain sickness have not been unambiguously shown, sex-dependent physiological reactions to hypoxia may contribute to an increased acute mountain sickness vulnerability in some women. Adequate acclimatisation, slow ascent speed and/or preventive medication (e.g. acetazolamide) are solutions. (2) Targeted training of the respiratory musculature could be a valuable preparation for altitude training in women. (3) Sex hormones influence hypoxia responses and hormonal-cycle and/or menstrual-cycle phases therefore may be factors in acclimatisation to altitude and efficiency of altitude training. As many of the recommendations or observations of the present work remain partly speculative, we join previous calls for further quality research on female athletes in sports to be extended to the field of altitude and hypoxia.

Hypoxia Sensing and Responses in Parkinson's Disease

Parkinson's disease (PD) is associated with various deficits in sensing and responding to reductions in oxygen availability (hypoxia). Here we summarize the evidence pointing to a central role of hypoxia in PD, discuss the relation of hypoxia and oxygen dependence with pathological hallmarks of PD, including mitochondrial dysfunction, dopaminergic vulnerability, and alpha-synuclein-related pathology, and highlight the link with cellular and systemic oxygen sensing. We describe cases suggesting that hypoxia may trigger Parkinsonian symptoms but also emphasize that the endogenous systems that protect from hypoxia can be harnessed to protect from PD. Finally, we provide examples of preclinical and clinical research substantiating this potential.

Anxiety, depression, and brain overwork in the general population of Mongolia

In Mongolia, there is limited data on the prevalence and correlates of common mental health conditions. This study addresses this data gap by exploring anxiety, depression, and brain overwork. The aim of this study was to determine normative data on these conditions in the general population of Mongolia. This nationwide, population-based, cross-sectional study was conducted in 48 sampling centers across Mongolia in 2020. A total of 613 participants (190 men and 423 women) with a mean age of 41.8 ± 12.4 years were recruited. The participants completed the Hospital Anxiety and Depression Scale (HADS) and the Brain Overwork Scale (BOS-10). Vital signs, body measurements, and lifestyle determinants were also assessed. The prevalence of anxiety was 9.9%, depression was 4.9%, and brain overwork was 18.3% among the participants. Anxiety and depression were correlated with brain overwork symptoms. Brain overwork was associated with young age, unemployment, low income, and alcohol use. These findings suggest that anxiety, depression, and brain overwork are a significant problem in the general population of Mongolia. Further research is needed to develop effective interventions to reduce the prevalence and risk factors of anxiety, depression, and brain overwork.

Mitochondria as a sensor, a central hub and a biological clock in psychological stress-accelerated aging

The theory that oxidative damage caused by mitochondrial free radicals leads to aging has brought mitochondria into the forefront of aging research. Psychological stress that encompasses many different experiences and exposures across the lifespan has been identified as a catalyst for accelerated aging. Mitochondria, known for their dynamic nature and adaptability, function as a highly sensitive stress sensor and central hub in the process of accelerated aging. In this review, we explore how mitochondria as sensors respond to psychological stress and contribute to the molecular processes in accelerated aging by viewing mitochondria as hormonal, mechanosensitive and immune suborganelles. This understanding of the key role played by mitochondria and their close association with accelerated aging helps us to distinguish normal aging from accelerated aging, correct misconceptions in aging studies, and develop strategies such as exercise and mitochondria-targeted nutrients and drugs for slowing down accelerated aging, and also hold promise for prevention and treatment of age-related diseases.

Onge P, McDonald SM, Hecocks D, Wittels SH. Continuous Physiological Monitoring of the Combined Exposure to Hypoxia and High Cognitive Load in Military Personnel

Military aviators endure high cognitive loads and hypoxic environments during flight operations, impacting the autonomic nervous system (ANS). The synergistic effects of these exposures on the ANS, however, are less clear. This study investigated the simultaneous effects of mild hypoxia and high cognitive load on the ANS in military personnel. This study employed a two-factor experimental design. Twenty-four healthy participants aged between 19 and 45 years were exposed to mild hypoxia (14.0% O2), normoxia (21.0% O2), and hyperoxia (33.0% O2). During each epoch (n = 5), participants continuously performed one 15 min and one 10 min series of simulated, in-flight tasks separated by 1 min of rest. Exposure sequences (hypoxia-normoxia and normoxia-hyperoxia) were separated by a 60 min break. Heart rate (HR), heart rate variability (HRV), and O2 saturation (SpO2) were continuously measured via an armband monitor (Warfighter MonitorTM, Tiger Tech Solutions, Inc., Miami, FL, USA). Paired and independent t-tests were used to evaluate differences in HR, HRV, and SpO2 within and between exposure sequences. Survival analyses were performed to assess the timing and magnitude of the ANS responses. Sympathetic nervous system (SNS) activity during hypoxia was highest in epoch 1 (HR: +6.9 bpm, p = 0.002; rMSSD: -9.7 ms, p = 0.003; SDNN: -11.3 ms, p = 0.003; SpO2: -8.4%, p < 0.0000) and appeared to slightly decline with non-significant increases in HRV. During normoxia, SNS activity was heightened, albeit non-significantly, in epoch 1, with higher HR (68.5 bpm vs. 73.0 bpm, p = 0.06), lower HRV (rMSSD: 45.1 ms vs. 38.7 ms, p = 0.09 and SDNN: 52.5 ms vs. 45.1 ms, p = 0.08), and lower SpO2 (-0.7% p = 0.05). In epochs 2-4, HR, HRV, and SpO2 trended towards baseline values. Significant between-group differences in HR, HRV, and O2 saturation were observed. Hypoxia elicited significantly greater HRs (+5.0, p = 0.03), lower rMSSD (-7.1, p = 0.03), lower SDNN (-8.2, p = 0.03), and lower SpO2 (-1.4%, p = 0.002) compared to normoxia. Hyperoxia appeared to augment the parasympathetic reactivation reflected by significantly lower HR, in addition to higher HRV and O2 relative to normoxia. Hypoxia induced a greater ANS response in military personnel during the simultaneous exposure to high cognitive load. The significant and differential ANS responses to varying O2 levels and high cognitive load observed highlight the importance of continuously monitoring multiple physiological parameters during flight operations.

The role of IL-33 in depression: a systematic review and meta-analysis

Depression has long been considered a disease involving immune hyperactivation. The impact of pro-inflammatory cytokines such as TNF-α, IL-1β, IL-6, and IL-8 on depression has been widely studied. However, the effect of IL-33, another pro-inflammatory cytokine, has been less researched. Currently, research on the correlation between IL-33 and depression risk is inconsistent. In response to these divergent results, we conducted a review and meta-analysis aimed at resolving published research on the correlation between IL-33 and depression risk, and understanding the potential role of IL-33 in the development and treatment of depression. After searching different databases, we analyzed 8 studies. Our meta-analysis showed that IL-33 had a positive correlation with reduced risk of depression. The pooled standard mean differences (SMD) = 0.14, 95% confidence interval (CI): 0.05-0.24. Subgroup analysis results showed that IL-33 and ST2 levels in cerebrospinal fluid and serum is positive correlated with reduced risk of major depressive disorder (MDD) and bipolar disorder (BD). According to the characteristics of the included literature, the results mainly focuses on Caucasian. Furthermore, according to the subgroup analysis of depression-related data sources for disease or treatment, the correlation between IL-33 and depression risk is reflected throughout the entire process of depression development and treatment. Therefore, the change of IL-33 level in serum and cerebrospinal fluid can serve as useful indicators for assessing the risk of depression, and the biomarker provides potential treatment strategies for reducing the burden of the disease.

Neuropsychiatric Outcomes and Sleep Dysfunction in COVID-19 Patients: Risk Factors and Mechanisms

The ongoing global health crisis due to the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has significantly impacted all aspects of life. While the majority of early research following the coronavirus disease caused by SARS-CoV-2 (COVID-19) has focused on the physiological effects of the virus, a substantial body of subsequent studies has shown that the psychological burden of the infection is also considerable. Patients, even without mental illness history, were at increased susceptibility to developing mental health and sleep disturbances during or after the COVID-19 infection. Viral neurotropism and inflammatory storm damaging the blood-brain barrier have been proposed as possible mechanisms for mental health manifestations, along with stressful psychological factors and indirect consequences such as thrombosis and hypoxia. The virus has been found to infect peripheral olfactory neurons and exploit axonal migration pathways, exhibiting metabolic changes in astrocytes that are detrimental to fueling neurons and building neurotransmitters. Patients with COVID-19 present dysregulated and overactive immune responses, resulting in impaired neuronal function and viability, adversely affecting sleep and emotion regulation. Additionally, several risk factors have been associated with the neuropsychiatric sequelae of the infection, such as female sex, age, preexisting neuropathologies, severity of initial disease and sociological status. This review aimed to provide an overview of mental health symptoms and sleep disturbances developed during COVID-19 and to analyze the underlying mechanisms and risk factors of psychological distress and sleep dysfunction.

Exploring the Role of Drug Repurposing in Bridging the Hypoxia-Depression Connection

High levels of oxidative stress are implicated in hypoxia, a physiological response to low levels of oxygen. Evidence supports a connection between this response and depression. Previous studies indicate that tryptophan hydroxylase can be negatively affected in hypoxia, impairing serotonin synthesis and downstream pathways. Some studies also hypothesize that increasing hypoxia-inducible factor-1 (HIF-1) levels may be a new therapeutic modality for depression. Hence, this study delved into the influence of hypoxia on the cellular response to drugs designed to act in depression. By the induction of hypoxia in SH-SY5Y cells through a hypoxia incubator chamber or Cobalt Chloride treatment, the effect of Mirtazapine, an antidepressant, and other drugs that interact with serotonin receptors (TCB-2, Dextromethorphan, Ketamine, Quetiapine, Scopolamine, Celecoxib, and Lamotrigine) on SH-SY5Y cellular viability and morphology was explored. The selection of drugs was initially conducted by literature search, focusing on compounds with established potential for employment in depression therapy. Subsequently, we employed in silico approaches to forecast their ability to traverse the blood-brain barrier (BBB). This step was particularly pertinent as we aimed to assess their viability for inducing potential antidepressant effects. The effect of these drugs in hypoxia under the inhibition of HIF-1 by Echinomycin was also tested. Our results revealed that all the potential repurposed drugs promoted cell viability, especially when hypoxia was chemically induced. When combined with Echinomycin, all drugs decreased cellular viability, possibly by the inability to interact with HIF-1.

Environmental and behavioral regulation of HIF-mitochondria crosstalk

Reduced oxygen availability (hypoxia) can lead to cell and organ damage. Therefore, aerobic species depend on efficient mechanisms to counteract detrimental consequences of hypoxia. Hypoxia inducible factors (HIFs) and mitochondria are integral components of the cellular response to hypoxia and coordinate both distinct and highly intertwined adaptations. This leads to reduced dependence on oxygen, improved oxygen supply, maintained energy provision by metabolic remodeling and tapping into alternative pathways and increased resilience to hypoxic injuries. On one hand, many pathologies are associated with hypoxia and hypoxia can drive disease progression, for example in many cancer and neurological diseases. But on the other hand, controlled induction of hypoxia responses via HIFs and mitochondria can elicit profound health benefits and increase resilience. To tackle pathological hypoxia conditions or to apply health-promoting hypoxia exposures efficiently, cellular and systemic responses to hypoxia need to be well understood. Here we first summarize the well-established link between HIFs and mitochondria in orchestrating hypoxia-induced adaptations and then outline major environmental and behavioral modulators of their interaction that remain poorly understood.

Recent Developments in Protein Lactylation in PTSD and CVD: Novel Strategies and Targets

In 1938, Corneille Heymans received the Nobel Prize in physiology for discovering that oxygen sensing in the aortic arch and carotid sinus was mediated by the nervous system. The genetics of this process remained unclear until 1991 when Gregg Semenza while studying erythropoietin, came upon hypoxia-inducible factor 1, for which he obtained the Nobel Prize in 2019. The same year, Yingming Zhao found protein lactylation, a posttranslational modification that can alter the function of hypoxia-inducible factor 1, the master regulator of cellular senescence, a pathology implicated in both post-traumatic stress disorder (PTSD) and cardiovascular disease (CVD). The genetic correlation between PTSD and CVD has been demonstrated by many studies, of which the most recent one utilizes large-scale genetics to estimate the risk factors for these conditions. This study focuses on the role of hypertension and dysfunctional interleukin 7 in PTSD and CVD, the former caused by stress-induced sympathetic arousal and elevated angiotensin II, while the latter links stress to premature endothelial cell senescence and early vascular aging. This review summarizes the recent developments and highlights several novel PTSD and CVD pharmacological targets. They include lactylation of histone and non-histone proteins, along with the related biomolecular actors such as hypoxia-inducible factor 1α, erythropoietin, acid-sensing ion channels, basigin, and Interleukin 7, as well as strategies to delay premature cellular senescence by telomere lengthening and resetting the epigenetic clock.

Oxidative Stress in Depression: The Link with the Stress Response, Neuroinflammation, Serotonin, Neurogenesis and Synaptic Plasticity

Depression is a prevalent, complex, and highly debilitating disease. The full comprehension of this disease is still a global challenge. Indeed, relapse, recurrency, and therapeutic resistance are serious challenges in the fight against depression. Nevertheless, abnormal functioning of the stress response, inflammatory processes, neurotransmission, neurogenesis, and synaptic plasticity are known to underlie the pathophysiology of this mental disorder. The role of oxidative stress in disease and, particularly, in depression is widely recognized, being important for both its onset and development. Indeed, excessive generation of reactive oxygen species and lack of efficient antioxidant response trigger processes such as inflammation, neurodegeneration, and neuronal death. Keeping in mind the importance of a detailed study about cellular and molecular mechanisms that are present in depression, this review focuses on the link between oxidative stress and the stress response, neuroinflammation, serotonergic pathways, neurogenesis, and synaptic plasticity's imbalances present in depression. The study of these mechanisms is important to lead to a new era of treatment and knowledge about this highly complex disease.

Molecular Mechanisms of High-Altitude Acclimatization

High-altitude illnesses (HAIs) result from acute exposure to high altitude/hypoxia. Numerous molecular mechanisms affect appropriate acclimatization to hypobaric and/or normobaric hypoxia and curtail the development of HAIs. The understanding of these mechanisms is essential to optimize hypoxic acclimatization for efficient prophylaxis and treatment of HAIs. This review aims to link outcomes of molecular mechanisms to either adverse effects of acute high-altitude/hypoxia exposure or the developing tolerance with acclimatization. After summarizing systemic physiological responses to acute high-altitude exposure, the associated acclimatization, and the epidemiology and pathophysiology of various HAIs, the article focuses on molecular adjustments and maladjustments during acute exposure and acclimatization to high altitude/hypoxia. Pivotal modifying mechanisms include molecular responses orchestrated by transcription factors, most notably hypoxia inducible factors, and reciprocal effects on mitochondrial functions and REDOX homeostasis. In addition, discussed are genetic factors and the resultant proteomic profiles determining these hypoxia-modifying mechanisms culminating in successful high-altitude acclimatization. Lastly, the article discusses practical considerations related to the molecular aspects of acclimatization and altitude training strategies.

Disparities in the prevalence of screened depression at different altitudes in Peru: A retrospective analysis of the ENDES 2019

INTRODUCTION

Depression is a public health concern, nearing 1.5 million cases and accounting for 9.7% of years lost due to disability. Several factors, including altitude, contribute to its development. Altitude has become a topic for recent research, but its association with depressive symptoms has not been fully clarified. Therefore, this study aimed to determine the association between altitude and depressive symptoms in the Peruvian population.

METHODS

A retrospective, cross-sectional study of the 2019 Demographic and Family Health Survey (ENDES in Spanish) was conducted. The dependent variable, depressive symptoms, was measured using the Patient Health Questionnaire (PHQ-9) and the independent variable, altitude, was categorized into: <1500 meters above sea level (masl), 1500-2499 masl and ≥2500 masl. To evaluate the association between altitude and depressive symptoms, we used Poisson regression model, constructing crude and multiple models.

RESULTS

Of those living at 1500 to 2499 masl and ≥2500 masl, 7.23% and 7.12% had depressive symptoms, respectively. After adjusting for confounding variables, high altitude was found to be associated with depressive symptoms (prevalence ratio adjusted (aPR): 1.38, 95% confidence interval: 1.04-1.84; aPR 1.41, 95% CI: 1.20-1.66).

CONCLUSIONS

A statistically significant association was found between high altitude and depressive symptoms. This may be attributable to hypobaric hypoxia that occurs at high altitudes and its effects on brain function. This study's findings should be considered to identify the population at risk and expand the coverage of preventive and therapeutic measures in high-altitude areas of Peru with poor access to health services.

Association of Pre-existing Mental Health Conditions with Acute Mountain Sickness at Everest Base Camp

Hüfner, Katharina, Fabio Caramazza, Evelyn R. Pircher Nöckler, Agnieszka E. Stawinoga, Paolo Fusar-Poli, Sanjeeb S. Bhandari, Buddha Basnyat, Monika Brodmann Maeder, Giacomo Strapazzon, Iztok Tomazin, Ken Zafren, Hermann Brugger, and Barbara Sperner-Unterweger. Association of pre-existing mental health conditions with acute mountain sickness at Everest Base Camp. High Alt Med Biol. 23:338-344, 2022. Background: Mental health disorders are common, but limited data are available regarding the number of people with a past medical history of psychiatric diagnoses going to high altitude (HA). It is also unknown whether mental health conditions are associated with an increased risk of acute mountain sickness (AMS). Methods: We analyzed data from a previous study at Everest Base Camp. Participants self-reported their past medical history and history of substance use and had a brief history taken by a physician. AMS was assessed using the self-reported 2018 Lake Louise AMS Score. Results: Eighty-five participants (66 men and 19 women, age 38 ± 9 years) were included. When questioned by a physician, 28 participants reported prior diagnoses or symptoms compatible with depression (23%), anxiety disorder (6%), post-traumatic stress disorder (1%), and psychosis/psychotic experiences (9%). The prevalence of psychiatric diagnoses in the past medical history was much lower in the self-reported data (2/85) compared to data obtained via physician assessment (28/85). Increased risks of AMS were associated with a past medical history of anxiety disorder (odds ratio [OR] 22.7; confidence interval [95% CI] 2.3-220.6; p < 0.001), depression (OR 3.6; 95% CI 1.2-11.2; p = 0.022), and recreational drug use ever (OR 7.3; 95% CI 1.5-35.5; p = 0.006). Conclusions: Many people who travel to HA have a past medical history of mental health conditions. These individuals have an increased risk of scoring positive for AMS on the Lake Louise Score compared with people without a history of mental health conditions.

Is altitude a determinant of the health benefits of nature exposure? A systematic review and meta-analysis

Introduction

Nature exposure is a widely accepted option for promoting public health owing to the recent surge of scientific evidence. However, the actual settings to facilitate this initiative is yet to be extensively reviewed. In this systematic review, we have aimed to provide an up-to-date summary of interventional studies investigating the psycho-physiological effects of forests and urban forests, including details on their physical settings, and investigate an effect-modifying role of altitude and summarize data on the magnitude and shape of the association.

Methods

A keyword search using five electronic academic databases (PubMed, Embase, PsycINFO, Web of Science, and Scopus) was conducted to identify relevant articles published in English from the inception year to the end of February 2022. The methodological quality was evaluated using the ROBINS-I or ROB2 tool, depending on the study design. Meta-regression and random effects model were jointly used to examine the relationship between altitude and health outcomes.

Results

We included 27 eligible studies and 31 cases extracted from 19 studies were used for the meta-analysis. In the meta-regression, we observed a non-linear association between altitude and psycho-physiological effects. Altitude had a positive quadratic association with anxiety (p < 0.000, adjusted R ² = 96.79%), depression (p < 0.000, adjusted R ² = 98.78%), and fatigue (p < 0.000, adjusted R ² = 64.74%) alleviating effects. Conversely, altitude demonstrated a negative non-linear association with the blood pressure-lowering effect (p = 0.009, adjusted R ² = 32.83%). Additionally, the thermal index (THI) and illuminance (lx) levels were significantly associated with effect sizes of psychological restoration.

Discussion

This review provides moderate-certainty evidence for an effect-modifying role of altitude. The meta-regression results suggested the optimal and minimal altitude ranges for psychological restoration and physiological relaxation, respectively. Despite some limitations, the study findings provide a significant basis for utilizing altitude, which is easily accessible and simple, to promote the health benefits of nature-based initiatives.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022310894, identifier: CRD42022310894.

The HMOX2 polymorphism contributes to the carotid body chemoreflex in European sea-level residents by regulating hypoxic ventilatory responses

This study investigates whether a functional single nucleotide polymorphism of HMOX2 (heme oxygenase-2) (rs4786504 T>C) is involved in individual chemosensitivity to acute hypoxia, as assessed by ventilatory responses, in European individuals. These responses were obtained at rest and during submaximal exercise, using a standardized and validated protocol for exposure to acute normobaric hypoxia. Carriers of the ancestral T allele (n = 44) have significantly lower resting and exercise hypoxic ventilatory responses than C/C homozygous carriers (n = 40). In the literature, a hypoxic ventilatory response threshold to exercise has been identified as an independent predictor of severe high altitude-illness (SHAI). Our study shows that carriers of the T allele have a higher risk of SHAI than carriers of the mutated C/C genotype. Secondarily, we were also interested in COMT (rs4680 G > A) polymorphism, which may be indirectly involved in the chemoreflex response through modulation of autonomic nervous system activity. Significant differences are present between COMT genotypes for oxygen saturation and ventilatory responses to hypoxia at rest. In conclusion, this study adds information on genetic factors involved in individual vulnerability to acute hypoxia and supports the critical role of the ≪ O2 sensor ≫ - heme oxygenase-2 - in the chemosensitivity of carotid bodies in Humans.