What Are The Causes Of Chronic Pain? Is It All In The Mind?

We have all expereinced pain at some stage in our lives and anticipate pain as a consequence of injury. Despite this anticipation though we expect that with healing and time, pain will resolve. However, an acute pain (a normal sensation that alerts us to possible injury) can persist for many months and years, becoming chronic (lasting longer than twelve week) in its nature; a prospect difficult for many of us to imagine.

Dr Sylvia Gustin, a Senior Research Fellow at the UNSW School of Psychology, conducts research into the central and psychological circuits underlying chronic pain in humans. She has found that through her studies, people who suffer from chronic pain often don't understand why they still have ongoing pain, even after their injury has healed. Some of these sufferers asked Sylvia if there is a "pain circuit" within our body, particularly in the brain, where pain is generated. One of Sylvia's chronic pain patients actually quipped: "If you tell me where the pain hub is I will go to a surgeon and let them cut it out". Unfortunately, there is no simple answer as multiple factors play a role in the development and maintenance of chronic pain. However, there is interesting work published which suggests that the causes of chronic pain may be maintained by alterations in the brain.

Older theories about the causes of chronic pain focused on the periphery (e.g. damage in a body part) or on the processing of nociception (signals from the periphery that signal damage or the potential of damage) at the level of the spinal cord. There now is consistent and compelling evidence that treatments based on these theories are not effective at reducing pain. Central brain processes are now recognised to play a key role in the experience of pain.

Dr Sylvia Gustin and her team of researchers at UNSW School of Psychology have been at the forefront of discovering the critical role of the brain in the development and maintenance of chronic neuropathic pain. They have showed that chronic neuropathic pain is associated with altered thalamic anatomy, biochemistry and activity which can disturb central processing and play a key role in the persistent experience of ongoing pain. Their research showed that inhibitory brain cells (which are normally blocking out pain) within the thalamus may have reduced functioning in individuals with ongoing pain. As a result the amount of chief inhibitory messenger of neurologic information from one cell to another, i.e. GABA, is decreased. This loss of inhibition may mean that the brain itself is altered which results in brain activity changes that are then perceived as pain. So the brain might have lost its ability to inhibit sensory information, is more sensitive and pain and sensory signals are amplified and result in the experience of chronic pain.

In another study, the team also found a decrease in GABA in the prefrontal cortex in people with chronic neuropathic pain. The prefrontal cortex is know to be involved in emotional processing. This decrease in GABA (which represents a loss of inhibition) might explain why people with chronic pain suffer additionally from emotional disorders such as anxiety and depression. A loss of inhibition within the prefrontal cortex might mean that people with chronic pain can't stop thinking about their pain and constantly anticipate pain with pessimistic, negative and fearful thoughts. They can't stop these ruminations as the prefrontal cortex lost parts of its ability to inhibit these thoughts.

In a new study, Dr Sylvia Gustin's team would like to target these brain alterations using a neuromodulatory approach that can provide pain relief via the primary source of pain: the human brain. They would like to modulate these functional, structural and biochemical changes via electroencephalography based neurofeedback which may lead to significant and sustained pain reduction. Neurofeedback teaches individuals to gain control over their brain states via electroencephalography biofeedback.

If you would like to find out more about Dr Sylvia Gustin's research into the causes of chronic pain, you can listen or view the following:

Pain on the brain - All In The Mind: ABC Radio

What chronic pain does to your brain - All In The Mind: ABC Radio

Catalyst - When pain persists: ABC TV Science

Visit Dr Sylvia Gustin's Pain Imaging Laborartory: www.gustinpil.com