Cusp Catastrophe Model of Suicide

From “Rethinking Suicide: Why Prevention Fails, and How We Can Do Better” - Craig J. Bryan

Five Properties of the Cusp Catastrophe Model of Suicide 

1.    Suicide risk has two distinct states. 

2.    Change between suicide-risk states can occur suddenly. 

3.    Certain suicide-risk states are highly improbable. 

4.    Small changes in suicide risk can lead to (very) big differences

5.    Becoming suicidal and recovering from suicidal states do not mirror each other

1. Suicide risk has two distinct states

In both studies, results suggested that suicide risk was comprised of two distinct subgroups—one low risk and one high risk—rather than existing on a unidimensional continuum. Both studies also found that the differences between the two subgroups were most pronounced for variables directly related to suicide risk, such as severity and intensity of suicidal thoughts. Differences between the high-risk and the low-risk groups, by comparison, were very small when considering variables such as depression, hopelessness, and other symptoms of mental illness.

Symptoms of mental illness did not meaningfully distinguish these two subgroups.

2. Change between suicide-risk states can occur suddenly.

Studies have found that half of suicide attempts occur within five to 20 minutes of deliberation over the act.

Millner interviewed 30 individuals who had recently attempted suicide and asked these individuals to reflect upon their experiences leading up to the attempt. On average, participants reported the following timeline: 

• Five years prior to the attempt, they first experienced suicidal thoughts and experienced these thoughts off and on for several years
  
  
• Two weeks prior to the attempt, these suicidal thoughts increased in intensity and frequency, such that they were occurring nearly continuously
  
  
• One week prior to the attempt, they started to think about where to attempt suicide
  
  
•  Six hours prior to the attempt, they experienced an internal debate about whether or not to attempt suicide
  
  
• Two hours prior to the attempt, they decided upon which method to use
  
  
• Thirty minutes prior to the attempt, they decided where to make the attempt and
  
  
• Five minutes prior to the attempt, they made the final decision to act.

For most individuals, suicidal thinking remained relatively low in intensity until just a few hours before making the attempt, at which point the progression toward suicidal behavior rapidly accelerated.

3. Certain suicide-risk states are highly improbable

While in a state of suicidal mulling, the very slightest of nudges in either direction could make the difference between returning to a lower risk state or transitioning to a higher risk state where the probability of suicidal behavior is greatly increased.

Certain states, or highly improbable.  A s discussed earlier in this chapter states characterized by severe levels of suicidal ideation, and/or suicidal planning, are the latest levels to be “skipped” by people in the time leading up to the suicide attempts. One possibility is that people truly are not experiencing these levels of suicide risk at all. Another possibility is that people do experience these levels of suicide risk, but spend such little time in the states that they are missed or unrecognized. In either case, people generally do not spend much time in these intermediate-risk states; they pass through or leave soon after arriving.

4. Small changes in suicide risk can lead to (very) big differences

The tipping point between two discrete suicide-risk states provides the basis for the fourth property of the cusp catastrophe model: Very small changes in conditions can lead to very different outcomes. If this property sounds familiar, that’s because it is also one of the key assumptions of emergence: nonproportionality.

when someone is not at the tipping point, very large changes in stress could have hardly any impact on their suicide-risk level.

Patients who had a very strong wish to die combined with no wish to live—the highest score possible—were more than six times more likely to die by suicide than everyone else. Among patients who had at least some wish to live, however, the risk of suicide was significantly reduced, suggesting that even a small wish to live could offset a whole lot of wish to die. Conversely, a relatively small decline in the wish to live could precipitate the emergence of suicidal behavior.

 When it comes to the tipping point between suicidal behavior and the absence of it, the wish to live seems to carry somewhat more weight than the wish to die. 

5. Becoming suicidal and recovering from suicidal states do not mirror each other

This brings us to the fifth and final property of the cusp catastrophe model: The change process in one direction is not always mirrored by the change process in the opposite direction. As applied to suicide risk, this suggests that the process of increasing suicide risk may differ from the process of decreasing suicide risk. If we want to move someone from a high-risk state to a low-risk state—a common goal of many suicide prevention interventions and treatments—simply “undoing” or reversing the conditions under which they became suicidal may not be enough. Returning to gymnastics, a gymnast who has fallen off the balance beam cannot get back up by waving her arms and legs around and shifting her weight back and forth, even though these things happened right before she fell. She must instead engage in a completely different set of behaviors—lifting herself up, for instance—to resume her routine.

The technical term for this property is hysteresis, and refers to the fact that a system’s current state depends on the system’s previous state. Said another way: history matters. Change will follow different pathways that are shaped by the system’s past. To understand hysteresis, think about how memory foam behaves. If you sit on a memory foam pillow, it will change shape almost immediately to conform to your body’s contour. After you stand up again, the memory foam will expand and recover its original shape, but this expansion process will be much slower and take much longer than the compression process. When being compressed, memory foam rapidly changes but when expanding in the opposite direction, memory foam changes much more slowly. Change in one direction therefore does not mirror change in the opposite direction.

The concept of hysteresis implicates the possibility that the process of becoming suicidal and the process of recovering from a suicidal state are not necessarily mirror images of each other. High-risk states can emerge rapidly, but returning to a low-risk state may take much longer.

Someone who has been psychiatrically hospitalized is more than 100 times more likely than someone who has never been hospitalized to die by suicide. This risk is highest in the weeks immediately following discharge and slowly declines over time, but remains elevated even a year after discharge. This slow, gradual decline in suicide risk after hospitalization stands in stark contrast to the rapid rise in suicide risk that precipitated the hospitalization in the first place. Someone can move from low risk to high risk very rapidly but take months or years to move back to a low-risk state.

The concept of hysteresis suggests that although an individual’s risk level when they are leaving the hospital may be lower than it was when they arrived, this reduction may not actually reflect a full return to a low-risk state.

I think a better explanation for the incredibly high suicide rate after psychiatric hospitalization is hysteresis. Just as memory foam quickly compresses under pressure but slowly recovers after the pressure has been removed, suicidal individuals may quickly transition from a low-risk to high-risk state when under pressure but experience a much slower recovery after that pressure has been removed.