The present study results show that PASs was an important element in the cases of suicide that occurred in the Brazilian Federal District between 2005 and 2014, confirming the established association between PASs use and suicide reported in previous studies [28, 29]. This association may be explained by the psychoactive effects of certain substances, which can trigger potentially lethal impulsive behavior. As shown in Fig. 1, the suicide rate of people who have used PASs before to die by suicide is growing at approximately 10 × the population growth, making this event alarming. Therefore, studies like this are essential to establish standards to reduce such cases.
Alcohol is a substance with psychoactive effects that can increase impulsivity and accentuate SB. A recently published study conducted in Brazil showed that being male and having cocaine identified in the toxicological test were the factors that showed a strong association with abusive alcohol beverage consumption among those who died by suicide [30]. According to the present results, the mean dose used before dying by suicide was 1.49 g of alcohol per liter of blood, and the blood alcohol concentration was between 1.5 g/l and 2.99 g/l in nearly 35%. According to Larini [31], this dose can cause disorientation, mental confusion, dizziness, an exaggerated emotional state (fear, annoyance, or distress), sensation/perception disturbance, balance deficit, muscle incoordination, and difficulty speaking. Another study concluded that, due to the acute effect of alcohol on neurotransmitters and cognitive functions, the use of this substance could drive SA through different mechanisms, enhancing dysphoria, aggressiveness, impulsivity, and disinhibition [32]. A vicious circle can be created between PASs/impulsivity/aggression/SB and the fact that it is often unclear whether the individual has used a substance to facilitate the transition to the act or whether the fact of chronically consuming a substance – drug addiction – predisposes, for a variety of reasons, to SB [33]. Indeed, there is a dose–response relationship between the amount of alcohol consumed and the risk of suicide [29]. These mechanisms could explain the amplifying effect of alcohol use on suicide mortality; when a stressful event occurs, high alcohol intake affects the central nervous system, which may amplify negative emotions [32].
The prevalence of suicide was higher among men than women, and men with a skin color black/pardo were 3.3-fold more likely to commit suicide. Data from the Brazilian Health Ministry show that the death rate due to suicide was 6.13 per 100 thousand people in 2016 (9.8 for men and 2.5 for women); moreover, men and black/pardo skin color were the most numerous groups among deaths by suicide in 2018 [15]. In Brazil, black and pardo individuals constitute a more socially vulnerable group, which may be a risk factor for suicide. An Australian survey that associated individual characteristics with lethal methods of suicide found that individuals with a more precarious social network and greater social vulnerability were at greater risk of dying by suicide [18]. Another study found that experiencing gendered racism significantly increased the risk for SI or SB among women [19].
The greater proportion of men among cases of suicide has also been reported in other studies; some of them show that, although women are more likely to SA more often and perform acts of self-mutilation, men tend to use more violent methods with greater lethality [34]. The use of medications and poisoning as a method of suicide is more socially acceptable for women than men, as confirmed in the present study, in which poisoning was the method most used by women. Other factors may influence the lower mortality rate due to suicide among women. Women generally have more protective factors, such as stronger religious beliefs, a solid and more effective social network, and a greater willingness to seek help for their mental disorders and SI [35].
Clinical and sociodemographic characteristics may distinguish the choice of method. A study analyzed 8,103 deaths by suicide between 2000 and 2013 and found that hanging accounted for 48.4% of the cases; moreover, males, indigenous people, and individuals who resided in rural and remote areas were more likely to die by hanging [18]. Given the easy availability of hanging materials and the difficult access to firearms among younger age groups, individuals who feel angry due to an interpersonal conflict in combination with alcohol use may be impulsively driven to hang themselves, as other methods would require a more extended preparation [36]. The results of the present study identified a similar profile, as men, young people, individuals with a lower education level, and individuals with black/pardo skin color chose the hanging method.
A previous Brazilian study involving an epidemiological analysis of suicide indices registered in the country between 1980 and 2006 found that the main sociodemographic characteristics of the individuals who die by suicide were a low educational level and being single. Also, the survey showed that one's own home was the primary location for suicide (51%), and among the deaths that occurred in the home, 64.5% were by hanging, and 17.8% were by firearms [37].
Individuals who jumped from a height to die by suicide were usually under the influence of PASs (except alcohol) in the present study. The use of PASs, especially cocaine, can increase the lethality of SB; individuals under the effect of cocaine/crack tend to SA using more lethal methods than those that have not used [38]. An American study analyzing suicides by hanging and firearms to explore how specific drugs are associated with the method of suicide as a function of demographic and social characteristics found that the association between the use of cocaine/opiates and a violent method varied with the level of schooling [28]. In our data, individuals with higher levels of education and younger people opted to use PASs (except alcohol), whereas older people and those with lower levels of schooling preferred alcohol.
In the sample, the use of PASs was non-significant among suicides by less violent methods, such as poisoning, and individuals who had recently changed their behavior preferred not to use drugs. Studies have shown that mental disorders constitute an important risk factor for SB, independently of the PASs use. A fatal and a non-fatal SA are more frequent among patients who suffer mood disorders than the other psychiatric disorders in comparison who do not present any mental health problems [39]. Anxiety and obsessive–compulsive disorder may also be associated with the attempted suicide of high lethality, mainly when associated with the use of PASs [40].
The present findings suggest that previous SA is a significant risk factor for dying by suicide. According to the World Health Organization, the main risk factors are suffering from a mental disorder and having a history of non-fatal SA [41]. Individuals with prior attempts have a 40-to-66-fold greater risk of dying by suicide than the general population [42].
The multivariate analysis of the data using PCA [43, 44] indicated a gradual change in the suicide profile, pointing to an increasing contribution of new determinant factors for suicide, forethought for suicide, and prior attempts, which underscores the need for the adoption of preventive public health policies explicitly directed at this population.
Suicide is a mental health problem that continues to pose a challenge for the scientific community and healthcare providers with regard to the identification of risks that can assist in the implementation of prevention measures. The PASs use and mental disorders are strongly associated with a fatal SA. However, these data per se are not capable to prevent the occurrence of so many deaths every year.
A comprehensive analysis of sociodemographic characteristics and suicide methods would better predict future risk groups and plan prevention measures “custom-made”. Identifying what sociodemographic characteristics are associated with a fatal SA among individuals who use PASs and those who do not use them, and those who have/do not have mental disorders and what methods are employed could be a path to better interventions. Professionals who work in specialized mental health/drug addiction services, as well as those in the primary care, can identify SB in large samples and among community-dwellers using easy-to-apply screening instruments, such as the PHQ-9 scale for initial screening of the presence of depression [45], the Beck SSI scale for the evaluation of the presence/intensity of suicidal ideation [46], and the Columbia Scale for the assessment of suicidal risk [47]. These prevention actions could be planned and directed to individuals with greater risk.
Limitations and strengths
Regarding limitations, we could not fit all variables to all individuals since the data were collected from police and coroners' reports, which did not always have all the fields correctly filled out. Data such as previous attempts, recent behavior changes, and reasons for the suicide were reported by relatives at the police station. While the coroner provided the skin color of the individuals investigated in the present study, the skin color of the population of the Brazilian Federal District is self-declared. It was not possible to obtain the BMI for the Brazilian Federal District population to compare it with the χ2 test for specified proportions.
The article's strengths are the sample size, the considered period, the post-mortem analysis with the toxicological test performed, and the diversity of analyzed and correlated variables, making it possible to identify specific clusters of populations at higher risk to create more targeted prevention interventions.