HEALTH NEWS

Study Title:

Back Pain and Cognitive Impairment

Study Abstract

Chronic pain is associated with reduced brain gray matter and impaired cognitive ability. In this longitudinal study, we assessed whether neuroanatomical and functional abnormalities were reversible and dependent on treatment outcomes. We acquired MRI scans from chronic low back pain (CLBP) patients before (n = 18) and 6 months after (spine surgery or facet joint injections; n = 14) treatment. In addition, we scanned 16 healthy controls, 10 of which returned 6 months after the first visit. We performed cortical thickness analysis on structural MRI scans, and subjects performed a cognitive task during the functional MRI. We compared patients and controls, as well as patients before versus after treatment. After treatment, patients had increased cortical thickness in the left dorsolateral prefrontal cortex (DLPFC), which was thinner before treatment compared with controls. Increased DLPFC thickness correlated with the reduction of both pain and physical disability. Additionally, increased thickness in primary motor cortex was associated specifically with reduced physical disability, and right anterior insula was associated specifically with reduced pain. Left DLPFC activity during an attention-demanding cognitive task was abnormal before treatment, but normalized following treatment. These data indicate that functional and structural brain abnormalities—specifically in the left DLPFC—are reversible, suggesting that treating chronic pain can restore normal brain function in humans.

From press release:

It likely comes as no surprise that low back pain is the most common form of chronic pain among adults. Lesser known is the fact that those withchronic pain also experience cognitive impairments and reduced gray matter in parts of the brain associated with pain processing and the emotional components of pain, like depression and anxiety.

In a longitudinal study published this week in the Journal of Neuroscience, a group of pain researchers from McGill University and the McGill University Health Centre (MUHC) posed a fundamental question: If you can alleviate chronic low back pain, can you reverse these changes in the brain?

The answer is yes, they say.

The team began by recruiting, through the Orthopedic Spine Clinic and the Alan Edwards Pain Management Unit at the MUHC, patients who have had low back pain for more than six months and who planned on undergoing treatment -- either spinal injections or spinal surgery -- to alleviate their pain. MRI scans were conducted on each subject before and six months after their procedures. The scans measured the cortical thickness of the brain and brain activity when the subjects where asked to perform a simple cognitive task.

"When they came back in, we wanted to know whether their pain had lessened and whether their daily lives had improved," said the study's senior author, Laura S. Stone from McGill's Alan Edwards Centre for Research on Pain. "We wanted to see if any of the pain-related abnormalities found initially in the brain had at least slowed down or been partially reversed."

Not only did the team observe recovery in the anatomical function of the brain, but also in its ability to function. After the subjects were treated, researchers found increased cortical thickness in specific areas of the brain that were related to both pain reduction and physical disability. And the abnormal brain activity observed initially during an attention-demanding cognitive task was found to have normalized after treatment.

While more research would be needed to confirm whether chronic pain actually causes these changes in the brain, Stone hypothesizes that chronic low back pain, at the very least, maintains these differences.

"If you can make the pain go away with effective treatment," she added, "you can reverse these abnormal changes in the brain."

Study Information

D. A. Seminowicz, T. H. Wideman, L. Naso, Z. Hatami-Khoroushahi, S. Fallatah, M. A. Ware, P. Jarzem, M. C. Bushnell, Y. Shir, J. A. Ouellet, L. S. Stone.
Effective Treatment of Chronic Low Back Pain in Humans Reverses Abnormal Brain Anatomy and Function.
Journal of Neuroscience
2011 May
McGill University Health Centre, Montreal, Quebec H3G 1A4, Canada.