As reported in the Scientific American’s article “How Chronic Pain Affects Memory and Mood,” researchers from Northwestern University have found a possible cause for the fuzzy thinking, memory problems, anxiety and depression that so many people with long-term pain endure. The culprit may lie with an impaired hippocampus.
Many of our clients are in chronic pain due to an objectively identifiable cause. However, along with the pain, they often complain about a change in their cognitive abilities and their personality. These subjective changes have a circumstantial connection to their pain. These additional complaints are often dismissed by insurance companies in deciding claims because there is no definitive link to the pain. That lack of a connection may be changing.
Using brain scans from people suffering from chronic back pain or Complex Regional Pain Syndrome (formerly known as RSD), researchers found these people had smaller hippocampus than healthy people. As reported in the Journal of Neuroscience, the researchers then began to study mice in an effort to obtain clues about how this part of the brain might impact the side effects experience by people suffering from chronic pain. It turned out those mice with chronic pain displayed greater anxiety like behaviors than normal mice. They also had disruptions in the functioning of their hippocampus. What was stated to be the most striking finding was that the mice in chronic pain had stopped producing new neurons in the hippocampus. Because the hippocampus is one of the few brain areas where new neurons can grow, this lack of growth may explain the smaller sized hippocampus in chronic pain sufferers.
Lead researcher A. Vania Apkarian suspects that the size difference seen in human’s hippocampus may reflect the lack of neuron growth and other problems seen in the mice. The hypothesis is that without new neurons forming, memory and emotional processes would become impaired. Apkarian says that this research underscores the importance of treating the suffering caused by chronic pain as a brain-based disorder in addition to trying to treat the source in the body.