Link Between Serotonin and Suicide Found with New Brain Imaging Methods
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 the University of Toronto.
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For further information, please contact Sylvia Hagopian at the Centre
for Addiction and Mental Health at 416-595-6015.
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1-800-463-6273
