Dr. King has contributed to science by looking at psychological and group-level (i.e., subgrouping of patients) factors underlying analgesic responses to opioid analgesics in healthy adults, opioid regulation of conditioned pain modulation (CPM), and ethnic differences in experimental pain sensitivity, clinical pain, and pain-related disability in patients with knee osteoarthritis (OA). CPM is used to look at the modulatory capacity in humans. It is reduce in chronic pain and older age. Reduction of CPM may contribute to pain and alter somatosensory processing and autonomic regulation. As part of the OA study, Dr. King also examined predictors of knee pain prospectively. Lastly, Dr. King has been involved in several independent studies exploring possible stress-related markers associated with cold pain, which is used as the conditioning stimulus in CPM. He has shown that pain induces the release of endocrine and immune markers, and that they can influence pain responsiveness in pain-free subjects.
Dr. King recently finished a study with naltrexone, an opioid antagonist, on pain modulation, which revealed an interesting interaction between the ability to inhibit pain through endogenous opioids and psychological functioning in pain-free subjects. The recent studies are a first step in a process to evaluate physiological responses induced by pain.