Can chronic pain shrink your brain?

I see a lot of patients who are referred for a neuropsychological evaluation due to memory complaints who also have chronic pain. Often the medications used to treat pain result in a litany of cognitive complaints so these referrals are not surprising.

The Journal of Neuroscience (May 18, 2011) recently published the results of an interesting study that found treatment of chronic lower back pain actually lead to an improvement in cognition.

According to researchers, chronic pain is often associated with a reduction in the amount of gray matter in the brain, resulting in cognitive problems. Gray matter or "the little gray cells" as Hercule Poirot is fond of saying, are responsible for the transmission of sensory signals in the brain. The more gray matter a person has, the more intelligent they are said to be. A reduction in gray matter, then, leads to a reduction in cognitive ability.

Researchers found that treating lower back pain lead to an increase in the thickness in the cortex (outer layer) of the dorsolateral prefrontal cortex (DLPFC) which in turn lead to a improvement in a patient's attentional skills. Since attention is the first step in memory  -- you have to be able to pay sufficient attention to something you want to remember -- an attention deficit can feel like a memory problem.  By increasing the cortical thickness of the DLPFC, clinicians were able to show an improvement in a person's overall brain function.  In addition, patient's also had less pain and physical disability than before the treatment!