Vivian M. Rakoff Positron
Emission Tomography Centre
Dr. Sylvain Houle, Director
Investigations in the Positron Emission Tomography (PET) Centre are concentrated
in the following areas: PET Methodology; Schizophrenia; Mood and Anxiety
Disorders; Addiction; Movement Disorders; Cognitive Neurosciences; Aging
and Dementias.
PET Radioligands Development
The radiochemistry group, led by Dr. Alan Wilson, is continuing its innovative
work in radioligand development. The past year has seen the successful
transfer to human studies of a new radioligand, [11C]-DASB, to investigate
the serotonin transporter. Since the latter is the target of the selective
serotonin reuptake inhibitors used in treating depression, this new ligand
has generated great interest in the psychiatric community. This achievement
has further strengthened the international leadership of our PET Centre
in psychiatric PET research. It is particularly noteworthy because many
leading PET facilities worldwide had been working for more than 20 years
to develop a suitable serotonin transporter PET ligand.
In another innovative research area, Dr. Jean DaSilva is continuing his
work aimed at imaging the second messenger system in humans using PET.
The work of the PET Methodology group has been enhanced by the recruitment
of Dr. Nathalie Ginovart, a PET neuroscientist who has worked previously
in the PET facilities of the Karolinska Institute in Stockholm, Sweden,
and the Centre d'Exploration et de Recherche Médicales par Émission
de Positons in Lyon, France.
Investigation of the
Mechanism of Action of Antipsychotics
The PET Schizophrenia Research Section, under the leadership of Dr. Shitij
Kapur, is exploring the role of the dopamine system in schizophrenia.
Although the benefits of antipsychotic medications are known to be linked
to their effect on the dopamine system, very little is known about their
actual mechanism of action in the brain. We are gaining new knowledge
of the therapeutic effects of antipsychotics by closely linking human
findings obtained by PET with those obtained from animal research. This
approach is already having clinical benefits, by providing objective means
of optimizing existing antipsychotic treatment and by offering new avenues
for developing more effective drugs.
Investigation of the
Role of Neuroreceptors in Depression
The PET Centre has initiated a new program of research into the role
of serotonin and dopamine neuroreceptors in depression. This effort is
being spearheaded by Dr. Jeff Meyer, who has now joined the Department
of Psychiatry after receiving his PhD for work done at the PET Centre.
A major portion of this research uses the new serotonin transporter ligand
as well as a dopamine transporter, [11C]-RTI32, developed a few years
ago at the PET Centre.
Also in the area of mood disorders, Drs. Helen Mayberg and Sidney Kennedy
are continuing to investigate the effect of antidepressant drugs on brain
functions by observing regional changes in glucose metabolism measured
with FDG PET scans.
Movement Disorders
Dr. Stephen Kish, in collaboration with Dr. Mark Guttman, is applying
the PET Centre's new serotonin transporter radioligand to Parkinson's
disease. We do not yet have a suitable PET tracer for the serotonin
transporter. The PET investigations in Parkinson's disease have focused
almost exclusively on the dopamine system, which is responsible for the
motor deficits associated with the disease. However, abnormalities of
the serotonin system may explain the onset of depression often experienced
by patients with the disease. This research may help elucidate the non-motor
aspects of the disease.
Equipment Upgrade
The PET Centre's new high-resolution, home sensitivity 3D tomograph is
currently under construction. This new scanner will bring the Centre to
the leading edge of technology and will greatly enhance our research capabilities.
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