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Depressed
Get a Lift from MRI
By William J. Cromie
Harvard News Office
Both the
patients and psychiatrists were startled. Manic-depressives
undergoing brain scans, not a really pleasant experience, came out of
the machine happier than when they went in.
One severely
depressed woman left the scanner laughing and joking. It
was totally not like her. After a 20-minute scan, another woman happily
asked a researcher, "What did you do to me?"
Aimee Parow,
the researcher, told Perry Renshaw, director of the Brain
Imaging Center at McLean Hospital, a psychiatric affiliate of Harvard
Medical School, where the scanning was done. The research team was
trying to determine how the brain chemistry of manic-depressives
differs from that of people who are free of the problem. Nobody
expected to find such a happy result. "It was amazing," Renshaw
comments.
He described
what happened to Bruce Cohen, president and chief
psychiatrist at McLean. "I was excited but skeptical," he recalls.
"One
part of me said, 'It's unlikely.' But another part said, 'Why not?'
People go in and out of depression on their own. Electromagnetic fields
generated by the scanner could nudge a depressed brain back toward
normal."
It was decided
to investigate the surprise further. Under the direction
of Michael Rohan, an imaging specialist, 30 people undergoing treatment
for manic depression, known as bipolar disorder, were selected for a
scanning experiment.
To make sure
it was the electromagnetic fields generated by the scanner
that were lifting spirits and not other aspects of patient treatment,
10 other patients underwent sham scans for comparison. Finally, to take
into account the placebo effect, 14 healthy people were scanned. (The
placebo effect causes people to feel better just because they are
getting medical attention.)
Twenty-three
people with bipolar depression (77 percent) felt better
after scanning than before it. Only three (30 percent) of those who
received sham scans said they felt better. Four of the healthy
comparisons (29 percent) reported that the scans elevated their moods.
Mood improvement
"It's
a small and preliminary study based on an accidental discovery,"
admits Cohen, who is also a professor of psychiatry at Harvard Medical
School. "But our results suggest that the electric fields produced
by
certain types of brain scans are associated with mood improvement in
people with bipolar disorder."
"We
were surprised at our good fortune in discovering this effect, and
we are excited about the initial findings," adds Rohan.
The next
step is do a larger study to answer such questions as how long
the effect lasts, and how such scans make bipolar people happy.
When asked
how long the effects of the happy machine lasted, some
people said hours, others, days. One woman said she felt better for a
week. Cohen says he hopes that a study that yields more definitive
results can begin as early as next month. Such experiments should
separate the effect of anti-depressant drugs taken by some of the
subjects.
The researchers
are intrigued by the fact that all of the
manic-depressives not on medication responded favorably, as opposed to
two-thirds of those taking drugs. Cohen doesn't know why, but he
speculates that "medication may reduce the sensitivity of brain cells
to the electromagnetic fields. If that turns out to be so, we may be
able to raise the intensity of the fields."
The type
of scan used is known as Echo-Planer Magnetic Resonance
Spectroscopic Imaging, or EP-MRSI. It uses low-intensity magnetic
fields to produce three-dimensional images of the brain's chemistry,
which reveal various abnormalities in its nerve-cell activity. The
specific timing and amplitude of the magnetic pulses induce electric
fields that may match the natural electrical firing rhythm of brain
cells, Rohan and Cohen speculate.
"The
pulses travel from right to left trough a thick cable of nerves
that coordinate activity between the two halves of the brain," Cohen
explains. The two halves perform different tasks; for example, the
right hemisphere is considered more involved in spatial processes like
map reading, while the left is more dedicated to logic and language in
many people. "In depression, the two halves of the brain may get
out of
balance, and the electromagnetic pulses may restore the balance,"
Cohen
says.
Head hits
of happiness
Researchers
at Harvard Medical School and elsewhere are experimenting
with another technique that uses electromagnetic pulses to treat
depression. Called transcranial magnetic stimulation, or TMS, it
involves holding a figure-of-eight-shaped wand near a person's head.
Two coils of wire on the wand generate a strong magnetic field that
induces electric currents in brain cells.
"We
believe that TMS works by normalizing disturbed levels of brain
activity," says Alvaro Pascual-Leone, an associate professor of
neurology at Harvard Medical School. In experiments at Beth Israel
Deaconess Medical Center in Boston, he and his colleagues lifted the
spirits of depressed patients who are resistant to anti-depressant
drugs.
"TMS
uses electric fields that are more localized and much stronger
than EP-MRSI," Cohen notes. "Some patients have reported feeling
discomfort and there is a some danger of causing seizures with TMS that
does not occur with our system. However, it may be that the two methods
use different techniques to achieve the same result."
Neither scanners
nor wands are ready for general use yet. If more
experiments show widespread effectiveness at relieving depression, the
electric fields may be better medicine than drugs. Anti-depressants can
have disturbing side effects, including fatigue, anxiety, loss of
libido, and increased blood pressure. They usually take weeks to work,
and sometimes they don't work at all. So far, the scanning technique
seems free of the side effects of drugs and TMS.
However,
brain scanners that fill a large room and cost a million
dollars or two are not a very practical alternative. McLean researchers
have begun working on the design of a smaller, much cheaper device. "We
plan to test a tabletop scanner in a study of a larger number of
patients," Rohan says. Someday, he speculates, patients may be able
to
get their depression eased during a 20-minute nap at a doctor's office.
Those not
suffering depression received as little benefit from scanning
as those who underwent a sham treatment, ruling out the possibility of
getting a quick hit of happiness at your doctor's office to brighten up
a bad day or prepare for a dreaded meeting.
SOURCE:
Harvard
Gazette
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