Editing Morphine (section)

=== Effects on human performance ===
Most reviews conclude that opioids produce minimal impairment of human performance on tests of sensory, motor, or attentional abilities. However, recent studies have been able to show some impairments caused by morphine, which is not surprising, given that morphine is a [[central nervous system]] [[depressant]]. Morphine has resulted in impaired functioning on critical flicker frequency (a measure of overall CNS arousal) and impaired performance on the [[Maddox wing]] test (a measure of the deviation of the visual axes of the eyes). Few studies have investigated the effects of morphine on motor abilities; a high dose of morphine can impair finger tapping and the ability to maintain a low constant level of [[isometric exercise|isometric force]] (i.e. fine motor control is impaired),<ref name="pmid1755931">{{cite journal | vauthors = Kerr B, Hill H, Coda B, Calogero M, Chapman CR, Hunt E, Buffington V, Mackie A | title = Concentration-related effects of morphine on cognition and motor control in human subjects | journal = Neuropsychopharmacology | volume = 5 | issue = 3 | pages = 157–66 | date = November 1991 | pmid = 1755931 }}</ref> though no studies have shown a correlation between morphine and gross motor abilities.

In terms of [[cognitive]] abilities, one study has shown that morphine may negatively impact [[anterograde amnesia|anterograde]] and [[retrograde amnesia|retrograde memory]],<ref>{{cite journal | vauthors = Friswell J, Phillips C, Holding J, Morgan CJ, Brandner B, Curran HV | title = Acute effects of opioids on memory functions of healthy men and women | journal = Psychopharmacology | volume = 198 | issue = 2 | pages = 243–50 | date = June 2008 | pmid = 18379759 | doi = 10.1007/s00213-008-1123-x | s2cid = 2126631 }}</ref> but these effects are minimal and transient. Overall, it seems that acute doses of opioids in non-tolerant subjects produce minor effects in some sensory and motor abilities, and perhaps also in [[attention]] and cognition. The effects of morphine will likely be more pronounced in opioid-naive subjects than in chronic opioid users.

In chronic opioid users, such as those on Chronic Opioid Analgesic Therapy (COAT) for managing severe, [[chronic pain]], behavioural testing has shown normal functioning on perception, cognition, coordination, and behaviour in most cases. One 2000 study<ref>{{cite journal | vauthors = Galski T, Williams JB, Ehle HT | title = Effects of opioids on driving ability | journal = Journal of Pain and Symptom Management | volume = 19 | issue = 3 | pages = 200–8 | date = March 2000 | pmid = 10760625 | doi = 10.1016/S0885-3924(99)00158-X | doi-access = free }}</ref> analysed COAT patients to determine whether they were able to safely operate a motor vehicle. The findings from this study suggest that stable opioid use does not significantly impair abilities inherent in driving (this includes physical, cognitive, and perceptual skills). COAT patients showed rapid completion of tasks that require the speed of responding for successful performance (e.g., [[Rey Complex Figure]] Test) but made more errors than controls. COAT patients showed no deficits in visual-spatial perception and organization (as shown in the [[Wechsler Adult Intelligence Scale|WAIS-R]] Block Design Test) but did show impaired immediate and short-term visual memory (as shown on the Rey Complex Figure Test&nbsp;– Recall). These patients showed no impairments in higher-order cognitive abilities (i.e., planning). COAT patients appeared to have difficulty following instructions and showed a propensity toward impulsive behaviour, yet this did not reach statistical significance. It is important to note that this study reveals that COAT patients have no domain-specific deficits, which supports the notion that chronic opioid use has minor effects on [[Psychomotor learning|psychomotor]], [[cognitive]], or [[neuropsychological]] functioning.