The stress diathesis model

A parsimonious model meeting the above criteria has been proposed by our group. (1) (Fig, 1) It is based on the following key observations.

Fig. 1 A stress diathesis model of suicide.

1. Over 90 per cent of suicides occur in the context of a psychiatric disorder.

2. The overwhelming majority of persons with psychiatric disorders do not make suicide attempts.

3. The objective severity of symptoms is not predictive of suicidal behaviours.

4. In a factor analysis, a combination of aggression and impulsivity was the most important predictive factor for suicidality.

5. Familial grouping of suicidal behaviour seems to indicate an inherited suicidal trait independent of the inheritance of particular diagnosis.

In addition there are the following intriguing biological findings: (1) suicide attempters and completers seem to have a dysfunction of the serotonergic system, similar to that found in aggressive or violent subjects; (2) abnormalities of the prefrontal cortex appear to be involved in suicide, and have long been known to be involved in aggression, disinhibition, and violence.

Based on these observations, the model postulates two independent components in suicidal behaviour that work in concert. The first consists of lifelong stable traits that comprise a diathesis, which predisposes to aggressive/impulsive behaviour in response to stressful circumstances or powerful emotions. This tendency might be conceived as a lowered threshold for motor activation, a diminution in natural inhibitory circuits, or as a volatile cognitive decision style.

This diathesis may be necessary but insufficient for suicide. Most people with this trait will never make a suicide attempt. Rather, it is a behavioural tendency to cope with powerful feelings by taking action—action that is often definitive, aggressive, and impulsive.

One biological correlate of this diathesis appears to be an overall diminution in serotonergic activity. Numerous elements can contribute to this diathesis, including genetics, early life experiences, chronic illness, chronic alcoholism, substance abuse, and even possibly cholesterol levels. Some factors operate via the serotonergic system.

The second component of the model is an acute stressor that supplies an intense desire to end one's life. Whether this is brought about by life circumstances, a psychiatric illness, or both, it results in the drive or desire to end the noxious experience. Psychological autopsy studies demonstrate that a psychiatric illness is almost always part of this stressor. Patients have portrayed the mental anguish of depression as worse than any experience of physical pain, and it is often accompanied by a sense of hopelessness.

Yet, the majority of psychiatric patients and of persons experiencing a major loss do not make suicide attempts. It seems that there are powerful protective inhibitory circuits that prevent most persons undergoing severe psychological stress from acting on these intense feelings, just as there are inhibitory circuits that preventing overt, outwardly directed aggression under most circumstances. An eloquent description of this restraint system is contained in Hamlet's soliloquy. Upon finding his father murdered and his own succession challenged, Hamlet has the stressor but not the diathesis. After convincing himself that suicide might be a reasonable option he notes his hesitation:

Thus conscience does make cowards of us all;

And thus the native hue of resolution

Is sicklied o'er with the pale cast of thought,

And enterprises of great pith and moment

With this regard their currents turn awry,

And lose the name of action. (Hamlet, Act III, Scene 1)

Suicide and suicide attempts occur in those relatively uncommon circumstances when both components coexist—someone with the aggressive/impulsive diathesis is undergoing a severe psychological stressor.

Coping With Stress In The 21st Century

Coping With Stress In The 21st Century

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