[Impact of age on pain perception and analgesic pharmacology]

INFLUENCE OF AGING ON PAIN: Although pain affects a large majority of the elderly population living in the community and in institutions, our knowledge of the evolution of pain experience with age is poor. Results of clinical surveys and experimental pain studies are contradictory, showing no change, an increase, or a decrease of pain with age. Many results suggest a decrease of pain perception with age that could be explained by peripheral and central neuroanatomical aging and psychological changes of the aging patient towards pain.Biological aging added to multiple pathologies and polymedication explains the pharmacological changes of analgesics. Among pharmacokinetic changes that are globally well known, vigilance must focus on renal excretion of analgesics and their metabolites and on the increased risk of side-effects and drug interactions. Information on pharmacodynamic changes of analgesics are scarce in aging patients who are susceptible to drugs and which demographical trend increases.A better fundamental knowledge of the evolution of pain with age could help to improve care in the elderly with pain, especially in very old subjects with cognitive impairment and loss of communication skills, where pain evaluation is particularly difficult. Also, more research is needed on the pharmacodynamics of analgesics in older subjects, with a view of a decreased iatrogenic risk, a better pain treatment and quality of life of the elderly.