Human Brain Adaptation to Chronic Pain and Its Effects on Opioid Use

The prevalence of chronic pain is very high in the US at approximately 30%. More than 10% of adults report having daily pain. Opioid pain medications [such as morphine] are prescribed for some pain conditions and, since they are very addictive, they can be used inappropriately and abused, to the point of causing overdose and death. This is currently a significant problem in the US and worldwide. Research on changes in the brain that cause addiction in pain patients is complicated, also because it is difficult to separate the effect of the drugs that cause addiction from the direct effect of pain on the brain. Studies in animals have found that pain per se can change the brain in ways that increase the risk of becoming addicted to pain medications. Therefore, we think that patients who have chronic pain and are prescribed opioid pain medications to treat surgery-related pain after surgery, although they never took opioids for a long time in their life, may be at increased risk of using too much opioid medications, and using opioids for a longer time than expected to treat their surgical pain.

The purpose of this study is to determine if the research results obtained in animal models of pain (that show that being in pain for some time increases opioid use beyond what is expected to treat the current pain) also apply to patients with chronic pain.

For our study we are looking to recruit patients scheduled for abdominal surgery at Barnes Jewish Hospital. If eligible and enrolled, subjects will undergo sensory testing (a test of the sensitivity of the skin to hot and cold temperature and pressure) and complete questionnaires about their experience with pain, anxiety, depression and risk of substance abuse. They will also have a one-time blood draw for genetic testing, to look for a particular gene that is potentially associated with how we respond to pain medications and, potentially, with increased risk for addiction. After the surgery, patients will be assessed by the research team on day 1, week 1, week 4, week 8, and after 6 months with similar questionnaires to those that were completed pre-surgery. Patient satisfaction with their pre-surgical and post-surgical pain control will also be assessed by questionnaire.