Quoted from link below:
Department of Anesthesiology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
Opioids are thought to worsen the performance of psychomotor tasks due to their sedating and mental-clouding effects. As a result, some safety regulations currently restrict the use of opioids when driving or using heavy equipment. We investigated the psychomotor effects of long-term opioid use in 144 patients with low back pain. All subjects were administered two neuropsychological tests (Digit Symbol and Trail Making Test-B) before being prescribed opioids for pain; tests were re-administered at 90- and 180-day intervals. Test scores significantly improved while subjects were taking opioids for pain, which suggests that long-term use of oxycodone with acetaminophen or transdermal fentanyl does not significantly impair cognitive ability or psychomotor function.