OLIVER MOORE Globe and Mail Update
Wednesday, May 1 – Online Edition, Posted
at 9:49 AM EST
A placebo not only has the power to make patients feel
better, it may also be able to cause the same physiological
change as the drug it replaces, a team of researchers led by a
Toronto neuropsychiatrist says.
Researchers at the University of Texas Health Science Center
found that depressed people given a placebo exhibited changes in
their brain that were remarkably similar to those given
fluoxetine (marketed under the brand name Prozac).
"What we found is that patients who responded to placebo
and those who responded to an antidepressant had similar, but
not identical, metabolic changes in cortical (thinking) and
limbic-paralimbic (emotional) regions [of their brains],"
University of Toronto Professor of Neurology and Psychiatry Dr.
Helen Mayberg says.
She cautions, though, that the effects may not be permanent.
"If you respond to a placebo, this may mean that your brain
has an inherent capacity to heal itself — but it is likely a
Researchers administered treatment to 17 depressed and
hospitalized men over a six-week period. In the double-blind
controlled experiment, neither the patients nor the doctors knew
who had received the drug and who had been given the placebo. Of
the 15 men who completed the study, eight had experienced a
improvement in their symptoms. Four of them had been taking the
bona fide drug and four had been taking a placebo.
"Our findings are consistent with the well-recognized
placebo phenomenon that 'expectation' that a treatment will be
helpful is a critical part of the therapeutic relationship
between a patient and their doctor," Dr. Mayberg said.
The study broke new ground, though, in showing that patients
exhibited similar changes in their brains. Patients on active
medication, however, did show "additional changes" in
their brain stem, striatum and hippocampus.
The clinical study — published in the May issue of the
American Journal of Psychiatry (Vol. 159, #5) — is being
called the first to identify, using positron emission tomography
(PET), the specific brain regions that change with placebo
response and compare them to brain regions that change with
active drug intervention.
All subjects were put on active medication at the end of the
six-week experiment, so it is not known if the placebo effect
would have continued.