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Abstract
Introduction Special operation diving is becoming increasingly prevalent but has received less attention. The anxiety profile in special operation divers and its influencing factors remain unclear, posing great challenges to medical and psychological security of this unique population. The current study aimed to investigate the anxiety profile and to analyse the correlations between anxiety with demographic and personality traits data among special operation divers.
Methods From July to October 2023, 650 special operation divers participated this analytical cross-sectional study. The Spielberg’s State-Trait Anxiety Inventory and the Neuroticism Extraversion Openness Five-Factor Inventory were used to evaluate anxiety and personality traits of special operation divers.
Results 27.2% and 30.3% special operation divers showed high scores on state anxiety and trait anxiety, respectively. Special operation divers who are 30 years or older and who have dived for 15 years or more are prone to higher level of trait anxiety and state anxiety (all p<0.001). Neuroticism showed a significantly positive correlation with both trait anxiety (r=0.675, p<0.001) and state anxiety (r=0.674, p<0.001). Extraversion, openness, agreeableness and conscientiousness are all negatively correlated with both trait anxiety and state anxiety (r=−0.670 to −0.400, all p<0.001). Additionally, significant differences in neuroticism, extraversion, openness, agreeableness and conscientiousness were observed between the high anxiety group and the low anxiety group (all p<0.001).
Conclusion The prevalence of trait anxiety and state anxiety are both relatively high among special operation divers. Individuals with older age and longer diving years are more prone to be anxious. Higher neuroticism, lower extraversion, lower openness, lower agreeableness and lower conscientiousness may be predictors of higher trait anxiety and higher state anxiety.
- anxiety disorders
- public health
- social medicine
Data availability statement
Data are available upon reasonable request.
This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/.
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WHAT IS ALREADY KNOWN ON THIS TOPIC
Anxiety is a good predictor of panic behaviour and motor impairment, which are the two most common factors contributing to diving accidents.
The relationship between anxiety symptoms and personality traits has been investigated in many occupational populations.
WHAT THIS STUDY ADDS
Special operation divers were the major subjects of this study.
The anxiety of special operation divers and its influencing factors were investigated.
HOW THIS STUDY MIGHT AFFECT RESEARCH, PRACTICE OR POLICY
Both prevalence of trait anxiety and state anxiety are relatively higher in special operation divers.
Special operation divers who are 30 years or older or who have dived for more than 15 years are prone to anxiety.
Individuals with certain personality traits are unsuitable for special operation diving.
Introduction
Special operation divers are highly trained individuals who perform underwater operations in support underwater construction, law enforcement or other specialised missions.1 They may be involved in a wide range of activities, including reconnaissance, underwater demolition, combat swimming, sabotage and recovery operations. These divers undergo rigorous training to develop the skills and capabilities required for their demanding roles. Compared with sports and recreational divers, they often work in more complex environments, with more difficult tasks and often unmanageable hours of operation. In addition, the tasks performed by special operation divers often require exceptional physical fitness, proficiency in diving techniques and the ability to operate effectively in challenging and often hostile environments. There is no doubt that special operation diving is much more physically and cognitively demanding. Thus, a sound emotional state is also essential for the successful and safe completion of special underwater operations.
Anxiety is a negative emotional experience induced by stress and can be exacerbated by equipment problems, poor physical conditions or psychological factors. Anxiety symptoms refer to excessive nervousness-related emotional and behavioural responses (eg, avoidance) and related cognitive patterns.2 DSM-5 (Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition), published by the American Psychiatric Association (APA), is the authoritative guide for the classification and diagnosis of mental disorders. According to the DSM-5, under certain conditions, anxiety symptoms may be linked to medical conditions, causing poorer physical health.3 Previous studies suggested that anxiety is a substantial consideration in diving. Research found that anxiety among divers can lead to declines in cognitive functions such as memory, attention and reaction speed in underwater environments, ultimately affecting their operational capabilities during dives.4–6 In addition, in underwater environment, among divers, anxiety influences motor skills7–9 and is a good predictor of panic behaviour.10–12 Motor impairment and panic are the two most common factors contributing to diving accidents. Considering the adverse impact of anxiety on divers’ personal health and operating capability, it is necessary to understand the profile of anxiety among underwater special divers.
Personality is defined as ‘a set of points falling along several behavioral dimensions, each corresponding to a trait, resulting in a unique profile, different from that of other individuals’.13 Research linking personality to behaviours has relied heavily on trait theory.14 Traits were believed to reside in the individual and to cause and effect behaviours when activated.15 The Five-Factor Model (FFM), which has emerged as the dominant framework for studying personality, was used in this research.15 According to the FFM, personality results from the combination of five key traits, often called the ‘Big Five,’ which include Neuroticism, Extraversion, Openness, Agreeableness and Conscientiousness.16 Numerous studies have investigated the relationship between personality traits and anxiety symptoms, while information about anxiety and personality traits, as well as their relationship in special operation divers, has been sparsely documented. Furthermore, the Big Five represents personality traits that usually precede the symptoms of anxiety, they are considered risk/protective factors for anxiety.17 Since personality traits are relatively stable and easy to measure, awareness of the relationship between anxiety and personality traits of special operation divers may be useful for the screening and selection of special operation divers.
The current study aimed (1) to investigate the anxiety and personality profile of special operation divers; and (2) to explore the relationship between anxiety and personality traits of special operation divers.
Materials and methods
Study design and participants
From July to October 2023, a cross-sectional study was carried out. The criteria for inclusion in the study group were as follows: 18–50 years old; being physically healthy; being engaged in the profession of special underwater operation. The criteria for exclusion in the study group were as follows: without explicit consent; with incomplete questionnaire responses; with neurological impairments; using medications or psychoactive substance known to influence neurological function/status and/or mood function/status. A total of 650 special operation divers were randomly selected and invited to take part in this analytical cross-sectional study and complete a questionnaire. The questionnaire asked about demographics including age, education level and diving years, anxiety levels and personality traits.
Data collection
All experimental procedures in this study were performed in accordance with the Declaration of Helsinki and approved by Naval Medical University. All subjects provided written informed consent before the initiation of the experiment. The study was conducted using a direct pen-and-paper interview method in the workplace of the studied special operation divers. Clear instructions on how to complete the questionnaire were given to participants and they were assured of the confidentiality of their responses.
Key measures
Anxiety
The Spielberg’s State-Trait Anxiety Inventory (STAI) was applied to evaluate anxiety18 and has been used among divers.4 In the STAI, higher scores indicate greater anxiety. Each item is rated on a scale of 1 to 4, with a rating of 4 indicating the presence of high levels of anxiety for certain items. The scoring weights for items without anxiety are reversed. The participants were categorised into two groups for anxiety based on their total scores: low (<39) and high (≥39).
Personality traits
The Neuroticism Extraversion Openness Five-Factor Inventory (NEO-FFI) personality questionnaire was used to determine personality traits using the Big Five model.19 The NEO-FFI consists of 60 self-descriptive statements, which are evaluated by respondents on a five-point scale for their accuracy. The questionnaire includes 5 domains and 12 statements in each subscale. The higher the scores on the subscales, the more indicative they are of the corresponding personality traits.
Statistical analysis
Statistical analyses were performed using IBM SPSS Statistics V.27.0 software by means of descriptive and analytic statistics. Means and SD were calculated for all variables. The normal distribution of numerical data was evaluated through the Shapiro-Wilk’s test. Unpaired two-tailed Student’s t-test was used for two-group comparisons, and one-way Analysis of Variance(ANOVA) followed by Least Significant Difference(LSD) multiple comparisons test was used for three-group or more-group comparisons. The relationships between personality traits and anxiety were measured using the Pearson’s correlation test. Statistical significance was set at p<0.05. All results were double-checked to ensure accuracy and reliability.
Results
Demographic characteristics
Characteristics of the study population were presented in table 1. A total of 620 special operation divers participated in this study, with 580 completing the questionnaire. Of them, 44.0% were younger than 25 years old, 32.6% were between 25 and 29 years old, and 23.4% were older than 30 years old. The mean±SD age presented was 26.35±5.03 years old. As to education, 32.8% were high school or vocational school, 44.3% were associate degree and 22.9% were bachelor’s degree. In addition, 44.0% have dived for no more than 5 years, 17.2% have dived for 6~9 years, 22.8% have dived for 10~14 years and 15.9% have dived for more than 15 years. The mean±SD diving years presented was 7.61±5.81 years.
Participants’ characteristics (n=580)
Anxiety and personality
Table 2 shows general findings of participants’ STAI and NEO-FFI scores. The SA score, TA score, Neuroticism score, Extraversion score, Openness score, Agreeableness score and Conscientiousness score of participants were 32.83±9.53, 34.28±9.11, 28.58±6.33, 45.59±6.76, 41.56±5.48, 43.43±6.01 and 48.27±6.81, respectively. According to the STAI data, 27.2% and 30.3% showed high scores on state anxiety and trait anxiety, respectively (table 1).
Descriptive statistics of STAI and NEO-FFI scores of special operation divers
Anxiety scores related to age and length of diving
The correlation of the STAI with demographic data among the population of underwater special operators is presented in table 3. There were significant differences in participant STAI scores concerning age and length of diving of participants. There was statistically significant difference in trait anxiety and state anxiety scores for the three age groups (<25, 25~29, >30): F(2, 577)=11.151, p<0.001, F(2, 577)=11.204, p<0.001, respectively. Post hoc comparisons using the LSD test demonstrated that the mean score of trait anxiety for those older than 30 years old (37.43±7.07) were significantly higher than those younger than 25 years old (33.11±10.94, 95% CI 2.46, 6.19) and those between 25 and 29 years old (33.60±6.98, 95% CI 1.86, 5.81). Besides, the mean score of state anxiety for those older than 30 years old (36.15±7.57) was significantly higher than those younger than 25 years old (31.81±11.34, 95% CI 2.39, 6.30) and those between 25 and 29 years old (31.80±7.37, 95% CI 2.28, 6.42). As for length of diving, there were statistically significant difference in trait anxiety and state anxiety scores for the five groups (<5, 5~9, 10~14, ≥15): F(3, 576)=6.654, p<0.001, F(3, 576)=6.650, p<0.001, respectively. Those who have dived for more than 15 years (37.93±6.16) scored significantly higher in trait anxiety than those who have dived for less than 5 years (33.11±10.94, 95% CI 2.68, 6.97), 5~9 years (33.73±7.81, 95% CI 1.66, 6.75) and 10~14 years (34.42±7.07, 95% CI 1.11, 5.91). Similarly, those who have dived for more than 15 years (36.75±6.63) scored significantly higher in state anxiety than those who have dived for less than 5 years (31.81±11.34, 95% CI 2.69, 7.18), 5~9 years (31.93±8.23, 95% CI 2.16, 7.48) and 10~14 years (32.74±7.51, 95% CI 1.50, 6.51). However, there were no significant differences in participant trait anxiety and state anxiety scores for three education levels, F(2, 579)=0.772, p=0.462, F(2, 579)=0.194, p=0.834, respectively. Taken together, special operation divers who are 30 years or older and who have dived for 15 years or more are prone to higher level of trait anxiety and state anxiety.
Relationship between demographic characteristics and anxiety
Anxiety scores related to personality traits
The correlation between anxiety symptom scores with personality traits among the population of underwater special operators are presented in tables 4 and 5. Scores of five dimensions of NEO-FFI are all significantly correlated with trait anxiety and state anxiety. Trait anxiety showed a significantly positive correlation with neuroticism (r=0.675, p<0.001) and a significantly negative correlation with extraversion (r=−0.670, p<0.001), openness (r=−0.402, p<0.001), agreeableness (r=−0.479, p<0.001) and conscientiousness (r=−0.666, p<0.001). Similarly, state anxiety was positively associated with neuroticism (r=0.674, p<0.001) and negatively with all other traits: extraversion (r=−0.664, p<0.001), openness (r=−0.400, p<0.001), agreeableness (r=−0.482, p<0.001) and conscientiousness (r=−0.663, p<0.001), as listed in table 4.
Relationship between anxiety and personality traits of special operation divers
Difference of personality traits between the high-score and the low-score anxiety groups
Finally, to further investigate the relationship between anxiety and personality traits, participants were categorised into high-score and low-score groups based on their scores for trait anxiety and state anxiety. We then proceeded to compare the scores for each personality trait between these two groups. The results revealed that special operation divers with higher levels of trait anxiety exhibited significantly higher levels of neuroticism compared with those with lower levels of trait anxiety (95% CI −8.83 to –7.00, p<0.001). Additionally, participants with higher levels of trait anxiety scored significantly lower in extraversion (95% CI 6.89, 8.91, p<0.001), openness (95% CI 2.67, 4.52, p<0.001), agreeableness (95% CI 4.39, 6.33, p<0.001) and conscientiousness (95% CI 7.35, 9.34, p<0.001) compared with those with lower levels of trait anxiety. Similarly, significant differences were observed between the high state anxiety group and the low state anxiety group. Special operation divers with higher levels of state anxiety showed significantly higher levels of depression and neuroticism compared with those with lower levels of state anxiety (95% CI −8.97 to –7.05, p<0.001). Furthermore, participants with higher levels of state anxiety scored significantly lower in extraversion (95% CI 7.12, 9.21, p<0.001), openness (95% CI 2.72, 4.63, p<0.001), agreeableness (95% CI 4.39, 6.41, p<0.001) and conscientiousness (95% CI 7.52, 9.59, p<0.001) compared with those with lower levels of state anxiety, as listed in table 5.
Discussion
To the best of our knowledge, this study represents the first attempt to investigate the anxiety profile and its influencing factors among the population of special operation divers. Our main findings are as follows.
First, the current study has investigated the profile of anxiety and personality traits of the special operation divers. According to our investigation, 27.2% and 30.3% showed high scores on state anxiety and trait anxiety, respectively. Few data are available on the prevalence of mental health conditions among divers, apart from the two studies that showed that the prevalence of anxiety in navy divers and sport divers is similar to or even less than the general UK population.20 21 Therefore, it can be said that the prevalence of anxiety in the special operation divers is relatively higher and deserves attention. As has been mentioned earlier, special operation diving is a more risky, difficult and arduous occupation compared with conventional diving. Therefore, it is understandable that they experienced higher anxiety levels. In addition, special operation divers tend to experience or witness more occurrence of accidents or even fatalities, which further predisposes them to anxiety. Available evidence suggests that anxiety is a substantial consideration in diving and may exert significant effect on a diver’s performance and safety. Therefore, higher levels of anxiety among special operation divers are of great concern.
Our research further explored the relationship between demographic and personality traits data with anxiety, aiming to provide some recommendations for the safety and security of underwater special divers. According to our investigation, special operation divers who are 30 years or older and who have dived for 15 years or more are prone to higher level of trait anxiety and state anxiety. The relationship between anxiety levels and age and years of diving seems reasonable. Factors including workplace stress, sensitive and critical situations, high job responsibilities, job stress, problems in the family and home, economic burdens, confusion about future career development, lack of confidence in individual abilities, physical and psychological fatigue caused by long-term hard and dangerous work, thinking the possibility of accidents and death are some of the causes of anxiety. In addition, prolonged diving activities can cause some physical symptoms such as middle ear barotrauma,22 lung barotrauma,23 bone and muscle aches and pains,24 etc. Physical discomfort can easily lead to psychological discomfort, thus making special operation divers with longer diving years prone to anxiety. The relationship between anxiety levels with age and length of diving in special operation divers suggests that we need to pay particular attention to the emotional state of older divers with more years of diving experience. In addition to career-related factors, their emotional state may be influenced by several other factors that make them more susceptible to anxiety. Of course, there is another possibility that older divers, who are more experienced, are more cautious when operating in an underwater environment, which may be one of the reasons for the higher levels of anxiety measured.
Personality traits have been identified as risk/protective factors for anxiety.25 The big five is one of the most relevant frameworks when examining the relationship between personality trait and anxiety and depression symptom.26 Considerable research has investigated the relationship between neuroticism, extraversion and conscientiousness dimensions and anxiety. Longitudinal studies found that high trait neuroticism, low extroversion and low conscientiousness temporally precede anxiety disorders.27 Consistently, our study found that individuals with higher trait anxiety and state anxiety scores scored significantly higher on the neuroticism dimension, significantly lower on the extraversion dimension and significantly lower on the conscientiousness dimension. In addition, the results of the correlation analyses showed that state anxiety and trait anxiety were both significantly positively correlated with neuroticism, and significantly negatively correlated with extraversion and conscientiousness, with the correlation coefficients all close to 0.7, indicating a moderately strong correlation. Besides, our study also supported the significant and relatively strong negative correlation between trait anxiety and state anxiety and openness and agreeableness. In addition, special operation divers with higher trait anxiety and state anxiety levels scored significantly lower in openness and agreeableness dimensions. The negative correlation between agreeableness and anxiety has been confirmed by many studies. Studies conducted during the COVID-19 found that agreeableness could protect patients against anxiety induced by the pandemic.28 In addition, a cross-sectional study on Taiwan college students also found that the correlation between agreeableness and anxiety scores was significantly negative.29
To our knowledge, no published data are available regarding anxiety levels and personality traits specifically among special operation divers. By gaining an understanding of anxiety profiles among special operation divers, as well as its influencing factors, relevant departments and managers may be able to identify individuals who are prone to anxiety and prevent them from participating in a high-demanding special underwater operation that could result in accidents or even casualties. The significant level of anxiety observed among divers suggests that the screening and selection process for this group is currently inadequate. Additionally, the percentage of individuals experiencing anxiety highlights the importance of providing support interventions for special operations divers. The association between personality traits and anxiety among special operations divers suggests that it is possible to predict an individual’s anxiety levels based on their personality traits, which are relatively stable and easier to be measured.
This study is also subject to several inherent limitations. First, this cross-sectional study, using correlation analysis, failed to obtain a causal relationship between anxiety and demographic factors and personality traits.30 Furthermore, the exclusive reliance on self-report questionnaires, while validated, may introduce self-reporting biases. Due to societal expectations, peer pressure or stigma, some participants might potentially under-report or overemphasise their psychological state. In addition, although the STAI is a well-established tool for measuring anxiety, its effectiveness in distinguishing between pathological and normal anxiety within the special operations community warrants further investigation.
Conclusions
First, the current study investigated the profile of anxiety and personality among special operation divers. Second, our study extended the research on the relationship between demographic and personality traits data with anxiety in special operation divers. We found that both prevalence of trait anxiety and state anxiety are relatively higher in special operation divers. The relationship between demographic data and anxiety suggests that attention must be paid attention to special operation divers who are 30 years or older or who have dived for more than 15 years. Correlations between personality traits and anxiety highlight that individuals with certain personality traits are unsuitable for special operation diving.
Data availability statement
Data are available upon reasonable request.
Ethics statements
Patient consent for publication
Ethics approval
This study involves human participants and was approved by the Naval Medical Center (protocol code 2021070201). Participants gave informed consent to participate in the study before taking part.
Acknowledgments
We thank the special operation divers who participated in this study, as well as the staff who participated in the data testing of this study.
References
Footnotes
Contributors HZ and YW conceived of the overarching study, served as the principal investigator, designed the study, implemented the study, performed the analysis of the data, wrote and revised the drafts of the manuscript and acts as guarantor. KL and JH collected and analysed the data. YF reviewed the study from its inception to the draft of the final manuscript and is the guarantor. All authors read and approved the final draft of the manuscript.
Funding The Project of Defence Science and Technology Application Promotion Plan (21AH0103).
Competing interests None declared.
Provenance and peer review Not commissioned; internally peer reviewed.