Link Between Serotonin and Suicide
Found With New Brain Imaging
Centre for Addiciton and Mental Health, Toronto
Embargo: January 1, 2003 (Toronto): Not all people
with
clinical depression have low serotonin levels
according to a
study published in the January issue of The American
Journal
of Psychiatry.
"There is a common misunderstanding that serotonin is
low
during clinical depression. It mostly comes from the
fact that
many antidepressants raise serotonin. This is a bit
like saying
that pneumonia is an illness of low antibiotics
because we treat
pneumonia with antibiotics," says Dr. Jeffrey Meyer,
the
principle investigator of the study, conducted by
researchers at
the Centre for Addiction and Mental Health (CAMH) and
the
University of Toronto.
According to Dr. Meyer, the main reason people
thought
serotonin was abnormally low during depression is
that suicide
victims have more serotonin binding sites, which
demonstrates
lowered serotonin levels. However, not all people who
are
victims of suicide have clinical depression (probably
about half
do) and there are other psychiatric illnesses that
increase the
risk for suicide.
The researchers used a brain imaging technique called
positron
emission tomography to scan people's brains for
serotonin
binding sites during episodes of clinical depression.
What they
found was that the serotonin abnormality happened in
brains of
people who had clinical depression and severely
negativistic
thinking. The study found that low serotonin levels
can increase
negativistic thinking. This is important because
severely
negativistic thinking is a major risk factor for
suicide.
Dr. Meyer says that this is an important finding in
that some
family members of people who commit suicide blame
themselves. "It's important for people to understand
that often
the severely negativistic perspective of their loved
ones in the
midst of a clinical depression can be caused by
chemicals in the
brain," he says.
Dr. Meyer is very positive about the future of
treatment for
depression with the aid of the brain imaging
technique, "In the
past, we could not look at brain chemicals in people
- the brain
was like a black box. With this new imaging
technology, we
can figure out how abnormal brain chemicals cause
symptoms.
If we can understand a mechanism for each symptom, we
should be able to better understand the illness."
So what are antidepressants that raise brain
serotonin doing?
Dr. Meyer suggests that replacing low brain serotonin
is only a
part of what antidepressants do. Other researchers
have shown
that raising brain serotonin gives brain cells
instructions to
grow, thrive and survive. Our understanding of
clinical
depression is getting more complicated, but this will
lead to
new advances in treatment.
The Centre for Addiction and Mental Health (CAMH) is
a Pan
American Health Organization and World Health
Organization
Collaborating Centre and a teaching hospital fully
affiliated with
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