Effects of lorazepam and oxazepam on perceptual and procedural memory functions.
BACKGROUND
Lorazepam has been found to consistently impair performance on both episodic and perceptual priming tasks, whereas other benzodiazepines have shown perceptual priming to be preserved. However, it has recently been postulated that benzodiazepines may exert time-dependent effects on implicit memory processes after research findings indicated some benzodiazepines, other than lorazepam, impair performance on priming tasks when tested at the time of peak plasma concentration level after benzodiazepine administration.


OBJECTIVE
To compare time-dependent effects of lorazepam and oxazepam on implicit memory tasks, specifically perceptual priming and procedural learning.


METHODS
Thirty-three healthy female undergraduates were randomised to one of three time groups (pre-peak, peak, post-peak) and administered placebo, 2.5 mg lorazepam, and 30 mg oxazepam, in counterbalanced order, at 1-week intervals. Assessments included word-stem completion (perceptual priming) and rotary pursuit (procedural learning) tasks.


RESULTS
At all time intervals, lorazepam but not oxazepam significantly impaired perceptual priming but procedural learning was preserved under both drugs.


CONCLUSIONS
These findings are consistent with previous research showing a differential effect of lorazepam in impairing perceptual memory but the notion that benzodiazepines exert time-dependent effects on implicit memory processes was not supported.
Martin
Janine
J
School of Psychology, University of Tasmania, GPO Box 252-30, Hobart, Tasmania 7001, Australia. Janine.Martin@utas.edu.au
Matthews
Allison
A
Martin
Frances
F
Kirkby
Kenneth C
KC
Alexander
James
J
Daniels
Brett
B
D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D014151:Anti-Anxiety Agents / Q000494:pharmacology*; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007858:Learning / Q000187:drug effects; D008140:Lorazepam / Q000097:blood / Q000494:pharmacology*; D008570:Memory, Short-Term / Q000187:drug effects*; D011939:Mental Recall / Q000187:drug effects; D010076:Oxazepam / Q000097:blood / Q000494:pharmacology*; D010147:Pain Measurement / Q000187:drug effects; D010465:Perception / Q000187:drug effects*; D011581:Psychological Tests; D011597:Psychomotor Performance / Q000187:drug effects*; D011930:Reaction Time / Q000187:drug effects; D013831:Thiamine / Q000494:pharmacology
D014151:Anti-Anxiety Agents; D010076:Oxazepam; D008140:Lorazepam; D013831:Thiamine