In the past two decades, China’ economy has experienced remarkable changes. China’s total annual GDP is increasing with an average of 10% growth rate. Some social indicators such as crime rate and unemployment rate are also on the rise according to the yearbook data. These rapid changes pose particular challenges for sociologists and psychologists. Fortunately, the social medicine and psychological problems that accompany rapid social changes of contemporary China have received attention [1–3]. China’s rapid urbanisation may have important consequences for public health [2]. A series of cross-temporal meta-analyses conducted by researchers had showed that anxiety [4], depression [5], psychopathology [6] and mental health [3, 7] changed a lot over time and associated with the changes of environmental factors including overall threat (e.g., crime rate), economic conditions (e.g., unemployment rate), and social connections (e.g., divorce rate). Besides, researchers suggested that social changes might be expected to lead to rising suicide rates [8]. Moreover, a meta-analysis conducted by Li [9] revealed that socio-family environment is one of the factors associated with suicidal behaviors in mainland China. Numerous studies demonstrated that a measure of psychological traits would changes over time. Many cross-temporal meta-analyses have been conducted to investigate the changes over time in measure of psychological traits, including anxiety [4, 10], extraversion [11], self-esteem [12], children’s depression [5], locus of control [13], young people’s sexual behavior and attitudes [14], social desirability [15], ego [16], IQ [17], psychopathology [6], narcissistic personality [18], dispositional empathy [19], and mental health [3, 7]. In the method of cross-temporal meta-analysis, researchers correlate the mean scores on a measure with the year of data collection, weighting for sample size, to assess changes over time on particular measures (e.g., Twenge [4]). Previous studies have demonstrated that anxiety would get severer over time in American college students [4] and Chinese adolescents [10]. Some studies [1, 4, 10] suggested that environmental factors including overall threat, economic conditions, and social connections may have significantly impact on individuals’ anxiety levels. Previous research has shown that anxiety scores do change as a function of social factors [4]. As for military personnels, only one study regarding changes scores in the Symptom Checklist 90 (SCL-90) of members of the Chinese army was conducted [3]. Contrary to the decreased of anxiety in American college students and Chinese adolescents, Yi et al. [3] found that the mental health of Chinese army were getting better and better over time. Yet, such researches on military have rarely been carried on to evaluate the changes of anxiety over time.

The Chinese armed forces have undergone various changes, including the Millions of Disarmament in eighties and nineties, and the missions had new targets as well. The Chinese armed forces not only have to defend the motherland to guarantee people’s normal life, but also have the duty to participate in the rescue and stabilizing missions which make them face with all kinds of threats. The Chinese military personnels often have to fight at the front providing disaster relief such as in the 1998 Changjiang River flood, the 2008 Wenchuan Earthquake and the Yushu Earthquake in 2010 as well as Ya’an Earthquake in 2013. Unlike people living in common surroundings, the military environment is quite different and Chinese military personnels are likely to confront more threats. Additionally, some researchers have labeled the twentieth century “the age of anxiety” (e.g., [4, 20]). These assertions suggest that fierce competition of modern life produces high levels of anxiety. Taken all these findings together, we may conclude that anxiety level may increase in general populations. To our knowledge, only one study about psychological traits changes in military personnels was found. However, Yi and his colleagues [3] found that the scores of SCL-90 in Chinese army had decreased which suggested that the mental health of Chinese army were getting better and better over time. Studies about psychological traits changes in military personnels over time are scarce and inconclusive. Thus, it is doubtful whether anxiety of Chinese military personnels would get severer over time.

To sum up, we need a cross-temporal meta-analysis to address the issue. The purpose of this study was to conduct a cross-temporal meta-analysis to explore the changes of anxiety in Chinese military personnels over nearly past two decades. Previous empirical works have led us to hypothesize that there would be a rise in anxiety of Chinese military personnels over the past two decades.

By examining data collected from 45 studies over the past two decades, we were able to evaluate changes of anxiety in Chinese military personnels from 1991 to 2011 and to compare these changes to social indicators. As expected, the finding of present study showed that state anxiety and trait anxiety had rise significantly over the past two decades (0.88 and 0.63 standard deviation, respectively). Besides, we found significantly correlations between anxiety scores and environmental factors including overall threat, economic conditions, and social connections. A cross-temporal meta-analysis conducted by Xin [1] found an increase of anxiety in Chinese College school students. Additionally, the finding from present study is consistent with earlier studies indicating an increase of anxiety in American college students over time [4, 10]. Twenge’ study [4] suggested that environmental factors including overall threat, economic conditions, and social connections may have significantly impact on individuals’ anxiety levels. Xin [1, 10] found the same pattern in Chinese middle school students and adolescents. Besides, our results indicated that the sociocultural environment might have significant effect on the anxiety of Chinese military personnels beyond genetics and their family environment [4, 19]. Taken all these findings together, we may speculate that the sociocultural environment might have significant effect on the anxiety of people inside of military context and outside of it. In our study, both state anxiety and trait anxiety were increasing over the past two decades, and effect sizes for state anxiety and trait anxiety were 0.88 and 0.63, respectively. According to Tables 1 and 2, the slopes of regression equations of predicting state anxiety and trait anxiety were 0.45 and 0.26, respectively (without controls, unstandardized coefficient). These results indicate that state anxiety is increasing greater than trait anxiety. Perhaps this is because state anxiety is not so stable, and is more vulnerable to external environment. However, trait anxiety is a kind of personality trait, and not easily affected by external environment as state anxiety. State anxiety is temporary, and trait anxiety is a stable part of personality [21, 33–35]. Noticing that trait anxiety score mean of military students and second artillery force were higher than army (the reference group), the sample collected is heterogeneous to some extent, and the trait anxiety would increase with controls. If the persistent trend of changes of anxiety last, the anxiety level of Chinese military personnels will continue to rise. This should cause the attention of the military and the related departments.

Yet, a vast amount of social changes have occurred simultaneously in China over the past two decades. We also examined the relationship between anxiety and environmental factors including overall threat, economic conditions, and social connections. In present study, some social indicators had a significant relationship with anxiety, and the strongest correlations appeared between the Z-scored scale combination of social indicators and anxiety in the actual year. Overall threat can be evaluated using environmental indicators such as crime rates, fear of diseases, per capita health expenditure, and fear of terrorism. Consistent with previous studies [1, 4, 10], our study reveals that indicators of overall threat are associated with increased anxiety, especially with state anxiety. Overall threat indicates a dangerous outside environment and may increase the anxiety by creating a sense of danger. For example, fear of victimization may be created by crime, thus anxiety is induced. Unemployment rate and military expenditure are indicators of economic conditions, and have a significant relationship with higher levels of depression and anxiety [36]. Despite the increasing of military expenditure of China, Chinese military personnels gets a relative low wage than military personnels of most developed countries (e.g., The USA). Although the allowance has been gradually raised up, economics of China is in a state of inflation, and the consumer price index (CPI) substantial rose up in recent years. Additionally, the rise of unemployment rate may gain the anxiety of Chinese military personnels when they confront their retirement and secondary employment. Nevertheless, somewhat differing from previous study [4], divorce rate was not significant associated with increased anxiety. Noticing that, the population of China has increased sharply over the past several decades. The divorce rate in China seemed increasing slowly during the past two decades with a minimum, maximum and mean as 0.88‰, 2.00‰, and 1.43‰ respectively. Another reason for the null results of association between anxiety and divorce rate may be that there are items for special protecting servicemen’s marriage in “Marriage Law” of China. The divorce rate of Chinese military personnels may be lower than the overall populations’. Additionally, the military people are generally young and not married and the social indicators utilized for this study were representative of the entire China. Thus, the divorce rate in China may not link to Chinese military personnels’ anxiety. Some other indicators of social connections should be needed to examine the relationship between them and anxiety. Although the Chinese armed force is gradually increased foreign exchange and more and more open and transparent, military context is a relative close environment to some extent, and some other indicators related to military context should be used in studies to examine the relationship between them and anxiety. However, other indicators were unavailable due to military secret. Although the social indicators utilized for present study were representative of the entire China, according to previous research [3, 4], the social indicators in present study were conventional necessary to evaluate the changes of sociocultural environment factors. For instance, divorce rate can reflect social connectedness; unemployment rate can reflect economic conditions and crime rate can reflect overall threat. The Chinese military personnels connected more and more with civil society, and social indicators in present study may be the best data available so far. Some limitations in the current study should be addressed. First, only studies using STAI were collected in our across-temporal meta-analysis. Future researchers are advised to use other measurements of anxiety or combine them in the across-temporal meta-analysis (as Twenge [4] did). Second, someone may argue that the data measured anxiety only through self-report scales is vulnerable to social desirability. This limitation cannot be completely overcome. Besides, researchers said that self-report measures were the best data available for studying changes over time in anxiety [4]. Third, military personnels is a men dominant career. Military personnels are not necessarily representative of the overall population. Thus the generalizability of the findings may be limited. The sample collected is heterogeneous to some extent. In the terms of China’s military service system, however, army, navy, air forces, second artillery force, armed police and military students are members of Chinese military personnels. So we should include these participants in our across-temporal meta-analysis. Actually, Chinese military personnels have common military rules and regulations, administrative regulations and similar life pattern. In Chinese military context, all Chinese military personnels are under strict military and work discipline, and military training and political study are common life contents of them. Additionally, they share the common surrounding sociocultural environment. So the sample collected may broadly reflect the composition of Chinese military personnels and they have much in common. Finally, correlations between anxiety scores and social indicators cannot prove causation, but show which social indicators covary with the personality traits.

Despite its limitations, the present study considerably extends our insight into the changes of anxiety in Chinese military personnels over time and which social indicators covary with anxiety scores. Moreover, the findings of present study can provide some practical implications. As anxious people predispose to depression [37], and have a higher mortality rate [38], some measures must be taken to tackle the problem of rising anxiety scores. Given that Chinese military personels are continuing to experience high levels of anxiety, it is crucial to consider the implications for mental health care and treatment.