Researchers at Northwestern University's Feinberg School of Medicine have uncovered a clue that may explain how people dealing with long-term pain also suffer from other symptoms like sleep disorders, depression, anxiety and difficulty in making decisions.
The study led by Dante Chialvo, associate research professor of physiology at the Feinberg School, is the first demonstration of brain disturbances in chronic pain patients not directly related to the sensation of pain.
It was found that all the regions in a healthy brain exist in a state of equilibrium. While one region is active others automatically quiet down.
However, Chialvo said that in people with chronic pain, a front region of the cortex mostly associated with emotion "never shuts up. The areas that are affected fail to deactivate when they should."
They are fully stuck up and tire out the neurons by altering their connections to each other.
The researchers used functional magnetic resonance imaging (fMRI) to scan the brains of people with chronic low back pain and a group of pain-free volunteers while both groups were tracking a moving bar on a computer screen.
The results of this study demonstrated that those suffering from pain performed the task well but "at the expense of using their brain differently than the pain-free group," said Chialvo.
It was indicated that when certain parts of the cortex were activated in the pain-free group, some others were deactivated, in order to maintain a cooperative equilibrium between the regions. This equilibrium also is known as the resting state network of the brain.
However, the researchers indicated that in the chronic pain group, one of the nodes of this network did not quiet down unlike in the pain-free subjects. Chialvo said that this constant firing of neurons these regions of the brain coul eben lead to permanent damge.
"We know when neurons fire too much they may change their connections with other neurons and or even die because they can't sustain high activity for so long. If you are a chronic pain patient, you have pain 24 hours a day, seven days a week, every minute of your life. That permanent perception of pain in your brain makes these areas in your brain continuously active. This continuous dysfunction in the equilibrium of the brain can change the wiring forever and could hurt the brain," said Chialvo.
He also assumed that the subsequent changes in wiring "may make it harder for you to make a decision or be in a good mood to get up in the morning. It could be that pain produces depression and the other reported abnormalities because it disturbs the balance of the brain as a whole."
According to him the findings show that it is essential to study new approaches to treat patients not just to control their pain but also to assess and check the dysfunction that may be generated in the brain by the chronic pain.
The study is published in The Journal of Neuroscience.