Mind and Life Institute
Medical Research Council
University of Manchester
At the University of Manchester, we used EEG to monitor brain states during the anticipation of pain. We found that expectations change how the brain anticipates and experiences pain. Negative expectations appear to exert their effect on increasing pain via a mechanism within a brain region that is known to be involved in sensing the body and feeling emotions, the anterior insular cortex. Using these mechanisms, the brain can reduce or increase how bad pain feels when individuals are given false information that a treatment might make their pain better or worse – which we've also studied in terms of placebo and nocebo effects.
We also found that the insula cortex is more active in some patients with chronic pain such as those with fibromyalgia, but are also linked to pain symptoms in patients with arthritis. However, this brain area may not be the only contributor to the mental suffering of chronic pain; we also found that the prefrontal cortex, an important brain area in regulating our mental and emotional life, is less responsive when anticipating pain in patients with chronic pain who are suffering the most. We think this lack of response may put patients at risk of chronic pain and especially psychological distress, because we found the lower response here to be related to anxiety and catastrophically negative thoughts about pain. More recently, we investigated individuals who “catastrophise” about pain in more depth, finding that their brains are particularly over-responsive to cues in the environment that help them to predict pain, pointing to the possibility that this negative mental state might be linked to brain mechanisms supporting learning-by-association (i.e. learning that certain cues predict pain). At the University of Liverpool we are taking this research forward by further investigating these learning processes.
Further research at the University of Manchester studied how the brain can be better optimised towards pain resilience and well-being by studying individuals who have trained in mindfulness meditation. We found that mindfulness training has the effect of improving the response of the prefrontal cortex during anticipation of pain (which was linked to an improvement in perceived control over pain), after patients with chronic pain underwent an 8-week mindfulness training programme. Studying people with many years of experience with mindfulness meditation, we found that these individuals are able prevent the activation of certain areas of the brain that we know contributes to the emotional suffering of pain, namely the mid-cingulate cortex. This work points to potential targets in the brain to focus the development of new neurotherapies.
At the Wolfson Molecular Imaging Centre, we have performed complex and demanding neuroimaging research using Positron Emission Tomography (PET) scans in patients with chronic pain to find out what neuro-chemistry might make them more vulnerable or more resilient to pain. We studied the brain’s natural opioid system, whose neurotransmitters (opiates) have a profound effect on diminishing pain. We found that patients with chronic arthritis pain who have recently experienced the worst pain have actually increased numbers of opioid receptors in the brain. Such a finding might suggest that the brain naturally increases opioid receptors in the brain when the pain is worse, in order to act as a natural “break” to maintain homeostasis (i.e. avoiding physiologically extreme states that are intolerable). Consistent with this idea, we found that people with more opioid receptors in the brain had a greater pain threshold (meaning decreased pain sensitivity). I wrote about this work and its implications in a recent blog post.