COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC.
New research
addresses the
wrenching question
left when someone
ends his or her
own life
WHY???
The neuroscience
of suicide
By Carol Ezzell
www.sciam.com SCIENTIFIC AMERICAN 45
COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC.
MATT MAHURIN
In 1994, two days after returning from a happy family
vacation, my 57-year-old mother put the muzzle of a handgun
to her left breast and fired, drilling a neat and lethal hole through
her heart and, metaphorically, through our family s as well.
It was around midnight on a Saturday havioral tip-offs and are also exploring
night in July, the time of year, I was later clues to anatomical and chemical differ-
surprised to learn, that has the highest in- ences between the brains of suicides and
cidence of suicide in the Northern Hemi- of those who die of other causes. If such
sphere. My stepfather was at home but changes could be detected in medical
didn t hear the single shot because he was imaging scans or through blood tests,
taking a shower in a bathroom at the oth- doctors might one day be able to identify
er end of the house. When he returned to those at highest risk of dying by suicide
their bedroom, she was crumpled on the and therefore attempt to prevent the
carpet in her pajamas, almost gone. She tragedy from occurring. Sadly, that goal is
SUICIDE IS THE 11TH
tried to say something to him before she not immediately in sight: many who have
LEADING CAUSE OF died, but he couldn t make out what it suicidal tendencies still end up taking their
was. The emergency medical technicians own lives, despite intensive intervention.
DEATH IN THE U.S.,
arrived to find a patient, but not the one
ACCOUNTING FOR
they expected: my stepfather nearly died My Mother s Legacy
1.2 PERCENT OF ALL FATALITIES.
himself that night after hyperventilating THE QUESTION of what drove my
from the shock, which all but over- mother to her desperate act that humid
whelmed lungs already compromised by night nearly nine years ago is the second
emphysema. most difficult thing I live with. Scarcely
A PERSON DIES BY SUICIDE
Through it all, I was asleep in my a day has gone by that I haven t been
ROUGHLY EVERY 18
apartment 200 miles away. I was awak- pierced by the anguish of wanting to
MINUTES IN THE U.S.
ened at 2 A.M. by a call from my building s know exactly what prompted her suicide
front desk, telling me that my sister-in- on that particular night as well as the
SOMEONE ATTEMPTS SUICIDE
law was downstairs and wanted to come crushing guilt over what I could have
EVERY MINUTE.
up. My first words to her when I opened done should have done, would have
my door were, It s Mother, isn t it? done to stop her. The hardest thing I
Our family has too much company in have to live with is the realization that I
FOUR MALES DIE BYSUICIDEFOR
suffering the agony of having a loved one will never know the answer for sure.
die by suicide: annually, 30,000 people in In the future, some parts of her story
EVERY FEMALE, BUT AT LEAST
the U.S. take their own lives. That is rough- should become less mysterious, because
TWICEAS MANY WOMEN
ly half again the number who died of AIDS researchers are studying those very issues.
AS MEN ATTEMPT SUICIDE.
last year. Why do they do it? One age-old question, whether a tenden-
Like an estimated 60 to 90 percent of cy to commit suicide is inborn or the re-
U.S. suicides, my mother had a mental ill- sult of an accumulation of bad experi-
ness. In her case, it was manic-depression, ences, is at least closer to resolution.
APPROXIMATELY
also called bipolar disorder. Unless they Although the nature-versus-nurture
80 AMERICANS TAKE
are taking and responding well to the debate still rages in some psychiatric cir-
THEIR OWN LIVES EVERY DAY.
appropriate medication, manic-depres- cles, most researchers who study suicide
sives oscillate between troughs of despair fall somewhere in the middle. You need
and peaks of elation or agitation. Most several things to go wrong at once, ex-
who end their lives have a history of de- plains Victoria Arango of the New York
THE SUICIDE RATE FOR
pression or manic-depression, but people State Psychiatric Institute, which is affili-
WHITE MALES
with severe depression differ in their ated with Columbia-Presbyterian Medical
AGED 15 TO 24
propensity for suicide. Center. I m not saying that suicide is
Scientists have begun uncovering be- purely biological, but it starts with having
HAS TRIPLED SINCE 1950.
FEBRUARY 2003
COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC.
PHYSICAL CLUES TO SUICIDE
CHANGES IN THE ORBITAL IN PEOPLE WHO DIE BY SUICIDE, anatomical and chemical changes occur in two brain regions:
PREFRONTAL CORTEX the orbital prefrontal cortex, which lies just above the eyes, and the dorsal raphe nucleus of
the brain stem. The alterations are evidence of a reduced ability to make and use serotonin, a
Slices from the brain of a suicide
key neurotransmitter known to be lacking in the brains of impulsive people and in those
victim contain fewer neurons in a
suffering from depression. Neurons in the dorsal raphe nucleus produce serotonin; they have
subsection (circled) of the orbital
long projections (blue arrow) that carry the neurotransmitter to the orbital prefrontal cortex.
prefrontal cortex.
In suicide victims, the dorsal raphe nucleus sends less than normal amounts of serotonin to
the orbital prefrontal cortex. C.E.
SINGLE HEMISPHERE OF BRAIN
Plane of
sectioning
Throughout the cortex, serotonin
transporters (gold) absorb
serotonin. In the marked
subsection, the number of these
transporters is reduced.
Orbital
prefrontal
cortex
Plane of
sectioning
Dorsal raphe
nucleus
The analyzed area also exhibits
more binding of serotonin
CHANGES IN THE DORSAL RAPHE NUCLEUS
(orange) per neuron. Together
Neurons in the dorsal raphe nucleus of the brain stem of someone who died by suicide
the analyses indicate that the
contain more of the enzyme that synthesizes serotonin (dark staining) than the
brain tried to make the most of
corresponding brain region of someone who died of another cause. The difference
the serotonin it had.
indicates that the brains of suicides are attempting to produce more serotonin.
SUICIDE VICTIM CONTROL
www.sciam.com SCIENTIFIC AMERICAN 47
COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC.
VICTORIA ARANGO ET AL.
New York State Psychiatric Institute
(
brain slices
); REPRODUCED WITH PERMISSION FROM
BIOLOGICAL PSYCHIATRY,
VOL. 46, NO. 4; 1999 (
neuron micrographs
); CLEO VILETT (
brain diagram
)
BETWEEN 1980 AND 1996 an underlying biological risk. Life expe- sion on a very bad day. So Arango and
rience, acute stress and psychological fac- Mann search in these brains for clues to
THE SUICIDE RATE FOR
tors each play a part, she asserts. At the the biological basis for that impulsivity.
AFRICAN-AMERICAN
root of the mystery of suicide, however, One focus is on differences in the avail-
MALES AGED 15 TO 19
lies a nervous system whose lines of com- ability of the brain chemical serotonin
INCREASED 105 PERCENT. munication have become tangled into un- previous research on the basis of impul-
bearably painful knots. sivity has indicated a dearth of it.
Arango and her Columbia colleague Serotonin is a neurotransmitter, one
J. John Mann are leading the effort to of the molecules that jumps the tiny gaps
SUICIDE IS THE
pick apart those knots and discern the known as synapses between neurons to
THIRD-RANKING
neuropathology of suicide. They have as- relay a signal from one such brain cell to
sembled what is generally acknowledged another. Tiny membranous bubbles called
CAUSE OF DEATH FOR
to be the country s best collection of brain vesicles erupt from each signal-sending,
TEENS AGED 10 TO 19.
specimens from suicide victims. Twenty- or presynaptic, neuron, releasing sero-
five deep freezers in their laboratories tonin into the synapse. Receptors on the
hold a total of 200 such brains, which the receiving, or postsynaptic, neurons bind
WHITE MEN 85 AND
researchers are examining for neuroana- to the neurotransmitter and register bio-
tomical, chemical or genetic alterations chemical changes in the cell that can
OLDER DIE BYSUICIDE
that might be unique to those compelled change its ability to respond to other stim-
AT SIXTIMES THE OVERALL
to end their lives. Each brain is accompa- uli or to turn genes on or off. After a short
NATIONAL RATE.
nied by a psychological autopsy, a com- while, the presynaptic cells reabsorb the
pendium of interviews with family mem- serotonin using molecular sponges termed
bers and intimates probing the deceased s serotonin transporters.
state of mind and behavior leading up to Serotonin somehow exerts a calming
SUICIDE RATES FOR
his or her final act. We try to get a com- influence on the mind. Prozac and similar
WOMEN PEAK BETWEEN
plete picture, Mann says, and come up antidepressant drugs work by binding to
THE AGES OF 45 AND 54 AND
with an aggregate explanation for that serotonin transporters and preventing
SURGE AGAIN AFTER AGE 85. person. A suicide brain is matched against presynaptic neurons from soaking up the
a control brain from a person of the same secreted serotonin too quickly, allowing
sex without a psychiatric disorder who it to linger a bit longer in the synapse and
died at approximately the same age of a continue to transmit its soothing effect.
ALCOHOLISM IS A FACTOR
cause other than suicide.
IN ROUGHLY 30 PERCENT OF ALL
Contained within the three-pound Traces of Pain
gelatinous mass of the human brain are MORE THAN two decades of reports
COMPLETED SUICIDES.
the cells and molecules that were inextri- have linked low serotonin levels in the
cably linked to what that person once brain to depression, aggressive behavior
thought and, indeed, once was. Mann s and a tendency toward impulsiveness, but
APPROXIMATELY 7 PERCENT OF
and Arango s research concentrates in part the evidence has been particularly con-
PEOPLE WITH
on the prefrontal cortex, the portion of the fusing with regard to suicide. A number
brain encased in the bone of the forehead. of studies have found reductions in sero-
ALCOHOL DEPENDENCE
The prefrontal cortex is the seat of the so- tonin in the brains of suicides, whereas
WILL DIE BYSUICIDE.
called executive functions of the brain, in- others have not. Some have observed a
cluding the internal censor that keeps in- lack of serotonin in one part of the brain
dividuals from blurting out what they re- but not elsewhere. Still others have de-
EIGHTY-THREE PERCENT OF ally think in awkward social situations or scribed increases in the number of recep-
acting on potentially dangerous impulses. tors for serotonin or deficits in the chain
GUN-RELATED DEATHS
The impulse-dampening role played of chemical events that convey the sero-
IN THE HOME ARE THE RESULT
by the prefrontal cortex particularly in- tonin signal from those receptors to the
OF SUICIDE.
terests Mann and Arango. Scientists have inside of a neuron.
looked to impulsivity as a predictor for Despite the inconsistencies, the bulk
suicide for decades. Although some peo- of evidence points strongly to a problem
ple plan their deaths carefully leaving in the brains of suicides involving the
DEATH BY FIREARMS IS THE
notes, wills and even funeral plans for serotonin system. That line of thinking
FASTEST-GROWING
many, including my mother, suicide ap- has been bolstered by the recent findings
METHOD OF SUICIDE.
pears to be spontaneous: a very bad deci- of Arango and Mann.
FEBRUARY 2003
COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC.
THE MAGIC OF LITHIUM
Lithium appears to prevent suicide.
Why do so few suicidal people take it?
Lithium . . . is the lightest of the solid elements, and it is
perhaps not surprising that it should in consequence possess
certain modest magical qualities. G. P. Hartigan, psychiatrist
Only crazy people take lithium! my mother shouted during one
of our many arguments over her not receiving the best
treatment for her manic-depression. She accused me and my
stepfather of wanting to medicate her so she would just shut
LITHIUM is the
up. To be honest, she was partially right: it is very trying to be
lightest of the solid
around someone in the grip of a mania, which often brings on
elements and, in its
pure form, floats
incessant, stream-of-consciousness talking.
(left). When
Many people find lithium which generally comes in
compounded in pill
capsules of lithium carbonate or lithium citrate difficult to
form as lithium
take. It can cause hand tremors, constant thirst, frequent
carbonate or lithium
urination, weight gain, lethargy, reduced muscle coordination,
citrate (above),
it can be taken to
blurred thinking and short-term memory deficits. People on it
stabilize moods.
must also have its concentration in their blood assessed
regularly to ensure that it is within the therapeutic range: the
drug is usually ineffective below 0.6 millimole per liter of blood
serum and can cause life-threatening toxic reactions if the level
becomes higher than two millimoles per liter.
Lithium is used routinely to even out the extreme mood
swings of patients with manic-depressive illness, or bipolar
disorder. Increasingly, however, it is also offered to people with
depression. But a growing body of evidence indicates that this Scott and Marie Pope of the University of Glasgow reported that
compound can literally keep people who are at risk of suicide half of a group of 98 patients who were taking a mood-
alive. In 1998 lithium pioneer Mogens Schou of the Psychiatric stabilizing drug such as lithium failed to stick with their drug
Hospital in Risskov, Denmark, pulled together the results of regimen. Yet, the researchers noted, just 1 percent of scientific
various studies of lithium as a suicide preventive and observed publications on the subject of mood stabilizers looked at why
that people not taking the drug were three to 17 times as likely patients did not take their lithium as prescribed.
to end their own lives as depressed people who took the J. John Mann of the New York State Psychiatric Institute
medication. Likewise, Schou determined that lithium reduced says that a major factor in noncompliance is the human desire
suicide attempts by a factor of between six and 15. not to want to think of oneself as ill. There s a natural reluctance
How does it exert its salutary effects? Despite a number of to take any medicine long-term, Mann explains. When a person
tantalizing leads, researchers are still not certain. It s hard to is depressed, they have a problem imagining ever getting better.
say at this time, says Ghanshyam N. Pandey of the University When they re well, they can t imagine getting sick again.
of Illinois. There are so many modes of action. Lithium is The side effects of lithium also play a role. Kay Redfield
thought to affect tiny ports called ion channels on the surfaces Jamison, a psychiatrist at Johns Hopkins University who
of nerve cells, or neurons. As they open and close, ion channels studies manic-depression and suicide and who is a manic-
admit or bar charged atoms that determine the electrical depressive herself has found that the most common reasons
potential within the cells, thereby dictating their activity and patients stop taking the drug are cognitive side effects, weight
ability to communicate with other neurons. Scientists posit that gain and impaired coordination. In her moving memoir, An
the drug stabilizes the excitability of the neurons by influencing Unquiet Mind, she recounts her own struggle to come to terms
the ion channels or by skewing the chain reaction of with the fact that she will probably be coping with lithium s side
biochemical events that occur within an excited cell. effects for the rest of her life. Perhaps if my mother had lived to
A drug only works, though, if someone takes it properly. In read it, she would have been heartened by Jamison s example
the May 2002 issue of the Journal of Clinical Psychiatry, Jan and motivated to begin lithium therapy. C.E.
www.sciam.com SCIENTIFIC AMERICAN 49
COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC.
THOMAS SIELNACHT (
container
); CUSTOM MEDICAL STOCK PHOTO (
pill
)
they can compile an overall model of how Ghanshyam N. Pandey of the Univer-
SUICIDES OUTNUMBER
those abnormalities might work in concert sity of Illinois agrees that the brain s sero-
HOMICIDES TWO TO ONE
to affect a complex behavior. tonin system is key to understanding sui-
EVERY YEAR IN THE U.S.
At a conference of the American Col- cide. There is a lot of evidence to suggest
lege of Neuropsychopharmacology in serotonin defects in suicide, but these de-
2001, Arango reported that the brains of fects do not exist in isolation but in con-
people who were depressed and died by cert with other deficits, he says. The
SUICIDE ACCOUNTS FOR NEARLY
suicide contained fewer neurons in the whole system appears to be altered.
57 PERCENT OF ALL
orbital prefrontal cortex, a patch of brain The serotonin hypothesis does not
FIREARM DEATHS IN THE U.S.; just above each eye. What is more, in sui- rule out important contributions by oth-
cide brains, that area had one third the er neurotransmitters, however. Serotonin
60 PERCENT OF ALL SUICIDES
number of presynaptic serotonin trans- is only one molecule in the intricate bio-
INVOLVE FIREARMS.
porters that control brains had but rough- chemical network named the hypothala-
ly 30 percent more postsynaptic sero- mic-pituitary-adrenal (HPA) axis, in
tonin receptors. which the hypothalamus and pituitary
Together the results suggest that the glands in the brain communicate with the
brains of suicides are trying to make the adrenal glands atop the kidneys. The
most of every molecule of serotonin they HPA is responsible for the so-called fight-
have, by increasing the molecular equip- or-flight response exemplified by the rac-
ment for sensing the neurotransmitter ing heartbeat and sweaty palms you get
while decreasing the number of trans- after a close scrape while driving, say. In
porters that absorb it back again. We be- particular, corticotrophin-releasing fac-
lieve there is a deficiency in the serotoner- tor, which the hypothalamus releases in
gic system in people who commit sui- times of stress, causes the anterior pitu-
cide, Arango concludes. They can be so itary to make adrenocorticotropic hor-
sick Prozac can t help them. Inhibiting mone, which in turn causes the adrenal
In a second-floor laboratory at the up- the reuptake of serotonin isn t always cortex to produce glucocorticoids such as
per tip of Manhattan, Arango s techni- enough to prevent suicide: it wasn t for cortisol. Cortisol prepares the body for
cian leans into an open freezer to use a my mother, who died despite taking 40 stress by raising blood sugar concentra-
machine called a microtome to pare a milligrams of Prozac a day. tions, increasing heart rate and inhibiting
feather-light slice from a frozen brain do- Mann and his colleagues are now try- the overreaction of the immune response.
nated by grieving relatives anxious to help ing to devise a positron emission tomog- Serotonin fits into the HPA because it
science address the mystery of suicide. Us- raphy (PET) test that might one day aid modulates the threshold of stimulation.
ing a chilled brush, she delicately coaxes doctors in determining which among Researchers such as Charles B. Nemeroff
the rime of icy tissue onto a glass slide the their depressed patients have the most of the Emory University School of Medi-
size of a snapshot. With the body heat skewed serotonin circuitry and are there- cine and his colleagues are finding that ex-
from her own gloved hands, she then fore at highest risk of suicide. PET scans tremely adverse early life experiences,
melts the brain sliver onto the glass; ob- mirror brain activity by monitoring which such as child abuse, can throw the HPA
serving the process is reminiscent of brain regions consume the most blood axis off kilter, literally leaving biochemi-
watching bright sunlight on a frigid win- glucose; administering drugs, such as fen- cal imprints on the brain that make it vul-
ter day dissolve frost on a window. fluramine, that cause the release of sero- nerable to depression as a result of over-
The scientists working with the Co- tonin can help scientists zero in on active reacting to stress later on.
lumbia collection divide the brains into brain areas using serotonin. In 1995 Pandey s group reported in-
left and right hemispheres and then care- In the January Archives of General dications that the abnormalities in sero-
fully section each hemisphere into 10 or Psychiatry, Mann and his co-workers re- tonin circuitry present in those at risk for
12 blocks from front to back. Once ported a relation between activity in the suicide could be detectable using a rela-
frozen and put through the microtome, prefrontal cortex of people who had at- tively simple blood test. When he and his
every block yields roughly 160 slices that tempted suicide and the potential deadli- co-workers compared the number of
are thinner than a human hair. ness of the attempt. Those who had used serotonin receptors on platelets (clotting
The chief benefit of this approach is the most dangerous means for example, cells) in the blood of suicidal people with
that Arango s and Mann s groups can per- by taking the most pills or jumping from those of nonsuicidal people, they ob-
form several different biochemical tests on the highest point had the least serotonin- served that individuals considering sui-
the same brain slice and know the exact based activity in the prefrontal cortex. cide had many more serotonin receptors.
anatomical locations of the variations they The more lethal the suicide attempt, the (Platelets just happen to have receptors
find. By reassembling the slices virtually, bigger the abnormality, Mann observes. for serotonin, although it is unclear why.)
50 SCIENTIFIC AMERICAN FEBRUARY 2003
COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC.
Pandey says that his group concluded
that the boost in receptors reflects a sim-
ilar increase in the suicide-prone brains
a vain attempt to garner as much sero-
tonin as possible. To prove the link, Pan-
dey would like to determine whether the
association holds up in people who go on
to take their own lives. We want to
know if platelets can be used as markers
for identifying suicidal patients, Pandey
says. We are making progress, but it s
slow.
A Curse of Generations
UNTIL RESEARCHERS can develop
tests to forecast those at highest risk for
suicide, doctors might concentrate their
efforts on the biological relatives of sui-
cide victims. In the September 2002 issue
of Archives of General Psychiatry, Mann,
David A. Brent of the Western Psychiatric
Institute and Clinic in Pittsburgh and their
colleagues reported that the offspring of
suicide attempters have six times the risk
of people whose parents never attempted
suicide. The link appears in part to be ge-
netic, but efforts to pin down a predis-
posing gene or genes have not yet yielded
any easy answers. In studies in the early
1990s Alec Roy of the Department of
Veterans Affairs Medical Center in East
Orange, N.J., observed that 13 percent of
the identical twins of people who died by
suicide also eventually took their own
lives, whereas only 0.7 percent of frater-
nal twins traveled the same path as their
suicidal siblings.
These statistics serve as warnings to
me and to others with biological ties to
suicide. In a small jar in my bedroom I
keep a bullet from the same box that con-
tained the one that killed my mother. The
police took the gun after her death, and I
myself threw away the remaining bullets
while cleaning out her bedroom closet.
But I like to think that I hold on to that
single, cold pellet of metal as a reminder
of how tenuous life is and how one im-
MORE TO EXPLORE
pulsive act can have immense and rip-
Night Falls Fast: Understanding Suicide. Kay Redfield Jamison. Vintage Books, 2000.
pling consequences. Perhaps someday sci-
Reducing Suicide: A National Imperative. Institute of Medicine. Edited by Sarah K. Goldsmith,
ence will better understand the basis for
Terry C. Pellmar, Arthur M. Kleinman and William E. Bunney. National Academies Press, 2002.
such harrowing acts so that families like
Information and education materials on preventing suicide can be obtained from the National
mine will be spared.
Mental Health Association (www.nmha.org), the American Foundation for Suicide Prevention
(www.afsp.org) and the American Association of Suicidology (www.suicidology.org). The groups
also have support materials for the survivors of loved ones who died by suicide.
Carol Ezzell is a staff editor and writer.
www.sciam.com SCIENTIFIC AMERICAN 51
COPYRIGHT 2003 SCIENTIFIC AMERICAN, INC.
MATT MAHURIN
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