Chronic
pain seen altering how brain works
Brain scans of people in
chronic pain show a state of constant activity in areas that should be at rest,
They
said chronic pain seems to alter the way people process information that is
unrelated to pain.
"It
seems that enduring pain for a long time affects brain function in response to
even minimally demanding attention tasks completely unrelated to pain," the
researchers wrote in the Journal of Neuroscience.
Dante
Chialvo, a researcher at Northwestern University in Chicago who
worked on the study, said: "People with chronic pain -- meaning pain that
lasts more than six months after their injury -- have many other issues that
affect their quality of life as much as pain. It is not known where they come
from."
Recent
studies have shown that in healthy people, certain regions of the brain take
over during a resting state, something known as a default mode network.
"It takes care of your brain when your brain is at rest," Chialvo
said in a telephone interview.
When a
person performs a task, this network quiets down, he said, but not in people
with chronic pain.
Instead,
a front region of the cortex mostly associated with emotion is constantly
active, disrupting the normal equilibrium.
To
study this activity, Chialvo did a type of brain scan known as functional
magnetic resonance imaging on 15 people with chronic back pain and 15 healthy
people.
They
gave their volunteers a simple attention task -- tracking a moving bar on a
computer screen -- to observe the brain shifting out of default mode to handle
the task.
Both
groups performed the task well but when they measured areas of the brain
activated, differences emerged.
"Where
we were surprised is the difference in how much brain they used to do the task
compared with the healthy group. It was 50 times larger," Chialvo said.
They
said disruptions in this default network could explain why pain patients have
problems with attention, sleep disturbances and even depression.
"These
findings suggest that the brain of a chronic pain patient is not
simply a healthy brain processing pain information but rather it is altered by
the persistent pain in a manner reminiscent of other neurological conditions
associated with cognitive impairments," they wrote.