Genetic and hormonal basis of pain states

Among the many sources of variability in human pain and analgesic responses are influences intrinsic to the organism—genetic and hormonal factors that contribute to individual differences. This chapter serves as a review of the clinical and experimental evidence that highlights the importance of these factors in effectively understanding clinical pain states and variability in pain and analgesic responses. Epidemiological and linkage studies have been carried out in humans, and observational studies of variability in pain and analgesic responses across genders and within the menstrual cycle provide a much needed human perspective. However, the experimental approach, with its inherent explanatory power, contributes much of the knowledge in this area. Much of the basic experimental work in this area is in its early stages, but it suggests the potential for using these factors to tailor pain treatment to the individual.