Biology of Suicide
Wednesday April 29 All Things Considered

What drives people to suicide? NPR's Michelle Trudeau reports that in laboratories around the country, neuro-scientists are trying to find out. They're studying the brains of people who've committed suicide and comparing them with people who died suddenly. People who commit suicide appear to have different brain chemistry than others.

You can read the transcript:

NOAH ADAMS, HOST: Every year, 30,000 Americans kill themselves. More than half of these people are clinically depressed, but that doesn't explain why they commit suicide. Eighty percent of all people suffering from depression never try to take their own lives. So, researchers want to know what distinguishes the two groups biologically. As part of our series on the end of life, NPR's Michelle Trudeau visited a suicide research lab in New York City.

MICHELLE TRUDEAU, NPR REPORTER: For the team of researchers at the New York State Psychiatric Institute, trying to predict suicide begins every morning around 5:30 a.m. at the fax machine in the home of neuropathologist Andrew Dworck (ph). A single page arrives from the medical examiner of New York City -- a list of about a dozen names, of people who died suddenly during the previous 24 hours.

ANDREW DWORCK, NEUROPATHOLOGIST, THE NEW YORK STATE PSYCHIATRIC INSTITUTE: And usually around 6:30 in the morning, I take a look at the list. And usually from the information I get on the list, I can figure out who is likely to be a candidate for inclusion in our study.

TRUDEAU: The list contains clues as to which persons may have committee suicide -- age, sex, time and place of death. In New York City for example, many suicides are by hanging or jumping from heights. Dworck will eliminate cases caused by drug overdose, because drugs would confuse the study of brain chemistry. Also needed for comparison purposes: people who died suddenly but not by suicide.

DWORCK: OK, so then we have, the next case is a 27-year-old, died suddenly of apparently natural causes. So, that's a case that we could use.

TRUDEAU: Although it's barely sunrise, Dworck has to work fast now, for the autopsies by the medical examiner will begin at 8:00 a.m. And before those begin, Dworck needs to get permission from the families of the victims, to take some brain tissue during the autopsy for his team's research. Families usually agree, says Dworck.

DWORCK: Sometimes people are even quite enthusiastic about it, especially with suicide cases. They say, "oh, yes, we're glad that people are doing research on suicide and we hope that this will help" and so on.

TRUDEAU: During the autopsy, half of the brain of the victim is removed and rushed back to the lab of team member Dr. Victoria Aranga (ph).


VICTORIA ARANGA, DOCTOR, RESEARCHER,THE NEW YORK STATE PSYCHIATRIC INSTITUTE: The brain arrives and this is the top of the brain. This is the bottom of the brain...

TRUDEAU: The brain is immediately flash-frozen so that they cells aren't damaged.


And then cut into thin, thin slices. Looks kind of like meat slicer in a butcher shop.

ARANGA: It is exactly that, but very fine, very finely calibrated.

TRUDEAU: So that each slice of brain is paper thin, then gently glided onto a frozen glass slide by Aranga's lab assistant.

ARANGA: Very nice Manuella (ph), beautiful. There are no wrinkles. There are no rips. It's totally intact. I will be able to study every aspect of that brain once we do the experiment.

TRUDEAU: That experiment seems daunting: to search for some biological mark or trace amongst the billions of nerve cells, circuits, and cables in the brains of suicide victims that's not in the brains of people who've died of natural causes. But at least the team knows in which direction to head. Previous research has uncovered clues implicating a brain chemical called serotonin. Now, the job of serotonin is to regulate our moods. Many studies have shown that if a person's serotonin system is malfunctioning, then that person is apt to be more aggressive and impulsive, and also could be at higher risk for depression. So, our serotonin system is the brake on our reckless tendencies.

ARANGA: What we really think that is happening in suicide is that the person is unable to inhibit the desire to go ahead and kill himself or herself.

TRUDEAU: After a decade of work studying over 175 brains, the research group in New York has found that the serotonin braking system is defective in many suicide victims. Their brains are anatomically different than the brains of people who have died of natural causes. Specifically, Aranga has discovered a malfunction in the area of the brain right above the eyes called the pre-frontal cortex, the place where executive decisions are made dictating what feelings we will act upon and what feelings we will inhibit.



TRUDEAU: Another team member, neuroscientist Mark Underwood (ph), is looking at a different part of the brains of suicide victims, at the back, an area called the brain stem. Enlisting the power of the computer, Underwood counts the number of serotonin nerve cells. There too, the serotonin system looks faulty.

MARK UNDERWOOD, NEUROSCIENTIST, NEW YORK STATE PSYCHIATRIC INSTITUTE: We have found hat there are approximately 30 percent more of these serotonin neurons in the suicide victims than in the controls. To find more neurons would suggest something very fundamental, such that you may in fact be born with your biological risk for suicide behavior.

TRUDEAU: That's because you're born will all the neurons you'll ever have, and not only are there more serotonin neurons in the brain stem than there should be, but, Underwood adds, they're smaller, and they don't work right.


In another part of the building, the head of the research team, psychiatrist John Mann (ph) sits in front of his computer.

JOHN MANN, PSYCHIATRIST, DIRECTOR, BRAIN CHEMISTRY RESEARCH, NEW YORK PSYCHIATRIC INSTITUTE: Just give me a second here while I find the file with the pictures.

TRUDEAU: Vivid colored pictures of brains pop up on the screen with the click of a mouse. These are images of the brains of living patients, because Mann wants to see if the faulty serotonin system can be detected in patients who may be suicidal, before it's too late.

MANN: So, this restraint mechanism, which seems to be at fault in completed suicides, may be detectable, by these kinds of imaging techniques, in live patients before they actually act on those thoughts.

TRUDEAU: And there does seem to be something detectable in these PET-scan pictures. Depressed patients who have tried to kill themselves seem to have lower serotonin activity than depressed patients who have never attempted suicide. The serotonin system that governs impulsive self-destructive behaviors is defective.

MANN: In other words, what we've identified are chemical transmitters in the brain that regulate, or seem to be associated with, serious suicidal behavior.

TRUDEAU: Many of these same patients, intent on trying to kill themselves, frequently can have trouble controlling other strong impulses Mann has found, turning their assault outward, being more aggressive verbally and physically toward others.

MANN: So, suicide really is an outcome of a combination of feelings and stressors that make a person feel like committing suicide, and the individual's particular propensity for acting on those feelings.

TRUDEAU: So, these researchers are narrowing in on a number of features that characterize suicide attempters and victims. But being able to reliably predict who will act on the impulse to commit suicide, and who will control that impulse, is still a scientific frontier. There's so many individual differences -- age, gender, psychological profile, genetic background, but these researchers are uncovering common biological threads that link victims of suicide, so that eventually, predicting suicides may be more reliable, and preventing suicides may be possible. Michelle, Trudeau, NPR News.

NOAH ADAMS: That report, part of our series on the End of Life: Exploring Death in America, which will continue on ALL THINGS CONSIDERED and other NPR programs in the months ahead. For more reading, visit our website at

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