Dr. Åsberg: There are at least four different biological markers that are connected with an increased risk of suicide. They are:

1. Reduced serotonin function. Serotonin is a neurotransmitter, which means that it is a chemical substance which conveys signals between nerve cells in the brain. These cells regulate sleep, memory, aggressive behavior, and other functions.

2. Increased production of the stress hormone, cortisol. Cortisol production increases in stressful situations, especially in situations that are beyond the individual's control.

3. Rapid habituation of the skin conductance reaction to unexpected stimuli. The skin's conductance of small electrical currents is affected by the rate of sweating (this phenomena was once used in the so called "lie detector"). Habituation of skin conductance is just one example where the body's alarm systems stop reacting when the person is repeatedly exposed to strong stimulation. In suicidal people, the skin conductance reaction diminishes especially fast.

4. Abnormal electro-encephalogram (EEG). The EEG records the electrical impulses on the surface of the brain. The EEG's of suicidal people suggest very minor brain dysfunctions, not epilepsy or other obvious pathological states.

Other biological markers of suicide risk have also been described, but it is these four that have been most confirmed in several research studies.

AFSP: Biological markers usually mark diseases, but suicide is not a disease, it is a complex behavior. How can it be connected with a simple biochemical variable?

Dr. Åsberg: This is indeed very surprising. Suicide is definitely not a disease, it is an exclusively human behavior: it is intentional and it presupposes an awareness of the possibility of self-inflicted death. Animals do not kill themselves and small children do so extremely rarely.

Naturally, a biochemical abnormality does not cause suicide. Suicide is an act performed by an unhappy or desperate or angry human being, who perceives this as the only remaining solution to his problems. However, human beings differ in their tolerance for the adversities that give rise to such desperate feelings, and also in their capacity to block impulses, to sit down and think, and to construct solutions to their problems. We believe that the biological markers are related to such differences in personality, rather than directly to suicidal behavior.

AFSP: What led you to investigate serotonin as a biological marker for suicide?

Dr. Åsberg: The associaffon between biology and suicide emerged as an unexpected finding during studies of the biochemical basis of depression. Serotonin was studied, because so many effective and depressant drugs affect serotonin turnover.

The connection between serotonin and suicide has since been reproduced in more than a dozen studies and is deffnitely a fact. It is not confined to depressive illness, but occurs in many other psychiatric disorders as well. It is the serotonin metabolite 5-HIAA that is measured in the spinal fluid, rather than serotonin itself, which is less accessible. Low concentrations of 5-HIAA also occur in normal people.

AFSP: Are there biological markers for other extraordinary behaviors ?

Dr. Åsberg: Some studies show a relationship between certain violent crimes (manslaughter, arson) and low 5- HIAA in the spinal fluid. There is some evidence of a disturbance of other neurotransmitters in pathological gambling.

AFSP: . . .and other connections between personality type and brain chemistry?

Dr. Åsberg: There seems to be a relationship between certain personality features and certain biological markers. 5-HIAA in spinal fluid is, for instance, correlated with a tendency to fear reactions -- people with high 5-HIAA tend to be more fearful. Other markers are correlated with other features. This is a very interesting research field where we are likely to have suggestive findings within a few years.

AFSP: What makes it important to find biological markers for suicide?

Dr. Åsberg: If we find different biological markers for suicide, we can presumably identify different personality profiles that are at risk for suicidal behavior in situations of extreme stress. This will help us to identify individuals at risk, and it might enable us to create better programs for intervention and prevention of suicide.

AFSP: Could this work lead to finding a gene for suicide?

Dr. Åsberg: This is a very difficult topic. The genes involved in serotonin production are to my knowledge not identified, but I have no doubt that they will be. However, as I pointed out before, while low serotonin may be connected with suicide, high serotonin may be connected with increased fear. Which of these would we like to manipulate? We had better think very carefully about what processes the transmitters are involved in, and all the other processes they also regulate, before we proceed to try to change anything -- either by manipulation of genes, or by drugs.

AFSP: How were you affected by this work and the reception it received?

Dr. Åsberg: When we first discovered the relationship between biological variables and suicide, I had quite mixed feelings. First, it is always a wonderful feeling for a researcher to find something new. Second, I found it very hard to believe -- from my background in clinical psychiatry -- that such a relationship could exist. Third, it gave rise to some disquieting thoughts about the factors that may govern human lives. I suppose my reaction is still similar, although I am by now thoroughly convinced that the relation exists, and that we have to accommodate our thinking about human nature to this and similar research findings.

It took some time for other researchers to replicate the 5-HIAA findings, but when they did, I was naturally pleased. I do sometimes feel a certain fear, however, of simplistic explanations, and that these and similar findings may lead to a naive and premature rejection of the vast knowledge that has been accumulated about suicide and its philosophical existential and psychological dimensions.

AFSP: Has the discovery affected the direction of your research?

Dr. Åsberg: I work in multidisciplinary group, where we try hard to integrate different types of knowledge on suicide. We are continuing and extending our studies of people who have made suicide attempts. Besides the different markers of serotonin, we also study other biochemical substances, such as neuropeptides. We plan to use imaging techniques like positron emission tomography (PET) to study serotonin neurons in the living brain.

We also study psychodynamic aspects of suicide with a recently constructed psychodynamic rating profile and with personality inventories. We are working on methods to study existential and religious orientation in our patients. Many of our current studies are transcultural - we collaborate with centers in Uruguay and in Israel.

We are currently working on better programs for intervention with suicide attempters in order to prevent their ultimate

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