A Review of the Effects of Opioids on Psychomotor and Cognitive Functioning in Humans

The literature on the effects of opioids on psychomotor and cognitive functioning in humans is evaluated. Some studies have examined the acute and chronic effects of various opioids on different subject populations. In addition, epidemiologic studies have examined the neuropsychological functioning and the risk of accidents for persons who have (or have had) opioids in their systemic circulation. In general, it appears that some opioids (mixed agonist-antagonists) more than others (morphine or codeine) impair psychomotor and cognitive functioning in healthy volunteers who have no history of opioid abuse. However, perhaps because of tolerance mechanisms, those who use opioids occasionally or habitually (patients with chronic pain or opioid abusers) are much less likely to have impairment of psychomotor or cognitive processes by opioids. Past research and present gaps in knowledge are used to make recommendations regarding worthwhile future directions in research.