Older adults are prone to experiencing more frequent pain due to surgeries, age-associated diagnoses, and/or accumulated injury. Opioids are the most effective treatment for pain, but negative side effects and age-associated pharmacokinetic and pharmacodynamics changes limit their safe use in older adults. Endomorphins (EMs) are endogenous opioid ligands whose analogs show improved analgesic properties with fewer side effects. This study examines the antinociceptive properties and motor side effects of an EM analog at a high dose in young animals and in isolated (IH) and environmentally enriched (EE) housed older animals. Young mice given high doses of Morphine (MS) and EM analog experienced ¬equal antinociception, but when compared to vehicle animals the MS mice were significantly impaired on a test of motor coordination (rotarod) while the EM animals were not. In older animals, possible stress-induced analgesia (SIA) was observed in IH animals while not in EE animals. An overall main effect of housing was detected at p≤.0.05, and the effect of SIA began as soon as 7 days after housing assignment. Animals in IH or EE given an EM analog were statistically different at p≤0.01, while the difference between IH and EE animals given MS reached only p≤0.05. In older adults, participants who attended a day program with scheduled activities showed significant decreases from Time 1 to Time 2 in pain intensity and number of medications, and scores were trending toward significance pain control. By Time 2, patients attending the day program had significantly lower scores of pain intensity compared to adults who received in-home services only. Loneliness and isolation decreased in groups receiving either in-home services or attending the day program. In general, adults who increased services experienced the greatest decreases in pain and psychosocial variables. This study suggests that the response to EE is similar in both humans and rats and that a careful increase in stimulation is the best practice in activity planning for older adults. Policy requirements for EE in older adults residential and day facilities may positively impact the pain medication consumption in this growing population. / 1 / Penny Roberts