The happy force: Researchers have discovered – by accident – that electroma=
gnetic
fields produced during some MRI scans can cheer manic depressives. ANJANA A=
HUJA
reports

SQUEEZING yourself into a narrow, dark metal tube and lying still for 20 m=
inutes is
not a fun thing to do. So Dr Michael Rohan, an imaging physicist at McLean =
Hospital,
a psychiatric facility in Massachusetts attached to Harvard Medical School,=
was
surprised when some patients emerged from their magnetic resonance imaging =
scans
feeling happier than when they went in.
What made it especially astonishing was that these were individuals with b=
ipolar
disorder, or manic depression. "It was not a subtle effect," Rohan says. "I=
t was very
marked and totally unexpected."
Nor was the effect peculiar to just a few patients, who were supposed to b=
e helping
McLean researchers study the effect of different antidepressants on the bra=
in. Of 30
patients with the disorder, 23 felt better after the scan than before, alth=
ough one felt
worse. The scans made no difference, however, to the spirits of healthy vol=
unteers.
Rohan and his colleague, Perry Renshaw, professor of psychiatry, were so s=
truck by
the serendipitous observations that they published them in the American Jou=
rnal of
Psychiatry. The report raises the possibility that the particular scanner u=
sed at the
hospital at that time produces a pulsing, low-level electromagnetic field t=
hat interacts
with brain cells.
During 10 years and 10,000 MRI scans at McLean, such an effect had never b=
een
seen. Rohan guessed it must have been the unusual fields generated by that =
scanning
tube. Whatever the interaction is, it appears to improve mood in bipolar pa=
tients.
Rohan explains that the beneficial effect comes not from the scanner's main=
magnet
but instead from the much gentler fields that are switched on and off rapid=
ly to
produce the scan pictures.
To see whether it was an aberration or not, the McLean team developed a he=
adset
mimicking this gently oscillating field and tested it on depressed rats. Th=
e results
were spectacular. "It was comparable to giving them Prozac," Rohan reveals.=
"We
don't know anything about how long these effects last. A couple of our pati=
ents rang
us a week after their scans saying they still felt well."
Rohan also gave some patients "sham" scans to see if the patients' new-fou=
nd
joviality was just a placebo effect – while three out of 10 patients did re=
port mood
improvement, those receiving genuine scans showed bigger improvements.
There's a precedent for the use of electromagnetic fields to improve mood.=

Electroconvulsive therapy – or shock treatment – has a controversial histor=
y, although
more refined and effective modern techniques that don't cause seizures and =
tongue-
biting have brought about a quiet renaissance.
Another therapy, repetitive transcranial magnetic stimulation, involves ho=
lding an
electromagnetic coil against the scalp. Up to half of those undergoing rTMS=
, a
relatively experimental therapy, are said to benefit (although its effectiv=
eness is under
debate), but the intense field means it can be painful. As a result, it ten=
ds to be used
only on patients with severe depression who fail to get better with medicat=
ion. The
fields used in the McLean experiments are 200 times weaker than those used =
in rTMS
and cannot be felt.
All of these techniques exploit the fact that brain cells, or neurons, res=
pond to
electrical and chemical stimulation. Depression, along with other brain dis=
orders, is
often thought of as a malfunction in the human brain's unimaginably complex=

circuitry.
However, there are many reasons why Rohan remains cautious. The accidental=

observations were made during a study involving patients who were switching=

medicines, introducing an unfortunate variability among subjects. Apart fro=
m the two
delighted patients who rang Rohan's department days later, the researchers =
do not
know how persistent the benefits are.
The effect also varied among patient groups – the unmedicated patients all=
felt
better, with a 100 per cent response rate. Among those taking drugs for the=
ir
depression, 63 per cent felt better. Overall, 77 per cent reported mood imp=
rovement.
Why the discrepancy between medicated and unmedicated volunteers? "That's a=

tough question," Rohan says. "Maybe patients who are unmedicated have a dif=
ferent
degree of bipolar disorder. Maybe these techniques work better in people wh=
o are not
on medication. Or perhaps those on medication were less depressed, and so f=
elt less
of an effect. In future studies we plan to separate these groups out."
Most importantly, the mechanism by which these fields are boosting mood re=
mains
mysterious. Rohan suggests two possibilities. The first concerns the freque=
ncy of the
electromagnetic field. Its pulse-rate is 1 kHZ (which means it pulses or os=
cillates
1,000 times per second). That matches the rate at which neurons, or brain c=
ells, fire.
The second possibility is that pulses affect the bundle of nerves called t=
he corpus
collosum, which connects the left and right hemispheres of the brain: "When=
we look
at the big picture in depression, we find there's a laterality. Very genera=
lly speaking,
you get a difference (in activity) between hemispheres that you don't see i=
n healthy
people. The corpus collosum is the only connection between the two hemisphe=
res, so
perhaps the fields are working on that.
"We'll be looking at all of these things in future studies. I'm very excit=
ed but I'm
trying to be guarded... So often you first see an effect at the molecular l=
evel, then in a
piece of tissue in the laboratory and then in animal experiments. Only then=
do you try
it out on patients. But we've seen it in patients right off the bat."

— The Times, London.

http://www.thestatesman.net/page.news.php?clid=4&theme=&usrsess=1&id=38540