Zolpidem and memory: a study using the process-dissociation procedure.
BACKGROUND
There is a dearth of studies which have employed sophisticated paradigms to investigate the effects of zolpidem on memory.


OBJECTIVE
To explore anterograde cognitive deficits induced by acute oral doses of zolpidem by means of the process-dissociation procedure (PDP).


METHODS
The present study followed a placebo-controlled, double-blind, parallel-group design. Young, healthy females were randomly allocated to one of three treatments with 12 subjects each: placebo, 5 mg and 10 mg zolpidem. Two word-stem completion tasks were carried out close to theoretical peak-plasma concentration: a) direct inclusion task with cued recall, in which participants had to try to use words seen at study to complete stems; and b) direct exclusion task, in which words seen at study were to be avoided as completions. The PDP was applied to the results in these tasks to yield indices of explicit/controlled (C) and implicit/automatic (A) memory. Classical psychometric tests were also carried out.


RESULTS
Zolpidem 10 mg led to cognitive effects similar to benzodiazepines (except for the atypical lorazepam), including impairment of exclusion, but not inclusion-task performance. Results of the application of the PDP were inconclusive but concurred with the pattern established in previously published work on benzodiazepine effects, i.e. that zolpidem (10 mg) impaired C.


CONCLUSIONS
Zolpidem leads to cognitive effects similar to most benzodiazepines. Although the application of PDP in drug studies may be counterproductive in view of methodological difficulties that are discussed, the pattern of effects on the stem-completion tasks involved in this paradigm is potentially useful in the investigation of cognitive effects of psychoactive drugs.
Departamento de Psicobiologia, UNIFESP, 925 R. Napoleão de Barros, CEP 04024-002 São Paulo, Brazil.
S
S
Pompéia
L M
LM
Lucchesi
O F A
OF
Bueno
G M
GM
Manzano
S
S
Tufik
D000284:Administration, Oral; D000328:Adult; D000704:Analysis of Variance; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D018755:GABA Agonists / Q000009:adverse effects*; D006801:Humans; D008569:Memory Disorders / Q000139:chemically induced* / Q000503:physiopathology; D011939:Mental Recall / Q000187:drug effects; D010147:Pain Measurement / Q000379:methods; D011594:Psychometrics / Q000379:methods; D011725:Pyridines / Q000009:adverse effects*; D013647:Task Performance and Analysis; D014706:Verbal Learning / Q000187:drug effects; D000077334:Zolpidem
D018755:GABA Agonists; D011725:Pyridines; D000077334:Zolpidem