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Responding to Violence, Suicide, Psychosis and Trauma

(Interview) The Neurobiology of Suicide, by Dr. John Mann of Austral

For those interested in the whole interview, there is a link to the whole transcript at the end.


Iain Bourne


Natasha Mitchell: You’re with ABC Radio National across Australia. This is All in the mind, I’m Natasha Mitchell, going global on Radio Australia and as podcast.

So let’s come back to Professor John Mann and his efforts to unravel why some deeply depressed souls take their lives, and yet others hold back. Your individual circumstances, social supports, sense of self, are all obviously crucial factors but do clues lie in our neurobiology as well?

. Natasha Mitchell: You’ve been focused on this area for perhaps 20 years now, and I imagine that looking at the biological underpinnings of suicide would have been a sort of novel way to approach the problem of suicide at the time.

– John Mann: Suicide was traditionally regarded very much as a kind of consequence of social factors. Émile Durkheim in France, in fact many others before him, had noticed the relationship of suicide to social changes involving people having been alienated from society and isolated and so on. But relatively recently it became more apparent that suicide was in fact related to major psychiatric disorders.

This was done through psychological autopsies: that is, interviewing the families of people who had been unfortunate enough to die by suicide. It turned out that over 90 per cent of all suicides had a psychiatric disorder.

There was a spate of youth suicide that began in the United States in the 1980s and a little later began to appear in other countries, including Australia, where it became the leading cause of death amongst young people.

And, at first, one had the impression that these were well adjusted, popular young individuals who had everything to look forward to in life and their suicide was a complete mystery. One had a sense that this was a shock to everybody.

But in fact a careful interview by a professional revealed that in fact over 90 per cent of these young people had a psychiatric illness that antedated the suicide. It was almost certainly the principle cause of their suicide, and most of them are not treated at the time when they’re committing suicide.

. Natasha Mitchell: Key to this, John Mann, though, is that we don’t see all people who experience major depression committing suicide.

– John Mann: Yes, that’s been an enormous challenge to clinicians and society. Most people who have these mood disorders never attempt suicide, let alone commit suicide. So the big challenge is trying to—

. Natasha Mitchell: They might think about it, but they may not actually carry through.

– John Mann: That’s true. They may have suicidal ideation—
they have thoughts that life is not worth living—but only a proportion of them have some kind of predisposition which causes them to be more likely to act on those feelings.

. Natasha Mitchell: In order to really get into the neurobiology of suicide—that underpins suicide potentially—you’ve had to do post-mortem biopsies of brains of people who have died. That’s pretty grisly work. What do the families say when you’re requesting permission pretty soon after a person’s taken their own life?

– John Mann: Well the autopsy’s going to be done anyway, in order to determine the cause of death. And obviously we never request permission from anybody’s family to have some brain tissue unless the coroner or the medical examiner is going to do an autopsy anyway.

Even when they’re asked, as we have to ask them, the organ has to be as fresh and as intact as possible, but these families in the height of their distress deserve an enormous amount of credit because they are very altruistic and they see it right away.

. Natasha Mitchell: Let’s climb into the brain of someone who has committed suicide. And it feels quite strange to do this, in a sense, to think of suicide from a chemical point of view, but a key neurotransmitter or brain chemical that you’ve focused your attention on is serotonin. People will be familiar with serotonin because it’s also targeted by anti-depressants.

– John Mann: Yes, it really isn’t as mysterious as it sounds. Every time we have a thought, or a good idea, or a feeling, or an impulse, the brain is involved. The brain is the machinery, and feeling suicidal is just a very sad and terrible feeling that’s most commonly associated with being depressed or having a depressive illness.

Serotonin actually plays a role in many aspects of our lives and functioning. It forms part of the chemical transmission mechanism of the brain, how one neurone talks to another neurone. It’s involved in the modulation of mood, but it also has important functions in memory, anxiety, sexual drive, appetite, sleep.

It also has been shown to be abnormal in many psychiatric disorders, including depression, bipolar disorder, anxiety disorders, schizophrenia, Alzheimer’s disease. How can it do so many different things in those different psychiatric disorders?

Well, they don’t all involve the same part of the brain and so the serotonin input to those different areas is important. Now, suicidal behaviour actually involves a very small part of the brain in the prefrontal cortex, which is at the front of the brain—

. Natasha Mitchell: Which is our sort of executive brain, it kind of co-ordinates our decisions and our actions?

– John Mann: It is where we make executive decisions, but also [has] other decision making components. So, whether or not to act on powerful feelings, to act impulsively, these are all determined by parts of the prefrontal cortex.

The predisposition to suicide involves a very focal abnormality in the serotonin system, which is located in the decision-making part of the brain; the part of the brain that is involved in determining how impulsive or how deliberate we are about decisions. There’s a casino right next door to this convention centre where this conference is taking place and there are a lot of people there who have trouble with impulse control.

. Natasha Mitchell: Low serotonin?

– John Mann: Low serotonin in the wrong place.

. Natasha Mitchell: And a compounding factor for struggling teenagers could well be that this prefrontal cortex, so key in impulse control, is really only fully developed by our early twenties, it turns out.

Might this contribute to suicide rates amongst young people? For all of us, John Mann’s suggestion is that impulse control lies at the heart of a person’s decision to take their own life.

– John Mann: The story with suicidal behaviour is that, in a particular area of the brain, this decision making area of the brain, they’ve got low serotonin function. So that if they get depressed and they feel suicidal, or if they get angry and they want to hit somebody, they are more likely to do it.

. Natasha Mitchell: You have found interesting linkages in this whole discussion between aggression, suicide and serotonin haven’t you?

– John Mann: Yes, we’ve actually found that lifetime aggressive behaviours are proportional in their severity to how low the serotonin system is as a kind of background biochemical trait. You can predict future aggression as well.

The same with suicidal behaviour—the more lethal the suicidal behaviour, the lower the background serotonin biochemical trait. And you can also predict future suicide by this biochemical trait. We’ve done two types of studies.

One is involved in interviewing the families of people who have died of suicide and getting a lot of information from those families. We’ve also been studying live people. We examine the brain directly using brain scans and we examine serotonin function somewhat indirectly by looking at spinal fluid levels.

And when it’s low, it increases the risk of future suicide in people who have a mood disorder of some sort. That actually has proven to be one of the best predictors of future risk. We eventually think that’ll be replaced by the brain scans. When you just measure a single biochemical sample in the spinal fluid, you’ve got no idea where in the brain is the origin of an altered level.

. Natasha Mitchell: John Mann, what you’re talking about is incredibly powerful science, socially powerful science here. Because if you’re talking about developing a genetic and biochemical picture of a brain from birth that predicts that someone might be at greater risk of major depression and, even more significantly, at greater risk of suicide at some later stage in their life, it’s a very powerful sort of set of conclusions to make about someone and their biology.

– John Mann: Well what it really boils down to is that we know that mood disorders are transmitted familially and that suicidal behaviour, its predisposition, is transmitted familially.

People don’t commit suicide when they’re not ill; they do it when they’re ill. So knowing who is at risk is potentially powerful and valuable, because there may be ways of preventing the development or manifestation of the mood disorder.

. Natasha Mitchell: This conversation, though, about preventing the manifestation of, say, a major depression or suicidal thoughts from a very early stage, even before they’ve ever first appeared in a person, that has some fairly complicated dimensions.

What do you do? Do you sort of ascertain whether a child is at risk and then intervene before they’ve had the opportunity to feel depressed?

– John Mann: Well obviously we’re not doing that. And this comes up in the clinic, in a clinical situation all the time. The patient comes to see you and they’ve got a parent, and maybe a grandparent, that’s committed suicide.

And they’ve felt very suicidal and they have a severe mood disorder and you treat them and they get better. The next thing you know is that their teenage child is worrying them, because a teenage child is talking about feeling suicidal and depressed.

So they then want to know, have they transmitted the predisposition for suicidal behaviour and the mood disorder to their child? You know, ‘Doctor, can you see my kid and make an evaluation?’ So we are already clinically confronted with these types of challenges.

No-one is going as far as actually treating perfectly normal-looking kids and trying to make evaluations. But what we’re doing is we are keeping a lookout for the early manifestation that may indicate that these kids are at risk and warrant intervention.

You have to remember that bipolar disorder on average takes about 9 or 10 years to be diagnosed for a lot of people, and on average, people who are going to commit suicide with a bipolar disorder do so 8 years after the illness starts—which explains why most people kill themselves before they get any treatment.

We’re certainly not talking about, at this point, starting before a person gets sick. But we can do a better job in the early phase of the illness when things look more ambiguous.

Natasha Mitchell: Professor John Mann, who’s vice-chairman for research in psychiatry at Columbia University and

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