Introduction

Suicide is one of the major causes of death worldwide, and approximately one million people commit suicide each year [1]. The incidence of suicide attempts peaks during the mid-adolescent years, and suicide mortality, which increases with age steadily through the teenage years, is the third leading cause of death in young people between the ages of 10 and 24 [2].

Suicidal acts and behaviours are a matter of great concern for clinicians who deal with paediatric patients with mental health problems. Despite its importance, research on suicidality among children and adolescents has been hampered by the lack of clarity of definition. Beyond suicidal ideation and suicide plans, there are a number of behaviours in which there is an intention to die, including suicide attempts, interrupted attempts, aborted attempts, and other suicidal preparatory acts. Suicidal behaviours require, not only the self-injurious act, but also there must be a suicidal intent. By contrast, when individuals engage in self-injurious behaviours for reasons other than ending their lives, this behaviour is termed non-suicidal self-injury. Deliberate self-harm behaviours comprise self-injurious behaviours regardless their intentionality.

The features of suicidality in children and adolescents are different from those occurring in adults [3] and there is a need for tools to identify those young people at higher risk. Depression is a factor strongly associated with suicidality in this population [4], but it is not present in all cases [5], indicating that suicidal behaviour is a result of the interaction of multiple factors. Furthermore, not all depressed children and adolescents develop suicidal ideation or behaviour [6], indicating the importance of, e.g. social and temperamental factors. Predicting which adolescents are likely to repeat their suicidal behaviour would help to establish prevention and intervention strategies for suicidality in children and adolescents.

Biological, psychological, and social factors contribute to a risk profile in children and adolescents. However, the specific purpose of this paper is to review the literature focusing on psychosocial risk factors and suicidality among children and adolescents.

Methods

Search strategy

A systematic two-step search was carried out following the PRISMA statement guidelines [7]. A PubMed search was performed using the following terms: (suicidality, suicide, and self-harm), combined with (infant, child, adolescent) according to the US National Library of Medicine and the National Institutes of Health classification of ages using the filters (humans, clinical trial, randomized controlled trial, English), and limiting the search up to December 2016. This search detected 710 papers. In a second step, the references found in the relevant papers were reviewed, identifying 8 additional publications that had not emerged in the initial search.

Selection criteria

Three researchers (JJC, CL, LK) independently evaluated the abstracts of the 710 studies (see Fig. 1 for flowchart of the literature review). Definitions of suicidal behaviour have varied over time and sometimes differ between the US and Europe. For this review, we considered suicidality a continuum and we used the broader definition of the term self-harm (which includes both suicidal and non-suicidal self-injurious behaviour as described at the Introduction section).

Fig. 1
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Study selection flowchart (using PRISMA guidelines) [7]

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Papers were selected when they met the following criteria:

  • Original articles published in English language from initial online databases until December 2016.

  • Child and adolescent participants (under 18 years of age). In publications that included adults, only those that reported on children or adolescents separately were considered.

  • Publications whose main aim was to examine risk factors for suicidal behaviour/ideation or that included psychosocial variables as risk factors.

Papers were excluded as follows:

  • Reviews, editorials, letters, meta-analyses, and guidelines were not considered for this review.

  • Studies that investigated the benefit of a therapy (pharmacological, psychotherapeutic, or community intervention), or only analysed suicidal methods, or evaluated psychometric properties of assessment instruments, were excluded.

As a result of this selection process, 77 full-text articles were further assessed.

Data extraction

The same three researchers (JJC, CL, and LK) reviewed the selected manuscripts. For each study, the following data were extracted: author names, year of publication, number of subjects, age of subjects, inclusion criteria, methodology, and outcome measures.

Data synthesis and analysis

Studies were classified according to the type of risk factors assessed (psychological factors, adverse life events, and temperament and character factors) and as to sample recruited (clinical vs non clinical samples). Adjusted results were presented.

Results

Psychological factors

Twenty-five of the papers reviewed focused on psychological issues as a key outcome measure, and we summarize them below. Depression, previous suicidal attempts, and substance abuse were embedded within a large proportion of the reviewed literature, so we present the studies grouped accordingly. These 25 studies are listed in Tables 1 and 2 (reporting studies based on clinical and non-clinical samples, separately).

Table 1 Clinical variables and psychological factors. Clinical samples
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Table 2 Psychological factors. Non-clinical samples
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Depression

Depression is considered a major factor in the aetiology of suicidality in children and adolescents [4, 8,9,10,11,12], and it has been reported in both clinical and non-clinical samples. Major depressive disorder was associated with a fivefold higher risk for suicide attempts, even after controlling for other disorders [4], gender, age, race, and socioeconomic status [8, 13]. In addition, results from a cross-sectional study conducted by Spann et al. suggest that depressive symptomatology (measured by means of the Beck Depression Inventory) mediate the relationship between hopelessness and suicidal behaviours [9].

Nevertheless, non-depressed adolescents may also report suicidal ideation and/or display suicidal behaviours [5, 14].

Previous suicide attempt

Converging results from longitudinal studies indicate that a previous suicide attempt is an important predictor of a future suicide attempt, reported in both clinical and non-clinical samples, increasing the risk more than threefold during follow-up [15, 16]. Similarly, results from other prospective studies have shown that prior suicidal behaviour is strongly associated with suicide plans [17], and a previous history of non-suicidal self-injury may predict the occurrence of future non-suicidal self-injury [18].

Drug and alcohol misuse

Cross-sectional and longitudinal studies evaluating alcohol consumption among adolescents have consistently shown that alcohol misuse is a risk factor for suicidal behaviour in clinical and non-clinical samples [5, 8, 18, 19]. Furthermore, alcohol misuse may trigger suicidal ideation even in the absence of high levels of depressive symptoms [5].

Relatedly, smoking and abuse of drugs (such as cannabis) may increase the risk of suicidal behaviour [8, 11, 13, 20,21,22], and the risk increases even more when drugs are used simultaneously with alcohol [4], which occurs quite frequently [23].

Other psychiatric diagnoses

Suicidal behaviour in children and adolescents may occur in relation to other psychiatric disorders, such as anxiety disorders [8, 20], eating disorders [24,25,26], bipolar disorder [16], psychotic disorders [25, 27], affective dysregulation [5], sleep disturbances [28], and externalizing disorders [29]. A growing interest has focused on the study of suicidal behaviour in autism spectrum disorders [30]. Risk for suicidality seems to be increased as a function of the number of comorbid disorders [4]. In addition, as illustrated in a follow-up study, rehospitalisation appears to be a strong indicator of a future risk of a suicide attempt [31].

Other risk behaviours

Suicidality in this age range may be associated with low instrumental and social competence, and having been in a fight in which there was punching or kicking in the previous year [8].

Adverse life events

Serious adverse life events have been reported as preceding some suicides and/or suicide attempts [8, 14, 32]. They are rarely a sufficient cause for suicide/suicide attempts in isolation, and their importance lies in their action as precipitating factors in young people who are at risk by virtue of, e.g. a psychiatric condition and/or of other risk factors for suicidality as detailed below. In this vein, stress-diathesis models proposed that stressful life events interact with vulnerability factors to increase the probability of suicidal behaviour. Nevertheless, stressful life events vary with age. In children and adolescents, life events preceding suicidal behaviour are usually family conflicts, academic stressors (including bullying or exam stress), trauma and other stressful live events. In this review, 11 studies assessed stressors that occur before suicidal behaviour, with similar results for both studies using clinical and non-clinical samples (see Tables 3 and 4).

Table 3 Adverse life events. Clinical samples
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Table 4 Adverse life events. Non-clinical samples
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Family conflicts

Family conflict has been associated with suicidal behaviour [18], even after controlling for gender, age, and psychiatric disorders [8]. Adolescents with a history of a suicide attempt more frequently than controls report stress related to parents, lack of adult support outside of the home, physical harm by a parent, running away from home, and living apart from both parents [33,34,35]. Other family situations associated with risk for suicidality are: parental suicidal behaviour, early death, mental illness in a relative, unemployment, low income, neglect, parental divorce, other parent loss, and family violence [20, 25, 29, 36].

Academic stressors

Students who perceive their academic performance as failing seem to be more likely to report suicidal thoughts, plans, threats, and attempts or deliberate self-injury [37]. Perfectionism has been reported as a personality construct that may be associated with suicidality in adult samples. However, results from a pioneering study in children and adolescents evaluating the Perfectionism Social Disconnection Model suggest that the association between perfectionism and suicidality is mediated by stressful life events (being bullied) or by other psychological features such as learned helplessness [38].

Trauma and other adverse life events

In addition to family conflicts or academic performance problems, early traumatic experiences and other adverse life events have been associated with suicidal behaviours. A history of childhood sexual abuse is associated with a 10.9-fold increase in the odds of a suicide attempt between the ages of 4 and 12 years and a 6.1-fold increase in the odds of an attempt between the ages of 13 and 19 years [36].

Victims of bulling have higher rates of suicidal behaviour and ideation [39, 40], and some victims may be particularly vulnerable to suicidal ideation due to parental psychopathology and feelings of rejection at home [41].

Change of residence may result in loss of a familiar environment as well as a breakdown of the social network, which may induce stress and adjustment problems, and therefore, increase the risk of suicidal behaviour [42].

Other stressful circumstances that may precede suicidal behaviour are peer conflict, legal problems, physical abuse, worries about sexual orientation, romantic breakups, exposure to suicide/suicide attempts, and physical and/or sexual violence among trafficked victims [11, 12, 20, 32, 39, 43,44,45].

Temperament and character

Some personality traits have been identified as predisposing factors for suicidality. Neuroticism, perfectionism, interpersonal dependency, novelty-seeking, pessimism, low self-esteem, a perception that one is worse off than one’s peers, and self-criticism have been implicated as risk factors for suicidality in adolescents [20, 37, 46,47,48,49]. Similarly, maladaptive coping styles have been described as a risk factor for both depression and suicidal ideation [50].

Impulsivity has emerged as an important issue in suicidality [17, 20, 51, 52], with 50% of adolescents having only started thinking about self-harm less than an hour before the act itself [20] (Tables 5, 6).

Table 5 Temperament and character. Clinical samples
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Table 6 Temperament and character. Non-clinical samples
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Discussion

Suicidality among children and adolescents is a topic of increasing concern, and this is reflected in the strong/large increase in the amount of literature assessing suicidality over recent years. While deaths in these populations due to other causes are decreasing, rates of suicide remain high [2]. This highlights the importance of suicidality research and a move to improving and developing suicide prevention strategies.

This review identifies several psychosocial risk factors for suicidality (Table 7).

Table 7 Studies investigating risk factors for suicidality among children and adolescents by type of self-injurious thought and/or behaviour
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The majority of publications reviewed in this present work indicate that young people with suicidal behaviour had significant psychiatric problems, mainly depressive disorders and substance abuse disorders. The presence of a major depressive disorder increases the risk of suicide attempts [4]. Nevertheless, mood disorders do not explain all suicidal ideation and behaviours [5], and important distinctions must exist between depressed adolescents who have experienced suicidal ideation but have never attempted suicide and those who have done so. The evidence clearly highlights the complexity of suicidality and points towards an interaction of factors contributing to suicidal behaviour. Previous history of suicide attempts can identify a population at risk [15, 17], as does the concurrence of different disorders [4].

However, predicting which adolescents are likely to repeat their suicidal behaviour is still an area that needs further development. The natural history of suicidal behaviour among children and adolescents is not completely delineated. Clearly, more information is needed to understand the complex relationship between risk factors for suicidality and to be able to establish prevention strategies for suicidality in children and adolescents. Prospective studies with adequate sample sizes are needed to investigate these multiple variables of risk concurrently and over time.

Drug and/or alcohol misuse may also increase the risk for suicide attempt [8, 11, 18]. Acute intoxication may even trigger the suicidal act in vulnerable individuals by increasing impulsiveness, enhancing depressive thoughts and suicidal ideation, limiting cognitive functions and ability to see alternative coping strategies, and reducing barriers to self-inflicted harm [53]. In this vein, drug and/or alcohol misuse may act as proximal but also distal risk factors for suicidality and also may mediate or moderate the influence of other risk factors on suicidality [54]. Moreover, common neurobiological vulnerability has been described in depression, impulsivity and drug and/or alcohol use disorders such as a greater serotonergic impairment [53], which may help explain their frequent co-association and also their relationship with suicidal behaviour, a violent behaviour associated with disturbances in the serotonergic system [53].

In addition, vulnerability to suicidal behaviour may be, at least to some degree, mediated by some personality traits, such as neuroticism and impulsivity [17, 20, 48, 51, 52]. The association of poor emotional regulation strategies and behavioural impulsivity with suicidal behaviour leads to consider the existence of affective regulation vulnerability among children and adolescents at risk for suicidality.

Stressful life events may act as precipitating factors for suicidal behaviour. Our review identified several circumstances, such as family problems and peer conflicts that may exceed the coping strategies of some adolescents [8, 18, 20, 25, 29, 33,34,35,36]. Nevertheless, it is important to note that some investigations suggest that it is the accumulation of stressful life events, and not the presence of one isolated stressful life event that appears to be related to later suicidal behaviours [55]. However, as not all children exposed to stressful life events develop suicidal behaviours, some authors state that suicidality is not simply a logical response to extreme stress [54], which in turn leads to the hypothesis of a stress diathesis model of suicidal behaviour [56]. Thus, from a suicidal behaviour prevention standpoint, further investigation is needed to clarify the relationship between stressful life events and suicidality in the paediatric population.

Limitations

The conclusions that can be made regarding the strength of association between the risk factors presented in this review and suicidality are limited due to the relatively small amount of prospective studies that have been conducted to date [4, 5, 12, 15, 17, 18, 22, 27, 29, 31, 37, 39, 40, 43, 48]. In addition, the majority of clinical studies used/studied/observed small populations. Publication bias is likely to be present as studies reporting no association between a risk factor and suicidal behaviour may not have been published. Suicidality was not measured by means of the same instrument across all the studies. Similarly, different instruments were used to measure psychopathology or to determine other psychosocial variables, which is another limitation. The age range of participants and sociodemographic variables differs between the different studies making direct comparisons and summaries across studies difficult/troublesome.

In conclusion, this review has pulled together relevant scientific literature addressing psychosocial risk factors for suicidality in children and adolescents. It suggests that various components and factors may contribute to the risk/development of suicidality and suicidal behaviour in a young person, e.g. impulsivity, mood disorder, substance abuse, history of self-injury, and family and/or peer conflicts, to be considered as a cumulative/interactive process. The identifications of paediatric patients at high risk for suicidality and elements of resilience will improve preventative measure in targeted subgroups.