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The Neuroscience of Suicidal Behavior


In my journey in the wake of suicide, the most common thing that I hear is “it doesn’t make sense” or “it is so senseless.” The survivors who must clean up the mess that the person who committed suicide left are wondering why. The Neuroscience of Suicidal Behavior offers no definitive answer but does offer clues towards our own understandings of the tragedy.

The Pseudo Why

There is an answer to “why,” but unfortunately the answer isn’t satisfying. Van Heeringen explains, “Every suicide is the tragic outcome of profound personal suffering and mental pain.” Mental – or psychological – pain drives the desire for suicide, whether planned or impulsive. (See The Suicidal Mind for “psychache,” Shneidman’s term for this condition.) Suicide isn’t a problem for the person attempting it, it’s a solution. It is too often the “only” solution that they see available to them.

The answer is unsatisfying, because too often we ask what kind of psychological pain could be so pervasive and large that someone could find no way out or around the problem. Those on the outside objectively view the problem and recognize that most of the problems in life – the things introducing psychological pain – are solvable. Thus, the idea that the suicidal person saw something difficult is difficult to see.

Degrees of Suicide

It seems as if suicide is binary. Either the person killed themselves, or they did not. However, the edges aren’t so easy. Consider attempted suicides. Should they be considered suicidal? Do you only count them as suicidal if their attempt would have succeeded if not for the intervention of others? What about those who are self-harming (e.g. cutting)? Are they considered suicidal before their first attempt? What about those who claim to have attempted suicide, but it’s later discovered that they made no attempt? How do we classify those who run their cars off the road into trees? Were they being intentional – or not?

Given that ~70% of suicidal attempts are successful on their first attempt, it’s worth being concerned about where we draw the lines. Thus, instead of one word for suicide, van Heeringen shares a few terms: parasuicide, pseudo-suicide, deliberate self-harm, self-harm, and non-suicidal self-injury (NSSI).

To categorize suicidal attempts, three dimensions are introduced:

  • Lethality – To what degree is the action (or inaction) going to lead to death? Will it be immediate or take a long time to complete?
  • Planning – How much work did the person put into planning their attempt? Was it meticulously planned or seemingly impulsive?
  • Intent – Did the person intend death, or did they create situations that would likely lead to their avoidance of death?

Non-Suicidal Self Injury (NSSI)

Thomas Joiner in Why People Die by Suicide was clear that he views the willingness to inflict self-harm as a key factor in suicide. Van Heeringen seems to agree, indicating that NSSI may be a “gateway” to unlock more lethal forms of self-harm that lead to suicide.

Economic Uncertainty

An odd statistic arises. In the quest for correlation, unemployment was considered as a contributing factor to suicide. However, the odd conclusion was that suicide rates rose before unemployment rates. There are several potential explanations for this. (Emile Durkheim said, “These being the facts, what is the explanation?”)

One explanation is that it is economic uncertainty that causes suicide rates to rise. This is consistent with Durkheim’s suggestion that it’s the transition in the economic situation that causes the rise in suicide rates. Both at the top and bottom of the business cycle, suicide rates are reduced.

This is supported by the idea that victims of suicide typically have an inconsistent work history. The prospect that competitors or a new technology will invalidate the need for someone – or discussions of performance on the job – can easily drive people to the belief that their only answer is suicide.


The neurochemicals inside the brains of those who have committed suicide are different than those of a representative sample of the general population. They have a blunted reaction to cortisol, suggesting that they may have habituated to abnormally high levels because of persistent stress. (See Why Zebras Don’t Get Ulcers for comprehensive coverage of neurological and physical aspects of the stress response.)

Other impacts of stress may create challenges as well. For instance, tryptophan is a precursor to serotonin, a key neurochemical associated with feelings of happiness. Stress causes pathways for tryptophan that may cause a reduction in the amount available for the creation of serotonin. Thus, stress management is a key tool for preventing suicide. (See Emotion and Adaptation for more on stress management.)


One of the other insights from Why Zebras Don’t Get Ulcers is Helicobacter pylori. It’s the pathogen (bacteria) that causes ulcers. Many people are infected with it, but it lives in homeostasis in the stomach. It survives the acidic environment but rarely gets the upper hand. Introduce stress, and the body reduces immune response and repeatedly decreases digestion. The result is that H. pylori gets the upper hand and eats through the lining of the stomach.

A parasite called Toxoplasma gondii may have a similar relationship with our immune system – reaching a balance that doesn’t seem to impact us but may have important implications for suicide. It’s estimated that 30-40% of humans are infected with T. Gondii, but for most of us, it doesn’t seem to be a problem. However, immunocompromised patients may succumb to toxoplasmosis.

This is moderately troubling, but the story gets more troubling when you realize that, in rats, T. Gondii inhibits fear of cat urine. (See Dreamland for more.) T. Gondii replicates in cats. Obviously, rats’ natural predators are cats. They should fear cat urine, because it means that a cat is around. T. Gondii seems to shut down this fear. The result is an infected rat is eaten by another cat who becomes a host for T. Gondii and the cycle of replication increases.

If we consider that suicide isn’t a desire to die but rather the conflict of the desire to live and the desire to die, tipping the scales towards less fear of death can have tragic consequences. Multiple research studies have shown an increased prevalence of T. Gondii in suicide attempters and those who have completed a suicide attempt successfully. If Worm at the Core is correct in that the fear of death drives us all in persistent but unseen ways, removing the fear of death could have tragic consequences. This means that T. Gondii may play a sinister role in suicidal deaths.


One of the key unanswered questions with suicide is the degree to which suicides are planned. Some factors point to the idea that all suicides are planned – but much research implies that it’s not. For instance, it’s estimated that 1 in 6 people have considered suicide at some point – and Thomas Joiner argues in Myths about Suicide, this should be considered preplanning.

Conversely, we know that more restrictive gun control laws, which limit access to lethal weapons, tends to reduce the incidence of suicide. In short, removing the weapon from a time of impulsivity has the effect of preventing the suicide. However, impulsivity of self-harming behaviors doesn’t appear to correlate well with the personality trait of impulsivity.

Not All Indicators Are Created Equal

Perhaps the largest problem in preventing suicide is that there are no clear indicators that indicate a high likelihood that someone will – or won’t – attempt suicide. Even the opening quote regarding mental (psychological) pain isn’t sufficient on its surface. There are many people who experience both physical and psychological pain who don’t commit suicide. Consider Vicktor Frankl who wrote Man’s Search for Meaning. He experienced unimaginable pain as a prisoner of a concentration camp and yet took that experience and developed logotherapy to help others – rather than end his own life.

Even though 1 in 6 people may at some point in their lives consider suicide, only about 12 in 100,000 are successful in a suicide attempt. Clearly, there’s a large discrepancy between those that give suicide some thought and those who act on their thoughts.

However, one of the recurring concepts is the sense of hopelessness that those who are attempting suicide feel. They feel as if suicide is their only escape from their pain. In fact, at least one person who attempted suicide has felt suicide was their only option until they leaped from the Golden Gate Bridge, at which point they realized every problem in their life was solvable – except for having just leapt from the bridge. (See The Hope Circuit for more on hope, and The Suicidal Mind for more on the story.)

Normal and Abnormal

As survivors struggle to understand, they often recognize that the situation the suicidal person found themselves in wasn’t unique or abnormal. Suicide is not, therefore, a normal reaction to an abnormal situation. It is instead an abnormal reaction to a normal situation. We all lose love, get divorced, and suffer all kinds of loss. (See The Grief Recovery Handbook for grief as a response to loss, and Divorce for more on the specific loss of divorce.) Since the precipitating factors are normal, we can only conclude that suicide is an abnormal response to the normal situations that many of us find ourselves in from time to time.

If we’re going to find a way to reduce suicide, we need to be able to develop skills in everyone to avoid these abnormal reactions, and we must be able to detect when these abnormal responses might occur. One clue may be the ability to assign value to long-term risks and outcomes – or not.

Constricted Thinking

In Why People Die by Suicide, Thomas Joiner explains the constricted and constrained thinking that often happens with suicide attempters. However, there may be an even earlier indicator available – that is their ability to properly assign risk to long-term consequences. If you’re going to predict well, you might look at Nate Silver and his book The Signal and the Noise or Philip Tetlock and his work in Superforecasting. Both look at the process of predicting future events and how to make those predictions more accurate. Tetlock in particular made a striking observation. Those forecasters with the greatest precision had greater cognitive diversity.

The best forecasters are those who consider the situation from multiple perspectives. Instead of viewing things with one point of view, they intentionally cultivate alternative views – and try to evaluate the relative merits. It’s the same sort of thing that Scott Page encourages in The Difference. However, instead of the diversity being experienced inside the mind of one person, it’s shared across a team of people – which may be a way to accomplish both diversity of thought and social connection.

Entrapment and Hopelessness

The problem with constricted thinking is that it leads to the perception that there is no way out – or only one way out. This can lead to a feeling of entrapment in a situation – whether you actually are or not. Often, it’s constricted thinking preventing visibility of other options, like blinders on a horse. You can only see the most obvious and easy solutions before you, no matter how bad or even ridiculous they are when evaluated rationally.

The problem with entrapment – as it pertains to suicide – is that it’s difficult to identify when someone might feel trapped, because it happens due to internal mental processes being decoupled from reality. (Sometimes with the assistance of alcohol.) It’s equally true to say that the suicidal person is entrapped by their own thinking as much as – or more than –the circumstances they find themselves in. They’re in a prison of their own making. Other options and those who care are all locked out.

Because of mental entrapment, people feel hopeless – and that’s one of the most dangerous situations that someone can find themselves in. Like a trapped animal, there’s no telling what a hopeless person will do – and as evidence, I offer that they sometimes attempt suicide.

I explained in my review of Why People Die by Suicide how too few people really understand how hope works – and what can be done to cultivate it as a cognitive process.


“They come from good stock.” It’s a statement that exposes the layperson view of genetics. Born (literally) from agricultural beginnings, the statement hints to the kind of genetic predisposition that our research into the details of the human genome has led to. However, genetics have their limits, as we’ve discovered. Instead of the genes laying out a predetermined path for a person (or animal), they seem to interact with the environment to form the lives of people. The question isn’t nature (genetics) or nurture (environment) – it’s both. (See No Two Alike and The Blank Slate for more.)

Some of the strangest observations in all of science are things like the Adverse Childhood Experiences (ACE) study, and how the health of adults is substantially influenced by the number of stressful events that a child faced decades earlier. (See How Children Succeed for more.) It appears that the causal arrow can come from a quiver even earlier in the life of children. FOAD – Fetal Onset of Adult Disease – proposes that the life of a child is influenced by the stress that the mother faces during pregnancy. (This is the research of David Barker, and it’s recounted in Why Zebras Don’t Get Ulcers.)

Specific Memories

One of the keys to knowing if someone is being completely truthful is the degree to which they’re able to recall specific memories. In hiring, it’s suggested that we look for specific examples. (See Who: The “A” Method for Hiring for more on hiring, ) If we’re trying to determine whether someone is lying or not, we’re encouraged to use specific language and questions to trigger a monitorable response. (See Telling Lies for more.) When speaking with children, we know that we’re not getting real answers if they don’t involve specifics. (See How to Talk So Kids Will Listen & Listen So Kids Will Talk.)

In the context of suicide, research shows that those with a higher probability of suicidal behavior are less likely to access specific autobiographical memories. They respond with generalities about how their childhood was okay or that they were happy. Those who are less likely to have a suicidal behavior are able to access specific memories – both positive and negative.

Physical vs. Psychological Trauma

One of the common factors in those with suicidal behaviors is some sort of abuse as a child. Both physical and sexual abuse are associated with future suicidal behaviors, but there is an interesting intermediating factor. It’s not the age at which the abuse started or even its duration. The factor is the relational proximity between the abuser and the child. Parents seem to have the greatest impact, followed by siblings, relatives, and close friends.

This seems to suggest that it’s not the physical trauma that is the primary factor. It suggests that it’s the betrayal and resulting lack of safety that create the greatest difficulty. (See Trust and Betrayal in the Workplace for more on betrayal and Find Your Courage for more on safety.)

No matter what brings you to interest in suicide, The Neuroscience of Suicidal Behavior will increase your awareness and understanding of the tragedies that occur before the tragedy of suicide.