Improvement of mental health among Chinese plateau military personnel, 1993–2017: a cross-temporal meta-analysis of the Symptom Checklist-90
Received 18 January 2019
Accepted for publication 4 July 2019
Published 18 October 2019 Volume 2019:15 Pages 2971—2980
Checked for plagiarism Yes
Review by Single anonymous peer review
Peer reviewer comments 2
Editor who approved publication: Dr Yuping Ning
Mengxue Zhao, Zhengzhi Feng, Guoyu Yang
School of Psychology, Army Medical University, Chongqing, People’s Republic of China
Correspondence: Zhengzhi Feng
School of Psychology, Army Medical University, No. 30 Gao Tanyan Street, Sha Pingba District, Chongqing, People’s Republic of China
Tel +86 1 322 868 8828
Fax +86 0 236 877 1779
Email [email protected]
Abstract: Extreme occupational environments influence the military personnel’s psychological functions. This study aims to investigate Chinese plateau soldiers’ mental health, its changes over time and its correlation with social indicators. A cross-temporal meta-analysis of Symptom Checklist-90 (SCL-90) was employed to resolve these problems. Forty-six valid data with 23,481 samples at high altitude were screened from 34 journal articles between 1993 and 2017. The mental health of Chinese plateau soldiers showed significant improvement. The eight factor scores of SCL-90 showed a significantly negative correlation with years. The scores of Chinese plateau soldiers presented several peaks in the years 2000, 2008, and 2017, suggesting that the mental health may be influenced by momentous military events. The current-year ratio of defense budget to gross domestic product and divorce rate showed a significant correlation with mental health. The improvement of consumption level index could better explain the improvement of mental health in plateau soldiers. Also, the mental health level of soldiers might affect the 5-year-later consumption level index. The influence of social changes on mental health cannot be neglected. The characteristics of military mental health should be considered when designing the prevention, intervention, and treatment programs, and preparing policies to care military service members.
Keywords: cross-temporal meta-analysis, military personnel, mental health, Symptom Checklist-90
The plateau is considered as an important defense area for the Chinese military. On June 18, 2017, the China–India border standoff occurred, making the Chinese military duty to maintain border stability and keep territorial integrity very onerous.1
The plateau soldiers work and live in a special military operating environment. Their mental health has been a major concern for many of the researchers. The research on Chinese plateau soldiers’ mental health has been carried on over the past 30 years, and these researches were related to symptoms, characteristics, influence factors, interventions, and so on.2–5 A self-reporting psychometric instrument of Symptom Checklist-90 (SCL-90) was used to investigate the status of mental health in Chinese plateau soldiers, but the results based on this instrument were widely divergent. The incidence rate range of mental health problems or disorders was from 6.44% to 73.10%.6,7 Most of the studies focused on the influential factors, such as gender, age, education, length of military service, rank, and so on. Personality, coping style, social support, life events, and army motivation were also reported as influential factors.8
Besides, some studies believed that Chinese plateau soldiers’ mental health was worse than that of Chinese adults and soldiers,9–11 while few other studies showed a contradictory conclusion.7 By meta-analysis,12 Chinese plateau soldiers’ mental health was proved to be worse than that of garrison troops present in cities and towns.13 They also suggested that military and environmental factors must be considered while evaluating the mental health levels of military personnel.13 However, this research did not answer the questions of how plateau soldiers’ mental health was changed over time and how social changes affected it.
The cross-temporal meta-analysis is an effective practice to explore the relationship between the psychological values and the social indicators.14–16 This method has been used in many Chinese mental health studies among middle school students,17 college students,18 teachers,19 urban peasant-workers,20 and servicemen.21 The research conducted in the Chinese military from 1990 to 2007 suggested that the level of Chinese military mental health has been improved over time, but it did not reveal the relationship with social indicators. Hence, it is necessary to investigate the relationship between social indicators and military mental health with the help of Military Demand-Resource (MDR) model.
US army has proposed MDR model for evaluating the military personnel mental health.22 This model integrated the internal and external resources. Family and policy serve as the key external resources for strengthening individuals’ performance and resilience. Based on this, three social indicators were chosen to quantify the external resources. The divorce rate (DR) and the consumption level index (CLI) reflect the family resource, and the ratio of defense budget to gross domestic product (DB/GDP) reflects the policy resource. These sources are officially obtained from the China National People’s Congress, Ministry of Civil Affairs, National Bureau of Statistics, Chinese White Papers on National Defense, and central and regional government drafted budget.
This study aimed to investigate these plateau soldiers’ mental health, its changes over time, and its correlation with social indicators.
Method and materials
The validity and reliability of SCL-90 scale
The SCL-90 scale consists of 90 items and 9 factors,23,24 and it is regarded as the most popular psychological inventory in China.25–28 It is widely used among the Chinese military till today. A number of studies have evaluated the clinical validity of this self-rating scale.29–32 A large body of evidence confirmed the validity and reliability of SCL-90 as a measure of military mental health.33–38
All the studies were retrieved by using the China Academic Journal Network Publishing Database (CJAD), ScienceDirect and Web of Science (for journal articles). The following keywords of “plateau” or “high altitude”, and “mental health” or “mental hygiene”, and “military” or “soldiers” or “officers” were used as topics, keywords, and titles to search the relevant literature. If the data collection year was not mentioned in the article, the variable of the year was set as the published year of the article minus 2.39 Thus, the year range in our research was from 1993 to 2017. The data in the year 1994 and 2016 were missing.
The studies should meet the following criteria for inclusion:
The studies with the following criteria were excluded:
According to the steps of meta-analysis and the suggestions from Rosenthal (1995),40 the journal types, plateau areas, and nationalities of each article were encoded. The plateau areas were divided according to garrison locations reported in the articles.
The cross-temporal meta-analysis emphasized the time effect and was supposed to be a within-scale meta-analysis.41–43 According to the previous research,44 the changes between M and SD with the year in both unweighted and weighted ways by sample size (n) were examined. These data showed ecological correlations.45
We used linear regression equations based on the weighted means (y) of the year (x) to evaluate the concrete number of psychological indexes that changed over time.44,46 Based on these equations, the mean scores of the first year 1993 (M1993) and the last year 2017 (M2017) could be obtained by calculation. MSD was the mean of standard deviations. Mchange = M1993–M2017, d was effect size (d=Mchange/MSD), r2 = d2/(d2+4). According to Cohen (1988),43 the effect size was low, middle, and high if the effect size (d) ranged from 0.2 to 0.5, 0.5 to 0.8, and more than 0.8.
With the help of lag correlation analysis, it might be possible to reveal whether sociocultural environment changed the mental variables or the mental variables changed the sociocultural environment.17,47,48 So, we matched the SCL-90 scores with the current-year, 5-years-ago, and 5-years-later social indicators (China’s national economic and social development is basically considered as a five-year cycle) and examined their correlation with DB/GDP, CLI, and DR separately. The data of social indicators from 2018 to 2020 and the DR of 2017 are missing.
SPSS 24.0 and Excel 2016 were used to perform statistical analyses.
Total sample and variable-encoding
Table 1 Total samples
Table 2 Variables encoding assignment
Changes over time
The SCL-90 scores of Chinese plateau military personnel were decreased steadily between 1993 and 2017, showing a negative correlation between 8 factor scores and year. But the somatization showed no significant effect over time and the score was relatively high. Only the SD of paranoid ideation showed a significant difference with the year (see Table 3 and Figure 1). By taking obsessive-compulsive and interpersonal sensitivity factors as examples, the changes in the 8 factor scores were linear and not curvilinear overtime (see Figures 2 and 3).
Table 3 Correlation coefficients between SCL-90 scores and year
Figure 1 SCL-90 scores of Chinese plateau military personnel, 1993–2017.
Figure 2 Mean score of obsessive-compulsive over time.
Figure 3 Mean score of interpersonal sensitivity over time.
The effect of year
The SCL-90 score was considered as a dependent variable in the regression equation. No matter whether the journal types, the plateau areas, and the nationalities were accepted into the equation or not, the effect of the year was shown to be significant (see Table 4).
Table 4 Year effect in stepwise regression equation
The 8 factor scores were ranged from 1.028 (paranoid ideation) to 2.865 (hostility) in 1993 and were from 0.476 (paranoid ideation) to 2.481 (hostility) in 2017. The mean SD was from 0.50739 (phobic anxiety) to 0.6504 (interpersonal sensitivity). The means of 8 factor scores were declined from 0.60 (obsessive-compulsive) to 0.24 (phobic anxiety) over time. The effect size d was ranged from 0.473 (phobic anxiety) to 0.98996 (obsessive-compulsive), and the rate (r2) was ranged from 5.297% (phobic anxiety) to 19.68% (obsessive-compulsive). According to Cohen (1988),49 the variation of phobic anxiety remained the lowest and belonged to “low effect”; the declination in hostility, anxiety, and psychotism belonged to the middle degree; the range of ability of depression, interpersonal sensitivity, paranoid ideation, and obsessive-compulsive belonged to “high effect”. The decent degree of obsessive-compulsive was the highest (see Table 5).
Table 5 Variable quantity of Chinese plateau military personnel mental health
Correlation with social indicators
The current-year DB/GDP showed a significant effect on the interpersonal sensitivity, depression, and anxiety of Chinese plateau military personnel, while the 5-year-ago and 5-year-later DB/GDP almost did not get affected (see Table 6).
Table 6 Correlation coefficients between SCL-90 scores and DB/GDP
Most of the SCL-90 scores were influenced by current-year, 5-year-ago, and 5-year-later CLI and the correlation degree remained high. Only phobic anxiety showed no relationship with the current-year and 5-year-ago CLI and the hostility had nothing to do with 5-year-later CLI (see Table 7).
Table 7 Correlation coefficients between SCL-90 scores and CLI
The current-year DR had a correlation with SCL-90 scores, except anxiety, while the 5-year-later DR was influenced only by obsessive-compulsive and interpersonal sensitivity. The 5-year-ago DR had nothing to do with SCL-90 scores (see Table 8).
Table 8 Correlation coefficients between SCL-90 scores and DR
Although the improvement is not smooth, the mental health of Chinese plateau military personnel is getting better indeed. Its improvement degree was significant without any influence of journal types, plateau areas, and nationalities. A similar conclusion has also been reported.21 This might be due to rapid economic development, improvement of citizens quality, national defense modernization, and development of psychological service work in China. Nonetheless, the mental health and well-being of service members in the United States were influenced by combat deployments.50 There are different mental health outcomes observed between US and UK military personnel returning from Iraq.51 The mental health of soldiers in cities is much better than those at high altitude.13 As shown in the MDR model, the mental health of military personnel is affected by different resources, such as countries, combat deployments, and defense areas.
In addition, there are some differences in the mental health characteristics among the plateau army members. The somatization symptoms were stable and had a high score, showing no significant changes over time. This could be explained due to the special environmental effects of angiocarpy, gastrointestinal tracts, and respiratory system. Many researchers have demonstrated that high-altitude environment causes frequent awakenings, headaches, acute mountain sickness (AMS), visual impairment as well as other somatic damages.25,52,53 So, somatization symptoms do not change quickly and easily over time. The score of other factors showed a linear downward trend with year, especially the obsessive-compulsive. This symptom was the most decreased factor with year and also had a high score. Obsessive-compulsive symptom that manifests as meaningless and uncontrollable ideations and behaviors according to SCL-90 showed correlation with cognitive function. The results are consistent with those of the previous studies.54 Ascending to extreme altitudes can cause brain damage, forming subcortical lesions and cortical atrophy on magnetic resonance imaging (MRI).55 We can conclude that high altitude makes obsessive-compulsive symptom of Chinese army man more serious than that at low altitude. And the high-altitude exposure on the brain areas can influence the cognition speed, sensitivity, reaction time and conflict control.56–59 High risk and high intensity of military tasks might aggravate the obsessive-compulsive symptom.
Chinese plateau military personnel have a high anxiety score and both anxiety and depression vary a lot over time. Few researchers have found the relationship between emotional regulation function and high altitudes, especially depression.60–62 The phobic anxiety score of Chinese plateau military personnel was at a moderate level and its variation remained the lowest. The research conducted by Yi et al21 demonstrated that the Chinese army had problems of phobic anxiety, while this symptom in soldiers at high altitude might be better than those present at low altitude. However, for those with low-score or relatively stable factors, such as interpersonal sensitivity, paranoid ideation, and phobic anxiety, the mental-health evaluation cycle was increased to reduce the economic as well as labor costs.
The SCL-90 scores of Chinese plateau soldiers showed several peaks in the years 2000, 2008, and 2017. Review of the major events in China from 1993 to 2017, we found that the military events likely caused the declination in mental health among Chinese soldiers. For example, the 1998 Yangtze River floods were considered to be the worst in Northern China flood over 40 years.63 Indo–Pakistani War of 1999 led to tensions on the plateau border;64 the situation of NATO bombing on the Chinese embassy in Yugoslavia affected China’s national defense readiness;65 Chen Shuibian, a Democratic Progressive Party (DPP) member, became the eventual winner in 2000 Taiwan presidential election.66 The Chinese disarmament especially began from 1997 to 1999, and the Chinese Army was cut by 19%. On June 18, 2017, Sino-Indian Dong Lang standoff occurred, making the Chinese military nervous.1 Chinese military is still in the stage of a new round of military reformation today. The mental health of Chinese soldiers might be influenced by military events. So, it is necessary to pay attention to military mental health in critical moments.
The current-year DB/GDP was directly related to Chinese plateau soldiers’ depression, anxiety, and interpersonal sensitivity symptoms. DB is a special expense for safeguarding national survival and developing security and also involves the cost of military activities carried out by the state to prevent and resist aggression, stop armed subversion, safeguard national sovereignty, and unify territorial integrity and security, as well as political, economic, diplomatic, scientific, and technological education activities related to military affairs.67 GDP is recognized as the best indicator to measure the economic condition of a country.68 The DB/GDP reflects the ratio of China’s defense construction to the economic input. So, this index can influence the current-year mental health level of Chinese plateau soldiers directly. This was consistent with the previous studies.19 CLI has a full-dimension and space-time effect on the mental health of soldiers at high altitudes. CLI showed a significantly negative correlation with many factors. The improvement of CLI can better explain the improvement of mental health level of Chinese military personnel at high altitudes. At the same time, the mental health level of soldiers might also affect the 5-year-later CLI. The current-year DR has a correlation with the mental health of Chinese plateau military personnel, except the anxiety symptom. And the effect of 5-year-ago and 5-year-later DR on mental health was limited. Only the obsessive-compulsive and interpersonal sensitivity symptom might help in predicting the 5-year-later DR. The reality is that the obsessive-compulsive and interpersonal sensitivities scores of Chinese plateau soldiers’ scores were decreased and the Chinese population DR tended to rise.69
The mental health of Chinese plateau military personnel is getting better. To monitor the development and changes of Chinese plateau soldiers’ mental health over time, not only the high-score factors but also the changeable factors should be focused. At the same time, the influence of social indicators on military mental health cannot be neglected. We should continuously work on how to maintain the plateau soldiers’ mental health with the help of social resources, military policies, medical security, and psychological training.
This study cannot be generalized to Chinese military population because it was examined only in Chinese plateau soldiers. In addition, the SCL-90 can only be used to assess one’s psychological status within a week. Besides, the causal chain between society and psychological variables is relatively far away, and the interpretation of some results lacked the quantitative analysis. But our research has shed light on the relationship of mental health, policy, economy, and society.
This research was supported by the Major Logistics Research Project (AWS17J014), Military PsychologyYouth Innovation Fund (KY2018102) and the Foundation for Humanities and Social Science (2018XRW001).
The authors report no conflicts of interest in this work.
1. Barry SLM, Ellen F. How India and China have come to the brink over a remote mountain pass. The New York Times. 2017.
2. Liu J, Zhang X. The influence of doing Tai Chi on military mental health in Tibet high altitude. Chin J Behav Med Sc. 2006;15(4):373.
3. Zhao J, Xie Y. Plateau military mental health status and its influencing factors. J Preventive Med Chin People’s Liberation Army. 2006;24(1):64–67.
4. Zhang L, Jin G, Zhang H, et al. The physiological change of ground missile forces at high altitude and the revelation of medical support. J Preventive Med Chin People’s Liberation Army. 2012;30(4):294–295.
5. Yun L, Feng Z, Wang T, Fei H. Mental quality of army residents in high-altitude plateau. J Third Mil Med Univ. 2013;35(07):669–672.
6. Zhang L, Liu B. Mental health and its correlative factors of soldiers at high altitude. Chin J Clin Rehabil. 2004;8(18):3481–3483.
7. You H, Li X, Tao P. Analysis on the mental health situation of 233 military personnel stationed at high altitude. China J Health Psychol. 2011;19(2):182–184.
8. Liu X, Xie Y, Bai Z, Wang W. Mental stress and its related factors in armed police soldiers at high altitud. Chin J Clin Rehabil. 2006;10(30):60–62.
9. Fan Y. A mental health survey of automotive soldiers on highland. Chin J Health Educ. 1998;14(9):23–24.
10. Cheng X, Gao J, Liu H. A mental health survey of junior officers in Xinjiang. J Preventive Med Chin People’s Liberation Army. 2001;19(6):422–423.
11. Yang GY, Feng ZZ, Liu YB, Yan Z, Zhang J. Dynamic characteristics of mental health level in the training of soldiers at high altitude. Chin J Clin Rehabil. 2005;9(28):83–85.
12. Glass G. Primary, secondary, and meta-analysis of research. Educ Res. 1976;5(10):3–8. doi:10.3102/0013189X005010003
13. Feng Z, Dai Q. A meta-analysis concerning the mental health status of members of the Chinese army. Acta Psychologica Sinica. 2008;40(3):358–367. doi:10.3724/SP.J.1041.2008.00358
14. Twenge JM. Changes in masculine and feminine traits over time: a meta-analysis. Sex Roles. 1997;36(5–6):305–325. doi:10.1007/BF02766650
15. Twenge J. Attitudes toward women, 1970–1995: a meta-analysis. Psychol Women Q. 1997a;21(1):35–51. doi:10.1111/j.1471-6402.1997.tb00099.x
16. Hou J, Xin Z, Huang S, Mei Z, Dou D. Cross-temporal meta-analysis: principles,procedures and applications in demography. Popul Res. 2015;39(01):104–112.
17. Xin Z, Zhang M. Changes in Chinese Middle School Students’ Mental Health (1992～2005): a Cross-Temporal Meta-Analysis. Acta Psychologica Sinica. 2009;44(5):664–679. doi:10.3724/SP.J.1041.2012.00664
18. Xin Z, Zhang M, He L. Changes in college students’ mental health: a cross-temporal meta-analysis. Acta Psychologica Sinica. 2012;44(5):664–679. doi:10.3724/SP.J.1041.2012.00664
19. Yi X, Zhao Q, Hu W, Li J. Changes in mental health of Chinese teachers (1994~2011): a cross-temporal meta-analysi. J Beijing Normal Univ (Social Sciences). 2014;243(3):12–22.
20. Huang S, Hou J, Zhang M, et al. A Cross-Temporal Meta-Analysis of Changes in Chinese Migrant Workers’ Mental Health:1995～2011. Acta Psychologica Sinica. 2015;47(4):466. doi:10.3724/SP.J.1041.2015.00466
21. Yi X, Zhao Q, Cai S. Changes in Mental Health of Members of the Chinese Army (1990~2007): a cross-temporal meta-analysis. Acta Psychologica Sinica. 2012;44(2):226–236. doi:10.3724/SP.J.1041.2012.00226
22. Bates MJ, Bowles S, Hammermeister J, et al. Psychological fitness. Mil Med. 2010;175(8S):21–38. doi:10.7205/milmed-d-09-00046
23. Derogatis LR, Lipman RS, Covi L. SCL-90: an outpatient psychiatric rating scale–preliminary report. Psychopharmacol Bull. 1973;9(1):13–28.
24. Derogatis LR, Cleary PA. Confirmation of dimensional structure of SCL-90 - study in construct-validation. J Clin Psychol. 1977;33(4):981–989. doi:10.1002/1097-4679(197710)33:4<981::AID-JCLP2270330412>3.0.CO;2-0
25. Jin H, Wu W, Zhang M. The preliminary analysis of SCL-90 assessment results of Chinese normal person. Chin J Nerv Mental Dis. 1986;12(5):260–263.
26. Tang Q, Cheng Z. The use and reanalysis of SCL-90 in China. Chin J Clin Psychol. 1999;7(01)19–23.
27. Hu S. Confirmatory factor analysis and norms comparison of SCL-90 in middle school students. Stud Psychol Behav. 2006;4(2):114–119.
28. Fan H, Li J, Zhao M. Mental health of kindergarten teachers: meta-analysis of studies using SCL-90 scale. Adv Psychol Sci. 2016;24(1):9–20. doi:10.3724/SP.J.1042.2016.00009
29. Carrozzino D, Vassend O, Bjorndal F, et al. A clinimetric analysis of the Hopkins Symptom Checklist (SCL-90-R) in general population studies (Denmark, Norway, and Italy). Nord J Psychiatry. 2016;70(5):374–379. doi:10.3109/08039488.2016.1155235
30. Carrozzino D, Morberg BM, Siri C, Pezzoli G, Bech P. Evaluating psychiatric symptoms in Parkinson’s Disease by a clinimetric analysis of the Hopkins Symptom Checklist (SCL-90-R). Prog Neuropsychopharmacol Biol Psychiatry. 2018;81:131–137. doi:10.1016/j.pnpbp.2017.10.024
31. Carrozzino D, Siri C, Bech P. The prevalence of psychological distress in Parkinson’s disease patients: the brief symptom inventory (BSI-18) versus the Hopkins symptom checklist (SCL-90-R). Prog Neuropsychopharmacol Biol Psychiatry. 2019;88:96–101. doi:10.1016/j.pnpbp.2018.07.012
32. Arrindell WA, Urban R, Carrozzino D, et al. SCL-90-R emotional distress ratings in substance use and impulse control disorders: one-factor, oblique first-order, higher-order, and bi-factor models compared. Psychiatry Res. 2017;255:173–185. doi:10.1016/j.psychres.2017.05.019
33. Yang Z, Xiao R, Gong Z. The application of the symptom chechlist-90 to evaluate the state of the mental health in armymen. J Preventive Med Chin People’s Liberation Army. 1995;13(1):9–13.
34. Li L, Hu J, Xiao T, Feng L, Yang Y. Tibetan garrison mental health survey. Chin Mental Health J. 1996;10(1):18–19.
35. Yao G, Shao M, Yuan A, Liu H, Yang J. Survey on mental health of young soldiers in plateau area. J Preventive Med Chin People’s Liberation Army. 1997;15(4):267–268.
36. Wang H, Sun J, Haiying YU. The establishment of symptom check list 90 norm of Chinese armymen. Chin J Psychiatry. 1999;32(01):37–39.
37. Feng Z, Hu F, Liu Y. Establishment of norm of symptom chechlist-90 (2016 edition) for Chinese military personnel. J Third Mil Med Univ. 2016;38(20):2210–2214.
38. Zhao M, Luo X, Wang LA. 2017 edition of the norm of symptom chechlist-90 (SCL-90) for the Chinese army on the Qinghai-Tibet plateau. J Third Mil Med Univ. 2016;39(19):1875–1882.
39. Oliver MB, Hyde JS. Gender differences in sexuality: a meta-analysis. Psychol Bull. 1993;114(1):29. doi:10.1037/0033-2909.114.1.29
40. Rosenthal R. Writing meta-analytic reviews. Psychol Bull. 1995;118(2):183–192. doi:10.1037/0033-2909.118.2.183
41. Twenge JM. The age of anxiety? Birth cohort change in anxiety and neuroticism, 1952–1993. J Personality Social Psychol. 2000;79(6):1007–1021. doi:10.1037/0022-3522.214.171.1247
42. Twenge JM. Birth cohort changes in extraversion: a cross-temporal meta-analysis, 1966–1993. Personality Individual Differences. 2001;30(5):735–748. doi:10.1016/S0191-8869(00)00066-0
43. Twenge JM. Changes in women’s assertiveness in response to status and roles: a cross-temporal meta-analysis, 1931–1993. J Pers Soc Psychol. 2001;81(1):133–145.
44. Twenge JM, Campbell WK. Age and birth cohort diGerences in self-esteem: a cross-temporal meta-analysis. Personality Social Psychol Rev. 2001;5(5):321–344. doi:10.1207/S15327957PSPR0504_3
45. Rosenthal R, Rosnow RL, Rubin DR. Contrasts and Effect Sizes in Behavioral Research: A Correlational Approach. New York: Cambridge University Press; 2000.
46. Twenge JM, Im C. Changes in the need for social approval, 1958–2001 ☆. J Res Pers. 2007;41(1):171–189. doi:10.1016/j.jrp.2006.03.006
47. Twenge JM, Zhang L, Im C. It’s beyond my control: a cross-temporal meta-analysis of increasing externality in locus of control, 1960–2002. Pers Soc Psychol Rev. 2004;8(3):308–319. doi:10.1207/s15327957pspr0803_5
48. Wells BE, Twenge JM. Changes in Young People’s Sexual behavior and attitudes, 1943–1999. A cross-temporal meta-analysis. Rev Gen Psychol. 2005;9(3):249–261. doi:10.1037/1089-26126.96.36.199
49. Cohen J. Statistical Power Analysis for the Behavioral Sciences. New York: Academic Press; 1988:24–27.
50. Castro CA, Hassan AM. Military mental health and combat deployments. Encycl Mental Health. 2016;3:137–143.
51. Sundin J, Herrell RK, Hoge CW, et al. Mental health outcomes in US and UK military personnel returning from Iraq. Br J Psychiatry. 2014;204(3):200–207. doi:10.1192/bjp.bp.113.129569
52. Mclaughlin CW, Skabelund AJ, George AD. Impact of high altitude on military operations. Curr Pulmonol Rep. 2017;6(2):146–154. doi:10.1007/s13665-017-0181-0
53. Zhang L, Jin G, Zhang H. The physiological change of ground missile forces at high altitude and the revelation of medical support. J Preventive Med Chin People’s Liberation Army. 2012;30(4):294–295.
54. Li LP, Wang L, Cui H, Yang G, Li C. Investigation on mental health of new recruits and veterans at high altitude. J Preventive Med Chin People’s Liberation Army. 2015;33(1):94.
55. Nicolás F, Modrego PJ, Humberto M. Evidence of brain damage after high-altitude climbing by means of magnetic resonance imaging. Am J Med. 2006;119(2):
56. Hochachka PW, Clark CM, Brown WD, et al. The brain at high altitude: hypometabolism as a defense against chronic hypoxia? J Cereb Blood Flow Metab. 1994;14(4):671–679. doi:10.1038/jcbfm.1994.84
57. Dykiert D, Hall D, van Gemeren N, et al. The effects of high altitude on choice reaction time mean and intra-individual variability: results of the Edinburgh Altitude Research Expedition of 2008. Neuropsychology. 2010;24(3):391–401. doi:10.1037/a0018502
58. Hill CM, Dimitriou D, Baya A, et al. Cognitive performance in high-altitude Andean residents compared with low-altitude populations: from childhood to older age. Neuropsychology. 2014;28(5):752–760. doi:10.1037/neu0000065
59. Ma H, Wang Y, Wu J, et al. Long-term exposure to high altitude affects conflict control in the conflict-resolving stage. PLoS One. 2015;10(12):e0145246. doi:10.1371/journal.pone.0145246
60. Luo Q, Xu W. Impact of automatic thoughts and life events on anxiety in soldiers at high altitude. Chin J Clin Rehabil. 2005;9(4):90–91.
61. Betz M, Valley MA, Lowenstein SR, Honigman B. Suicide at high altitude: the importance of sociodemographic and mental health care factors. High Alt Med Biol. 2012;13(2):138. doi:10.1089/ham.2012.1017
62. Ishikawa M, Yamanaka G, Yamamoto N, et al. Depression and altitude: cross-sectional community-based study among elderly high-altitude residents in the Himalayan Regions. Cult Med Psychiatry. 2016;40(1):1–11. doi:10.1007/s11013-015-9462-7
63. Spignesi SJ. Catastrophe!: The 100 Greatest Disasters of All Time. New York: Citadel Press; 2004. ISBN 0-8065-2558-4:37.
64. Wolpert S. Recent Attempts to Resolve the Conflict”. India and Pakistan: Continued Conflict or Cooperation? Oakland: University of California Press; 2010. ISBN 9780520271401:73.
66. Lin C. Soong draws top ticket lot. Taipei Times. February 15, 2000:1. Available from: http://www.taipeitimes.com/News/front/archives/2000/02/15/0000024163. Accessed July 25, 2019.
67. Statistics on Defense Expenditures in the U.S. per Capita, 1990–2011. NATO, New York: Statista. April, 2012. Available from: https://www.statista.com/statistics/203090/defense-expenditures-of-the-us-per-capita/. Accessed July 25, 2019.
68. Coyle D. GDP: A Brief but Affectionate History 2014. New Jersey: Princeton University Press; September 22, 2015.
69. Wang GH. From acquaintances society to strangers society: a social perception of the increase of urban divorve rate. J Univ Sci Technol Beijing. 2007;23(01):5–9.
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