In Session With Sidney H. Kennedy, MD, MBBS, FRCPC
Dr. Kennedy is Psychiatrist-in-Chief, University Health Network, Toronto
Deep Brain Stimulation
Dr. Sidney Kennedy is a Professor of Psychiatry at the University of Toronto, with extensive experience in treating depression.
He was the recipient of the 2006 Canadian College of Neuropsychopharmacology Medal, which recognizes individuals who
have made outstanding contributions to Neuropsychopharmacology. He is a member of the Toronto team working on targeted
deep brain stimulation for the treatment of refractory depression.
Q. Who are the patients that get referred for deep brain stimulation?
A. Deep brain stimulation (DBS) isn’t for patients who can be successfully treated with less invasive therapeutic
options. However, there’s a population of patients with depression who have failed the entire treatment gamut, from
psychotherapy and pharmacology to electroshock treatment, and for some of these patients, we’ve shown that targeted
DBS can be remarkably effective. For the last 3 years, I’ve been the collaborating psychiatrist on the DBS team with
neurologist, Dr. Helen Mayberg and neurosurgeon, Dr. Andres Lozano. We’ve treated 15 patients who were “treatment
resistant” and we’ve seen a striking improvement in more than half of these patients. Seven of the 15 have
returned to work after years of disability and have experienced a full remission of depressive symptoms. A further third
of the patients have shown considerable improvement although several have not responded at all.
Q. How did this treatment develop?
A. Our rationale comes from a confluence of knowledge about the brain circuits involved in depression
and advances in neurosurgery techniques. Dr. Mayberg initially showed that a switch in metabolic activity in a region
of the brain, cingulate area 25, appeared to coincide with a successful response to fluoxetine. In several other studies
Dr. Mayberg and I showed with psychologist, Dr. Zindel Segal, that CBT and other antidepressants also appeared to modify
the same brain region. At the same time Dr. Lozano and his team had acquired extensive experience with DBS in a different
brain region for the treatment of Parkinson’s disease. It made sense to use this technique in cingulate area 25
for depressed patients who had failed just about all other treatment options.
Q. How does the treatment work?
A. We’re still not exactly sure. For some patients, DBS works almost immediately; unlike the antidepressants or
psychotherapies that usually take weeks to produce an effect. But more importantly, these effects aren’t transient.
They’ve lasted several years in the patients who got DBS at the beginning of the study. Interestingly, in the first
group of patients, cingulate area 25 showed the same kind of changes as we saw in the antidepressant and CBT responders.
Stimulating this region seems to reset the balance between frontal and limbic regions of the brain. While more systematic
studies are obviously needed, this treatment is ground breaking because it has taken a theory of depression circuitry and
shown that stimulating a key region of this circuit has a powerful antidepressant effect.
For more info: http://www.neuron.org/content/article/abstract?uid=PIIS089662730500156X
Disclosure: Dr. Kennedy is on the speaker’s bureau of Biovail, Eli Lilly, GlaxoSmithKline,
Janssen-Ortho, Lundbeck, Organon, and Wyeth; receives grant support from AstraZeneca, Eli Lilly, GlaxoSmithKline, Janssen-Ortho,
Lundbeck, and Merck Frosst; and is a consultant to Biovail, Boehringer Ingelheim, Eli Lilly, GlaxoSmithKline, Janssen-Ortho,
Lundbeck, Organon, Pfizer, Servier, and Wyeth.