Suicide claims the lives of more than 804 000 individuals worldwide, every single year (WHO, 2014). It is the leading cause of death among middle-aged men and is the second leading cause of death in those aged 15–29 years old (WHO, 2014). Attempted suicide is thought to have a global prevalence of 2.7 per cent (Nock et al., 2008), and research suggests that as many as 40 per cent of people in the community know someone who has died by suicide (Cerel et al., 2013); thus the toll of suicide is immense, and as such it represents a significant public health issue. The suicide prevention research landscape is evolving rapidly, moving beyond psychiatric explanations, with considerable efforts focused on identifying more specific psychosocial markers of risk. For example, there has been a concerted focus on distinguishing between those who have thoughts of suicide (ideation) and those who attempt suicide (enactment). Indeed, the process of transition from ideation to enactment has been pinpointed as a key target for research and intervention development (Klonsky & May, 2014; O’Connor, 2011; O’Connor & Nock, 2014). Consistent with this, several prominent contemporary models of suicidal behaviour have been proposed in recent years: the interpersonal psychological theory of suicide (IPT; Joiner, 2005; Van Orden et al., 2010); the three step theory (3ST; Klonsky & May, 2015); and the integrated motivational–volitional model of suicidal behaviour (IMV; O’Connor, 2011; O’Connor et al., 2016).
For the purpose of this chapter, we will focus on the IMV model as a contextual framework as it can account for the biological, social and psychological factors involved in the aetiology and course of suicidal behaviour, and it describes the final common pathway to suicide.
Self-harm is a term employed frequently across the United Kingdom and Europe; it encompasses ‘self-injury or self-poisoning, irrespective of suicidal intent’ (National Institute of Health and Care Excellence, 2004, 2011). In recent years, the term ‘non-suicidal self-injury’ (NSSI) has gained currency, particularly in the United States, and is used to refer exclusively to behaviours carried out in the absence of suicidal intent (Nock & Favazza, 2009); this definition specifically excludes self-poisoning. Much controversy surrounds the differential use of NSSI vs self-harm (Butler & Malone, 2013; Kapur et al., 2013), however, this debate is beyond the scope of the present chapter. For further discussion see Zetterqvist (2015). Herein we employ the term ‘self-harm’ when referring to behaviours irrespective of their suicidal intent. However, where the suicidal intent of a self-injurious behaviour has been established, such behaviour is described as a suicide attempt or suicidal behaviour.
Although 804 000 is the published global suicide rate (WHO, 2014), this is likely to be an underestimate given the widely acknowledge disparities in how suicide deaths are recorded globally (Silverman et al., 2007). The most recent available statistics for the United Kingdom and the Republic of Ireland show that 6581 suicides were recorded in 2014, and that the highest rate of suicide was among men aged 45–49 (Samaritans, 2016); this is in contrast to the commonly held belief that suicide is highest in young men and illustrates the demographic shift in suicide, from young to middle-aged men. While more males than females die by suicide (a ratio of 3–4 to 1 is commonly reported), suicide rates among women have been rising (Samaritans, 2016), and females are consistently overrepresented in self-harm figures (Hawton, 2000; O’Connor & Nock, 2014). Annually, more than 200 000 people present to hospital following self-harm in the United Kingdom (Hawton et al., 2007), but as the majority of people who self-harm do not present to hospital (Hawton et al., 2006), the true prevalence of self-harm is likely to be far greater.
The IMV model (O’Connor, 2011) is a contemporary tripartite model of suicide that describes the pathway to suicidal behaviour, but focuses upon the transition from suicidal thoughts to behaviours. The model comprises the pre-motivational (background and vulnerability factors), motivational (ideation/intention formation) and volitional (behavioural engagement) phases (see Figure 162.1). The volitional phase is arguably the most crucial phase of the model, as it describes the factors that are thought to differentiate between those who will act upon their thoughts of suicide (i.e. by attempting suicide/dying by suicide) and those who will not. Each phase of the model is discussed in greater detail below, encompassing a range of risk and protective markers for suicidal thoughts and behaviours.
The pre-motivational phase of the model is based around the stress–diathesis paradigm whereby pre-existing vulnerability for suicidal thinking is activated in the presence of acute distress (Mann et al., 1999; Van Heeringen, 2012). These vulnerability factors can include genetic markers for mental illness, childhood adversity, socioeconomic disadvantage, and also stable personality characteristics such as socially prescribed perfectionism – a pernicious risk marker for suicidal ideation where individuals constantly feel that they are failing to meet the (unachievably high) standards/expectations of others (O’Connor, 2007). The presence of underlying vulnerability (i.e. the diathesis) increases the likelihood that individuals faced with an acute stressor, such as a relationship breakdown, financial crisis or poor test results, will be at increased risk of experiencing thoughts of suicide. These factors do not, however, differentiate between those who will act upon their thoughts of suicide and those who will not (Dhingra et al., 2015).
Central to the motivational phase of the IMV model are three components from Williams’ seminal ‘Cry of Pain’ hypothesis (1997): defeat, humiliation and entrapment, which combine to increase the likelihood that suicidal thinking emerges. Indeed, experiencing higher levels of defeat and entrapment have both been associated with suicidal ideation and enactment (Rasmussen et al., 2010; Taylor et al., 2011). Two ‘classes’ of factors (‘threat to self’ moderators (including social problem-solving or coping skills) and ‘motivational’ moderators (e.g. presence of social support and positive future thoughts)) strengthen or weaken (i.e. moderate) the pathway from suicidal ideation to suicide attempts. Take, for example, the way we think about the future: a greater presence of positive thoughts about the future is associated with lower scores on measures of entrapment, and a reduced likelihood of engaging in repeat suicidal behaviour (O’Connor & Williams, 2014). Conversely, poor social problem-solving ability is correlated with higher levels of suicidal ideation (Pollock & Williams, 2004), as are feelings of burdensomeness and a lack of belongingness (Van Orden et al., 2010). In short, threat to self and motivational moderators can inhibit or facilitate the progression from feelings of defeat or humiliation to entrapment, and thereafter to the emergence of suicidal ideation and suicidal intent. As with factors within the pre-motivational phase, components within the motivational phase of the IMV help us to understand how and why suicidal ideation develops; they are not central to distinguishing between individuals who think about suicide and those who attempt suicide.
A key challenge for suicide prevention is being able to distinguish between individuals who ideate about suicide, without engaging in the behaviour, and those who will make a suicide attempt. It is this final phase of the model, the volitional phase, which maps out the factors that differentiate between those with suicidal ideation and those who engage in suicidal behaviour or die by suicide. Impulsivity and exposure to suicidal behaviour (i.e. knowing friends or family who have self-harmed, attempted suicide or died by suicide) are two such variables that are thought to be more strongly associated with suicidal behaviour than suicidal thinking per se (Dhingra et al., 2015, 2016; O’Connor et al., 2012). Increased ability to endure physical pain and reduced fearlessness about death are also volitional moderators, as they are thought to increase one’s capability (or capacity) for suicide (see the interpersonal theory of suicide; Joiner, 2005; Van Orden et al., 2010). The work on physical pain sensitivity is at an early phase; indeed, the precise nature of its relationship with suicidal behaviour is as yet unknown (Kirtley et al., 2016).
Suicide is a major worldwide public health issue that claims hundreds of thousands of lives each year around the world, with millions devastated by such loss. Every suicide is a story of personal tragedy, borne out of immense and overwhelming psychological pain. Although risk factors for suicide span the clinical, cultural, social and biological domains (see Hawton et al., 2012 and Turecki & Brent, 2016 for an overview of risk factors), given that an individual makes a decision to end their own life, understanding the psychological underpinnings of suicidal thoughts and behaviours is vital to suicide prevention. Theoretical models like the IMV model help to identify treatment targets, to point to opportunities for intervention, as well as prioritizing those factors which are likely to offer most promise in terms of reducing risk of suicide (Armitage et al., 2016; O’Connor & Nock, 2014). Future research should continue to take a nuanced and multifaceted approach to investigating the psychological factors that lead individuals to take their own lives. Models of suicidal behaviour, such as the IMV model (O’Connor, 2011), have significant utility for delineating testable hypotheses for suicide research, and promising targets for treatment and intervention development.