Acute effects of opioids on memory functions of healthy men and women.
BACKGROUND
Although several psychotropic drugs can acutely induce an anterograde impairment of memory which impedes new learning, they do not produce retrograde impairments, reducing memory for information learned prior to the drug being administered. However, both anterograde and retrograde memory impairments have been reported following an acute dose of morphine in palliative care patients (Kamboj et al., Pain 117:388-395, 2005).


OBJECTIVE
The present study was designed to determine: (1) whether similar amnestic effects would be found after a single oral dose of either morphine or oxycodone in healthy volunteers, (2) how generalisable such effects were across a broader range of memory tasks and (3) whether men and women showed a differential response.


METHODS
A double-blind, placebo-controlled crossover design was used with 18 participants (nine men, nine women) who were administered 10 mg morphine, 5 mg oxycodone and placebo on three separate test days.


RESULTS
On a working memory task, subtle impairments were found in women following both opioids whilst in men only following morphine. On an episodic memory task, women made significantly more source attribution errors after oxycodone and men made more after placebo. Most gender differences were weight related and a range of other measures showed no drug-induced impairments.


CONCLUSIONS
We conclude that these standard doses of opioids have only marginal effects on memory. If these findings can be extrapolated to patients with pain, then clinicians can feel confident in prescribing them on an outpatient basis without impacting on patients' daily functioning.
Friswell
James
J
Clinical Psychopharmacology Unit, Clinical Health Psychology, University College London, Gower St, London WC1E 6BT, UK.
Phillips
Caroline
C
Holding
James
J
Morgan
Celia J A
CJ
Brandner
Brigitta
B
Curran
H Valerie
HV
D000328:Adult; D000339:Affect / Q000187:drug effects; D000701:Analgesics, Opioid / Q000494:pharmacology*; D003071:Cognition / Q000187:drug effects; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000187:drug effects*; D008570:Memory, Short-Term / Q000187:drug effects; D011939:Mental Recall / Q000187:drug effects; D009483:Neuropsychological Tests; D012727:Sex Characteristics
D000701:Analgesics, Opioid