Effect of Altitude on Veteran Suicide Rates

Exploring the Link between Altitude of Residence and Smoking Patterns in the United States

INTRODUCTION

Smoking-related diseases affect 16 million Americans, causing approximately 480,000 deaths annually. The prevalence of cigarette smoking varies regionally across the United States, and previous research indicates that regional rates of smoking-related diseases demonstrate a negative association with altitude. The purpose of this study was to determine the relationship between altitude and the prevalence of cigarette smoking by county (N = 3106) in the United States. We hypothesized that smoking prevalence among adults would be negatively associated with mean county altitude.

METHODS

A multivariate linear regression was performed to examine the relationship between county-level mean altitude and county smoking rate. Covariates were individually correlated with 2020 smoking data, and significant associations were included in the final model.

RESULTS

The multivariate linear regression indicated that the county-level smoking rates are significantly reduced at high altitudes (p < 0.001). The model accounted for 89.5% of the variance in smoking prevalence, and for each 1000-foot increase in altitude above sea level, smoking rates decreased by 0.143%. Based on multivariate linear regression, the following variables remained independently and significantly associated: race, sex, educational attainment, socioeconomic status, unemployment, physical inactivity, drinking behavior, mental distress, and tobacco taxation.

CONCLUSIONS

Our results indicate that smoking rates are negatively associated with altitude, which may suggest that altitude affects the pharmacokinetics, pharmacodynamics, and mechanistic pathways involved in cigarette use. Further research is needed to explore the relationship between altitude and smoking and how altitude may serve as a protective factor in the acquisition and maintenance of tobacco use disorders.

Sudden death in the southern region of Saudi Arabia: A retrospective study

BACKGROUND

Sudden death is unanticipated, non-violent death taking place within the first 24 h after the onset of symptoms. It is a major public health problem worldwide. Moreover, the effects of living at moderate altitude on mortality are poorly understood.

AIM

To retrospectively report the frequency and the main causes of sudden deaths in relation to total deaths at Asir Central Hospital, 2255 m above sea level, in the southern region of Saudi Arabia over a period of 4 years from 2013 to 2016.

METHODS

The medical records of 1821 deaths were examined and showed 353 cases (19.4%) of sudden death.

RESULTS

The highest incidence of sudden death was among the elderly (51%), whereas, the lowest was among children and adolescents (6.5%). With regard to gender, the incidence of sudden death was higher in males (54.4%) compared to 45.6% in females. In this study, we found that the most common direct causes of sudden death were cardiovascular diseases (29.2%), respiratory disease (22.7%), infectious disease (12.2%), cancer (9.4%) and hematological diseases (6.2%). With respect to seasonal variation, the highest incidence was during winter (31.32%) followed by summer (25.8%).

CONCLUSION

The results of this study will help emergency physicians and health care providers to exercise due care to reduce the incidence of sudden death and raise public awareness about the impact of sudden death.

Sudden death in the southern region of Saudi Arabia: A retrospective study

BACKGROUND

Sudden death is unanticipated, non-violent death taking place within the first 24 h after the onset of symptoms. It is a major public health problem worldwide. Moreover, the effects of living at moderate altitude on mortality are poorly understood.

AIM

To retrospectively report the frequency and the main causes of sudden deaths in relation to total deaths at Asir Central Hospital, 2255 m above sea level, in the southern region of Saudi Arabia over a period of 4 years from 2013 to 2016.

METHODS

The medical records of 1821 deaths were examined and showed 353 cases (19.4%) of sudden death.

RESULTS

The highest incidence of sudden death was among the elderly (51%), whereas, the lowest was among children and adolescents (6.5%). With regard to gender, the incidence of sudden death was higher in males (54.4%) compared to 45.6% in females. In this study, we found that the most common direct causes of sudden death were cardiovascular diseases (29.2%), respiratory disease (22.7%), infectious disease (12.2%), cancer (9.4%) and hematological diseases (6.2%). With respect to seasonal variation, the highest incidence was during winter (31.32%) followed by summer (25.8%).

CONCLUSION

The results of this study will help emergency physicians and health care providers to exercise due care to reduce the incidence of sudden death and raise public awareness about the impact of sudden death.

Suicide and altitude: A systematic review of global literature

OBJECTIVE

The purpose of this systematic review was to synthesize the existing global literature examining the relationship between altitude and suicide.

METHOD

Using the electronic databases PubMed, CINAHL, EMBASE, and PsychInfo published articles in English that addressed the relationship between altitude and suicide as a primary or secondary aim, and included human subjects, where identified. Studies were assessed for quality based on methodological approach and data relevance on a three-point scale (strong, moderate, or weak).

RESULTS

Of the 19 studies related to the purpose and aims, 17 reported evidence of a positive correlation between altitude and increased suicide. Vast design differences were employed within the literature, individual-level suicide data was identified as the preferred level of analysis.

DISCUSSION

The relationship between altitude and suicide is an evolving science with a small but growing body of literature suggesting altitude is associated with an increased risk of suicide. This review identifies the need for additional studies examining both individual-level suicide data and improving geographic precision. Public health nurses have a responsibility to carefully examine the quality of studies and the strength of the evidence when addressing variables associated with suicide.

An examination of the association between altitude and suicide deaths, suicide attempts, and suicidal ideation among veterans at both the patient and geospatial level

Suicide is a major public health problem affecting US Veterans and the US in general. Many variables (e.g., demographic, clinical, biological, geographic) have been associated with risk for suicide and suicidal behavior, including altitude; however, the exact nature of the relationship between altitude and suicide remains unclear in part due to the fact that previous studies have used either geospatial data or individual-level data, but not both. Prior research has also failed to consider the full range of suicidal thoughts and behaviors, ranging from suicidal ideation to suicide deaths. Accordingly, the objective of the present research was to use both geospatial data (county and zip codes) and individual-level data to comprehensively assess the association between altitude and suicide mortality, suicide attempts, and suicidal ideation among US Veterans between 2000 and 2018. Taken together, our results demonstrate that there is a strong correlation between altitude and suicide rates at all the levels investigated and using different statistical analyses and even after controlling for significant covariates such as percent of age >50yr, percent male, percent white, percent non-Hispanic, median household income, and population density. We show that there is a positive correlation between altitude and suicide attempts especially when controlling by the covariates and a weak correlation between altitude and suicide ideation and the combination of suicide, suicide attempts and suicide ideation.

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

Adequate oxygen supply is essential for the human brain to meet its high energy demands. Therefore, elaborate molecular and systemic mechanism are in place to enable adaptation to low oxygen availability. Anxiety and depressive disorders are characterized by alterations in brain oxygen metabolism and of its components, such as mitochondria or hypoxia inducible factor (HIF)-pathways. Conversely, sensitivity and tolerance to hypoxia may depend on parameters of mental stress and the severity of anxiety and depressive disorders. Here we discuss relevant mechanisms of adaptations to hypoxia, as well as their involvement in mental stress and the etiopathogenesis of anxiety and depressive disorders. We suggest that mechanisms of adaptations to hypoxia (including metabolic responses, inflammation, and the activation of chemosensitive brain regions) modulate and are modulated by stress-related pathways and associated psychiatric diseases. While severe chronic hypoxia or dysfunctional hypoxia adaptations can contribute to the pathogenesis of anxiety and depressive disorders, harnessing controlled responses to hypoxia to increase cellular and psychological resilience emerges as a novel treatment strategy for these diseases.

High altitude is associated with pTau deposition, neuroinflammation, and myelin loss

Mammals are able to adapt to high altitude (HA) if appropriate acclimation occurs. However, specific occupations (professional climbers, pilots, astronauts and other) can be exposed to HA without acclimation and be at a higher risk of brain consequences. In particular, US Air Force U2-pilots have been shown to develop white matter hyperintensities (WMH) on MRI. Whether WMH are due to hypoxia or hypobaria effects is not understood. We compared swine brains exposed to 5000 feet (1524 m) above sea level (SL) with 21% fraction inspired O₂ (FiO₂) (Control group [C]; n = 5) vs. 30,000 feet (9144 m) above SL with 100% FiO₂ group (hypobaric group [HYPOBAR]; n = 6). We performed neuropathologic assessments, molecular analyses, immunohistochemistry (IHC), Western Blotting (WB), and stereology analyses to detect differences between HYPOBAR vs. Controls. Increased neuronal insoluble hyperphosphorylated-Tau (pTau) accumulation was observed across different brain regions, at histological level, in the HYPOBAR vs. Controls. Stereology-based cell counting demonstrated a significant difference (p < 0.01) in pTau positive neurons between HYPOBAR and C in the Hippocampus. Higher levels of soluble pTau in the Hippocampus of HYPOBAR vs. Controls were also detected by WB analyses. Additionally, WB demonstrated an increase of IBA-1 in the Cerebellum and a decrease of myelin basic protein (MBP) in the Hippocampus and Cerebellum of HYPOBAR vs. Controls. These findings illustrate, for the first time, changes occurring in large mammalian brains after exposure to nonhypoxic-hypobaria and open new pathophysiological views on the interaction among hypobaria, pTau accumulation, neuroinflammation, and myelination in large mammals exposed to HA.

Optimism and Health Self-Perception-Related Differences in Indigenous Kiwchas of Ecuador at Low and High Altitude: A Cross-Sectional Analysis

Ortiz-Prado, Esteban, Katherine Simbaña-Rivera, Diego Duta, Israel Ochoa, Juan S. Izquierdo-Condoy, Eduardo Vasconez, Kathia Carrasco, Manuel Calvopiña, Ginés Viscor, and Clara Paz. Optimism and health self-perception-related differences in indigenous Kiwchas of Ecuador at low and high altitude: a cross-sectional analysis. High Alt Med Biol 00:000-000, 2021. Background: Living at high altitude causes adaptive responses at every physiological and molecular level within the human body. Emotional and psychological short- or long-term consequences, including mood changes, higher mental overload, and depression prevalence, as well as increased risk to commit suicide have been reported among highlanders. The objective of this report is to explore the differences in self-reported dispositional optimism and health perception among sex-, age-, and genotype-controlled indigenous Kiwcha natives living at two different altitudes. Methods: A cross-sectional analysis of the comparison of means of subscales and summary scores of the 36-item short-form health survey (SF-36) self-reported questionnaire and the Life Orientation Test-Revised was conducted among 219 adults Kiwchas living at low (230 m) and high altitude (3,800 m) in Ecuador. Results: High-altitude dwellers presented lower scores in all the studied dimensions of SF-36 and the total score. Differences were found for the role limitation sphere due to vitality (p = 0.005), mental health (p = 0.002), and social functioning (p = 0.005). In all the cases, participants living at low altitudes scored higher than those living at high altitudes. Lowland women were more optimistic than their high-altitude counterparts. Conclusions: We observe that populations located at high altitudes have more unfavorable self-reported health states. Although our results depict the existence of significant differences in the health status of indigenous peoples living at different altitudes, further studies are needed to explain in depth the sociodemographic and/or environmental factors that might underlie these differences.

Methamphetamine exacerbates pathophysiology of traumatic brain injury at high altitude. Neuroprotective effects of nanodelivery of a potent antioxidant compound H-290/51

Military personnel are often exposed to high altitude (HA, ca. 4500-5000m) for combat operations associated with neurological dysfunctions. HA is a severe stressful situation and people frequently use methamphetamine (METH) or other psychostimulants to cope stress. Since military personnel are prone to different kinds of traumatic brain injury (TBI), in this review we discuss possible effects of METH on concussive head injury (CHI) at HA based on our own observations. METH exposure at HA exacerbates pathophysiology of CHI as compared to normobaric laboratory environment comparable to sea level. Increased blood-brain barrier (BBB) breakdown, edema formation and reductions in the cerebral blood flow (CBF) following CHI were exacerbated by METH intoxication at HA. Damage to cerebral microvasculature and expression of beta catenin was also exacerbated following CHI in METH treated group at HA. TiO2-nanowired delivery of H-290/51 (150mg/kg, i.p.), a potent chain-breaking antioxidant significantly enhanced CBF and reduced BBB breakdown, edema formation, beta catenin expression and brain pathology in METH exposed rats after CHI at HA. These observations are the first to point out that METH exposure in CHI exacerbated brain pathology at HA and this appears to be related with greater production of oxidative stress induced brain pathology, not reported earlier.

The Effect of Meteorological, Pollution, and Geographic Exposures on Death by Suicide: A Scoping Review

Suicide is a significant public health concern worldwide and in the United States. Despite the far-reaching impact of suicide, risk factors are still not well understood and efforts to accurately assess risk have fallen short. Current research has highlighted how potentially modifiable environmental exposures (i.e., meteorological, pollution, and geographic exposures) can affect suicide risk. A scoping review was conducted to evaluate the strength of the historical and current literature on the environment’s effect on suicide and suicide risk. Three databases (i.e., Medline, Embase, and PsychInfo) were reviewed to identify relevant studies and two authors independently reviewed studies considering pre-determined inclusion criteria. A total of 46 meteorological studies were included as well as 23 pollution studies and 12 geographic studies. Descriptive statistics, including counts, percentages, review of studies’ sample size (minimum, maximum, median, and interquartile range), were calculated using Excel and SAS 9.4. Overall, strong evidence supports that exposure to sunlight, temperature, air pollution, pesticides, and high altitude increases suicide risk, although effect sizes range from very small to small.

Does living at moderate altitudes in Austria affect mortality rates of various causes? An ecological study

OBJECTIVES

The effects of altitude residence on ageing, longevity and mortality are poorly understood. While adaptations to chronic exposure to altitude may exert beneficial effects on cardiovascular risk factors and some types of cancer, an elevated risk to die from chronic respiratory diseases has been reported. Moreover, high-altitude residence may be correlated with increased depression and suicide rates. The present study tested the hypothesis that living at moderate altitudes (up to 2000 m) is associated with reduced mortality from all causes.

SETTING AND PARTICIPANTS

We used a dataset comprising all deaths (n=467 834) across 10 years of a country (Austria) characterised by varying levels of altitudes up to 2000 m.

MAIN OUTCOME MEASURES

Total number of deaths, age-standardised mortality rates (ASMRs) per 100 000 population, cause-specific ASMRs.

RESULTS

ASMRs for residents living in higher (>1000 m) versus lower (<251 m) altitude regions (with agriculture employment below 3%) were 485.8 versus 597.0 (rate ratio and 95% CI 0.81 (0.72 to 0.92); p<0.001) for men and 284.6 versus 365.5 (0.78; 0.66 to 0.91); p=0.002) for women. Higher levels of agriculture employment did not influence mortality rates. Diseases of the circulatory system and cancers were main contributors to lower mortality rates at higher altitude. Residence at higher altitude did not negatively affect mortality rates from any other diseases. We highlight gender effects and-beside environmental factors-also discuss socioeconomic factors that may be responsible for conflicting results with data from other populations.

CONCLUSIONS

Living at moderate altitude (1000-2000 m) elicits beneficial effects on all-cause mortality for both sexes, primarily due to lower ASMRs from circulatory diseases and cancer. The presented analysis on cause-specific ASMRs over a 10-year period among the entire population of an alpine country will contribute to a better understanding on the effects of altitude-related mortality.

Elevating the level of hypoxia inducible factor may be a new potential target for the treatment of depression

Hypoxia inducible factor-1 (HIF-1) is a transcriptional factor that regulates gene expressions in response to decreased oxygen levels in the tissue, or hypoxia. HIF-1 exerts protective effects against hypoxia by mediating mitochondrial metabolism and consequently reducing oxidative stress. Recently, increased levels of oxidative stress and abnormal energy metabolism in the brain have been suggested to play essential roles in the pathogenesis of depression. Given that HIF-1 activates creatine metabolism and increases phosphocreatine levels in the intestinal epithelial cells, we assume that HIF-1 may induce similar processes in the brain. Elevated phosphocreatine levels in the brain, as measured by magnetic resonance spectroscopy, were associated with better treatment response to the antidepressants in individuals with depression. In addition, oral creatine supplements, which led to increased phosphocreatine levels in the brain, also enhanced the effects of antidepressants in individuals with depression. As such, we hypothesized that increasing the HIF-1, which potentially facilitates creatine metabolism in the brain, might be a new therapeutic target in depression. With this regard, we suggested that interventions to elevate the HIF-1 levels in the brain, including the intermittent hypoxia conditioning and hyperbaric oxygen therapy, might be considered as new additional treatments for depression.

Creatine for the Treatment of Depression

Depressed mood, which can occur in the context of major depressive disorder, bipolar disorder, and other conditions, represents a serious threat to public health and wellness. Conventional treatments are not effective for a significant proportion of patients and interventions that are often beneficial for treatment-refractory depression are not widely available. There is, therefore, an immense need to identify novel antidepressant strategies, particularly strategies that target physiological pathways that are distinct from those addressed by conventional treatments. There is growing evidence from human neuroimaging, genetics, epidemiology, and animal studies that disruptions in brain energy production, storage, and utilization are implicated in the development and maintenance of depression. Creatine, a widely available nutritional supplement, has the potential to improve these disruptions in some patients, and early clinical trials indicate that it may have efficacy as an antidepressant agent.