Introduction

Suicide is a deliberate act in which a subject causes his/her death with knowledge or expectation of a fatal outcome. Attempted suicide is a non-fatal act of self-destruction often with the purpose of mobilizing aid (^{World Health Organization, 2000}). Suicide represents the sixteenth cause of death worldwide (^{Olfson et al., 2017}). In Mexico, suicide rate grew 275% in the period between 1970 and 2007 (^{Borges, Orozco, Benjet, & Medina-Mora, 2010}). Until a few years ago, the suicide rate among the US military has been below the civilian population, but in 2008 the suicide rate in US soldiers began to outpace that of the civilian population and in certain years (2010 and 2011) mortality due to suicide exceeded mortality due to combat or accidents (^{Kuehn, 2009}; ^{Castro & Kintzle, 2014}; ^{Nock et al., 2013}).

In several studies and taking as a framework the Army Study to Assess Risk and Resilience in Servicemembers (STARSS), lifetime prevalence of suicidal ideation has been found to be between 13.9% and 14.1%, suicide planning between 2.3%, and 5.3% and suicide attempt between 1.9% and 2.4%, with a suicide attempt rate of 377 per 100,000 person years in soldiers and 27.9 per 100,000 person years in officers (^{Nock et al., 2014}; ^{Ursano et al., 2015b}; ^{Ursano et al., 2017}). The suicide rate in the US military has been estimated at 18.5 per 100,000 person-years, representing the second cause of death in this population (^{Schoenbaum et al., 2014}).

Due to the increasing participation of the Mexican military in actions aimed at facing the risks and threats to preserve the integrity, stability, and permanence of the Mexican State (^{Diario Oficial de la Federación, 2013}), it is considered necessary to know the impact of such actions on mental health of military personnel, and in particular, to understand the factors associated with suicidal risk. To our knowledge, there are no studies that describe suicidal behavior among Mexican military personnel. The aims of the present study are to know the frequency of suicidal ideation and suicide attempt in the last 12 months in Mexican naval military who attend assessment at the psychiatric service at the Hospital Naval de Veracruz and to determine the risk factors with both ideation and suicide attempt. We expect a greater proportion of suicidal ideation and suicide attempts in the military with the following variables as risk factors: young personnel, women, single marital status, low military rank, less than four years of service, family history of suicide, participation in combat, depressive disorders, and personality disorders.

Method

Results

A total of n = 246 naval military were sent to psychiatric assessment in the study period. No patient refused to participate in the study. The mental disorders and characteristics of the sample are described in Tables 1 and 2 . The mean age of the military evaluated was 33.14 years (SD = 8.43).

The mental disorders most frequently diagnosed in the sample were depressive disorders (n = 48, 20.51%; 89.5% with mild to moderate severity), personality disorders (n = 41, 17.52%; 24.39% with full criteria and 63.41% without full criteria for borderline personality disorder), anxiety disorders (n = 32, 13.68%; 59.37% generalized anxiety disorder or unespecified), and post-traumatic stress disorder (n = 27, 11.54%) (Table 1). In twelve military no psychiatric diagnosis was made because they were incorrectly sent to assessment for non-clinical reasons (disciplinary aspects).

Suicidal ideation and suicide attempt in the last 12 months occurred in n = 60 cases (24.39%) and n = 24 cases (9.76%), respectively. All cases with suicide attempt had suicidal ideation before the act. The most frequent method was drug intoxication (n = 10 cases, 41.67%), followed by forearm cuts (n = 6 cases, 25%), and hanging (n = 4 cases, 16.67%). One case presented a failed suicide attempt with a firearm and three cases used other methods, such as car crash or having been run over by a vehicle.

Military with lower military rank, suicide family history, depressive disorders, and personality disorders were at a greater risk for presenting suicidal ideation (Table 2). It was observed in young people, in singles, and in personnel exposed to combat a trend to present suicidal ideation more frequently; however, differences were not statistically significant. The military with anxiety disorder had a significantly lower risk of presenting suicidal ideation, while in the military with post-traumatic stress disorder no risk for suicidal ideation was observed.

Regarding the presentation of attempted suicide, it was observed that the mean age in the cases was significantly lower than that of the military without attempt (28.2 years vs. 33.67 years, respectively, t = -3.06, p < .01). There was also a higher frequency of attempted suicide in singles or without a couple, in personnel with four years or less in service, and in patients with personality disorder. Contrary as expected, depression was not associated with a higher percentage of suicide attempts in the sample. In this sample, there were no cases of attempted suicide in the military with anxiety disorders or with post-traumatic stress disorder (Table 3).

Discussion and conclusion

To our knowledge, this is the first study that describes suicidal behavior among Mexican military naval personnel. We found a 12-month frequency of suicidal ideation and attempted suicide of 24.39% and 9.76%, respectively, higher than those reported in the US Army Study to Assess Risk and Resilience in Servicemembers (STARSS), 13.9% - 14.1% for suicidal ideation and 1.9% - 2.4% for attempted suicide (^{Nock et al., 2014}). However, it should be noted that the sample of the STARSS study included all the personnel in service, not only those sent to mental health service and suicidality was evaluated not only in the past 12-months but through life.

In the present study, greater risk for suicidal ideation and attempt were observed, specifically in young personnel (suicide attempt), in singles (suicide ideation and attempt), in Classes and Seaman (ideation), and in soldiers with four years or less in the service (suicide attempt). In our study, no gender differences were observed, possibly due to a lower proportion of women in the present study. It is consistently known that in females there are more suicide attempts than in men (^{Street et al., 2015}; ^{Brendel, Brezing, Lagomasino, Perlis, & Stern, 2016}). Except for gender, our data replicate previous reports in the literature (^{LeardMann et al., 2013}; ^{Drummet , Coleman, & Cable, 2003}; ^{Nock et al., 2014}; ^{Ursano et al., 2015a}; ^{Reger et al., 2015}), with greater risk of suicidal behavior in military under 29 years, in soldiers with less academic training, in the lower grades, in those with four or less years of service, and in those with a personal history of mental disorders, especially those who had been diagnosed in the previous month.

Personality disorders, particularly in the case of the emotionally unstable personality disorder, are widely associated with suicidal behavior (^{Hong, 2016}; ^{Moukaddam, Flores, Matorin, Hayden, & Tucci, 2017}). In the present study, personality disorders were consistently associated with both suicidal ideation and suicide attempts. Although the STARSS study did not include the diagnosis of personality disorders, the authors of the study emphasize that disorders associated with problems of aggressiveness/impulsivity can increase suicide risk independently or in comorbidity with other disorders (^{Nock et al., 2013}). Patients with personality disorders such as emotionally unstable and dissocial often present affective instability and make impulsive suicidal threats or attempts; these attempts may become progressively more lethal if they are not taken seriously (^{Blais, Smallwood, Groves, Rivas-Vazquez, & Hopwood, 2016}). It is possible that high levels of stress generate a greater suicide risk in these patients, even without fulfilling all the criteria necessary to make an specific diagnosis (unspecified disorders) (^{Nock et al., 2013}; ^{Hawton, Houston, Haw, Townsend, & Harris, 2003}; ^{Boden, Babdon, Vujanovic, Short, & Bon-Miller, 2013}).

In the present study, a greater proportion of suicidal ideation was observed in patients with depressive disorders but, unlike to what was expected, we did not observe a statistically significant association in the presentation of suicide attempts in soldiers with depressive disorders. This negative result could have been secondary to the low frequency of suicide attempt cases. Due to the above, it is possible that the transition from ideation to attempted suicide in these patients could have been interrupted by receiving early and adequate treatment. In relation to suicidal ideation, a lower risk was observed in the study in the military with anxiety disorders; however, the small number of cases (n = 2) does not allow for definitive conclusions, and the same is true for the military with post-traumatic stress disorder.

The results of the present study cannot be generalized to the rest of the Mexican naval military because it was a clinical sample, overrepresented by men, with a low military grade, and with administrative or naval health functions. Another limitations of the study are that a structured interview was not applied and mental health problems may go undiagnosed because it has been reported in the literature that military personnel do not perceive a need for treatment or do not seek help (^{Naifeh et al., 2016}). During general practitioner evaluations, military personal with mental health problems are not regularly assessed (^{West et al., 2014}; ^{Hoge et al., 2004}); do not report symptoms during high impact operations (^{Bliese, Wright, Adler, Thomas, & Hoge, 2007}); or are screened as positives but do not follow up on the referral (^{Burnam, Meredith, Tanielian, & Jaycox, 2009}; ^{Hoge et al., 2014}). Similarly, the presentation of substance use disorders and psychiatric comorbidity were not analyzed. These variables should be included in future studies.

Ensuring adequate functioning of programs to facilitate detection and treatment is essential and may be aided by improving mental health knowledge among military personnel and maximizing a culture of honest symptom reporting (^{Warner et al., 2011}; ^{Thomas, Adrian, Penix, Wilk, & Adler, 2016}). Detection may be enhanced nationwide through expanded mental health screening in primary care and timely reference to the naval psychiatry services available in Mexico. Screening before basic training would benefit new soldiers because many enter the armed forces with a history of mental health problems and suicide ideation (^{Ursano et al., 2015a}; ^{Rosellini et al., 2014}; ^{Ursano et al., 2018}). Finally, the information generated from the screening programs can generate future studies that determine risk factors among the naval military nationwide.

In conclusion, we observed increased OR for suicidal ideation and suicide attempt in Mexican naval personnel in clinical practice, particularly in young people, with less experience in the military field (lower military grades, four years or less in service), with a family history of suicide, and with depressive or personality disorders. Greater emphasis in the detection of mental health problems in the military population and more representative studies at the national level are needed.